3 EEE-09-10-1 seml

3/4 EEE Ramappa Engineering College

1.1 DEPARTMENT PROFILE

The Department of Electrical & Electronics Engineering has been in existence since 2002. Present intake of the department is 60 in the UG level and 18 in the M.Tech (High Voltage Engineering and Control Systems) course.

Two batches of students have successfully completed their graduation.

The pass percentage in 2004-05 was 93% with 39 first classes.The pass percentage in 2005-06 was 90% with 22 first classes.The pass percentage in 2006-07 was 50% with 8 first classes.The pass percentage in 2007-08 was 50% with 12 first classes.

The Department has 1 Asst. Professor, 1 Senior Lecturer and 07 Lecturers as on date. The Department is recognized by dedicated teachers, devoted students, committed supporting staff and expert technical staff.

STAFF

A total of 9 faculty members and 3 technical staff are committed for the development of the department. In addition to the departmental load, the department offer 6 theory courses and 4 lab courses as service subjects on an average per semester.

Some of the faculty members have improved their qualifications during the recent past.

STUDENTS ACHIVEMENTS:

The students of EEE department are the most studious and devoted toward studies.

In addition, about 55 students excelled in GATE Examination by securing more than 91 percentile.

2003 Batch ------- 6 Students qualified in GATE2002 Batch ------- 5 Students qualified in GATE

PAPER PRESENTATION

The following students have participated in the paper presentation competition held at various colleges.

1. “Energy Conversion Techniques” held in the Month of October at Jayamukhi Institute of Technical Sciences, NarsampeParticipants : Surender. Ch. and Akshay (06’ Batch)

2. “HVDC” held in the Month of November at Vidyabharathi Institute of Technical Sciences, JangaonParticipants : Usha Rani and Rama Krishna.G (06’ Batch)

3. “Convertion of energy” held in the Month of November at BITS college.Participants: Naresh, Sudheer (03’ batch)

4. “HVDC” systems held in the month of October at KITS college.Participants: Noorullah, Sudheer (03’ batch)

5. “Fuse blown & overload” data transmitter of a distribution T/F’, held in the month of March at NIT, Warangal.Participants: Noorullah, Sudheer, Naresh Secured 1st Prize (03’ batch)

6. “Breakdown of user indication” held in the month of February at OU, Hyderabad.Participants: Sudheer, NareshSecured 2nd Prize (03’ batch)

7. “VSLI Design” embedded systems, held in the month of March.

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BITS Pilani – All India Level.Participants: Sudheer (03’ batch)

8. “Urban Electrical Development”, held on 2nd June, at NIT, Warangal.Participants: Shiva Shanker Reddy (02’ batch)

9. “Advanced Control Systems”, held on 2nd June, at NIT, WarangalParticipants: M. Venkatesh (02’ batch)

10. “An efficient scheme for rural electrification”, held on 9th May at Medak College of Engineering & Technology, SiddipetPaticipants: Shekhar (02’ batch)

11. “NANO Techonologies” , held on 10th May, at Hi-tech College of Engineering, Hyderabad.Participant: B. Shivani (02’ batch)Secured 1st Prize.

CO-CURRICULAR ACTIVITIES

1. AMPERE – Association of modern power engineers for recreational excitation. Established December, 2004 by students and staff of EEE. This is the 1st student association in Ramappa Engineering College. The main aim of AMERE is to develop the leadership qualities, communication skills among the students.

2. Students Seminar: The students groups are well scheduled and organized for seminar presentation, which helps them improve their abilities.

3. Industrial Visits: Students were taken to various R & D organizations in order to expose them to the practice of technology. In this regard technical visits by our department. Staff members accompany the students, to guide and to have quicker access to the technical staff.

i. Vishakhapatnam steel plant, 01-09-2005.ii. Nagarjuna Sagar dam and power house, Nalgonda 10-10-2005.iii. Srisailam Dam and Power houses – Mahboobnagar, 01-08-2005.iv. Kinerasani Dam and KTPS Palvancha – Kothagudem, 02-02-2008

In order to the above trips, students will be taken to the near-by sub-stations to correlate their theoretical and practical knowledge.

4. AMPERE – Association of Modern Power Engineers for Recreational Excitation organized Quiz on the Eve of Republic Day – 2008.

5. VIGNANITHA – 2008

VIGNANITHA – 2008 – A National Level Technical Meet on 08-03-2008 to 09-03-2008 held at our College. The department of EEE conducted Technical Quiz and Technical Paper Presentation competitions as a part of the programme.

The following students have participated in the Technical Paper Presentation competition.

1. “HVDC” held in the Month of March at Ramappa Engineering CollegeParticipants: Usha Rani, Prathyusha (06’ batch)Secured Consolation Prize

2. “Recent Trends in Industrial Drives” held in the Month of March at Ramappa Engineering College.Participants:Ch.Surender, Ch. Srinivas (06’ batch)

3. “Non-Conventional and Renewble Energy Soruces” held in the Month of March at Ramappa Engineering College.Participants:Jagadeesh Reddy, Akshay Reddy (06’ batch)

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The following students have participated in the Technical Quiz competition.

1. Ch. Surender and Ch.Ashok have participated and won 1st Prize.2. Usha Rani & Divya have participated and won 2nd Prize.

PLACEMENTS

D.Shekhar, Swapna, Madhu Latha, Sridhar, Venu Gopal Reddy and many others are placed in various companies by the placement co-ordination in Ramappa Engineering College.

Swathi, Ranjith, B. Abhimnan Naik, P. Harika, K. Ashwin Kumar, Mohd. Khajamonuddin Ahmed, M. Venkatesh, B. Rajith Kumar, S. Maruthi are few of our students who are in USA, and pursuing their MS. Sridhar, Harika and few others show for MS from our college. Proper guidance and assistance is always given to the students from the department

FUTURE PLANS

1. Steps will have to be taken to improve pass percentage. In this perception, it is necessary to identity the weak students, accordingly special guidance will be given to them.

2. Strict attendance monitoring will be continued vision. Students whose attendance falls below 75% will have to be warned.

3. Adjunct courses to make students aware of new technologies will have to be conducted.

2 LABORATORIES

The electrical department is well equipped with 10 laboratories.

NAME OF THE LAB FACILITIES PROVIDED

Electrical Circuit LabThis laboratory carries out the experiments on AC & DC networks and verification of network theorems

Electrical Machines LabA total of 22 DC & AC machines and six 1- (single phase) transformers with all experimental set up facility is well established in this lab

Control System LabThis lab is well established to deal with the experiments on frequency and time order analysis, analog and digital PID controller, AC & DC servomotor etc.

Measurements LabThis lab is well equipped for calibrating, testing and measuring all parameters

Power Electronics LabPower electronics laboratory is full fledged equipped with all types of AC & DC converters with RLC loads, firing circuits. Different kits & CRD’s are provided for conducting experiments

Electrical Simulation LabThis lab consists of 30, Pentium 4 systems with licenced software like spice, MATLAB – 6.5 and power system simulation packages.

High Voltage Lab This lab is being established for the care of M.Tech students

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3. TREE DIAGRAM

3.1 SUBJECT TREE

36

EDCC&DS

MEFA, ES

EM-III

EM-I, II

MS

STLD

EM, INS

NN&FL

CO

PDC

VLSI

DSP MP&MC

Embed. Sys

PSIM, MATLAB

CS

OTPSDHVDC

PS-II

PSA

Software Engineer,Hardware Engineer,ASIC, CPLD&FPGA,Embedded designer etc

Software Engineer,Hardware Engineer,ASIC, CPLD&FPGA,Embedded designer etc

PSOC

HVE S & P

EDS, NCES

PE, Drives & Traction Engineer for various industrial control application industries, etc

PE, Drives & Traction Engineer for various industrial control application industries, etc

Power System Engineer (AE) for Electricity boards Power plants, Public sectors etc,

Power System Engineer (AE) for Electricity boards Power plants, Public sectors etc,

Managerial posts in various Electrical Industries,etc

Managerial posts in various Electrical Industries,etc

LDSA

UEE

LDICA

AP

M-IIIPS-I

PE

EMF

ECAM-I, MM

PSPICE, MATLABECAD, MATLAB

DCS,ACSDBMS, SE


3.2 OPPORTUNITIES TREE

37

PED

HIGHER EDUCATION

Electricity BoardsPrivate

Industries

UPSC Public sector(Trainees)

Defense Services

L &T, ABB etc,Asst. Eng. S/W (national)Companies

MS, Intel, DEL etc

IESCivils

BHELL BEL HAL ISRONTPC

R& D IAF IN IA

RRB Telecom

Qualifying Examinations

TOFEL, GRE(Studies at abroad)

HVE Embedded

GATE(Studies at IIT’s, NIT’s, Universities & Colleges)

InstrumentationHVDC VLSI systems

Research

EMPLOYMENT

CompetitiveExams (State level)

Competitive Exams( All India)

APPSC

MNC

DRDO

BSRB

CAT(Studies at IIM’s)

Finance HRMarketing IT


4. COURSE STRUCTURE

CODE SUBJECT T P C

CS 05140 Computer Organization 4+1* - 4

EE 05198 Electrical Measurements 4+1* - 4

EE 05468 Power Systems – II 4+1* - 4

EE 05459 Power Electronics 4+1* - 4

EE 05195 Electical Machines – III 4+1* - 4

EE 05343 Linear and Discrete Systems Analysis 4+1* - 4

EE 05197 Electrical Machines Lab – II - 3 2

EE 05150 Control Systems Lab - 3 2

Total 30 6 28

T- Theory P- Practicles C- Credits * - Tutorial

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5. SUBJECTWISE DETAILS

5.1. COMPUTER ORGANIZATION

5.1.1 Objectives and Relevance

5.1.2 Scope

5.1.3 Prerequisites

5.1.4 Syllabus

i. JNTU

ii. GATE

iii. IES

5.1.5 Suggested Books

5.1.6 Websites

5.1.7 Expert details

5.1.8 Journals

5.1.9 Recent Findings and Developments

5.1.10 Session Plan

5.1.11 Student Seminar Topics

5.1.12 Question Bank

i. JNTU

ii. GATE

iii. IES

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5.1.1 OBJECTIVES AND RELEVANCE

The fundamental knowledge of organization of a computer forms one of the essential requirements for effective use of a computer. Computer organization provides an insight into the design and development aspects of a general purpose computer. The course gives a overview of the picture of the construction of a computer. The course also aims at giving inputs to enhance the performance of a computer. The theoretical foundations and research issues provide an idea to how various techniques are used in the computer design.

5.1.2 SCOPE

This paper starts by giving an overview of the computer system. The various components and peripherals of a computer system are discussed in detail. Memory and various addressing schemes are also covered. Among the advanced topics Input/Output organisation and vector processing/parallel processing is discussed. At the end the student has a solid understanding of the subject and is well prepared to take up advanced topics in computer architecture, parallel architecture etc.

5.1.3 PREREQUISITES

A basic course in switching theory and logic design exposure to a high level language program preferably C. Exposure to assembly language programming on any process architecture will be advantage.

5.1.4.i SYLLABUS - JNTU

UNIT – IOBJECTIVE

In this unit we will discuss about the overview of the Computer Organization also deals with the Computer types, Functional types, Bus Structure, Basic Operational units and Software. Data Representation in fixed points and floating point and error detection codes.SYLLABUS

Computer types, Functional Unit, basic operational concepts. Bus structures, software, performance, multiprocessors and multi computers. Fixed point representation, Floating point representation, error detection codes.

UNIT-IIOBJECTIVE

In this unit we will discuss about the Register Transfer Language it explains the transfer of the data by using registers and also discuss the various operations like Arithmetic, Logic, Shift and Memory reference. Stack Organization and Addressing modes.

SYLLABUS

Register transfer language, register transfer bus and memory transfers. Arithmetic micro operations, logic micro operations, shift micro operations, Arithmetic logic shift unit. Instruction codes. Computer registers, computer instructions –instruction cycle.

Reference Instructions. Input – Output and interrupt. STACK organization, instruction formats. Addressing modes. Data transfer and manipulation. Program control. Reduced Instruction Set Computer(RISC).

UNIT-IIIOBJECTIVE

In this we know about the how we can specify each and every address in the Memory. Design the Hardwired control and micro programmed control.SYLLABUS

Control memory, Address sequencing, micro program example, design of control unit, hard-wired control. Micro Programmed Control.

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UNIT- IVOBJECTIVE

In this unit we discuss about the Calculation part of the Arithmetic Operations like Addition, Subtraction, Multiplication and Division.

SYLLABUS

Addition and Subtraction, multiplication algorithm, division algorithm. Floating point Arithmetic operations. Decimal arithmetic unit. Decimal arithmetic operations.

UNIT-VOBJECTIVE

In this unit we will discuss about different types of memories like catch, virtual and semi-conductor ram memories.SYLLABUS

Basic concepts semi conductor RAM memories. Read Only memories. Cache memories, performance consideration, virtual memories, secondary storage. Introduction to RAID.

UNIT-VIOBJECTIVE

In this unit we will discuss about the different types of peripheral devices such as input-output interface, Asynchronous data transfer, Direct memory access and input-output processor(IOP) and also discuss the protocols like RS232,USB,IEEE1394.

SYLLABUS

Peripheral devices. Input-output Interface, Asynchronous data transfer. Modes of transfer, priority interrupt. Direct Memory Access, Input-Output Processor(IOP), serial communication, Introduction to peripheral component interconnect(PCI) bus. Introduction to standard serial communication protocols like RS232, USB, IEEE 1394.

UNIT-VIIOBJECTIVE

In this unit we will discuss about the concept of parallel processing, pipelining, vector processing and array processors.

SYLLABUS

Parallel processing, pipelining, arithmetic pipeline, Instruction pipeline. RISC pipeline vector processing, array processors.

UNIT-VIIIOBJECTIVE

In this unit we discuss about the different characteristics of Multiprocessors, Inter-Connection Structures Inter Process and shared memory multiprocessors.SYLLABUS

Characteristics of Multiprocessors. Interconnection structures, inter processor arbitration. Inter processor communication and synchronization. Cache coherence, shared memory.

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5.1.4.ii SYLLABUS – GATE

UNIT-IALU and Data path.

UNIT-IIMachine Instructions and addressing modes, CPU control design.

UNIT –IIINot applicable

UNIT-IVNot applicable

UNIT-V Memory Interface, cache memory, main and secondary storage.

UNIT-VII/O interface(Interrupt and DMA mode), Serial communication interface.

UNIT-VIIInstruction pipelining.

UNIT - VIIINil.

5.1.4.iii SYLLABUS - IES

Not Applicable.

5.1.5 SUGGESTED BOOKS

TEXT BOOKS

TI Computer System Architecture: M.Moris Mano, IIIrd Edition, Pearson/PHI

T2 Computer Organization: Car Hamacher, Zvonks Vranesic, Safea Zaky, Vth Edition, Mc Graw Hill.

T3 Computer Architecture and Organization: Jhon P.Hayes TMH III edition.

REFERENCE BOOKS

R1 Computer Organization and Architecture-Willam Stallings, VI Edition.

R2 Structured Computer Organization-Andrew S. Tanenbaum, IV Edition, PHI/Pearson

R3 Fundamentals of Computer Organization and Design-Sivarama Dandamudi Springer Int Edition

R4 Computer Organization,Anjaneylu, Himalaya Pub. House

5.1.6 WEBSITES

1. www.acm.org.dl2. www.cs.wise.edu3. www.umiacs.umd.edu4. www.ieee.org5. www.ittg.ernet.in6. www.tcpipguide.com7. www.en.wikipedia.org8. www.compnetworking.com

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5.1.7 EXPERT DETAILS

REGIONAL

1. Name : Govindarajulu Designation : Professor Department : CSE

Office Address : IIIT, Gachjbowli, Hyderabad,Phone : 91-40-23001967Ext:15

Email : [email protected]/[email protected]

2. Name : Ch Sudhakar Designation : Sr. lecturer, Department : CSE Office Address : NIT, Warangal Phone : 9247539341 Email : [email protected]

3. Name : R.Govinda rajulu Designation : Professor Department : CSE Office Address : IIIT, Gachibowli, Hyderabad Phone : 91-40 23001967 Fax : 91-40 23001413 Email : [email protected] NATIONAL

1. Name : Dr. M.P.Sebastian Designation : Professor & HOD of CSE Dept.

Department : CSE Office Address : NIT-Calicut Phone : 0495-2286800 Fax : 2286803 Email : [email protected]

2. Name : Dr. Priya ChandranDesignation : Asst. Prof CSE DeptDepartment : CSEOffice Address : NIT CalicutPhone : 0495-2286804

Email : [email protected]

INTERNATIONAL

1. Name : James E.Smith Designation : Professor Department : Electrical and Computer Engineering Office Address : Univ. of Wisconisn-Madison Email : [email protected]

2. Name : Shirharesh majumdar.Designation : ProfessorDepartment : Computer and system EngineeringOffice Address : Carleton University, Olcaw Canada.


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3. Name : William J. Dally Designation : Professor Department : Information Technology Office Address : Standford university, gatesroom 301, Stanford CA94305, Phone : ( 650)25-8945, Fax : (650)725- 6949 Email : [email protected]

4. Name : David A. Petterson, Designation : Professor Department : CSE Office Address : U.C Berkeley, CA 94720-1776, Phone : (510) 642-6587, Fax : (510) 643-7352. Email : [email protected]

5.1.8 JOURNALS

1. Name of Journal : IEEE transaction on computerPublisher : IEEE Publishers

2. Name of Journal : IEEE transaction on parallel and distributed computing.Publisher : IEEE Publishers

3. Name of Journal : IEEE Computer MagazinePublisher : IEEE Publishers

4. Name of Journal : CSI JournalPublisher : Tech Focus Media

5. Name of Journal : IETE Technical reviewPublisher : IETE Publishers

6. Name of Journal : ACM Transaction on computer systems Publisher : ACM Publishers

7. Name of Journal : Journal of parallel Computing

Publisher : MIT Press Journal

8. Name of Journal : Journal of parallel & Distributing Computing Publisher : IETE Publishers

9. Name of Journal : Journal of organizational Computing

Publisher : IETE Publishers

10. Name of Journal : Journal of Computing SystemsPublisher : Wiley Publications

11 Name of Journal : Journal of New generation ComputingPublisher : MIT publishers

12. Name of Journal : International journal of super computer application & High performance Computers

Publisher : Inder science Publications

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5.1.9 RECENT FINDINGS AND DEVELOPMENT

1. Title : Nanoscale Design and test ChallengesAuthor : Yerwant ZorianJournal : IEEE magazine on computersVol.,Year &Pageno : volume 38, Number 2, Feb 2005

2. Title : Emerging Grid Standards,Author : Mark Baker, Amy, Apow, Clayton, Journal : IEEE Journal on computers Vol.,Year & Pageno : Volume 38, number 4, April 2005

3. Title : Low Cost Test Scheduling for Distributed- Memory MachinesAuthor : A Radulescue and A J C Van Gemund, Journal : IEEE trans of parallel and distributed systemsVol.,Year & Pageno : volume 13, Number 6, June 2002

4. Title : OCR in Indian SciptsAuthor : Survey, Peeta Basa Pati and A G Rama KrishnanJournal : IETE Technical A ReviewVol.,Year & Pageno : Vol.22, No.2., May-June 2005

5. Title : A survey on Fast packet switching techniques, Author : A Shanmuga and G Shanthi, Journal : IETE Technical Review, Vol..,Year & Pageno : Vol.22,No.2, March-April 2005

6. Title : Stable Statesand Sufficient conditions for correct retrieval in the bidrectional associative memory

Author : V Ravi Chandran, Narayanan, SrinivasanJournal : IETE Journal of ResearchVol.,Year & Pageno : Vol.22,No 5, Jan – Feb 2003.

7. Title : Computer Aided simulation tools for the analysis of semiconductor lasers

Author : D Nyaneshwar, S Patiland D K GautamJournal : IETE Technical Review,Vol.,Year & Pageno : Vol.20,No.6., Nov. – Dec 2003

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5.1.10 SESSION PLAN

Sl. No.

Topics covered in JNTU Syllabus

Modules and Sub modulesNo. of

LecturesSuggested Books Remarks

UNIT – I – INTRODUCTION (No. of Lectures – 09)

1Basic Structure or Computers

Introduction Computer types L1T2-Ch1(P:2)R1-Ch1 (P:5)

2 Functional UnitInput Unit, Memory Unit, ALU, Output Unit, Control Unit

L2 T2-Ch1 (P:3)

GATE3

Basic Operational Concept Basic Operational ConceptBus StructureSoftware

L3 T2-Ch1 (P:7-10)Bus StructureSoftware

4Performance

Processor Clock

L4, L5

T1-Ch2 (P:14)R1-Ch1(P:37)

Basic Performance EquationT1-Ch2 (P:14)R1- Ch1 (P:37)

Pipelining and Super Scalar Operation

T1-Ch2 (P:15) R1-Ch1 (P:37)

Clock rate T1-Ch2 (P:16) R1- Ch1 (P:37)

Instruction set: CISC and RISCT1-Ch2 (P:16) R1- Ch1 (P:37)

CompilerT1-Ch2 (P:17) R1- Ch1 (P:37)

Performance MeasurementT1-Ch2 (P:17) R1-Ch1 (P:37)

Multi Processor & Multi computers

Multi Processor & Multi computers

T1-Ch2 (P:17) R1-Ch1 (P:37)

5 Data Representation

Data Types

L6, L7T1-Ch3 (P:85-94)T2-Ch1 (P:25 to 33)R1-Ch1 (P:1to 9)

Number SystemsOctal and Hexadecimal NumbersDecimal RepresentationAlpha Numeric RepresentationComplements(r-1)'s complementr's complementSubtraction of Unsigned Numbers

6 Fixed Point Representation

Integer Representation

L8T1-Ch3 (P:96-99) T2-Ch1 (P:25-33)R1-Ch1 (P:1-9)

Arithmetic AdditionArithmetic SubtractionOverflowDecimal Fixed Point Representation

7Floating Point Representation Floating Point Representation

Error Detection CodesL9

T1-Ch3 (P:101-109)R1-Ch8 (P:307)

Error Detection CodesUNIT – II – REGISTER TRANSFER LANGUAGE AND MICRO OPERATIONS (No. of Lectures – 20)

1Register Transfer Language Register Transfer Language

L10T1-Ch4 (P:111-134)R4-Ch1 (P:10-12)

GATERegister Transfer Register Transfer

2 Bus and Memory TransfersThree State Bus Buffers

L11Memory Transfer

3 Arithmetic Micro Operations

Binary Adder L12, L13Binary Adder-SubtractorBinary IncrementerArithmetic Circuit

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4 Logic Micro OperationsList of Logic Micro Operations

L14Hardware ImplementationSome Applications

5 Shift Micro Operations Hardware ImplementationL15

6 Arithmetic Logic Shift Unit 7 Instruction Codes Stored Program Organization

L16

T1-Ch5 (P:143-174)T2-Ch3 (P:104-127)R1-Ch9 (P:414-420)R2-Ch5 (P:340-358)

Indirect Address8 Computer Registers Common Bus System L179 Computer Instructions Instruction set Completeness

L18, L1910 Instruction Cycle

Fetch and DecodeDetermine the type of InstructionRegister Reference Instructions

11Memory Reference Instructions

AND to AC

L20, L21

ADD to ACLDA: Load to ACSTA: Store ACBUN: Branch UnconditionallyBSA: Branch and Save Return AddressISZ: Increment and Skip if zeroControl Flowchart

12 Input, Output and Interrupt

Input-Output Configuration

L22, L23Input-Output InstructionsProgram InterruptInterrupt Cycle

13 STACK Organization

Register Stack

L24

T1-Ch8 (P:265-271)R1-Ch5 (P:371-376)R2-Ch4 (P:218-219) (P:338-341)

Memory StackReverse Polish NotationEvaluation of Arithmetic Expressions

14 Instruction Formats

Three Address Instructions

L25


GATE

Two Address InstructionsOne Address InstructionsZero Address InstructionsRISC Instructions

15 Addressing Modes Numeric Example L26

T1-Ch8 (P:282)T2-Ch2 (P:47-49)R2-Ch5 (350-365)R1-Ch11 (P:382-389)

16Data Transfer and Manipulation

Data Transfer Instructions

L27T1-Ch8 (P:285-289)R1-Ch10 (P:343-344)

Data Manipulation InstructionsArithmetic InstructionsLogical and Bit Manipulation InstructionsShift Instructions

17 Program Control

Status bit Conditions

L28T1-Ch8 (P:292-299)T2-Ch4 (P:204)

Conditional Branch InstructionsSubroutine call and ReturnProgram InterruptTypes of Interrupts

18Reduced Instruction Set Computer

CISC Characteristics

L29

T1-Ch8 (P:301-306) T2-Ch1 (P:17, 97)R1-Ch2 (P:64-65)R2-Ch2 (P:64-71)

Overlapped Register Windows

Berkeley RISC I

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UNIT – III – MICRO PROGRAMMED CONTROL (No. of Lectures – 04)1 Control Memory

L30


GATE

2 Address Sequencing

Conditional Branching Mapping of Instruction

3 Microprogrammed Example

Computer Configuration

L31, L32, L33

Micro Instruction FormatSymbolic Micro InstructionsThe Fetch routineSymbolic MicroprogramBinary Microprogram

4 Designer Control Unit Microprogram SequencerUNIT – IV - COMPUTER ARITHMETIC (No. of Lectures – 09)

1Introduction, Addition, Subtraction

Addition, Subtraction with Signed - Magnitude Data

L34, L35T1-Ch10 (P:353-356) T2-Ch6 (P:368-410)

Hardware ImplementationHardware AlgorithmAddition, Subtraction with Signed-2's Complement Data

2 Multiplication Algorithm

Hardware Implementation for Signed Magnitude Data

L36T1-Ch10 (P:359-364)T3-Ch8 (P:277-285) T2-Ch6 (P:368-410)

Hardware AlgorithmBooth Multiplication AlgorithmArray Multiplier

3 Divison Algorithms

Hardware Implementation for Signed Magnitude Data

L37T1-Ch10(P:367-371)T3-Ch8 (P:286-288) T2-Ch6 (P:368-410)

Divide OverflowHardware AlgorithmOther Algorithms

4Floating Point Arithmetic Operations

Basic Considerations

L38, L39T1-Ch10 (P:372-380)T3-Ch8 (P:289-294)T2-Ch6 (P:368-410)

Register ConfigurationAddition and SubtractionMultiplicationDivision

5 Decimal Arithmetic UnitBCD Adder

L40

T1-Ch10 (P:382-394)

BCD Subtraction

6Decimal Arithmetic Operations

Addition and Subtraction

L41, L42MultiplicationDivisionFloating Point Operations

UNIT – V – THE MEMORY SYSTEM (No. of Lectures – 05)

1Basic Concepts

Basic Concepts Semiconduct RAM Memories

L43 T1-Ch12 (P:445-482) Semiconduct RAM Memories

2 Read Only Memories Read Only Memories

L44

T2-Ch5 (P:309-317)T1-Ch12 (P:445-482)R1-Ch4 (P:95-192)

3 Cache Memories

Associative Mapping T2-Ch5 (P:314-325)T1-Ch12 (P:121-139)T3-Ch4 (P:482-487)R1-Ch4 (P:95-192)

GATEDirect MappingSet Associative MappingWriting into Cache

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4Virtual Memories Secondary Storage

Address Space and Memory Space

L45, L46 T2-Ch5 (P:337-339)R1-Ch4 (P:95-192)T3-Ch4 (P:482-487)

Address Mapping Using PagesAssociative Memory Page TablePage Replacement

5 Introduction RAID L47UNIT – VI - INPUT - OUTPUT ORGANIZATION (No. of Lectures –08)

1 Peripheral Devices ASCII Alpha Numeric Characters

L48

T1-Ch11 (P:401-455)T2-Ch4 (P:204-272)R1-Ch7 (P:195:233)R4-Ch8 (P:184-212)

GATE

2 Input - Output Interface

I/O Bus and Interface ModulesI/O Vs Memory BusIsolated Vs Memory Mapped I/OExample of I/O Interface

3Asynchronous Data Transfer

Strobe Control

L49

Hand ShakingAsynchronous Serial TransferAsynchronous Communication InterfaceFirst In, First Out Buffer

4 Modes of TransferExample of Programmed I/O

L50 Interrupt Initiated I/OSoftware Considerations

5 Priority Interrupt

Daisy - Chaining Priority

L51

Parallel Priority InterruptPriority EncoderInterrupt CycleSoftware RoutinesInitial and Final Operations

6 Direct Memory Access DMA Controller

L52 GATEDMA Transfer

7 Input - Output ProcessorCPU-IOP CommunicationIBM 370 I/O ChannelIntel 8089 IOP

8 Serial Communication

Character Oriented Protocol

L53Transmission ExampleData TransferencyBit Oriented Protocol

9Introduction to Peripheral Component

Introduction to Peripheral Component

L54

10 Interconnect (PCI) Bus Interconnect (PCI) Bus

L55 11

Introduction to Standard Serial Communication Protocols like RS 232, USB, IEEE 1394

Introduction to Standard Serial Communication Protocols like RS 232, USB, IEEE 1394

UNIT – VII – PIPELINE AND VECTOR PROCESSING (No. of Lectures – 06)

1 Parallel Processing Parallel Processing

L56

T1-Ch9 (P:317)T2-Ch12 (P:619-621)R1-Ch18 (P:643-687)R2-Ch6 (P:454-463)

2 Pipeline PipelineT1-Ch9 (P:320)T2-Ch8 (P:454)R1-Ch18 (P:643-687)

3 Arithmetic Pipeline Arithmetic Pipeline L57 T1-Ch9 (P:325)T2-Ch8 (P:454)

49


R1-Ch18 (P:643-687)

4 Instruction Pipeline

Example: Four Segment Instruction Pipeline T1-Ch9 (P:328-332)

R1-Ch18 (P:643-687)GATE

Data Dependency Handling of Branch Instructions

5 RISC Pipeline

Example: Three Segment Instruction Pipeline

L58T1-Ch9 (P:333-336)R1-Ch18(P:643-687)

Delayed Load Delayed Branch

6 Vector Processing

Vector Operations

L59, L60T1-Ch9 (P:337-343)R1-Ch18 (P:643-687)

Matrix MultiplicationMemory InterleavingSuper Computers

7 Array ProcessorsAttached Array Processor

L61T1-Ch9 (P:344-345)T2-Ch12 (P:620-621)R1-Ch18 (P:643-687)

SIMD Array Processor

UNIT – VIII - MULTI PROCESSORS (No. of Lectures – 05)

1Characteristics of Multi Processors

Characteristics of Multi Processors

L62

T1-Ch13 (P:507)T2-Ch12 (P:618)R1-Ch18(P:648-652)

2 Inter connection Structures

Time - Shared Common Bus

T1-Ch13 (P:509-516)T2-Ch12 (P:624-637)R1-Ch1(P:67-69)

Multi Port MemoryCrossbar SwitchMulti Stage Switching NetworkHyper Cube Interconnection

3 Inter Processor Arbitration

System Bus

L63 T1-Ch13 (P:518-523) Serial Arbitration ProcedureParallel Arbitration LogicDynamic Arbitraction Algorithms

4

Inter Processor Communication

Inter Processor Communication L64

T1-Ch13 (P:525-527)T2-Ch12 (P:641-645)R1-Ch18 (P:651-659)

And Synchronization Inter Processor SynchronizationL65

Mutual Exclusion with aSemaphore

5 Cache CoheranceConditions for Incoherance

L66 Solutions to the Cache Coherence Problem

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5.1.11 STUDENT SEMINAR TOPICS

1. Title : Functionall Units of ComputerAuthor : Yerwant ZorianJournal : IEEE magazine on computersVol., Year & Page No. : volume 38, Number 2, Feb 2005

2. Title : Addressing Modes Author : Mark Baker, Amy, Apow, ClaytonJournal : IEEE Journal on computers Vol., Year & Page No. : Volume 38, number 4, April 2005

3. Title : Booth’s Multiplication Algorithm and Division Algorithm BoothAuthor : A Shanmuga and G Shanthi.Journal : IETE Technical Review Vol., Year & Page No. : Vol.22,No.2, March-April 2005

4. Title : Input output Organisation,Author : F.J. and G.R. PetersonJournal : IEEE Journal on computers Vol., Year & Page No. : Volume 38, number 4, April 2005.

5. Title : Data RepresentationAuthor : Mark Baker, Amy, Apow, Clayton, Journal : IEEE Journal on computers Vol., Year & Page No. : Volume 38, number 4, April 20056.

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5.1.12 QUESTION BANK

UNIT- I

1. a. Discuss the interconnection structure design of a computer.b. Explain various bus lines.c. What do you mean by multiple - bus hierarchies. (JNTU May 08)

2. a. Define PCI. Explain the applications of PCIb. Describe any ten mandatory PCI signals (JNTU May 08)

3. a. Explain about IAS memory formats.b. List various registers in a computer along with their purpose (JNTU May 08)

4. a. Explain the top level view of componentsb. What do you mean by hard wired program?

c. List the basic functions perfomed by a computer. (JNTU Feb 08, Nov 07)

5. Explain the expanded structure of IAS computer with a neat block diagram.(JNTU Feb 08, Nov 07)

6. a. Explain about sign magnitude and 2’s complement approaches for representing the fixed point numbers. Why 2’s complement is preferable.

b. Give means to identify whether or not an overflow has occurred in 2s complement addition or subtraction operations. Take one example for each possible situaion and explain. Assume 4 bit registers.

c. Distinguish between tightly coupled microprocessors and tightly coupled Microprocessors. (JNTU Feb 08, Sep 07)

7. a. Explain the terms compiler, linker, assembler, loader and describe how a C program or any other high level language program is executed in a system. Indicate entire process with a figure.

b. Distinguish between high level and low level languages?. What are the requirements for a good programming language? (JNTU Sep 07)

8. a. Explain the terms computer architecture, computer organization and computer design in a detailed fashion.

b. Explain about MIPS, FLOPS rating of a processor. How do we arrive at these values.(JNTU Sep 07)

9. a. What is meant by normalization in floating point representation?. Why do need it? What is bias? What b. Explain about NaN and denormalised numbers in IEEE 754 standards. (JNTU Sep 07)

10. Difference between multiprocessors and multicomputers. (JNTU Feb 07)

11. i. Differentiate between dedicated and multipludged bus line.ii. Discuss various methods of bus arbitration.iii. What do you mean by bus width? (JNTU Feb 07)

12. Discuss about error detecting and correcting code. (JNTU Feb 07)

13. Explain the architecture of I A S computer and explain each block. (JNTU Nov 06, 04, 03)

14. i. List type of transfers supported by interconnection structure. ii. Discuss the reasons for undermining bus performance.iii. Explain various bus configuration examples. (JNTU Nov 06)

15. i. Discuss the interconnection structure design of a computer.ii. Explain various bus lines.iii. What do you mean by multiple – bus hierarchies. (JNTU May 05)

16. i. Differentiate between traditional and high performance bus architectures.ii. List the key elements of bus design. (JNTU May 05)

52


17. i. Differentiate between traditional and high performance bus architecturesii. List the key elements of bus design. (JNTU Nov 04)

18. i. What are the various bus configurations and bus data transfer types? Explain them.ii. Represent the binary equivalent of -8 in 3 different ways using register of 12 bits.( JNTU May 04)

19. What are various ways of representing negative numbers. (JNTU Nov 04, 03)

20. i. Discuss the interconnection structure design of a computer.ii. Explain various bus lines.iii. What do you mean by multiple – bus hierarchies. (JNTU Nov 04)

21. i. Describe various arithmetic and logical instruction set operations.ii. List CPU actions for various types of operations. (JNTU Nov 04)

22. Explain the generic structure of IAS computer in detail with the help of a block diagram.(JNTU May 04)

23. Explain the expanded structure of the IAS computer with a neat block diagram. (JNTU May 04)

24. Prove that the multiplication of two n-digit numbers in base B gives a product of no more than 2n digits. (JNTU Jun 03)

25. Describe how an instruction is executed using flow chart in an IAS computer. (JNTU Jun 03)

26. Give the functional organization of a digital computer and explain the function of each element of a computer. (JNTU Jun 03)

27. Describe with suitable illustrations the partial program execution on showing the relevant portions of memory and CPU registers, to perform addition of contents of two memory locations.

(JNTU Nov 03)

28. What are the various computer components. Explain them (JNTU Jun 03)

29. A 36-bit floating-point binary number has 8-bits plus a sign for the exponent. The mantissa is assumed to be a normalized functions. Negative numbers in the mantissa and exponent are in signed-magnitude representation. What are the largest and smallest positive quantities that can be represented, excluding zero? (JNTU Jan 02)

30. Discuss the various schemes for representing fixed and floating numbers stressing the merits and demerits of each scheme. (JNTU Jan 02, May 08)

31. Write short notes on: Control unit. (JNTU Nov 02)

32. Describe 8085 cpu organization. (JNTU Nov 02)

33. A digital computer has bus system for 16 registers of 32 bits each. The bus is constructed with multiplexers.

i. How many selection inputs are there in each multiplexer?ii. What size of multiplexers are needed?iii. How many multiplexers are there in the bus? (JNTU Nov 02)

34. i. With a neat diagram, explain the first generation computers.ii. Explain the basic structure of an ALU. (JNTU May 02)

35. Write notes on :ii. Instruction pipeline (JNTU May 02)

36. Discuss the advantages of floating-point representation over fixed-point representation. (JNTU May 01)

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37. Design a digital circuit that performs four logic operations of Exclusive OR, Exclusive-NOR, NOR and NANIV. Show the logical diagram of one typical stage. (JNTU May 01)

38. Write a brief note on error detection codes. (JNTU Nov 00, May 08)

39. What is a bus? Discuss two typical bus structures. (JNTU Nov 00)

40. What is the purpose of the system bus controller? Explain how the system can be designed to distinguish between references to local memory and references to common shared memory.

(JNTU May 00)

41. Describe the functional diagram of the 8 registers and memory of the basic computer to a common Bus system.

42. A CPU has 24 bit instructions. A program starts address 300 of (in decimal). which one of the following is a legal program counter (all values in decimal)? (GATE 06)i. 400 ii. 500 iii. 600 iv. 700

43. Consider the values A = 2.0 x 10 30, B = -2.0 x 1030, C = 1.0, and the sequenceX : = A + B Y : = A + CX: = X + C Y : = Y + BExecuted on a computer where floating point numbers are represented with 32 bits. The values for X and Y will bei. X = 1.0, Y = 1.0 ii. X = 1.0, Y = 0.0iii. X = 0.0, Y = 1.0 iv. X = 0.0, Y = 0.0 (GATE 00)

44. The instruction format of a CPU is (GATE 93)OP CODE MODE RegROne Memory wordMode and RegR together specify the operand, RegR specifies a CPU register and Mode specifies an addressing mode. In particular, Mode=2 specifies that ‘the register RegR contains the address of the operand, after fetching the operand, the contents of Reg R are incremented by 1’.An instruction at memory location 2000 specifies Mode = 2 and the Reg R refers to program counter (PC).

i. What is the address of the operand?ii. Assuming that this is a non-jump instruction, what are the contents of PC after the execution of this

instruction.

45. A single bus CPU consists of four general purpose register, namely, R0......... R3, ALU, MAR, MDR, PC, SP and IR (Instruction Register). Assuming suitable microinstructions, write a microroutine for the instruction, ADD R0, R1 (GATE 90)

46. The exponent of a floating-point number is represented in excess-N code so thati. the dynamic range is largeii. the precision is high.iii. the smallest number is represented by all zeros.iv. overflow is avoideiv. (GATE 87)

47. Explain briefly about following i. Signed magnitude representation ii. Signed 1’s complement representation iii. Signed 2’s complement representation

48. Explain about system performance measurement

49. What is digital computer? Explain about various types of computers.

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UNIT – II

1. a How subtraction is done on the binary numbers represented in one’s complement notation give an examples.

b. What do you mean by r’s complement. (JNTU May 08)

2. Write an algorithm to substract binary numbers represented in normalized floatingpoint mode with base 2 for exponent (JNTU May 08)

3. a. Find the output binary number after performing the arithmatic operation using 1’s complement representation.

i. 111.01 + 10.111ii. 110.11 - 111.01b. Explain steps involved in the addition of numbers using 2’s complement notation.

(JNTU May 08)

4. a Find the output of the following binary expressions using 2’s complementrepresentation.i. 111.01 + 10.111ii. 110.11 - 111.01

b Explain the steps involved in the subtraction of a number from a given number using 1’s complement notation (JNTU Feb 08)

5. a Explain about the arithmetic in excess - 3 code.b. Discuss about normalized floating point representation. (JNTU Nov 07)

6. Explain about error detecting and correcting codes. What is their relevance. (JNTU Nov 07)

7. a Find the output binary number after performing the following arithmetic operationsi. 111.01 + 10.111ii. 11.01 + 110.11iii. 110.11 - 111.01b Explain about the longhand division of binary integers (JNTU May 08 ,Nov 07)

8. Write an algorithm to find all allowable weights for a ”weighted BCD code”. Assume that all weights are positive number (JNTU Nov 07)

9. Design a circuit for parallel load operation into one of the four 4-bit registers from a bus. Mention clearly control/selection bits and selection logic. Assume D flip-flops. (JNTU Sep 07)

10. a. Design a circuit transferring data from a 4bit register which uses D flip-flops to another register which employs RS flip-flops.

b. What are register transfer logic languages. Explain few RTL statement for branching with their actual functioning. (JNTU Sep 07)

11. a Design a circuit transferring data from a 4bit register which uses D flip-flops to another register which employs RS flip-flops.

b. What are register transfer logic languages. Explain few RTL statement for branching with their actual functioning. (JNTU Sep 07)

12. a. Explain about stack organization used in processors. What do you understand by register stack and memory stack?

B Explain how X=(A+B)/(A-B) is evaluated in a stack based computer. (JNTU Sep 07)

13. i. Define element of machine instruction.ii. How various instructions are categorized?iii. Explain about simple instruction format (JNTU Feb 07)

14. Convert the following decimal numbers to base three to base five.i. 73

55


ii. 10.333iii. 21.25 (JNTU Feb 07)

15. i. Explain how floating point division is done?ii. Explain the addition binary number in 1’s Complement notation. (JNTU May 08, Feb 07, Nov 06)

16. i. Draw and explain the instruction cycle state diagram that includes interrupt cycle processing.ii. Discuss about transfer of control with multiple interrupts. (JNTU Feb 07)

17. i. Describe various arithmatic and logical instructions.ii. List CPU action for various type of instructions. (JNTU Nov 06)

18. i. Explain the subtraction of binary numbers in twos complement notationii. Discuss about floating point addition. (JNTU May 05)

19. i. Find the output binary number after performing; the following arithmetic operationsi. 111.01 + 10.111ii. 11.01 + 110.11iii.110.11 – 111.01.

ii. Explain about the longhand division of binary integers. (JNTU May 05)

20. Write an algorithm to find all allowable weights for a weighted BCD code. Assume that all weights are positive numbers. (JNTU May 05)

21. i. Explain about IAS memory formats.ii. List various registers in a computer along with their purpose (JNTU May 05)

22. i. What is BCD representation. List the advantages of it.ii. Convert the following binary numbers to decimal and octal forms i) 101101110 ii) 1.011101

(JNTU May 05)

23. Discuss about various Pentium operation types with examples. (JNTU May 05)

24. i. List and describe Load/Store instructions of MIPS R-series processorii. Discuss about synthesizing other addressing modes with MIPS addressing mode.(JNTU May 05)

25. i. Explain about the machine state register.ii. List the characteristics of CISC and RISC processors (JNTU May 05)

26. i. Explain the key design elements of typical a RISC system.ii. Differentiate between RISC and non-RISC systems.

27. Discuss about various Pentium operation types with examples. (JNTU Nov 04)

28. i. Explain the key design elements of most RISC systems.ii. Differentiate between RISC and non-RISC systems.iii. What is semantic gap problem? (JNTU Nov 04)

29. i. Compare CISC and RISC processors.ii. Convert the expression (A*B+C*D)*E to postfix notation using Dijkstra’s algorithm. Show the steps

invlve (JNTU May 06, 04)

30. Write a microroutine for the instruction below.ADD (Rsrc) +, RdstWhere Rsrc and Rdst are general-purpose registers in the machine. (JNTU May 04)

31. i. What are the logical operation performed on machines? Describe each one of them.ii. Describe three most common uses of displacement addressing.

56


32. i. What is a micro-operation? With the help of a diagram explain the constituent elements of a program execution.

ii. Expand and explain the following terms. MAR, MBR, PC, IR (JNTU May 04)

33. i. Explain the instruction formats for Pentium processor.ii. Describe the providence for subtractions/addition of floating point numbers. (JNTU May 04)

34. i. Write a short note on RISC pipelining.ii. How optimization is achieved with respect to pipelining in RISC architecture? Explain.

(JNTU May 04)

35. i. Enumerate Input – Output and Conversion operations of a hypothetical computer.ii. Explain the CPU actions for various types of operations in a hypothetical computeiii. Explain the different type of SHIFT instructions with neat diagrams. (JNTU Nov 04)

36. i. List some of the major advances since the birth of the computer.ii. List the characteristics of some CISC and RISC processors. (JNTU Nov 04)

37. Elaborate on different types of registers in a register organization. (JNTU May 04)

38. i. What is instruction Cycle?ii. Elaborate the characteristics of a hypothetical machine.iii. Give an example of program execution. (JNTU Nov 04)

39. List integer arithmetic and logical and shift operations of power PC with description.( JNTU Nov 04)

40. i. Explain how ADD B,A instruction is executed with steps.ii. List various states of an instruction Cycle.iii. Explain different classes of interrupts. (JNTU Nov 04)

41. i. Multiply the following binary numbers i) -1110 x 0111 ii) 101110 x 101011ii. How is floating point multiplication done.

42. i. Find the sum and difference of the following pairs of binary numbers using 1’s complement representation. i. -111.01 + 10.111 ii. 110.11 – 111.01

ii. Explain the addition of numbers using 2’s complement notation. (JNTU Nov 04)

43. i. Divide -145 by 13 in 2’s compliment notation, using 12-bit words.ii. Explain the floating-point additions and subtraction operations with a flow chart.(JNTU May 04)

44. i. Subtract the following decimal numbers using 10’s complement representation. i) 23-12 ii) 17-6 iii) 23-29

ii. Write an algorithm to Multiply binary numbers represented in normalized floating point mode.(JNTU Nov 04)

45. i. Divide the following binary numbers. i. 110/111 ii. 0011/1011ii. Explain how floating point division is done. (JNTU May 04)

46. i. What is BCD representation. List the advantages of it.ii. Convert the following binary to decimal and octal forms.

i. 101101110 ii. 1.011101 (JNTU May 04)

47. i. Explain BCD addition using algorithm.ii. Explain the addition of numbers in one’s complement notation. (JNTU May 04)

48. i. Explain the subtraction of numbers in two’s complement notation.ii. Discuss about floating point addition. (JNTU May 04)

49. i. Find the sum and difference of the following pairs of binary numbers using 2’s complement representation. i. 111.01 + 10.111 ii. 110.11 – 111.01

57


ii. Explain the subtraction of numbers using 1’s complement notation. (JNTU Nov 04)

50. i. Explain the subtraction of numbers represented in floating point rotation with example.ii. Perform the following arithmetic operations assuming that the decimal digits are coded in 8,4,2,1 code.

i) 24 + 16 ii) 84 – 97 (JNTU Nov 04)

51. i, How subtraction is done between the binary numbers represented in one’s complement rotation with algorithm and examples.

ii. What do you mean by r’s complement? (JNTU Nov 04)

52. Discuss about general purpose registers and memory formats of IAS computer. (JNTU Nov 03)

53. i. Discuss about the basic instruction cycle with block diagram.ii. Represent the number (+47.5)10 with a normalized integer mantissa of 13-bit and an exponent of 7 bits

as a binary number. (JNTU Jun 03)

54. Describe the providence for subtraction/addition of floating point numbers. (JNTU Jun 03)

55. i. Perform the binary division of (66.25)10 and (50.625)10.

ii. In how many ways a negative number in binary can be representive. Explain them with an example.(JNTU Jan 02)

56. i. Write the major functional units in a general purpose digital computer system with the help of block diagram and clearly explain its functional operation starting from power-on.

ii. Define instruction cycle for a CPU. Explain clearly the steps of instruction cycle with a state diagram.(JNTU Nov 02)

57. Perform the following arithmetic operations in 1’s and 2’s compliment. i. 272-42 ii. -2-28 iii. 72-14 (JNTU Nov 02)

58. i. Perform the arithmetic operation of (+42) + (-13) using signed 2’s complementation representation?ii. Represent the number (+46.5)10 as a floating point binary number with 24 bits. (JNTU May 02)

59. i. Design a one – stage Arithmetic and logic unit giving the function table.ii. An 8 bit register contains a binary value 10011100. What is the register value with an arithmetic shift

right and arithmetic shift left. State whether there is any overflow or not. (JNTU May 02)

60. i. Using 8 bit, 2’s complement form, represent – 27 decimal?ii. Convert the hexadecimal number F3A7C2 in to binary and Octal? (JNTU Nov 02)

61. Derive an algorithm in flowchart form for adding and subtracting two fixed point binary numbers when negative numbers are in signed – 1’s Complement representation? (JNTU May 02)

62. Construct a BCD adder using two 4-bit binary adders. (JNTU May 02)

63. i. Convert the following hexadecimal number F3A7C2 binary and octal.ii. Obtain the 9’s complement of the following 8 digit decimal number :-

i. 12345678 ii. 00000000 (JNTU Nov 01)

64. i. Design a one-stage logic circuit giving the function table.ii. Design a 4 bit combinational circuit decrementor using 4 full adders. (JNTU Nov 01)

65. i. Discuss the relative advantages of sign-magnitude and twos-complement number cods in representing the mantissa of floating point number.

ii. Show how a 9 bit microoperation field in a microinstruction can be divided into subfields to specify 46 microoperations. How many microoperations can be specified in one microinstruction?(JNTU Nov 00)

66. Perform the arithmetic operations (+42) + (-13) and (-42) – (-13) in binary using signed – 2’s complement representation for negative number. (JNTU May 00)

58


67. A CPU has a five stage pipeline and runs at 1Ghz frequency. Instruction fetch happens in the first stage of the pipeline. A Conditional branch instruction computes the target address and evaluates a condition in the third stage of the pipeline. The processor stops fetching new instructions following a

conditional branch until the branch outcome in known. A program executes 109 instructions outof which 20% are conditional branches. If each instruction takes 1 cycle to complete on average, the total execution time of the program is i. 1.0 sec ii. 1.2 sec iii. 1.4 sec iv. 1.6 sec. (GATE 06)

68. Consider a new instruction named branch-on-bit-set (mnemonic bbs). The instruction “bbs reg, pos, lable” jumps to label if bit in position pos of register operand reg is one. A register is 32 bits wide and the bits are numbered 0 to 31, bit in position 0 being the least significant. Consider the following emulation of this instruction on a processor that does not have bbs implemented.temp reg and maskBranch to label if temp is non-zeroThe variable temp is a temporary register. For correct emulation, the variable mask must be generated byi. mask 0 x 1 << posii. mask 0 x ffffffff >> posiii. mask posiv. mask 0 x f (GATE 06)

69. Consider a three word machine instructionADD A [R0], @ BThe first operand (destination) “A[RO]” uses indexed addressing mode with R0 as the index register. The second operand (source) “@B” uses indirect addressing mode. A and B are memory addresses residing at the second and the third words, respectively. The first word of the instruction specifies the opcode, the index register designation and the source and destination addressing modes. During execution of ADD instruction, the two operands are added and stored in the destination (first operand).The number of memory cycles needed during the execution cycle of the instruction is :i. 3 ii. 4 iii. 5 iv. 6 (GATE 05)

70. A 5 stage pipelined CPU has the following sequence of stages :IF - Instruction fetch from instruction memory.RD - Instruction decode and register read.EX - Execute : ALU operation for data and address computation.MA - Data memory access - for write access, the register read at RD state is used.WB - Register write back.Consider the following sequence of instructions :I1: L R0, loc 1; R0 <= M [loc1]

I2: A R0, R0 1; R0 <= R0 + R0

Let each stage take one clock cycle.What is the number of clock cycles taken to complete the above sequence of instructions starting from the fetch of I1 ?

i. 8 ii. 10 iii. 12 iv. 15 (GATE 05)

71. Assuming all numbers are in 2’s complement representation, which of the following numbers is divisible by 11111011? (GATE 03)i. 11100111 ii. 11100100 iii. 11010111 iv. 11011011

72. Convert the following numbers in the given bases into their equivalents in the desired bases. (i.) 110.101 (2 = x)10 (ii). 1119(10 = y)Hi. ABE ii. DBC iii. DE5 iv. 9E7

59


73. The decimal value 0.25 (GATE 02)i. is equivalent to the binary value 0.1ii. is equivalent to the binary value 0.01iii. is equivalent to the binary value 0.00111...iv. can not be represented precisely in binary

74. The 2’s complement representation of the decimal value - 15 isi. 1111 ii. 11111 iii. 111111 iv. 10001

75. In 2’s complement addition, overflow (GATE 02)i. is flagged whenever there is carry from sign bit additionii. can not occur when a positive value is added to a negative valueiii. is flagged when the carries from sign bit and previous bit matchiv. None of the above

76. The 2’s complement representation of (-539) 10 in hexadecimal is (GATE 01)

77. The number 43 in 2’s complement representation is (GATE 00)i. 01010101 ii. 11010101 iii. 00101011 iv. 10101011

78. Fill in the blanks : (GATE 90)In the two bit full-adder/substractor unit shown in Fig. (1), when the switch is in position 2 ……………….. using ……………. Arithmetiiii.

79. A 32-bit floating number is represented by a 7-bit signed exponent, and a 24-bit fractional mantissi. The base of the scale factor is 16, (GATE 90)

i. The range of the exponent is ……………….ii. The range of the exponent is ………………. if the scale factor is represented in excess-64 format.

80. It is required to flash 8 LEDs connected to Port A of 8085 microcomputer system continuously. The last two instructions I the following assembley language program should be, (GATE 90)LEDFLS: LXI SP, STACKMVI A, FFFLASH: OUT PORT ACALL DELAY

81. The flags are affected when conditional CALL or JUMP instructions are executeiv. (GATE 90)

UNIT-III

1. Discuss about various Pentium addressing modes with algorithms (JNTU May 08)

2. a. Explain about user-visible registers.b. Compare register organizations Z 8000 with 8086 processors. (JNTU May 08, Nov 07)

3. NOOP instruction has no effect on the CPU state other than incrementing the program counter. Suggest some uses of this instruction with examples. (JNTU May 08, Nov 07)

4. a. What are the major design considerations in microinstruction sequencing?. b. Explain about microinstruction sequencing techniques, specifically variableformat address

microinstruction. (JNTU Sep 07)

5. a Explain nanoinstructions and nanometry. Why do we need them? b. Describe advantages and disadvantages of horizontal and vertical microcoded systems.

(JNTU Sep 07)

6. a Explain the various microinstruction encoding techniques. b. List and explain the implicit microinstruction address generation techniques. (JNTU Sep 07)

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7. i. Discuss about micro instruction sequencing containing the single address field.ii. Differentiate between explicit and implicit microinstruction address generation technique.

(JNTU Feb 07)

8. Distinguish between hardwired control and micro programmed control. Explain a micro programmed control unit with the help of a block diagram. (JNTU Feb 07/Nov 02)

9. i. List sequecing and branching control fields of IBM 3033 micro instructions.ii. Discuss the functioning of microsequence of with example. (JNTU Feb 07)

10. i. Elaborate on control of micro sequencer.ii. Discuss about 8832, which is a registered ALU (JNTU May 05)

11. Discuss about current applications of micro programming in detail. (JNTU May 05)

12. i. Clearly distinguish between i) Packed/Unpacked microinstructions ii) Hard/Soft microprogrammingii. List and briefly explain applications of microprogramming. (JNTU May 05)

13. i. With the help of a diagram, clearly explain the functioning of a micro programmed control unit.ii. Micro programmed unit is slower than hardwired unit. Justify this statements. (JNTU Nov 04)

14. i. Discuss about microinstruction execution.ii. Differentiate between packed and unpacked microinstruction.iii. Differentiate between hard and soft micro programming. (JNTU Nov 04)

15. i. Discuss about microinstruction sequencing containing single address fieliv.ii. Differentiate between explicit and implicit microinstruction address generation techniques.iii. Give different classifications of microinstructions. (JNTU Nov 04)

16. i. List sequencing and branching control fields of IBM 3033 microinstruction.ii. Discuss the functioning of micro sequencer with example. (JNTU Nov 04)

17. i. Elaborate on control of micro sequencer.ii. Discuss about 8832, which is a registered ALU (JNTU Nov 04)

18. Discuss about current applications of micro programming in detail. (JNTU Nov 04)

19. i. Explain the top level view of computer components.ii. What do you mean by hardwired program? (JNTU May 04)

20 i. Explain the register organization in a Power PC processor.ii. Classify interrupts on a Power PIII. (JNTU May 04)

21. i. What do you mean by hardwired program?ii. List the basic functions performed by a computer. (JNTU May 04)

22. i. Discuss various aspects of instruction set designii. Explain about various types of data in detail on which machine instructions operate.( JNTU May 04)

23. i. Explain about Machine state register.ii. Discuss about the sequence of steps that occurs when an interrupt occurs. (JNTU May 04)

24. Microprogrammed unit is slower than hardwired unit. Justify this statement (JNTU Nov 03)

25. Define the following:i. Control memory ii. Hardwired control iii. Micro code iv. Micro-operation v. Control word vi. Nano programming vii. Execute cycle vii. Paging (JNTU Nov 03)

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26. i. With the help of a diagram, clearly explain the functioning of a microprogrammed control unit.ii. Micro programmed unit is slower than hardwired unit. Justify this statement. (JNTU Nov 03)

27. i. With the help of a diagram, clearly explain the functioning of a microprogrammed control unit.ii. Microprogrammed unit is slower than hardwired unit. Justify this statement. (JNTU Jun 03)

28. i. What is a micro-operation? With the help of a diagram explain the constituent elements of a program execution.

ii. Expand and explain the following terms: MAR, MBR, PC, IR (JNTU Jun 03)

29. Clearly explain the following terms:i. Microprogram ii. Microinstruction ii. Microprogramming iv. Microprogramming language. (JNTU Jun 03)

30. With the help of a diagram, clearly explain the functioning of a microprogrammed control unit.(JNTU Jun 03)

31. i. Clearly explain the following terms: i) Control word ii) Control memory iii) Control address register iv) Control buffer register.

ii. Compare hardwired and micro programmed approaches to control unit design. (JNTU Jun 03)

32 i. Explain the sequences of micro of operations involved in an instruction cycle using a flow chart.ii. What is an executive cycle? Give the sequence of operations involved in SKIP and increment

instructions. (JNTU Jun 03)

33. i. Describe the functions performed by a control unit with the help of a functional diagram.ii. Give the organization of a control memory. (JNTU Jun 03)

34. i. Describe the working of a microprogrammed sequence.ii. Describe Wilke’s control unit design. (JNTU Jun 03)

35. Explain micro program sequencer with a block diagram. (JNTU Jun 03)

36. Write a sequence of micro-operation for the following: i) Fetch cycle ii) ISZ instruction.(JNTU May 02)

37. i. Explain the purpose of control memory?ii. Explain how a mapping from an instruction code to micro-instruction address can be done by means of

a read only memory? (JNTU May 02)

38. List four alternatives for achieving a conditional branch operation in a control memory.(JNTU May 02)

39. i. Clearly explain the following termsi) Micro program ii) Microinstruction iii) Micro programming iv) Micro programming language

ii. Draw the diagram of micro architecture control unit and explain. (JNTU Jan 02)

40. i. Distinguish between horizontal and vertical micro instructions.ii. Explain micro program control unit architecture. (JNTU Jan 02)

41. i. Explain manoprogrammed control unit with a diagramii. What are the applications of micro programming? (JNTU Jan 02)

42. Describe the organization and working of a micro programmed control unit with the help of a neat block diagram showing the flow of signals. (JNTU Nov 02)

43. Explain various applications of micro programming. (JNTU Jan 02)

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44. A microprogram sequencer uses a register stack eight levels deep: (JNTU May 02)i. Draw block diagram of the sequencer.ii. Formulate the sequence of internal operations.

Which are required to implement the call and return from subroutine microinstructions?

45. i. Define the following :-i. Micro-operation ii. Micro-instruction iii.Micro-program iv. Micro-Code.

ii. Explain the difference between Hardwired control and Micro-programmed control.(JNTU Nov 01)

46. List the disadvantages of hardwired control unit. (JNTU Nov 01)

47. Explain the difference between hardwired control and microprogrammed control. Is it possible to have a hardwired control associated with a control memory? (JNTU Nov 00)

48. Explain the difference between hardwired control an microprogrammed control. Is it possible to have hardwired control associated with a control memory. (JNTU Nov 00)

49. Horizontal microprogrammingi. does not require use of signal decodersii. results in larger sized microinstructions than vertical microprogrammingiii. uses one bit for each control signaliv. all of the above (GATE 02)

50. A micro instruction is to be designed to specify (GATE 97)i. none or one of the three microoperations of one kind andii. none or upto six microoperations of another kind

The minimum number of bits in the micro-instruction isi. 9 ii. 5 iii. 8 iv. none of the above

51. A microprogrammed control uniti. is faster than a hard-wired control unit.ii. facilitates easy implementations are to be run.iii. is useful when very small programs are to be run.iv. usually refers to the control unit of a microprocessor. (GATE 87)

UNIT – IV

1. a. List various R3000 pipeline stages. Also explain the function of each.b List and describe all shift and multiply/divide instructions of MIPS R-Series processors.

(JNTU May 08)

2. Elaborate on different types of registers in a register organization (JNTU May 08)

3. a List and describe Load/Store instructions of MIPS R-Series processorb. Discuss about synthesizing other addressing modes with MIPS addressing mode

(JNTU May 08, Feb 08)

4. Discuss about various Pentium addressing modes with algorithms. (JNTU Nov 07)

5. a. Differentiate between large register file versus cache.b. Discuss how compiler based register optimization is done.

c. Explain various characteristics of reduced instruction set architectures. (JNTU Nov 07)

a. List and describe integer arithmetic and logical instructions of Motorola 88000.b. Discuss about functioning of Motorola 88000 instruction unit pipeline (JNTU Nov 07)

6. a. Discuss the motivation for CISC. b. Differentiate between CISC and RISC characteristics. (JNTU Nov 07)

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7. a. How many bits are needed to store the result addition, subtraction, multiplication and division of two n-bit unsigned numbers. Prove.

b. What is overflow and underflow. What is the reason?. If the computer is considered as infinite system do we still have these problems?. (JNTU Sep 07)

8. a. Explain single precision and double precision calculations. In general howmany bytes are uses for both and what is the precision we get. Give some examples where double precision calculations are needed.

b. Explain booths algorithm with its theoretical basis. (JNTU Sep 07)

9. Write an algorithm to find allowable wieths for a “weighted BCD code”. Assume that all weiths are positive numbers. (JNTU Feb 07/Nov 06)

10. i. Explain how floating point division is done?ii. Explain the addition binary number in 1’s Complement notation. (JNTU Feb 07/Nov 06)

11. i. Explain about the airthmatic in excess-3 code.ii. Discuss about normalize floating point. (JNTU Nov 06)

12. i. List and describe all arithmetic instructions of MIPS R-Series processorsii. Discuss how R3000 pipeline can be modified to improve performance. (JNTU May 05)

13. i. Differentiate between direct and indirect microinstruction encoding with diagrams.ii. Explain the components of 8800 SDII. (JNTU Nov 04)

14. i. What is a Booth’s algorithm for 2’s compliment multiplications? Explain it with an example.ii. Explain the significance of guard bits in floating-point operation with an example.( JNTU May 04)

15. i. Explain about booth coding.ii. Find the booth coded numbers of the following binary numbers. i. 01101111101 ii. 000111110110

(JNTU Nov 04)

16. i. What are the different instruction formats available. Explain them giving two examples.ii. Discuss about bus Heirarchy. (JNTU Nov 02)

17. What are the micro-operations involved in fetching and decoding an instruction? Explain how they are executed? (JNTU Nov 02)

18. Compare hardwired control unit, micro programmed unit and nano programmed control unit with their merits and demerits. (JNTU Nov 02)

19. What is RISIII. What are the advantages of RISIII. (JNTU Nov 02)

20. i. Discuss different addressing modes with examples?ii. Write a assembly language program that evaluates the logic Exclusive OR of two logic operands.

(JNTU May 02)

21. i. Differentiate micro-operations from macro-operations.ii. Explain various addressing modes in 8085. (JNTU May 02)

22. i. Describe the rules of addition and multiplication of floating point numbers with suitable examples.ii. Using a numerical example, explain Booth’s algorithm for multiplication. (JNTU May 02)

23. i. An instruction is stored at location 300 with its address field at location 301. The address field has the value 401. A processor register contains the number 200. Evaluate the effective

address if the addressing mode of the instruction is:i direct ii. immediate iii. relativeiv. register indirect v. Index with R as the index register. (JNTU May 01)

24. Explain the implementation of fixed point arithmetic in a processor of your choice.( JNTU May’01)

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25. i. What is the difference between direct addressing and indirect addressing? How many reference to memory are needed for each type of instruction to bring an operand into a processor register?

ii. Write an assembly language program to multiply two positive number by a repeated addition methoiv.(JNTU Nov 01)

26. Write short notes on Micro Operations. (JNTU Jan 02)

27. Write short notes on Micro Operations. (JNTU Jan 02)

28. Compare horizontal and vertical micro instructions. (JNTU Nov 02)

29. Show the micro operations for the following instructions :-i. Load accumulator ii. Store accumulator iii. Add to accumulator iv. AND to accumulator v. JUMP vi. Complement accumulator. (JNTU May 01)

30. Briefly describe various micro-instruction formats. (JNTU May 01)

31. What is the difference between a direct and an indirect address instruction? How many references to memory are needed for each of instruction to bring an operand into a processor register?

(JNTU May 00)

32. A block-set-associative cache consists of a total of 64 blocks divided into 4-blocks sets. The main memory contains 4096 blocks, each consisting of 128 words.

a. How many bits are there in a main memory address? (JNTU May 00)

33. Consider a direct mapped cache of size 32 KB with block size 32 bytes. The CPU generates 32 bit addresses. The number of bits needed for cache indexing and the number of tag bits are respectivelyi. 10, 17 ii. 10, 22iii. 15, 17 iv. 5, 17 (GATE 05)

34. Match each of the high level language statements given on the left hand side with the most natural addressing mode from those listed on the right hand side.1) A[1] = B[J]; a) Indirect addressing2) while [*A++]; b) Indexed addressing3) int temp = *x; c) Autoincrementi. (1, c), (2, b), (3, a)ii. (1, a), (2, c), (3, b)iii. (1, b), (2, c), (3, a)iv. (1, a), (2, b), (3, c) (GATE 05)

35. Consider a direct mapped cache of size 32 KB with block size 32 bytes. The CPU generates 32 bit addresses. The number of bits needed for cache indexing and the number of tag bits are respectivelyi. 10, 17 ii. 10, 22iii. 15, 17 iv. 5, 17 (GATE 05)

36 Which of the following addressing modes are suitable for program relocation at run time? (GATE 04)i) Absolute addressing ii) Based addressingiii) Relative addressing iv) Indirect addressing

i. (i) and (iv) ii. (i) and (ii) iii. (ii) and (iii) iv. (i), (ii) and (iv)

37. Which of the following addressing modes are suitable for program relocation at run time?i) Absolute addressing ii) Based addressingiii) Relative addressing iv) Indirect addressing

i. (i) and (iv) ii. (i) and (ii)iii. (ii) and (iii) iv. (i), (ii) and (iv) (GATE 04)

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38. A device employing INTR line for device interrupt puts the CALL instruction on the data bus while(GATE 02)

i. INTA is activeii. HOLD is activeiii. READY is activeiv. None of the above.

39. In which of the following is absolute addressing mode (GATE 02)i. The operand is inside the instructionii. The address of the operand is inside the instructioniii. The register containing the address of the operand is specified inside the instructioniv. The location of the operand is implicit

40. A device employing INTR line for device interrupt puts the CALL instruction on the data bus whilei. INTA is activeii. HOLD is activeiii. READY is activeiv. None of the above. (GATE 02)

41. Match each of the high level language statements given on the left hand side with the most natural addressing mode from those listed on the right hand side.1) A[1] = B[J]; a) Indirect addressing2) while [*A++]; b) Indexed addressing3) int temp = *x; c) Autoincrementi. (1, c), (2, b), (3, a)ii. (1, a), (2, c), (3, b)iii.(1, b), (2, c), (3, a)iv.(1, a), (2, b), (3, c) (GATE 05)

42. The main difference(s) between a CISC and a RISC processor is / are that a RISC processor typicallyi. has fewer instructions ii. has fewer addressing modesiii. has more registers iv. is easier to implement using hard-wired control logiiii. (GATE 99)

43. The Link-load-and-go loading scheme required less storage space than the Link-and-go loading scheme. (GATE 90)

44. It is required to flash 8 LEDs connected to Port A of 8085 microcomputer system continuously. The last two instructions I the following assembley language program should be, (GATE 90)LEDFLS: LXI SP, STACKMVI A, FFFLASH: OUT PORT ACALL DELAY

45. The flags are affected when conditional CALL or JUMP instructions are executeiv. (GATE 90)

46. State the Booth’s algorithm for multiplication of two numbers. Draw a block diagram for the implementation of the Booth’s algorithm for determining the product of two 8-bit signed numbers.

(GATE 90)

47. Match the pairs in the following question (GATE 89)i) i) Base addressing v) Reentranecy

ii) Indexed addressing vi) Accumulatoriii) Stack addressing vii) Arrayiv) Implied addressing viii)Position independent

48. Design a fully-decoded address decoder circuit with minimum chip count. The RAM and ROM are to be mapped onto the highest and lowest order memory locations, respectively in the memory address space. The I/O locations are to occupy lower order I/O address space. (GATE 89)

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49. The most relevant addressing mode to write position-independent codes isi. Direct modeii. Indirect modeiii. Relative modeiv. Indexed mode (GATE 87)

UNIT - V

1. a. Differentiate between single versus two-level caches.b. Elaborate on Pentium Cache Organization. (JNTU May 08)

2. Discuss about address translation with segmentation and paging in the Intel Pentium(JNTU May 08)

3. Give a block diagram for a 4M×8 memory using 256K×1 memory chips. (JNTU May 08)

4. a. Discuss about address translation in paging.b. How does page size effects storage utilization and efective memory data transfer rate (JNTU May 08)

5. a. Explain the functioning of ROM cellb. Draw and describe the working of CMOS memory cell.c. Draw and explain about a single-transistor of dynamic memorycell. (JNTU Feb 08)

6. a. Discuss the principles of associative memory.b. Explain the functioning of 4 x 4 bit associative memory array.c. Explain the cache with two-way set-associative addressing (JNTU Nov 07)

7. a. Explain any three replacement algorithms with examples.b. Discuss in detail about set associative mapping in cache memory. (JNTU Nov 07)

8. a. Elaborate on functioning of inverted page table structure.b. Differentiate between ordinary page table and inverted page tablec. Why translation-look-aside buffer is used. (JNTU Nov 07)

9. a. What is demand paging. Explain it’s advantages and disadvantages.b. Explain the page table structure. Discuss it’s purpose. (JNTU Nov 07)

10. a. Explain how the Bit Cells are organized in a Memory Chip b. Explain the organization of a 1K x 1 Memory with a neat sketch‘ (JNTU Sep 07)

11. i. What is deman paging. Explain it’s advantage and disadvantageii. Explain the page table structure. (JNTU Feb 07)

12. Write short notes on the following approaches with suitable examples. What are merits and demerits of each.

i. First - fitii. Best – fitiii. Worst – fit (JNTU Feb 07/May 05)

13. i. Explain the major differences between cache main and main-secondary memory hierachies.ii. Discuss main features and basic structure of cache. (JNTU Feb 07)

14. i. Explain the cache execution of a read operation.ii. Explain look aside system organisation of cache. (JNTU Nov 06)

15. i. Elaborate about purpose and organization of data on magnetic tapeii. Differentiate between magnetic disk and magnetic tape.iii. Discuss the technology used for CD Rom system. (JNTU Nov 06)

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16. i. Define the following term.i. Hit ratioii. Miss ratio

ii. What do you mean by cache coherence problem?iii. Explain how cache memory can be used in pagging. (JNTU Nov 06)

17. A computer systems supports 32 bit virtual address as well as 32 bit physical address since the virtual address space is of the same size as the pysical address space, the operating system designer decide to get rid of the virtual memory entirely. which one of the followig is true?

i. Efficient implementation of multi-user support is no longer possible.ii. The processor cache organization can be made more efficient nowiii. Hardware support for mamory management is no longer needediv. CPU schedulig can bemade more efficient now.

18. i. What do you mean by virtual memory. Also explain about virtual memory organization.ii. Criticize he following statement: “Using a faster processor chip results in a corresponding increase in

performance of a computer, even if the main memory speed remains the same”. (JNTU May 05)

19. i. Discuss about principles of cache memory.ii. Elaborate on elements of cache memory.iii. Explain the purpose of replacement algorithms (JNTU May 05)

20. i. Explain any three replacement algorithms with examples.ii. Discuss in detail about set associative mapping in cache memory. (JNTU May 05)

21. i. Compare SRAM with DRAM.ii. Why are multilevel memories used in a computer system? (JNTU May 05)

22. Write short notes on the following page replacement schemesi. First in first out (FIF0)ii. Least Recently used (LRU) (JNTU May 05)

23. A block-set-associative Cache consists of a total of 64 blocks divided into four blocks sets. The main memory contains 4096 blocks each consisting of 128 words.

i. How many bits are there in main memory address?ii. How many bits are there in each of the TAG, SET, and WORD fields? (JNTU May 04)

24. i. What do you mean by virtual memory. Also explain about virtual memory organization.ii. Criticize the following statement: “Using a faster processor chip results in a corresponding increase in

performance of a computer, even if the main memory speed remains the same”. (JNTU May 04)

25. i. What do you mean by page fault?ii. Explain how number of page faults can be calculated for the given page trace using FIFO page

replacement strategy. (Assume 3 frames are available in the memory). (JNTU May 04)

26. i. Explain the following:i) Nanomemory ii) Nanoinstructions iii) Control memory iv) Writable control memory v) Microoperation.

ii. Explain a typical nanomemory control organization with a schematic for multiple memory level hierarchy. (JNTU May 04)

27. Write short notes on the following: (JNTU May 04)i. Look-aside organization for cacheii. Look-through organization for cache.

28. Explain the following in detail:i. Cache typesii. Performance of cache memory. (JNTU May 04)

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29. i. What is the use of associative memory?ii. Explain the direct mapping and set-associative address mapping techniques in detail.( JNTU May 04)

30. i. What are the advantages of paging?ii. Explain how logical address can be converted into physical address in a paging system?

(JNTU May 04)

31. What are the different mapping techniques of cache memory? Describe each technique with suitable diagram. (JNTU Nov 04)


(JNTU Nov 04)

33. i. What are memory management requirements.ii. Elaborate on address translation in virtual memories. (JNTU Nov 04)

34. i. Discuss the principles of associative memory.ii. Explain the functioning of 4 x 4 bit associative memory array.iii. Explain the cache with two-way set-associative addressing (JNTU Nov 04)

35. Explain different techniques of cache mapping function with merits and demerits of each.(JNTU May 04)

36. Write short notes on Virtual memory. (JNTU Nov 03)

37. Write short notes on Memory hierarchy (JNTU Nov 02)

38. It is required to transfer data between cache memory and main memory whenever there is a ‘miss’ (that is the required data is not available in cache memory). Explain three different mechanisms that will assist data transfer between main memory and cache memory. (JNTU Nov 02)

39. Write short notes on DRAM organization and Associative memory. (JNTU Nov 02)

40. Explain the concept of cache memory with a diagram and the three types of memory mapping techniques used to implement cache memory. (JNTU Nov 02)

41. i. Explain, how segmentation scheme is implementeiv.ii. Explain the basic cells of SRAM, ROM and DRAM. (JNTU Nov 02)

42. i. Describe Memory hierarchy.ii. What is Virtual memory? Explain, how demand paging is implementeiv. (JNTU Nov 02)

43. Write short notes on Cash memory. (JNTU Nov 02)

44. i. With the help of a block diagram explain a DMA controller.ii. What is the difference between isolated I/O and memory mapped I/O. List the advantages and

disadvantages of each. (JNTU May 02)

45. i. How many 128 x 8 RAM chips are needed to proved a memory capacity of 2048 bytes and ho many lines of the address bus must be used to access this memory.

ii. Explain the working of a CACHE memory. (JNTU May 02)46. i. Explain the concept of virtual memory with a diagram.

ii. Explain the principle of DMA operation. (JNTU May 02)

47. Write notes on DRAM. (JNTU May 02)

48. i. Explain about associate memory.ii. A ROM chip of 1024 X 8 bits has four select inputs and operates from a 5-V power supply. How many

pins are needed for the IC package? Draw a block diagram and label all i/p and o/p terminals in ROM.(JNTU Nov 02)

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49. Write short notes on i DRAM ii Instruction pipelining iii I-O Channels iv) Virtual memory. (JNTU Nov 02)

50. Describe the mechanism of data storage and retrieval in a magnetic disk. How do you access files in a magnetic tape? (JNTU May 02)

51. i. The access time of a Cache memory is 100 ns and that of main memory is 1000 ns. It is estimated 80 percent of the memory requests are for read and the remaining 20 percent for write. The hit

ratio for read access only is 0.9. A write through procedure is useiv.i What is the average access time of the system considering only memory read cycles?ii What is the average access time both for read and write cycles ?

ii. Describe how Omega network is acting as a switch to control processor-memory organization.(JNTU May 01)

52. Explain the following :- i) Associative Mapping ii) Direct Mapping iii) Set Associative Mapping.(JNTU Nov 01)

53. Write short notes on Memory Management. (JNTU Nov 01)

54. What is the need for memory hierarchy? Explain the different components and their characteristics like speed, cost….etc; in a typical memory hierarchy? (JNTU May 01)

55. How many times does the control unit refer to memory when it fetches and executes an indirect-addressing mode instruction if the instruction is

i. A computational type requiring an operand from memory ii. A branch type. (JNTU Nov 00)

56. i. How many characters per second can be transmitted over a 1200-band line in each of the following modes? (Assume a character code of 8 bits) :

i. Synchronous serial transmissionii. Asynchronous serial transmission with 2 stop bits.

ii. Describe the concept of virtual memory. (JNTU Nov 00)

57. Derive the advantages of a memory using the phenomenon of locality of reference.( JNTU Nov 00)58. Define :

i. Spooling ii. Critical code iii. Skew iv. Hardware lock. (JNTU Nov 00)

59. Explain segmented-page mapping. (JNTU May 00)

60. A computer system supports 32-bit virtual addresses as well as 32-bit physical addresses. Since the virtual address space is of the same size as the physical address space, the operating system designers decide to get rid of the virtual memory entirely. Which one of the following is true ?

i. Efficient implementation of multi-user support is no longer possible.ii. The processor cache organisation can be made more efficient nowiii. Hardware support for memory management is no logner needediv. CPU scheduling can be made more efficient now (GATE 06)

61. Consider two cache organisations: The first one is 32 KB 2-way set associative with 32-byte block size. The second one is of the same size but direct mapped. The size of an address is 32 bits in both cases. A 2-to-1 multiplexer has a latency of 0.6 ns while a k-bit comparator has a latency of k/10 ns. The hit latency of the set associative organization is h1 while that of the direct mapped one is h2.

62. The value of h1 is:i. 2.4 ns ii. 2.3 ns iii. 1.8 ns iv. 1.7 ns (GATE 06)

63. The value of h2 is:i. 2.4 ns ii. 2.3 ns iii. 1.8 ns iv. 1.7 ns (GATE 06)

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64. Consider a disk drive with the following specifications:16 surfaces, 512 tracks/surface, 512 sectors/track, a KB/sector, rotation speed 3000 rpm. The disk is operated in cycle stealing made whereby whenever one byte word is ready it is sent to memory; similarly, for writing, the disk interface reads a 4 byte word from the memory in each DMA cycle. Memory cycle time is 40 nseiii. The maximum percentage of time that the CPU gets blocked during DMA operation is i. 10 ii. 25 iii. 40 iv. 50 (GATE 05)

65. A device with data transfer rate 10 KB/sec is connected to a CPU. Data is transferred byte-wise. Let the interrupt overhead be 4 sec. The byte transfer time between the device interfaces register and CPU or memory is negligible. What is the minimum performance gain of operating the device under interrupt mode over operating it under program controlled mode ?i. 15 ii. 25 iii. 35 iv. 45

66. Increasing the RAM of a computer typically improves performance because :i. Virtual memory increases ii. Larger RAMs are fasteriii. Fewer page faults occur iv. Fewer segmentation faults occur (GATE 05)

67. Using a larger block size in a fixed block size file system leads to (GATE 03)i. Better disk throughput but poorer disk space utilizationii. Better disk throughput and better disk space utilizationiii. Poorer disk throughput but better disk space utilizationiv. Poorer disk throughput and poorer disk space utilization

68. In a system with 32 bit virtual addresses and 1 KB page size, use of one-level page tables for virtual to physical address translation is not practical because of

i. The large amount of internal fragmentationii. The large amount of external fragmentationiii. The large memory overhead in maintaining page tablesiv. The large computation overhead in the translation process (GATE 03)

69. Which of the following is not a form of memory? (GATE 02)i. Instruction cache ii. Instruction registeriii. Instruction opcode iv. Translation lookaside buffer

70. A CPU has 32-bit memory address and a 256 KB cache memory. The cache is organized as a 4-way set associative cache with cache block size of 16 bytes. (GATE 02)

i. What is the number of sets in the cache?ii. What is the size (in bits) of the tag field per cache block?iii. What is the number and size of comparators required for tag matching?iv. How many address bits are required to find the byte offset within a cache block?v. What is the total amount of extra memory (in bytes) required for the tag bits?

71. Which of the following is not a form of memory? (GATE 02)i. Instruction cacheii. Instruction registeriii. Instruction opcodeiv. Instruction look aside buffer

72. The main memory of a computer has 2 cm blocks while the cache has 2 c blocks. If the cache uses the set associative mapping scheme with 2 blocks per set, then lock k of the main memory maps to the seti. (k mod m) of the cache ii. (k mod c) of the cacheiii.(k mod 2c) of the cache iv. (k mod 2 cm) of the cache (GATE 99)

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73. Suppose we have a computer with a single register and only three instructions given below:LOAD addren ; load register ; from addrenSTORE addren ; store register; at addrenADD addren ; add register to; contents of addren; and place the result; in the registerConsider the following grammar:A id : = E E E + T | T T (E) | idWrite a syntax-directed translation to generate code using this grammar for the computer describe above. (GATE 94)

74. A computer system has a 4K word cache organised in block-set-associative manner with 4 blocks per set, 64 words per block. The number of bits in the SET and WORD fields of the main memory address format isi. 15, 40 ii. 6,4 iii. 7,2 iv. 4, 6 (GATE 94)

75. The correct matching for the following pairs is (GATE 94)i. DMA I/O 1. High speed RAMii. Cache 2. Diskiii. Interrupt I/O 3. Printeriv. Condition Code Register 4. ALU

i. a-4, b-3, c-1, d-2 ii. a-2, b-1, c-3, d-4 iii. a-4, b-3, c-2, d-1 iv. a-2, b-3, c-4, d-1

76. A ROM is used to store the Truth table for a binary multiplier unit that will multiply two 4-bit numbers. The size of the ROM (number of words x number of bits) that is required to accommodate the Truth table is M words x N bits. Write the values of M and N. (GATE 93)

77. In an 11-bit computer instruction format, the size of address field is 4-bits. (GATE 92)The computer uses expanding OP code technique and has 5 two-address instructions and 32 two-address instructions and the number of zero-address instructions it can support is.....

78. It is required to design a hardwired controller to handle the fetch cycle of a single address of an indexed instruction should be derived in the fetch cycle itself. Assume that the lower order 8 bits of an instruction constitute the operand fieliv.

i. Give the register transfere sequence for realising the above instruction fetch cycle.ii. Draw the logic schematic of the hardwired controller including the date path. (GATE 91)

79. RAM is a combinational circuit and PLA is a sequential circuit. (GATE 90)

80. Under paged memory management scheme, simple lock and key memory protection arrangement may still be required if the …………….. processors do not have address mapping hardware. (GATE 90)

81. Transferring data in blocks from the main memory to the cache memory enables an interleaved main memory unit to operate unit at its maximum speeiv. (GATE 90)

82. A block-set associative cache memory consists of 128 blocks divided into four block sets. The main memory consists of 16, 384 blocks and each block contains 256 eight bit words. (GATE 90)

i. How many its are required for addressing the main memory?ii. How many bits are needed to represent the TAG, SET and WORD fields?

83. Match the pairs in the following question (GATE 89)i) i) Virtual Memory v) Temporal Locality

ii) Shared memory vi) Spatial Localityiii) Look – ahead buffer vii) Address Translationiv) Look – aside buffer vii) Mutual Exclusion

84. What is the ht ratio? (GATE 89)

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85. A ROM has the following timing parameters:Maximum Address to valid Data Output delay = 30 n seiii.Maximum Chip Select to valid Data Output delay = 20 n seiii.Maximum Data Hold time (after address change or after chip deselect) = 10 n seiii.Assume that,

i. the chip is selected using one of the address lines, and,ii. the data set up time is negligible.

What is the maximum rate at which a CPU can continuously read data from this ROM? (Show your calculations step-by step).

iii. Briefly explain the term “Configuring a programmable peripheral chip.” (GATE 88)

86. The refreshing rate of dynamic RAMs isin the range of (GATE 87)i. 2 microseconds ii. 2 milliseconds iii. 50 milliseconds iv. 500 milliseconds

UNIT- VI

1. a Explain about magnetic disk layoutb. Elaborate on Winchester disk track format. (JNTU May 08)

2. Discuss about data organization and formatting of magnetic disk in detail (JNTU May 08)

3. a. Discuss about I/O channel architecture.b Discuss about I/O addressing in 8086.c Discuss the salient features of laser printer (JNTU May 08)

4. a. Explain the program flow of control with and without interrupts. Demonstrates with suitable figures.b Discuss the ideal situations for short and long I/O wait.c. How multiple interrupts will be handled (JNTU Feb 08)

5. a. Explain about CD-ROM block format.b. What is WORM? Also explain its uses.c. Differentiate between disk layout using constant angular velocity and constant linear velocity

(JNTU Nov 07)

6. a. Explain how bus arbitration is done in DMA transferb. Discuss about the generic model of an I/O module. (JNTU Nov 07)

7. Explain the following:a. Isolated Vs Memory mapped I/Ob. I/O Bus Vs Memory Busc. I/O Interfaced. Peripheral Devices (JNTU Sep 07)

8. a. Explain bit oriented and character oriented protocols in serial communicationb. What are the different issues behind serial communication? Explain. (JNTU Sep 07)

9. i. Explain about magnetic disk layout.ii. Elaborate on Winchester disk track format. (JNTU Feb 07)

10. Explain about ALU control field of IBM 3033 micor instruction. (JNTU Feb 07)

11. i. What is data strippting?ii. Explain the control commands operation enable be magnetic tape drive controller.( JNTU Feb 07)

12. i. Differentiate between I/O technique with and without the use of interrupts.ii. Explain different type of I/O commands.iii. Whatis isolated I/O. Differentiate between memory map and isolated I/O. (JNTU Feb 07)

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13. i. Explain about the magnetic disk principle along with its advantages.ii. Discuss the format of a disk address world. (JNTU Nov 06)

14. i. Discuss about I/O channel architecture.ii. Discuss about I/O addressing in 8086.iii. Discuss the sailent feature of laser printer. (JNTU Nov 06)

15. i. Discuss about interrupt structureii. Explain various register in a DMA interface. (JNTU Nov 06)

16. i. Explain the principal and working of dot matrix printerii. Differentiate between different type of printers. (JNTU Nov 06)

17. What is Asynchronous data transfer? Explain various methods of asynchoronous data transfer.(JNTU Nov 06)

18. i. Draw and explain the timing of read operation in both synchronous and asynchronous timing.ii. Discuss various data transfer types supported by buses. (JNTU May 05)

19. i. List various data transfer operations of IBM S/370 systemii. Explain about common transfer-of-control operations found in instruction sets.

20 i. Explain about the magnetic disk principles along with its advantages.ii. Discuss the format of a disk address woriv.iii. Discuss about disk operations. (JNTU May 05)

21. i. What is data striping?ii. Discuss about the recent disk system developments.iii. Explain the control command operations enabled by magnetic tape drive controller. Also explain about

cartridge tape system. (JNTU May 05)

22 i. Explain about magnetic disk layoutii. Elaborate on Winchester disk track format. (JNTU May 05)

23. Discuss about the evolution of I/O function. plain about magnetic disk layout (JNTU May 05)

24 i. Describe an asynchronous data transfer using stribe control with the help of timing diagram.ii. Describe any two methods of I/O addressing. (JNTU May 05)

25. i. List the major functions of disk controller.ii. Explain about disk arrays.iii. Differentiate between Winchester disks and floppy disks. (JNTU Nov 04)

26. i. Differentiate between magnetic-disk and CD-ROM systems.ii. Magnetic disks are used as the secondary storage for program and dta files in a virtual memory system.

Which disk parameter(s) should influence the choice of page size? (JNTU Nov 04)

27. i. Describe an asynchronous data transfer using store control with the help of mug diagram.ii. Describe any tow methods of I/O addressing. (JNTU May 04)

28. i. Draw and explain the timing of read operation in both synchronous and asynchronous timing.ii. Discuss various data transfer types supported by buses. (JNTU Nov 04)

29. i. List various data transfer operations of IBM S/370 system.ii. Explain about common transfer-of-control operations found in instruction sets. (JNTU Nov 04)

30. i. List and describe flow control instructions of Motorola 88000 instructions set.ii. Explain various Motorola 88000 instruction formats. (JNTU Nov 04)

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31. i. What is block hit ratio?ii. Explain major variables on which hit ratio depends.iii. Discuss about FIFO replacement with two different memory capacities with example.( JNTU Nov 04)

32. i. Discuss about stack processing of a page address trace using LRU.ii. Explain about random replacement. (JNTU Nov 04)

33. i. Explain cache execution of a read operation with a neat diagram.ii. Explain look-aside system organization for caches. (JNTU Nov 04)

34. i. Explain about cache management operation of power PIII.ii. List nine separate conditions for conditional branch instructions of power PIII. (JNTU Nov 04)

35. i. Explain cache execution of a write operation with a neat diagram.ii. Elaborate on look-through organization for caches. (JNTU Nov 04)

36. i. Describe a programmed I/O mode of data transfer and give its disadvantages.ii. Explain handshaking mode of data transfer using timing diagrams. (JNTU Nov 04)

37. i. Explain the working of a DMA Controller.ii. What is program controlled I/O Explain. (JNTU Nov 04)

38. i. Elaborate about purpose and organization of data on magnetic tape.ii. Differentiate between magnetic-disk and magnetic-tape systems.iii. Discuss the technology used for CD-ROM systems. (JNTU Nov 04)

39. i. What is ‘data striping’?ii. Discuss recent disk system developments.iii. Explain the control command operations enabled by magnetic tape drive controller. Also explain about

cartridge tape system. (JNTU Nov 04)

40. i. Explain how bus arbitration is done in DMA transfer.ii. Discuss about generic model of an I/O module. (JNTU Nov 04)

41. Discuss the major functions or requirements for an I/O module. (JNTU Nov 04)

42. Give general description of an I/O module structure.partner, and data rate. (JNTU Nov 04)

43. i. Explain about magnetic disk layout.ii. Elaborate on Winchester disk track format. (JNTU May 04)

44. i. Discuss about evolution of I/O function.ii. Explain the characteristics of I/O channels. (JNTU May 04)

45. i. Discuss about I/O channel architecture.ii. Discuss about I/O addressing in 8086.iii. Discuss the salient features of Laser Printer. (JNTU May 04)

46 i. Differentiate between characteristics of various types of disks.ii. Elaborate on fixed and movable head disks. (JNTU May 04)

47. Discuss about data organization and formatting of magnetic disk in detail. (JNTU May 04)

48. i. What is multiple-platter disk.ii. Differentiate between fixed and movable head disks.iii. Define ‘disk access time’, ‘seek time’ and ‘rotational latency’ (JNTU May 04)

49. Discuss about power PC interrupt structure. (JNTU May 04)

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50. i. Differentiate between interrupts and exceptions.ii. What do you mean by interrupt vector table?iii. Write Pentium exception and interrupt vector table. (JNTU May 04)

51. i. Explain any three replacement algorithms with examples.ii. Discuss in detail about set associative mapping in cache memory. (JNTU May 04)

52. i. Differentiate between single versus two-level caches.ii. Elaborate on Pentium Cache Organization. (JNTU May 04)

53. i. What is DMA? Explain the need for DMI.ii. How does priorities are arranged for interrupt. Explain. (JNTU May 04)

54. Discuss the followingi) Multi-bus ii) I/O channel iii) I/O modules iv) I/O processor (JNTU May 04)

55. What is an interrupt? Explain parallel priority and daisy chain interrupt system with necessary diagrams. (JNTU May 04)

56. What is the necessity of I/O modules. Explain (JNTU May 04)

57. i. Differentiate between programmed I/O and memory mapped I/O.ii. Compare interrupt I/O control with DMA I/O control. Why does DMA have priority over CPU when

both requests a memory transfer? (JNTU May 04)

58. i. Compare interrupt-handling mechanism in Pentium and Power PC processors.ii. Explain the arithmetic and data transfer instructions (JNTU Nov 03)

59. i. What do you mean by virtual memory?ii. Explain the demand paging technique in detail. (JNTU Nov 03)


(JNTU Nov 03)

61 i. Describe the organizing an associative memory.ii. Give the uternal organization of a typical associative memory cell. (JNTU Nov 03)

62. i. With the help of a diagram, clearly explain the functioning of a microprogrammed control unit.ii. Microprogrammed unit is slower than hardwired unit. Justify this statement. (JNTU Nov 03)

63 i. Differentiate among different semiconductor memories.ii. Describe set associative mapping technique of cache memory. (JNTU Nov 03)

64. i. Write and explain the timing diagram for Memory Read and I/O Write cycles with neat diagrams.ii. Write a program for 8085 microprocessor to, transfer a block of N data bytes to next N consecutive

locations. Value of N is known. (JNTU Nov 03)

65. What are the different mapping techniques of cache memory? Describe each technique with suitable diagram. (JNTU Nov 03)

66. i. What is Polling in hardware and in software?ii. Design a parallel priority interrupt hardware for a system with eight interrupt sources.(JNTU Nov 03)

67. i. Describe a programmed I/O mode of data transfer and give its disadvantages.ii. Explain handshaking mode of data transfer using timing diagrams. (JNTU Nov 03)

68. i. Describe Interrupt Cycle.ii. What programming steps are required to check when a source interrupts the computer white it is still

being serviced by a previous interrupt request from the same source? (JNTU Nov 03)

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69. i. What is the necessity of I/O modules. Explain.ii. What type of commands an I/O interface may receive? Explain. (JNTU Nov 03)

70. i. Describe the organization of DMI.ii. How are priority interrupt implemented? Explain. (JNTU Nov 03)

71. i. What is the purpose of I/O interface? Explain give the Communication link between the processors I/O bus and scheal Feriphwals.

ii. Describe different comments that an I/O with face receive from CPU. (JNTU Nov 03)

72. Why are read and write control lines in a DMA Controller bi-directional? Under what condition and for what purpose are they used as inputs? Under what condition and for what purpose are they used as outputs? Explain. (JNTU Nov 03)

73. Explain with a block diagram DMA controller. (JNTU Nov 03)

74. i. Describe an asynchronous data transfer using hand shaking with the help of timing diagram.ii. Give the block diagram of an I/O with fare and explain its operation. (JNTU Jun 03)

75. What are different types of I/O devices? Discuss the advantages of using I/O processor.(JNTU Jun 03)

76. i. What do you mean by trashing?ii. Explain how number of page faults can be calculated for the given page trace using LRU page removal

technique. (Assume 4 frames are available in the memory). (JNTU Jun 03)

77. Write short notes on I/O addressing. (JNTU Jun 03)

78. i. Describe an asynchronous data transfer using store control with the help of the mug diagram.ii. Describe a sample I/O interface. (JNTU Jun 03)

79. Why are associative memories needed? (JNTU Jun 03)

80. i. What are the advantages and disadvantages of keeping page tables in the main memory?ii. Briefly explain about multilevel page tables. (JNTU Jun 03)

81. i. What do you mean by virtual memory?ii. Explain the demand paging technique in detail. (JNTU Jun 03)

82. i. What are the disadvantages of segmentation technique?.ii. What do you mean by SWAP area?iii. Explain about demand segmentation technique in detail. (JNTU Jun 03)

83. i. What do you mean by page fault?ii. Explain how number of page faults can be calculated for the given page trace using FIFO page

replacement strategy. (Assume 3 frames are available in the memory). (JNTU Jun 03)

84. i. What is the difference between memory mapped I/O and isolated I/O? What are the advantages and disadvantages of each?

ii. What are the basic advantages of using interrupt –initiated data transfer over transfer under program control without an interrupt? (JNTU Jun 03)

85. i. Differentiate between programmed I/O and memory mapped I/O.ii. Compare interrupt I/O control with DMA I/O control. Why does DMA have priority over CPU when

both request a memory transfer? (JNTU Jun 03)

86. i. What are the uses of magnetic tapes?ii. What are the operations performed to manage memory? (JNTU Jun 03)

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87. a Explain the working of a DMA controller.ii. What is program controlled I/O? Explain. (JNTU Jun 03)

88. i. Explain the segmented – page mapping of memory management.ii. A digital computer has a memory unit of 64 K x 16 and a cache memory of 1 K words. The cache uses

direct mapping with a block size of 4 words. i. How many bits are there in the tag, index, block, and word fields of the address format.

ii. How many bits are there in each word of cache, and how are they divided into functions and Include a valid bit.

iii. How many blocks can the cache. (JNTU Jan 03)

89. i. Write notes on memory hierarchy.ii. Explain the concept of virtual memory. (JNTU Jan 03)

90. Explain the segmented-page mapping of memory management. (JNTU Jan 03)

91. i. Explain the salient features of associative memory with a block diagram.ii. An address space is specified by 16-bit and the corresponding memory space by 12 bits. (i) How many

words ar there in the address space and in the memory space. (ii) If a page consists of 256 words, how many pages and blocks are there in the system. (JNTU Jan 03)

92. Write short notes on i) Cache Memory ii) Memory Hierarchy. (JNTU Jan 03)

93. i. Explain the memory hierarchy.ii. A set-associative mapping cache has a block size of 4 words and a set size of 2. The cache can

accommodate a total of 2048 words from main memory.The main memory size is 128 K X 32.i Formulate all pertinent information required to construct the cache memoryii What is the size of the cache memory? (JNTU Jan 03)

94. i. Explain the implementation of segmentation scheme.ii. Describe associate memory organization. (JNTU Jan 03)

95. i. Explain the I/O module structure with a block diagram.ii. a DMA module in transferring characters to memory using cycle-stealing from a device transmitting at

9600 bps. The CPU is fetching instructions at the rate of 1 million instructions per second (1MIPS). By how much will the processor be slowed down due to the DMA module? (JNTU Jan 03)

96. Draw the block diagram of a typical DMA controller and explain the significance of each of the elements. (JNTU Nov 02)

97. Write short notes on i. Interrupt driven I/O ii I/O processor. (JNTU Nov 02)

98. Explain the direct memory access (DMA) technique of transferring data between main memory and a peripheral device with the help of a suitable block diagram. List out other techniques for doing similar data transfers. (JNTU Nov 02)

99. Write short notes on the CDROM device (JNTU Nov 02)

100. Explain programmed I/O and interrupt driver I/O. (JNTU Jan 02)

101. Describe the organization of DMI. (JNTU Jan 02)

102. What are he draw backs of programmed I/O and interrupt driven I/O. Explain the procedure to overcome these. (JNTU Jan 02)

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103. Write short notes on any two:i. Semiconductor Memoriesii I/O Processoriii. Priority Interrupts. (JNTU Jan 02)

104. i. What are different data transfer modes between computer and peripherals? Explain.ii. Draw the flow chart for memory operation with DMI. (JNTU Jan 02)

105. Give five examples of external interrupts and intern, interrupts each. What is the difference between a software interrupt and a sub-routine call? (JNTU May 00)

106. What is the basic advantage of using interrupt initiate data transfer over transfer under program control without an interrupt? (JNTU May 00)

107. Which one of the following is true for a CPU having a single interrupt request line and a single interrupt grant line ?

i. Neither vectored interrupt no multiple interrupting devices are possibleii. Vectored interrupts are not possible but multiple interrupting devices are possible.iii. Vectored interrupts and multiple interrupting devices are both possibleiv. Vectored interrupt is possible but multiple interrupting devices are not possible. (GATE 05)

108. Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O ?

i. I/O protetion is ensured by operating system routine (s)ii. I/O protetion is ensured by a hardware trapiii. I/O protetion is ensured during system configurationiv. I/O protetion is not possible (GATE 05)

109. A CPU has two modes - privileged and non-privilegeiv. In order to change the mode from privileged to non-privilegeiv. (GATE 01)

i. A hardware interrupt is neededii. A software interrupt is needediii. A privileged instruction (which does not generate an interrupt) is needeiv.iv. A non-privileged instruction (which does not generate an interrupt) is needeiv.

UNIT-VII

1. Discuss about horizontal and vertical instruction formats. Also dierentiate between horizontal and vertical instruction formats. (JNTU May 08)

2. a Explain different types of parallel processors.b. What do you mean by compound instruction? Give examplesc. Elaborate on registers of the IBM3090 vector facility. (JNTU May 08)

3. a. Discuss about exeception in multiple execution unit pipelined processors with examples.b Discuss about dispatch and superscalar operation in multiple execution unitpipelined processors

(JNTU Feb 08)

4. a. Differentiate between sequential and pipelined execution of a programb Explain about instruction execution and hardware organization of a four-stage pipeline

(JNTU Nov 07)

5. a. Why special handling is required for branch instruction in a pipelined processor. Explain with examples.

b. How would you determine the number of pipeline stages in a pipelined processor. (JNTU Nov 07)

6. a. Discuss how a pipeline stall is caused by a cache miss.b. Elaborate on instruction queue and it’s use in hardware organization. (JNTU Nov 07)

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7. Explain the following with related to the Instruction Pipelinea. Pipeline conflictsb. Data dependencyc. Hardware interlocksd. Operand forwardinge. Delayed loadf . Pre-fetch target instructiong. Branch target bufferh Delayed branch (JNTU Sep 07)

8. Disscus about instruction pipeline (JNTU Feb 07)

9. i. List the characteristics of super scalar processor and constrast with CICS processor.ii. Explain the instruction execution characteristics of RISK processor. (JNTU Feb 07)

10. Why special handling is require for branch instruction in pipeline processors? Explain with example.(JNTU Nov 06)

11. Give a summary of arithmatic and logical operation that are defined for the vector architecture.(JNTU Nov 06)

12. Why special handling is required for branch instruction in a pipelined processor. Explain with examples. (JNTU May 05)

13. How would you determine the number of pipeline of stages in a pipelined processor.( JNTU May 05)

14. Differentiate between high-level and low-level parallelism (JNTU May 05)

15. Discuss about Flynn’s classification of parallel processor systems. (JNTU May 05)

16. Explain different MIMD interconnection topologies. (JNTU May 05)

17. Differentiate between short and long pipeline which is more advantageous? (JNTU Nov 04)

18. Elaborate on depending constraints of pipelining. Give an example for pipeline stalled by data dependency.

19. Give an example for idle cycle caused by a branch instruction. (JNTU Nov 04)

20. Discuss how a pipeline stall is caused by a cache miss. (JNTU Nov 04)

21. Elaborate on instruction queue and it’s use in hardware organization. (JNTU Nov 04)

22. Explain various bus configuration examples. (JNTU Nov 04)

23. Discuss the organization of IBM 3090 with vector facility. (JNTU Nov 04)

24. i. Differentiate between multiprocessors and multicomputers.ii. Discuss about instruction pipeline. (JNTU Nov 04)

25. i. Differentiate between sequential and pipelined execution of a program.ii. Explain about instruction execution and hardware organization of a four-stage pipeline.

(JNTU Nov 04)

26. i. Differentiate between two-stag and four-stage pipelines.ii. Discuss the demerits of pipelined processing. (JNTU Nov 04)

27. Differentiate between high-level and low-level parallelism. (JNTU May 04)

28. Discuss about Flynn’s classification of parallel processor systems. (JNTU May 04)

29. Explain different MIMD interconnection topologies. (JNTU May 04)

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30. Explain different types of parallel processors. (JNTU May 04)

31. What do you mean by compound instruction? Give examples. (JNTU May 04)

32. Elaborate on register of the IBm3090 vector facility. (JNTU May 04)

33. Elaborate on continuous field simulation problems. (JNTU May 04)

34. What do you mean by branch prediction? Explain the various techniques of branch prediction with reference to instruction pipeline design (JNTU May 04)

35 Explain Intel 80486 instruction pipeline with an example. (JNTU May 04)

36. List the types of transfers supported by interconnection structure. (JNTU May 04)

37. Discuss the reasons for undermining but performance. (JNTU May 04)

38. For a pipelined CPU with a single ALU, consider the following situations (JNTU May 03, 02)i The j + 1 - st instruction uses the result of the j-th instruction as an operaniv.ii The execution of a conditional jump instructioniii The j-th and j + 1-st instructions require the ALU at the same time

Which of the above can cause a hazard?i. I and II only ii. II and III only iii. III only iv. All the three

39. Write short notes on i) IO addressing mechanism; ii) Instruction pipeline; (JNTU May 02)

40. Write short notes on Instruction pipeline. (JNTU Nov 02)

41. Explain the concept of instruction pipelining. (JNTU Nov 02)

42. Write short notes on: a) Memory hierarchy b) Multi-processor architecture c) Nano-programming(JNTU May 2)

43. Distinguish the difference between tightly coupled multiprocessors and loosely coupled multiprocessors from the viewpoint of hardware organization and programming technique.

(JNTU Nov 02)

44. What is the difference between a microprocessor and microprogram? Is it possible to design a microprocessor without a microprogram? Are all microprogrammed computers also micro-processors?

(JNTU Nov 02)

45. i. What is the purpose of system bus controller? Explain how the system can be designed to distinguish between reference to local memory and common shared memory.

ii. Discuss the difference between tightly coupled multiprocess and loosely coupled multi-process.(JNTU Nov 01)

46. Write short notes on Pipe-line Processing. (JNTU Nov 01)

47. i. Illustrate the main structural difference between shared-memory and distributed memory parallel processors.

ii. A non-pipeline system takes 50 nanoseconds to process a task. The same task can be processed in a six-segment pipeline with a clock cycle of 10 nanoseconds. Determine the speed up ratio of the pipeline for 100 tasks. What is the maximum speed up that can be achieved? (JNTU May 01)

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48. A 5 stage pipelined CPU has the following sequence of stages: (GATE 05)IF – Instruction fetch from instruction memory,RD – Instruction decode and register read,EX – Execute: ALU operation for data and address computation,MA – Data memory access – for write access, the register read at RD stae is used,WB – Register write back.Consider the following sequence of instructions:I1 : L R0, 1oc1; R0 <= M[1oc1]I2 : A R0, R0; R0 <= R0 + R0I3 : A R2, R0; R2 <= R2 - R0Let each stage take one clock cycle.What is the number of clock cycles taken to complete the above sequence of instructions starting from the fetch of I1?i. 8 ii. 10iii. 12 iv. 15

49. Comparing the time T1 taken for a single instruction on a pipelined CPU with time T2 taken on a nonpipelined but identical CPU, we can say that. (GATE 00)

i. T1<= T2 ii. T1 >= T2 iii. T1 < T2 iv. T1 is T2 plus the time taken for one instruction fetch cycle

50. Which of the following is true? (GATE 98)i. Unless enabled, a CPU will not be able to process interrupts.ii. Loop instructions can not be interrupted till they complete.iii. A processors checks for interrupts before executing a new instruction.iv. Only level triggered interrupts are possible on Microprocessors.

51. In a vectored interrupt (GATE 95)i. the branch address is assigned to a fixed location in memoryii. the interrupting source supplies the branch information to the processor through an interrupt vectoriii. the branch address is obtained from a register in the processoriv. none of the above.

UNIT-VIII

1. What is cache coherence problem. Discuss about different cache coherence approches.(JNTU May 08)

2. a Classify and explain different multiprocessorsb Explain the organization of tightly coupled multiprocessor system with a generic block diagram.

(JNTU May 08)

3. a Explain the functioning of omega switching network with a neat sketch.b In 8 x 8 omega switching network how many stages are there and in each stage how many Switches

are there. c How many stages and how many Switches in each stage are needed in a n x n omega sitching network.

(JNTU Feb 08, Sep 07)

4. What are the different kinds of Multi stage Switching networks? Explain with neat sketch. Compare their functioning. (JNTU Nov 07, Sep 07)

5. i. Explain about directory protocol.ii. Draw and explain the state diagram MESI protocol. (JNTU Feb 07)

6. What do you mean by cache coherence problem? (JNTU Feb 07)

7. i. Differentiate between short and long pieplining. Which is more advantageous?ii. Elaborate on depending constratints of pipelining. (JNTU Feb 07)

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8. i. Differentiate between high level and low level parallelism.ii. Discuss about Flynns classification of parallel processor system.iii. Explain different MIMD interconnection topology. (JNTU Feb 07)

9. i. Explain different types of parallel processor.ii. What do you mean by compound instruction? Give examples.iii. Elaborate on register of the IBM 3090 vector facility. (JNTU Nov 06)

10. Explain the characteristics of I/O channels. (JNTU May 05)

11. i. What do you mean by branch prediction? Explain the various techniques of branch prediction with reference to instruction pipeline design.

ii. Explain Intel 80486 instruction pipeline with an example. (JNTU May 04)

12. Explain with a block diagram, the salient features of 8085 microprocessor. (JNTU Jun 03)

13. Explain the organization of 8085 microprocessor. (JNTU Jun 03)

14. Explain the operation of processor control unit. (JNTU Jun 03)

15. i. Describe a CPU – I/O communication and give the sequence of operation involveiv.ii. Describe any two methods of I/O addressing and give them relative merits. (JNTU May 04)

16. i. Classify and explain about multiprocessors.ii. Explain the organization of tightly coupled multiprocessor system with a generic block diagram.

(JNTU May 04)

17. i. Elaborate on the functions of a multiprocessor operating system.ii. Explain the factors that led to practical realization of parallel processors.iii. What do you mean by low-level parallelism. Give examples for it. (JNTU May 04)

18. What are the micro-operations involved in fetching and decoding an instruction? Explain how they are executed? (JNTU Nov 03)

19. i. Describe the centralized and distributed bus arbitration schemes.ii. Discuss the need of interface circuits. (JNTU Jun 03)

20. Discuss the following:i. Multi-bus ii. I/O channel iii. I/O modules iv. I/O processor (JNTU Jun 03)

21. Explain the organization of I/O processor. (JNTU Jan 03)

22 Write short notes on: i IO channel/processorii. Cache memory. (JNTU Nov 02)

23. Describe the organization of DMA with the proper initialization of important registers.(JNTU Nov 02)

24. Write short notes on DMA break points. (JNTU Nov 02)

25. Explain, how interrupt driven I/O is implemented? (JNTU Nov 02)

26. Compare memory mapped I/O and I/O mappeiv. (JNTU Nov 02)

27. Write short notes on DMA (JNTU Nov 02)

28. What is the difference between isolated I/O and memory – mapped I/O? What are the advantages and disadvantages of each? (JNTU Nov 02)

29. i. What are different data transfer modes between computer and peripherals? Explain.ii. Draw the flow char for memory operation with DMI. (JNTU Nov 02)

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30. Write short notes on CDROM device. (JNTU Nov 02)

31. Explain the role of an input output processor (IOP) in computers using number of input output devices. With the help of timing diagrams, explain how data is transferred asynchronously between I/O devices and computer. Describe at least two techniques. (JNTU May 02)

32 i. Explain the following:i) Multi-port memory ii) Hyper cube system.

ii. What is CACHE coherence and why is it important in shared memory multiprocess systems.(JNTU May 02)

33. a What are the applications of microprogramming?ii. Describe the three types of mapping procedures for the organization of a memory which is using the

phenomenon of locality of reference. (JNTU May 01)

34. i. With help of a block diagram explain DMA transfer in a computer system.ii. Explain why does DMA have priority over CPU when both request a memory transfer.(JNTU Nov 01)

35. What is the transfer rate of an 8 track magnetic tape whose speed is 120 inch/second with a density of 1600 bits/inch. (JNTU Nov 01)

36. Write short notes on Priority Interrupts. (JNTU Nov 01)

37. Explain the working of a DMA using a flowchart of the various steps involve in. In virtually all systems that include DMA modules, DMA access to main memory is given higher priority over CPU access to main memory. Why? (JNTU May 01)

38. Distinguish between the interrupt and DMI. (JNTU May 01)

39. Why does DMA has priority over the CPU when both request a memory transfer?( JNTU May 01)

40. Discuss the differences between tightly coupled multiprocessors and loosely coupled multiprocessors from the view-point of hardware organization and programming techniques. (JNTU Nov 00)

41 Write shore notes on : i) Traps ii) MODEM. (JNTU Nov 00)

42. Give five examples of external interrupts and intern, interrupts each. What is the difference between a software interrupt and a sub-routine call? (JNTU May 00)

43. What is the basic advantage of using interrupt initiate data transfer over transfer under program control without an interrupt? (JNTU May 00)

44. Which one of the following is true for a CPU having a single interrupt request line and a single interrupt grant line?

i. Neither vectored interrupt nor multiple interrupting devices are possible.ii. Vectored interrupts are not possible but multiple interrupting devices are possible.iii. Vectored interrupts and multiple interrupting devices are both possible.iv. Vectored interrupt is possible but multiple interrupting devices are not possible. (GATE 05)

45. Which of the following devices should get higher priority in assigning interrupts? (GATE 98)i. Hard disk ii. Printer iii. Keyboard iv. Floppy disk

46. Formatting for a floppy disk refers to (GATE 98)i. Arranging the data on the disk in contiguous fashionii. Writing the directoryiii. Erasing the system areaiv. Writing identification information on all tracks and sectors.

47. Which of the following devices should get higher priority in assigning interrupts? (GATE 98)i. Hard disk iii. Keyboardii. Printer iv. Floppy disk

84


48. Under paged memory management scheme, simple lock and key memory protection arrangement may still be required if the .............................. processors do not have address mapping bardware.

(GATE 90)

49. A block-set associative cache memory consists of 128 blocks divided into four block sets. The main memory consists of 16,384 blocks and block contains 256 eight bit words.

i. How many bits are required for addressing the main memory?ii. How many bits are needed to represent the TAG, SET and WORD fields? (GATE 90)

50. The data transfer between memory and I/O devices using programmed I/O is faster than interrupt-driven I/O. (GATE 90)

51. Fill in the blanks: (GATE 90)The number of memory read and write operations performed by the 8085 A microprocessor in executing the instruction STR Addr, including the op-code fetch cycle, are respectively ………………… and …………………

52. Give memory map and I/O address map. (GATE 89)

53. On receiving an interrupt from a 10 device the CPUi. Halts for a predetermined time.ii. Hands over control of address bus and data bus to the interrupting device.iii. Branches off to the interrupt service routine immediately.iv. Branches off to the interrupt service routine after completion of the current instruction. (GATE 87)

54. The data transfer rate of a double-density floppy disk system is abouti. 5 K bits/seiii. ii. 50 K bits/seiii. iii. 500 K bits/seiii. iv. 5000 K bits/seiii. (GATE 87)

85


86


5. SUBJECT DETAILS

5.2 ELECTRICAL MEASUREMENTS


5.2.2 Scope of the subject

5.2.3 Prerequisites

5.2.4 Syllabus

i. JNTU

ii. GATE

iii. IES


5.2.6 Websites

5.2.7 Experts’ Details

5.2.8 Journals


5.2.10 Session Plan



i. JNTU

ii. GATE

iii. IES

87


88


5.2.1 OBJECTIVE AND RELEVANCE

The importance of measurements in engineering and sciences cannot be overemphasized. A very large part of the measuring instruments comprise of electrical measuring instruments which measure various electrical quantities and other non electrical quantities transducted into electrical variables. The study of electrical instruments therefore is essential, particularly to electrical engineering students.

The advancement of Science and Technology is in general also related to a parallel progress in measurement techniques. The reasons for this are obvious. As Science and Technology move ahead, new phenomena and relationships are discovered and these advances make new types of measurements imperative. New discoveries are not of any practical utility unless the results are backed by actual measurements. The measurements not only confirm the validity of a hypothesis but also add to its understanding. This result in an unending chain, which leads to new discoveries that require more, new and sophisticated measurement techniques. Hence modern Science and Technology are associated with sophisticated methods of measurement.

To know the theory, operation of PMMC and electrostatic instruments.To know the constructional and operational details of wattmeter, energy meter and potentiometerTo know the calibration of various meters like MC & MI To know the applications of bridges in instrumentation and magnetic field in measurement There are two major functions of all branches of engineering:

i. Design of equipment and processes, andii. Proper operation and maintenance of equipment and processes.

Both the functions require measurements. This is because proper and economical design, operation and maintenance require a feedback of information. Measurements play a significant role in achieving goals and objectives of Engineering because of the feedback information supplied by them.

The calibration is very important in measurement and instrumentation, studying this subject one can become familiar with instruments that, how it can be used for measuring various electrical and non electrical quantities.

5.2.2 SCOPE

Measurement of any electrical quantity with good accuracy is an essential requirement in maintaining power system stability and to ensure uninterrupted power flow. This necessitates the study of Electrical measurements in depth with good understanding .Since measurement of an electrical quantity without error makes the system control easier, this subject has great scope for development in order to improve system standards.

5.2.3 PREREQUISITES

To study this subject, the knowledge about the following subjects is required :Engineering Mathematics – I, II and IIIBasic Course in Electrical Engineering which deals with different types of machines and circuits namely Electrical Network Theory, Electro Machines – I and II.

5.2.4.i. SYLLABUS – JNTU

UNIT-IOBJECTIVE

This unit provides the constructional details and operational concepts of measuring instruments.

SYLLABUS

Measuring Instruments: Classification-deflecting, control and damping torques-Ammeters and Voltmeters-PMMC, moving iron type instruments–expression for the deflecting torque and control torque-Errors and compensations, extension of range using shunts and series resistance. Electro static Voltmeters-electrometer type and attracted disc type-Extension of range of Electro Static Voltmeters.

89


UNIT-IIOBJECTIVE

This unit focuses about the basic design and operational concepts of instruments transformers and power factor meters.

SYLLABUS

CT and PT-Ratio and phase angle errors-design considerations, Type of P.F. Meters-dynamometer and moving iron type-1 ph and 3 ph meters, frequency meters, resonance type and Weston type, synchoroscopes.

UNIT-IIIOBJECTIVE

To study the working principle of different types of wattmeters with their constructional details.

SYLLABUS

Single phase dynamometer wattmeter, LPF and UPF, Double element and three element dynamometer wattmeter, expression for deflecting and control torques, extension of range of wattmeter using instrument transformers, measurement active and reactive powers in balanced and un-balanced systems.

UNIT-IVOBJECTIVE

This unit an attempt is made to understand the working principle of single and three phase energy meter with their constructional details.

SYLLABUS

Single phase induction type energy meter-driving and braking torques-errors and compensations, testing by phantom loading using R.S.S. meter. Three phase energy meter-trivector meter, maximum demand meters.

UNIT-VOBJECTIVE

In this unit an attempt is made to understand the working principle and applications of potentio meters.

SYLLABUS

Principle and operation of DC Cromptons potentiometers-standardization, measurement of unknown resistance, current, voltage. AC Potentiometers: polar and coordinate types standardization, applications.

UNIT-VIOBJECTIVE

This unit gives the knowledge of how to measure low, medium and high resistance

SYLLABUS

Method of measuring low, medium and high resistance-sensitivity of wheat stones bridge-Carey Foster’s bridge, Kelvin’s double bridge for measuring low resistance, measurement of high resistance-loss of charge method.

UNIT-VIIOBJECTIVE

This unit gives the knowledge of how to measure inductance and capacitance using AC bridges

90


SYLLABUS

Measurement of Inductance, quality factor-Maxwell’s bridge, Hay’s bridge, Anderson’s bridge, owen’s bridge. Measurement of Capacitance and loss angle, Desauty bridge, Wien’s bridge, schering Bridge.

UNIT-VIIIOBJECTIVE

This unit focuses about the measurement of core losses by different methods.

SYLLABUS

Ballistic galvanometer, equation of motion–flux meter, constructional details, comparison with ballistic galvanometer. Determination of B-H loop methods of reversals six point method-AC testing, Iron loss of bar samples, core loss measurements by bridges and potentiometers.


UNIT-I

PMMC, Moving Iron type instruments - Principle and constructional details - Extenstion of range of Ammeters and voltmeters.

UNIT-II

Instrument transformer - Ratio and Phase angle errors - Testing of CT’s - Dynamo meter type instruments - Power factor meters - 3 phase power factor meters-Frequency measurements - Synchroscope-Wattmeter. UNIT-III

Wattmeters.

UNIT-IV

Energy meter- single phase and three phase energy measurements.

UNIT-V

D.C. and A.C potentiometers-Error analysis.

UNIT-VI

Resistance measurements by bridges - kelvin’s double bridge

UNIT-VII

Measurement of inductance, capacitance by using bridges.

UNIT-VIII

Not covered.

5.2.4.iii SYLLABUS – IES

UNIT-IMeasurement of current and voltage with indicating instruments, PMMC and moving iron type instruments.

UNIT-IIPower factor meters.

91


UNIT-III

Wattmeters - Dynamometers type instruments.

UNIT-IV

Energy meters - principle of operation

UNIT-V

Not covered.

UNIT-VI

Measurement of resistance.

UNIT-VII

Measurement of inductance and capacitance

UNIT-VIII

Not covered


TEXT BOOKS

T1 Electrical Measurements and Measuring Instruments, E.W. Golding and F.C. Widdis, 5th Edn., Wheeler Publishing.

T2 Electrical and Electronic Measurement and Instruments, A.K. Shawney Dhanpat Rai and Sons Publications.

T3 Electrical Measurements, Uday A Bakshi, Technical Publications

REFERENCE BOOKS

R1 A Text book of Electrical Technology, Vol. 1, B.L.Theraja, Multi Colour Edition, S.Chand Publications

R2 Principle of electrical Electronics and Measurement, V.K.Mehta, Multi Colour Edition, S.Chand Publications

R3 Modern Electronics Instrumentation and Measurement, Albert D. Herfrickc William D.Coopr, Prentice Hall of India Pvt. Ltd.

5.2.6 WEBSITES

1. www. zone.ni. com2. www. electronicstalk.com3. www. applianceaid.com4. www. eng.ksu.edu.sa5. www.nj.gov6. www. eng-tips.com7. www.ieee-imte.org8. www. onlinemeasurements. com9. www. online edu.com10. www.instrumentation online.com

92



REGIONAL

1. Name : G. Suresh Babu,Designation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering,

CBIT, Gandipet, Hyderabad,Phone No. : 040-24014567Email :

2. Name : Ashok ReddyDesignation : Assistant professorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering, KITS, Warangal,Phone No. : 9849234929.Email :

3. Name : Dr. A.D.RajkumarDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

University College of Engineering, Osmania University, Hyderabad-07Phone No. : +91- 040-27682382,E-mail : [email protected]

NATIONAL

1. Name : Dr. Jagadeesh kumar. VDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering,

IIT Madras, Chennai-600036Phone No. : +914422574406E-mail : [email protected]

2. Name : R.k. ShergaonkarDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

R.No. 206, IIT Bombay, powai, Mumbai-76Phone No. : +912225767440E-mail : rks@ ee.iitb.ac.in

3. Name : Dr. Prabhu K.M>M,Designation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

IIT Madras, Chennai 60036Phone No. : 914422574410,E-mail : prabhu @ ee.iitm.ac.in.

4. Name : Sanjit Kumar Singh,Designation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

s-137, Azad Bhawan, IIT Roorkee, Uttaranchal.Phone No. : 919412912127,Email : [email protected].

93


INTERNATIONAL

1. Name : Harman BanningDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics EngineeringPhone No. : 13023683700E-mail : [email protected]

2. Name : Theodore LaopoulousDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics EngineeringPhone No. : 3031998215E-mail : [email protected]

3. Name : Gary S.MaryDesignation : ProfessorDepartment : School of Electrical EngineeringOffice Address : Georgia Institute of Technology , USA.Phone No. :E-mail : [email protected]

5.2.8 JOURNALS

1. Name of the Journal : IEEE Transactions on Dielectrics and Electrical InsulationPublisher : IEEE Publications

2. Name of the Journal : International Journal of Circuit Theory and ApplicationsPublisher : John Wiley and Sons

3. Name of the Journal : Electric Power Components and SystemsPublisher : Taylor and Francis Group

4. Name of the Journal : IEEE Transaction Instrumentation& MeasurementPublisher : IEEE Publication

5. Name of the Journal : IEEE Instrumentation & Measurement Society Publisher : I&M Magazine

6. Name of the Journal : IEEE Transaction on Automatic controlPublisher : IEEE Publication

7. Name of the Journal : Electrical IndiaPublisher : Chary Publication Pvt Ltd

8. Name of the Journal : Elector- India Electronics Publisher : Century Publication Pvt Ltd

9. Name of the Journal : E-PowerPublisher : EFY Enterprises PVT Ltd

10. Name of the Journal : Electrical EngineeringPublisher : Institution of Engineers (India) Publishers

94

http://www.tandf.co.uk/

http://www.interscience.wiley.com/


5.2.9 RECENT FINDINGS AND DEVELOPMENTS

1. Title : Development of a High-Precision Calorimeter for Measuring Power loss in Electrical Machines

Author : W.Cao,K.J.Bradley, and A.FerrahJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No : March 2009, Vol. 58, Issue No 3, Page : 618-625.

2. Title : Advanced instrument for field calibration of Electrical Energy Meters

Author : A.Delle Femine , D.Gallo, C.Landi, and M.LuisoJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No : March 2009, Vol. 58, Issue No 3, Page : 618-625

3. Title : An improved UPFC control for oscillation damping Author : J.Guo, M.L.Crow, and J.SarangapaniJournal : IEEE transaction on Power systemsYear, Vol. & Page No. : Feb 2009, Vol. 24, Issue No.1, Page : 288-296.

4. Title : On-line hydrophobicity measurement for silicone rubber insulation on transmission lines

Author : L.Zhao, C.Li, J.Xiong, S.Zhang, J.Yao and X.ChenJournal : IEEE transaction on Power deliveryYear, Vol. & Page No. : Apr 2009, Vol. 24, Issue No.2, Page : 806-813

5. Title : A simple method for the calibration of traditional and electronic measurement current and voltage transformer

Author : A.Brandolini, M.Faifer and R.ottoboniJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No. : May 2009, Vol. 58, Issue No.5, Page : 1345-1353

6. Title : T-connected Autotransformer Based 24-Pulse AC-DC Converter for Variable Frequency Induction Motor Drives

Author : B.Singh, G.Bhuvaneswari and V.GargJournal : IEEE Transaction on Energy Conversion Year, Vol. & page No. : Sept 2007, Vol.21, Issue No.3, page : 663-672

7. Title : Digital measurements station for power quality analysis in distributed environments

Author : Giovanii Bucci, Edoardo FiorucciJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No. : Vol 52, No.1 PP75-84, Feb 2003.

8. Title : A strain gauge tactile sensor for Finger-mounted ApplicationsAuthor : Josivaldo Godoy da siliva, poriesdson dutra da silva Journal : IEEE transaction instrumentation and measurementYear, Vol. & Page No. : Vol 51, No. 1, pp 18-22, Feb.2002

9. Title : Sensors : the first stage in the measurement chainAuthor : Kim R. Fowler and John L.SchmagelJournal : IEEE transactions instrumentation and measurementsYear, Vol. & Page No. : Vol. 49 PP 60-65, Sept. 2004

10. Title : Medical measurements and uncertainitiesAuthor : Marco parvis and Alberto vallanJournal : IEEE transaction instrumentation and measurementsYear, Vol. & Page No. : vol. PP 12-17, June 2002.

95


5.2.10 SESSION PLAN

Sl.No

Topics in JNTU Syllabus

Modules and Sub-ModulesLecture

NoSuggested Books with

Page Nos.Remarks

UNIT- I - MEASURING INSTRUMENTS (No. of Lectures -10 )

1Introduction to the subject

Importance of Measurements L1 T1-Ch17 (P:634-635)T2-Ch1 (P:1-3)R2-Ch7 (P:210-216)R2-Ch17 (P:456-457)2

Review of Basic Electrical Laws

Faradays laws, Phasor diagrams L2

3Measuring Instruments, Classification

Definition of Electrical MeasurementsAbsolute, secondary instrumentsIndicating, Recording and Integrating instruments

L3

T1-Ch17 (P:634-636 & 651-652)T2-Ch7 (P:222-223)R1-Ch10 (P:376-377)R2-Ch25 (P:670-671)

GATE IES

4Deflecting, control and Damping torques

Effects utilized in measuring instruments Spring and gravity control Airfriction , fluid friction , eddy current damping

L4


5

Ammeters and voltmeters, PMMC instruments, Expression for deflecting and control torque, errors and compensations

Constructional details Expression for deflecting torque and control torqueErrors and compensationAdvantages and disadvantages

L5

T1-Ch18 (P:665-669)T2-Ch9 (P:292-296 & 306)R1-Ch10 (P:388-390)R2-Ch25 (P:678-679)

6

Moving Iron type instruments, Expression for deflecting torque and control torque, errors and compensations

Constructional details Expression for deflecting torque and control torqueErrors and compensationAdvantages and disadvantages

L 6

T1-Ch18 (P:658-665)T2-Ch 9 (P:315-318 & 321)R1-Ch10 (P:381-384)R2-Ch25 (P:685-689)

7Extension of range using shunts and series resistance

Extension of range of ammeters and voltmetersMulti range ammeters and voltmeters and problems

L7

T1-Ch19 (P:710-716)T2-Ch9 (P:297-303)R1-Ch10 (P:385-386 & 390-394)R2-Ch25 (P:680 & 689- 690)

8Electrostatic voltmeter, Attracted disc type

Principle of operationExpression for the deflecting torqueAttracted disc type

L8

T1-Ch18 (P:681 & 686)R1-Ch10 (P:405-406)R2-Ch25 (P:694-695)T3-Ch1(P:66-68 & 76-78)

9

Electro meter type voltmeters, extension range of electrostatic voltmeters

Quadrant type electro meterL9 T1-Ch18 (P:682-683)

R1-Ch10 (P:406-407)R2-Ch25 (P:695-696)T3-Ch1(P:69-75 & 77-78)

Extension range of electro static voltmeter and problems

L10

UNIT- II - INSTRUMENT TRANSFORMERS (No. of Lectures - 09 )

10Instrument transformers, CT and PT – Ratio and Phase angle errors

Instrument transformers introduction Advantages of Inst. Transformers

L11

T1-Ch19 (P:716-717)T2-Ch10 (P:384-385)R1-Ch10 (P:442-443)T3-Ch2 (P:1-2 )

GATECT, errors in CT, Theory of CT, transformation ratio and phase angle

L12

T1-Ch19 (P:717-743)T2-Ch10 (P:387-391)R1-Ch10 (P:442-445)T3-Ch2 (P: 9-14)

96


11Design consideration of CT and PT

Design construction of CT and PT Clamp on ammetersCharacteristics of CTPrecautions for use of CT

L13T1-Ch19 (P:721-725 & 739-741)T2-Ch10 (P:391-398 & 405-411)R1-Ch10 (P:446-447)T3-Ch2 (P:2-7)

Construction details of PTTurns ratio, Phase angle and theory of PT, Errors in PT

L14

12

Types of P.F meters, Dynamometer and Moving Iron type 1-phase and 3 –Ph. Meters

Single phase electro dynamo meter power factor meter, mathematical treatment

L15T3-Ch2 (P:32-37)T1-Ch22 (P:872-876)T2-Ch13 (P:494-502)R1-Ch10 (P:435-436)

GATEIES

3-phase dynamometer power factor meter, moving iron power factor meterAlternating field 3-phase power factor meter

L16

13

Frequency meters –resonance type and weston type –Synchroscope

Mechanical Resonance type of vibrating reed frequency meters

L17

T1-Ch22 (P:870-871)T2-Ch13 (P:500-501)R1-Ch10 (P:430-432)T3-Ch2 (P:38-39 )

Electrical Resonance frequency meterWeston frequency meter and problemsElectro dynamometer type synchoronoscopes

L18T1-Ch22 (P:869-872)T2-Ch13 (P:503-506)T3-Ch2 (P:39-43)

Moving iron synchroscope L19T1-Ch22 (P:878-880)T2-Ch13 (P:507-511)T3-Ch2 (P:47-50 )

UNIT-III - MEASUREMENT OF POWER (No. of Lectures -07 )

14

Measurements of Power single phase dynamometer wattmeter, expression for deflecting and control torques

Constructional details and theory of dynamometer type instruments

L20R2-Ch25 (P:683-684)T2-Ch9 (P:328-331)T1-Ch20 (P:763-785)T3-Ch3 (P:1-6)

GATE

Torque equation L21

Constructional details and theory of dynamometer type wattmeterExpression for deflecting torque and control torque

L22

T2-Ch11 (P:431-448)R2-Ch25 (P:704-706)T3-Ch3(P: 4-11)

15

LPF and UPF wattmeter, Double element and three element dynamometer wattmeter

Distinction between LPF and UPF wattmeter

L23

Expression for deflecting torque and control torque of double element and three element wattmeter

L24

16Extension of range of wattmeter using instrument transformers

Extension of range of wattmeter using inst. Transformers

L25T1-Ch20 (P:768-770)T2-Ch11 (P:448-451)T3-Ch3 (P:47-48)

Measurement of active and reactive power in three phase balanced and unbalanced systems

L26T1-Ch20 (P:804-805)T2-Ch11 (456-459)T3-Ch3 (P:26-27)

UNIT-IV - MEASURMENT OF ENERGY (No. of Lectures - 07)

17

Measurement of energy, 1-phase induction type energy meters, driving and braking torques

Single phase induction type energy meter- theory and constructional details

L27T2-Ch12 (P:463-465)T1-Ch21 (P:812-813)T3-Ch4 (P:1-3 ) GATE

Expression for driving and braking torques

L28T2-Ch12 (P:463-464)T3-Ch4 (P: 3-4)

97


18

Errors and compensations of 1phase energy meter-Testing by Phantom loading using RSS meter

Errors and compensation of energy meter

L29T2-Ch12 (P:472-473)T3-Ch4(P:6-8 )

Testing by Phantom loading using RSS meter

L30T2-Ch12 (P:482-486)T3-Ch4(P:26-28 )

19

Three phase energy meter,Trivector meter, Maximum demand meter

Polyphase energy meter L31T2-Ch12 (P:480-482)T1-Ch21 (P:824-836)T3-Ch4 (P:11-13 )

Maximum demand indicator trivector meter

L32 T2-Ch12 (P:475-477)T3-Ch4(P:24-25 )

Problems on energy meter L33UNIT-V - POTENTIOMETERS (No. of Lectures -07 )

20Principle of operation of DC crompton potentiometers

Principle of operation of DC crompton potentio meter

L34T1-Ch8 (P:343-347)T2-Ch15 (P:558-560)R1-Ch10 (P:437-438)

GATE IES

Standardization of potentiometers L35T2-Ch15 (P:559-560)R1-Ch10 (P:438-439)T3-Ch5(P: 1-10 )

Measurement of resistance, current, voltage

L36T1-Ch8 (P:354-356)T2-Ch15(568-569)T3-Ch5(P:15-18 )

21 Standardization

Principle of operation of AC potentiometer- polar type potentiometer

L37

T1-Ch8 (P:359-368)T2-Ch15 (P:573-574)R1-Ch10 (P:439-440)T3-Ch5(P:22-24 )

AC co-ordinate type potentiometer L38T1-Ch8 (P:363-365)T2-Ch15 (P:574-575)T3-Ch5(P:25-27 )22

Measurement of unknown resistance, current, voltage

Problems on DC and AC potentio meter

L39

23

AC Potentio metersPolar and Co-ordinate types standardization-application

Applications of Potentio meters L40T1-Ch8 (P:368-370)T2-Ch15 (P:578-579)T3-Ch5(P: 26-29 )

UNIT-VI - RESISTANCE MEASURMENTS (No. of Lectures - 06)

24

Resistance measurements method of measuring low, medium and high resistance- sensitivity of wheat stone bridge- Carey Foster’s Bridge method

Measurement of Resistance classification Ammeters and voltmeter methods

L41T1-Ch7 (P:286-287)T2-Ch14 (P:516-517)T3-Ch6(P:1-8 )

GATE IES

Wheatstone bridge method L42

T1-Ch7 (P:298-301)T2-Ch14 (P:520-521)R3-Ch5 (P:102-105)T3-Ch5(P: 8-10 )

Carey Foster’s Bridge method L43T1-Ch7 (P:304-306)T2-Ch14 (P:525-526)T3-Ch6(P:19-20 )

25Kelvin’s double bridge for measuring low resistance

Kelving’s double bridge method Advantages and disadvantages

L44

T1-Ch7 (P:290-297)T2-Ch14(534-540)R3-Ch5 (P:108-110)T3-Ch6(P: 21-24 )

26Measurement of high resistance- Loss of charge method

Direct deflection method L45T1-Ch7 (P:313-315)T2-Ch14 (P:540-541)T3-Ch6(P: 29-31 )

Loss of Charge methodMethod

L46T1-Ch7 (P:315-319)T2-Ch14 (P:542-543)T3-Ch6(P:31)

98


UNIT –VII - A.C. BRIDGES (No. of Lectures -06 )

27

AC Bridges- Measurement of Inductance, quality factor, Maxwell’s bridge, Hay’s bridge, Anderson’s bridge, Owen’s bridge

Maxwell inductance bridge L 47

T1-Ch6 (P:212-214)T2-Ch16 (P:585-589)T3-Ch7 (P:10-11)R3-Ch7 (P:117-118)

GATE IES

Maxwell’s Inductance- capacitance bridge

L 48T1-Ch6 (P:213-214)T2-Ch16 (P:589-590)T3-Ch7 (P:11-14)

Hay’s bridgeOwen’s bridge L49

T1-Ch6 (P:214-215& 236-237)T2-Ch16 (P:591-592 & 594)T3-Ch7 (P:18-22)R3-Ch7 (P:119-120)

Anderson’s Bridge L50T1-Ch6 (P:215-217)T2-Ch16 (P:592-593)T3-Ch7 (P:15-17)

28

Measurement of capacitanceEquivalent circuit of an imperfect capacitor

Measurement of capacitance by Desauty Bridge, Schering Bridge.

L 51T1-Ch6 (P:231-235)T2-Ch16 (P:596-600)T3-Ch7 (P:28-32)

Measurement of frequency Wein’s bridgeProblems on bridge

L52T1-Ch6 (P:237-238)T2-Ch16 (P:605-607)

UNIT-VIII - MAGNETIC MEASURMENT (No. of Lectures - 06)

29Ballistic Galvanometer-equation of motion

Magnetic measurements IntroductionBallistic Galvanometer- Theory and constructional details

L53T1-Ch9 (P:371-380)T2-Ch18 (P:660-661)T3-Ch8 (P:2-3)

30

Flux meter- constructional details, comparison with ballistic galvanometer

Grassot flux meter – theory and constructional details

L 54T1-Ch9 (P:382-386)T2-Ch18 (P:662-663)T3-Ch8 (P:9-11)

Extension of range of flux meterApplication of Ballistic galvanometer and Flux meter

L55

31

Determination of Magnetizing force,- B.H loop methods of reversals six point method

Determination of B-H curve Determination of Hysteresis loopReversals of six point method

L56T1-Ch9 (P:394-397)T2-Ch18 (P:663-667)T3-Ch8 (P:17-24)

32

AC testing – Iron loss of bar samples - core loss measurement by bridges and potentiometer

AC bridge method of core loss measurement

L57T1-Ch9 (P:417-424)T2-Ch18 (P:676-667)T3-Ch8 (P:28-30)

AC potentio meters method of core loss measurement

L58T1-Ch9 (P:430-431)T2-Ch18 (P:683-684)T3-Ch8 (P:36-40)

99



1. Title : Development of a High-Precision Calorimeter for Measuring Power loss in Electrical Machines

Author : W.Cao,K.J.Bradley, and A.FerrahJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No : March 2009, Vol. 58, Issue No 3, Page : 618-625.

2. Title : Advanced instrument for field calibration of Electrical Energy Meters

Author : A.Delle Femine , D.Gallo, C.Landi, and M.LuisoJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No : March 2009, Vol. 58, Issue No 3, Page : 618-625

3. Title : An improved UPFC control for oscillation damping Author : J.Guo, M.L.Crow, and J.SarangapaniJournal : IEEE transaction on Power systemsYear, Vol. & Page No. : Feb 2009, Vol. 24, Issue No.1, Page : 288-296.

4. Title : On-line hydrophobicity measurement for silicone rubber insulation on transmission lines

Author : L.Zhao, C.Li, J.Xiong, S.Zhang, J.Yao and X.ChenJournal : IEEE transaction on Power deliveryYear, Vol. & Page No. : Apr 2009, Vol. 24, Issue No.2, Page : 806-813

5. Title : A simple method for the calibration of traditional and electronic measurement current and voltage transformer

Author : A.Brandolini, M.Faifer and R.ottoboniJournal : IEEE transaction on Instrumentation and measurementYear, Vol. & Page No. : May 2009, Vol. 58, Issue No.5, Page : 1345-1353

6. Title : T-connected Autotransformer Based 24-Pulse AC-DC Converter for Variable Frequency Induction Motor Drives

Author : B.Singh, G.Bhuvaneswari and V.GargJournal : IEEE Transaction on Energy Conversion Year, Vol. & page No. : Sept 2007, Vol.21, Issue No.3, page : 663-672

7. Title : Real Time Monitoring of Iron Core and Copper Losses of Transformers under Non-Sinusoidal Operation

Author : Dr. Jan DeclercqJournal : Electrical Engineering UpdateYear, Vol. & page No. : Sept Oct 2006,Vol.14, No.5, pp.24-34

8. Title : Cost Optimal Design of Small transformers, Author : Gautam RoyJournal : Electrical IndiaYear, Vol. & page No. : Oct 2006, vol-46, No.10, pp.50-60,

9. Title : Power Transformers Troubles and Trouble Shooting Author : Bidyut ChatterjeeJournal : Electrical IndiaYear, Vol. & page No. : Aug 2006, vol-46, No.08, pp.68-76,

10. Title : Transformer Losses an OverviewAuthor : Bidyut ChatterjeeJournal : Electrical IndiaYear, Vol. & page no. : Aug 2006, vol-45, No.08, pp.60-70,

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11. Title : Induction Generator for Isolated Hybrid Power System Applications

Author : R.C.Bansal, Dr.T.S.Bhatti, Prof.KothariJournal : Journal of the Institution of Engineers (India)Year, Vol. & page No. : Aug 2006, vol 83, pp.262-269

12. Title : Design of a multispeed winding for a brushless DC Motor and its sensorless control.

Author : Chen C.H; Cheng M.YJournal : Electric Power applications, IEEE ProceedingsYear, Vol. & Page No. : 153, issue:6, November, 2006, Page 834-841.

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UNIT – I

1. a. Explain the construction and working of an attracted disc type kelvin absolute electrometer.b. What are the advantages and disadvantages of the above instrument?c. Can it be used for measurement of low voltages such as 100 V? Give the reason. (JNTU May 09)

2. a. Why electrostatic instruments cannot be used for measurement of low voltages? Give the reason.b. Explain the construction and working principle of Kelvin Multicellular voltmeter with a neat diagram.c. State the advantages of electrostatic instruments. (JNTU May 09)

3. a. Why is a controlling torque necessary in an analog indicating instrument? What would happen in the absence of a controlling torque?

b. Explain the different methods of producing controlling torque in an analog indicating instruments. List their advantages and disadvantages. (JNTU May 09)

4. a. Explain the working of an quadrant electrometer with a neat diagram.b. The spring constant of a 3000 V electrostatic voltmeter is 7.06×10−6Nm/rad. The full scale deflection

of the instrument is 800. Assuming the rate of change of capacitance with angular deflection to be constant over the operating range, calculate the total change of capacitance from zero to full scale.

(JNTU May 09)

5. a. Derive the expression for deflection for a rotary type electro static instrument using spring control. Comment upon the scale of the instrument.

b. An electrostatic voltmeter is constructed with six parallel, Semi circular fixed plates equispaced at Ymm intervals and five inter leaved semi circular movable plates that move in planer midway between the fixed plates in air. The instrument is spring controlled. If the radius of movable plates is 40mm, calculate the spring constant if 10kV corresponds to full scale deflection of 1000. Neglect edge effects and plate thickness. The permittivity of air is 8.85 x 10-12F/M (JNTU May 09)

6. a. Describe the constructional details of an attraction type moving iron instrument with the help of a neat diagram. Derive the equation for deflection if spring control is used and comment upon the shape of scale.

b. The Simpson multimeter model 260 uses a basic D‘Arsonval movement of 50µA with an internal resistance of 2000. The multi-voltmeter ranges of this instrument are 0-2.5V, 0-10V, 0-250V, 0-1000V and arrangement. Calculate the resistances values of R1, R2, R3, R4, R5 &R6. (JNTU May 09)

7. a. How would you extend the range of dc ammeters and voltmeters? Explain with suitable diagrams.b. Show that for a.c. operation, the time constant of the shunt and the ammeter must be equal for an

accurate reading at all frequencies. (JNTU May 09)

8. a. Derive the expression for capacitance to be connected across the multiplier of a moving iron voltmeter so as to make its circuit non inductive for frequencies up to 125Hz.

b. The copper coil of a 150V moving iron voltmeter has a resistance of 400 ohm and 15 0C and an inductance of 0.75H. The current for full scale deflection is 0.05A. The temperature coefficients of resistance for copper and eureka at 150C are 0.004/0C and 0.00001/C0 respectively. Calculatei. The percentage increase of resistance of this instrument per degree rise in temperatureii. The indication when 150V at 100Hz is applied, the instrument having been previously calibrated on direct current. (JNTU May 09)

9. a. What are the errors that occur in moving iron instruments with alternating current only? Discuss how can we eliminate those errors.

b. The law of deflection of a moving iron ammeter is given by I = 40n amperes where θ is the deflection in radian and n is a constant. The self-inductance when the meter current is zero is 10mH. The spring constant is 0.16 Nm/rad. i. Determine an expression for self-inductance of the meter as a function of θ and n.ii. With n=0.75 calculate the meter current and the deflection that corresponds to a self inductance of 60mH. (JNTU Nov 08)

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10. a. How would you extend the range of dc ammeters and voltmeters? Explain with suitable diagrams. b. Show that for a.c. operation, the time constant of the shunt and the ammeter must be equal for an

accurate reading at all frequencies. (JNTU Nov 08)

11. a. What are the different types of instruments that are used as ammeters and voltmeters? What are the errors that occur in ammeters and voltmeters?

b. Describe how can we obtain different voltage ranges by using a multi range dc voltmeter. Discuss about sensitivity and loading effects of PMMC voltmeters. (JNTU Nov 08)

12. a. How would you extend the range of dc ammeters and voltmeters? Explain with suitable diagrams. b. Show that for a.c. operation, the time constant of the shunt and the ammeter must be equal for an

accurate reading at all frequencies. (JNTU Nov 08)

13. a. Why electro static instruments cannot be used for measurement of low voltages while electromagnetic instruments can be? Illustrate your answer with some specific example comparing the energy densities produced in electrostatic instruments and electromagnetic instruments.

b. The movable range of a quadrant electrometer turns through 40 scale divisions when it is idiostatically connected to a potential of 100V. When it is used heterostatically with the quadrants connected to a small voltage “e”? and the needle to a 100v supply, the deflection is 15 scale divisions. Determine thevoltage “e”. (JNTU Nov 08)

14. a. Discuss with neat diagrams, the theory and working of an electro static voltmeter of the quadrant type. Draw the connections fori. heterostatically connected ii. ideostatically connected instruments.

b. Derive an expression for the force of attraction between the plates in a parallel plate electrostatic voltmeter. (JNTU Nov 08)

15. i. What are the different damping methods used in analog indicating instruments? List their advantages and disadvantages.

ii. A permanent magnet moving coil (PMMC) instrument has a full scale deflection of 900 for a current of 2A. The deflecting torque in a PMMC instrument is directly proportional to current in the moving coil. Find the value of current required for a deflection of 300 if the instrument is a. spring controlled and b. gravity controlled. (JNTU Feb 08)

16. i. Explain the various operating forces needed for proper operation of an analog indicating instrument.ii. Explain the operation of PMMC instrument with the help of a neat sketch.iii. The following data refers to a moving coil voltmeter.

Resistance = 10,000 ; dimensions of coil= 30 mm × 30 mm; number of turns of coil = 100; flux density in the air gap = 0.08 wb/m2: spring constant = 3×10-6 Nm per degree. Find the deflection produced by a voltage of 200V. (JNTU Feb 08)

17. i. Explain how a potential divider arrangement is used for multipliers used for multi range voltmeters. Derive the expressions for resistance of different sections for a 4 range voltmeter.

ii. A basic d’ Arsonval meter movement with an internal resistance Rm =100 and a full scale current of Im = 1 mA is to be converted in to a multi range d.c. voltmeter with ranges of 0-10 V, 0-50 V, 0-250 V, 0-500 V. Find the values of various resistances using the potential divider arrangement.

(JNTU Feb 08)

18. i. How is the current range of a PMMC instrument extended with the help of shunts? Explain a method of reducing errors due to temperature changes in the shunt connected instruments with suitable example.

ii. Explain the working of a universal shunt used for multi range- Ammeters. Derive expressions for resistances of different sections of a universal shunt used for a 3 range Ammeter.

(JNTU Feb 08, Nov 07)

19. i. A moving coil instrument whose resistance is 25 ohms gives a full-scale deflection with a current of 1mA. This instrument is to be used with a manganin shunt to extend its range to 100mA. Calculate the error caused by a 100C rise in temperature when :a. Copper moving coil is connected directly across the manganin shunt.

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b. A 75 ohm manganin resistance is used in series with the instrument moving coil . The temperature coefficient of copper is 0.004/0C and that of manganin is 0.00015/0C.

ii. Give brief description about Multi range Ammeters. (JNTU Feb 08)

20. i. What are the different types of instruments that are used as ammeters and voltmeters? What are the errors that occur in ammeters and voltmeters?

ii. Describe how can we obtain different voltage ranges by using a multirange dc voltmeter. Discuss about sensitivity and loading effects of PMMC voltmeters. (JNTU Feb 08, Nov 05)

21. i. Explain the working of a moving iron ammeter with the help of a neat diagram. Derive the expression for the deflecting torque of a moving iron ammeter in terms of current and rate of change of inductance with deflection.

ii. What are the main sources of errors in the instrument and the methods adopted to reduce the same. (JNTU Feb 08, Apr 05)

22. i. How are moving iron instruments classified? Describe briefly the construction and working of Ballistic Galvanometer

ii. Why the scale of a moving iron instrument is non uniform? Discuss briefly why the scale is compressed at lower and higher ends. (JNTU Feb 08)

23. i. Explain heterostatic and idiostatic connections of a quadrant electrometer with the help of neat sketchesand derive the torque equations for both the connections.

ii. Discuss about the advantages and disadvantages of Electrostatic instruments. (JNTU Feb 08)

24. i. Discuss with neat diagrams, the theory and working of an electro static volt-meter of the quadrant type. Draw the connections fora. heterostatically connected b. ideostatically connected instruments.

ii. Derive an expression for the force of attraction between the plates in a parallelplate electrostatic voltmeter. (JNTU Feb 08, Mar 06)

25. i. Explain the working and constructional details of an attraction type moving iron instrument.ii. Discuss its advantages and dis-advantages. (JNTU Nov 07)

26. i. Explain the constructional details of PMMC instrument with neat sketch.ii. Explain why PMMC instruments are the most widely used instruments? Explain their advantages and

disadvantages. (JNTU Nov 07)

27. i. What are the different types of instruments that are used as ammeters and voltmeters? What are the errors that occur in ammeters and voltmeters?

ii. Describe how can we obtain different voltage ranges by using a multirange dc voltmeter. Discuss about sensitivity and loading effects of PMMC voltmeters. (JNTU Nov 07)

28. i. Derive the expression for deflection for a rotary type electro static instrument using spring control. Comment upon the scale of the instrument.

ii. An electrostatic voltmeter is constructed with six parallel, Semi circular fixed plates equispaced at Ymm intervals and five inter leaved semi circular movable plates that move in planer midway between the fixed plates in air. The instrument is spring controlled. If the radius of movable plates is 40mm, calculate the spring constant if 10kV corresponds to full scale deflection of 1000. Neglect edge effects and plate thickness. The permittivity of air is 8.85 x 10-12F/M. (JNTU Nov 07)

29. i. Write short notes on the following:-a. Current drawn Electrostatic instrumentsb. Operating forces producedc. Frequency range

ii. The capacity of an electrostatic voltmeter reading from “0(zero)” to 2000v increases from 80 to 90PF as the pointer moves from zero to full scale deflection. Calculate the value of external capacitor used to increase its range to 20 kV. If the capacitor is adjusted to make the full scale reading correct, what will be the error at half scale reading? (JNTU Nov 07)

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30. i. Describe the construction & working of a PMMC instrument. Derive the equation for deflection if the instrument is spring controlled.

ii. A moving coil milli-voltmeter has a resistance of 200 and the full scale deflection is reached when a potential difference of 100 mV is applied across the terminals. The moving coil has effective dimensions of 30 mm x 25 mm and is wound with 100 turns. The flux density in the air gap is 0.2 wb/m2. Determine the control constant if the final deflection is 1000 and a suitable diameter of copper wire for the coil winding if 20% of the total instrument resistance is due to the coil winding. Resistivity of copper is 1.7 x 10-8/m (JNTU Feb 07, Nov 05)

31. i. Derive the force and Torque equations of Electrostatic instruments.ii. The capacity of an electrostatic voltmeter reading from 0 to 2000v increases from 80 to 90 PF as the

pointer moves from zero to full scale deflection. Calculate the value of external capacitor used to increase its range to 20 kV. If the capacitor is adjusted to make the full scale reading correct, what will be the error at half scale reading? (JNTU Feb 07)

32. i. How is the current range of a PMMC instrument extended with the help of shunts? Give the essential requirements for the construction of shunts. Describe a method of reducing errors due to temperature changes in the shunt connected instruments.

ii. Design an Ayrton shunt to provide an ammeter with current ranges of 1A, 5A, 10A & 20A. A basic meter with an internal resistance of 50W & a full scale deflection current of 1 mA is to be used.

(JNTU Nov 07, 06, Mar 06)

33. i. What are the different types of errors that occur in moving iron instruments? Explain each of them in detail.

ii. Compare between Attraction and Repulsion type of instruments.iii. Give the advantages and disadvantages of moving iron instruments. (JNTU Feb 07)

34. Give the classification of measuring instruments. Describe the working of deflection & null type of instrument. Give the differences between them by suitable examples. (JNTU Feb 07)

35. i Derive the general torque equation of moving iron instruments.ii Discuss about the shape and scale of moving iron instruments.iii. The inductance of a moving iron instrument is given by L=(10+50-02) µH where è is the deflection in

radians from zero position. The spring constant is 12 x 10.6Nm/rad. Estimate the deflection for a current of 5A. (JNTU Nov 06)

36. i Why electro static instruments cannot be used for measurement of low voltages while electromagnetic instruments can be? Illustrate your answer with some specific example comparing the energy densities produced in electrostatic instruments and electromagnetic instruments.

ii. The movable range of a quadrant electrometer turns through 40 scale divisions when it is idiostatically connected to a potential of 100V. When it is used heterostatically with the quadrants connected to a small voltage “e”? and the needle to a 100v supply, the deflection is 15 scale divisions. Determine the voltage “e”. (JNTU Nov 06)

37. i. Discuss the following types of errors in moving iron instruments.a. Hysterisis error b. Temperature errorc. Errors due to stray magnetic fields d. Errors due to change of frequency.

ii. Describe the working and constructional details of repulsion type moving iron instrument. Discuss its advantages and disadvantages. (JNTU Nov 06)

38. i. How are moving iron instruments classified? Describe briefly the construction and working of Ballistic Galvanometer

ii. Why the scale of a moving iron instrument is non uniform? Discuss briefly why the scale is compressed at lower and higher ends. (JNTU Nov 06)

39. i. Describe how a D‘ Arsonval basic meter can be converted into a voltmeter.Discuss about the requirements for the construction of multipliers and how the temperature effects can be eliminated in voltmeters.

ii. A moving coil instrument gives a full scale deflection of 10mA when the potential difference across its terminals is 100mV. Calculatei. the shunt resistance for a full scale deflection corresponding to 100A,

105


ii. the series resistance for full scale reading with 1000V. Calculate the power dissipation in each case. (JNTU Mar 06)

40. i. Describe with a neat sketch, the theory of operation, construction and uses of a moving coil voltmeter. Explain how the instrument can be made of high accuracy.

ii. The relationship between inductance of a moving iron ammeter, the current and the position of the pointer is as follows: Reading I. 0.8 1.0 1.2 1.4 1.6 1.8 2.0Deflection (degree) 16.5 26 36 46.5 57 70 2.0Inductance (µH) 527.8 573.9 575 577.3 578.35 579.45 -Calculate the deflecting torque when the current is 1.5A & 2.1A. (JNTU Mar 06)

41. i. A moving coil instrument whose resistance is 25 gives a full-scale deflection with a current of 1mA. This instrument is to be used with a manganin shunt to extend its range to 100mA. Calculate the error caused by a 100C rise in temperature when :a. Copper moving coil is connected directly across the manganin shunt.b. A 75 ohm manganin resistance is used in series with the instrument moving coil . The temperature coefficient of copper is 0.004/0C & that of manganin is 0.00015/0C.

ii. Give brief description about Multi range Ammeters. (JNTU Mar 06)

42. i. Derive the expression for the deflecting torque in an attraction type moving iron instrument.ii. How are controlling torque and damping torque produced in such moving iron instruments.

(JNTU Mar 06, Nov 05)

43. i. What are electrostatic instruments? What is the basic principle over which they operate?ii. Discuss the working of a repulsion type electrostatic instrument with a neat sktch. (Mar 06, May 04)

44. i. Derive the expression for capacitance to be connected across the multiplier of a moving iron voltmeter so as to make its circuit non inductive for frequencies up to 125Hz.

ii. The copper coil of a 150V moving iron voltmeter has a resistance of 400 ohm and 150C and an inductance of 0.75H. The current for full scale deflection is 0.05A. The temperature coefficients of resistance for copper and eureka at 150C are 0.004/0C and 0.00001/0C respectively. Calculatei. The percentage increase of resistance of this instrument per degree rise in temperatureii. The indication when 150V at 100Hz is applied, the instrument having been previously calibrated on direct current. (JNTU Apr 05)

45. i. Compare between spring and gravity control methods.ii. The deflecting torque of an ammeter varies as the square of the current passing through it. If a current

of 5 amps produces a deflection of 900, what will be the deflection for a current of 10 amps when the instrument isi. Spring controlled ii. Gravity controlled (JNTU Apr 05)

46. i. What are electrostatic instruments? What is the basic principle over which they operate?ii. Discuss the working of a repulsion type electrostatic instrument with a neat sketch.

(JNTU Apr 05, May 05)

47. i. What is a shunt referred to a PMMC instrument. How is it employed in extending the range of an ammeter?

ii. How temperature effect is corrected in the shunts? Discuss with a neat circuit diagram.(JNTU May 04)

48. i. Explain different types of electrostatic instruments. Discuss their principle of operation.ii. Explain the working of quadrant type electrometer. (JNTU May 04)

49. i. How a quadrant electrometer be modified for measurement of low voltages?ii. Discuss advantages, disadvantages and limitations of an electrostatic voltmeter. (JNTU May 04)

50. i. How are measuring instruments classified? Also explain the basic issues concerned with the measurement of electrical quantities.

ii. What are the requirements of an electrical indicating instrument? Discuss. (JNTU Nov 03)

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51. i. What is the principle of working of a repulsion type moving iron instrument?ii. Explain with the neat sketch the working of such an instrument.iii. Discuss the various errors in moving iron instruments and suggest methods to compensate these errors.

(JNTU May 03)52. i. With usual notation derive an expression for the deflecting torque in a PMMC instrument.

ii. Explain how the PMMC instrument can be employed to measure (JNTU May 03)i. Voltage ii. Current

53. i. Classify the electrical measuring instruments based on how the deflecting torques is produced.ii. Explain deflecting system, controlling system and damping system with reference to an electrical

indicating instrument. (JNTU May 03)

54. i. Explain the principle of operation of moving iron type of instruments.ii. The capacitance of a 0-2000 volts electrostatic voltmeter increase uniformly from 42 to 54mF from

zero to full scale deflection. If it is required to increase the range of the instrument to 20000 volts by means of an external capacitor. Calculate the capacitance required. (JNTU Nov 02)

55. i. Define the terms “Indicating Instruments” “Recording Instruments” and integrating instruments, give examples of each case.

ii. Describe the different methods of producing controlling torque in an analogue instrument.iii. How is the current range of a PMMC instrument extended with the help of shunts?

(JNTU May 02)

56. Describe the construction and working of permanent magnet moving coil instrument. Derive the equation for deflection if the instrument is spring controlled. Describe the method of damping used in these instruments. (JNTU May 01)

57. A DC ammeter has a resistance of 0.1 ohm and its current range is 0.100A. If the range is to be extended to 0.500A, the meter requires _______shunt resistance. (GATE 05)

58. The Q-meter works on the principle of ________________ (GATE 05)

59. A PMMC voltmeter is connected across a series combination of a DC voltage source V1=2V and an AC voltage source V2(t)-3 sin (4t). The meter reads (GATE 05)

60. A galvano meter with a full scal current of 10 mA has a resistance of 1000 ohms. the multiplying power ( the ratio of measured current to galvanometer current ) of a 100 ohm shunt with this galvanometer is _______ (GATE 04)

61. A moving coil of ameter has 100 turns, and a length and depth of 10mm and 20 mm respectively. It is positioned in a uniform radial flux density of 200mT. The coil carries a current of 50 m A. The torque on the coil is ______ (GATE 04)

62. A moving iron ammeter produces a full scale torque of 240 micro N-m with a deflection of 120 deg at a curent of 10 A. the rate of change of self inductance (micro H/radian) of the instrument at full scale is _________ (GATE 04)

63. A Manganin swamp resistance is connected in series with a moving soil ammeter consisting of milliammeter and a suitable shunt in order to _____ (GATE 03)

64. A rectifier type ac voltmer consists of a series resistance R, an ideal full-wave rectiier bridge and a PMMC instrument as shown in figure. The internal resistance of the instrument is 100 ohm and a full scale deflection is product\ed by a dc current of 1 mA. The value of Rs. required obtain full scal deflection with an ac voltage of 100 V(rms) applied to the input terminals is ___ (GATE 03)

65. The inductance of a certain moving-iron ammeter is expressd as L=10+3theta-theta square/4 micro H, where theta is the deflection in radians from the zero position. The control spring torque in 25X10ex-6 Nm/radian. The deflection of the pointer in radian when the meter carries a current of 5 A , is __________ (GATE 03)

107


66. A 100 micro A ammeter has an internal resistance of 100 om. For extending its range to measure 500 micro A, the shunt required is of resistance (in ohms)__ (GATE 01)

67. Resistances R1 and R2 have, respectively, nominal values of 10 ohm and 5 ohm , and tolerances of _+5%and -+10% . The range of values for the parallel combination of R1 and R2 is __ (GATE 01)

68. A moving coil instrument, whose resistance is 5 Ohms and whose working current (for full scale deflection) is 0.015 A, Is to be used, with a manganin shunt, to measure 100 A. Calculate the error caused by a 10°C in temperature, if the temerature coefficient of copper and manganin are 0.004 ohm/ohm°C, and 0.00014 ohm/Ohm°C respectively. (GATE 98)

69. In the circuit shown in Figure for measuring resistance ‘R’ if the ammeter indicates 1Aand the voltmeter indicates 100V, then the value of R is … Ohms and the error in measurement using the ratio V/1 is ……..% (GATE 97)

70. In the capacitor divider arrangement shown in figure for measurement of high voltages, the minimum resistance of the voltmeter for 1% error is ……… Ohms and the voltage reading will be …….. V

(GATE 97)

71. A periodic voltage whose waveform over one complete period is shown in figure is applied to the following types of commercial voltmeters:

i. Permanent magnet moving coil (PMMC). meter with center zeroii. Moving iron type meteriii. Full wave rectifier type AC voltmeteriv. Peak response type electronic voltmeter

Find the reading(s) of each instrument, considering the effect of the reversal of connection, if any.(GATE 92)

72. Drive the general torque equation for a moving iron instrument. The inductance of a moving iron ammeter is given by the following expression:L = (20 + 10q - 2q²) mHWhere q is deflection in radians. The spring constant is 24 x 10-6 Nm/rad. Calculate the value of deflection for a current of 5 A. (IES 01)

73. Give the basic principle of working of an electrostatic voltmeter. Explain how you would increasei. The operating forces andii. Voltage range of the voltmeter. (IES 95)

74. Give the meanings of the following termsi. Precision, ii. Accuracy, iii. Standard Deviation, iv. Probable error (IES 94)

75. Explain the different types of errors that may occur in measurements. (IES 93)

76. What is a digital voltmeter? What are its advantages? List different types of digital voltmeters. How can a DVM be used for the measurement of i. Current and ii. Resistance. (IES 92)

UNIT – II

1. a. Compare potential transformer with power transformer. b. A potential transformer, ratio 1000/100 volt has the following constants:

Primary resistance=94.5 ; secondary resistance=0.86 Primary reactance=66.2 ; Total equivalent reactance=110 .No load current=0.02 A at 0.4 p.f. Calculatei. Phase angle error of no load.ii. Burden in VA at unity power factor at which the phase angle will be zero. (JNTU May 09)

2. a. Explain in detail the effect of opening the secondary circuit of a current transformer when the primary winding is energized.

108


b. A current transformer has a single turn primary and 200 turn secondary which has a non-inductive burden of 1 resistance. The net cross sectional area of the core is 10cm2, the magnetizing flux needs 80AT in the primary. Calculate the ratio and phase angle errors of the current transformer for a secondary current of 5A. The supply frequency is 50Hz. (JNTU May 09)

3. Draw the equivalent circuit and phasor diagram of a potential transformer. Derive the expressions for

its ratio error. State the assumptions made for derivation of this error. (JNTU May 09)

4. a. Explain the disadvantages of shunts and multipliers when used for extension of range. Explain how instrument transformers are a better substitute for shunts and multipliers especially for high range values.

b. Define the following ratios of instrument transformers. i. Transformation ratio ii. Nominal ratioiii. Burden iv. Ratio correction factor. (JNTU May 09)

5. a. Draw the equivalent circuit and phasor diagram of a potential transformer and derive the expressions for actual transformation ratio and phase angle.

b. A current transformer of turns 1 : 199 is rated as 1000/5A, 25VA. The core loss and magnetizing component of the primary current are 4 and 7A under rated conditions. Determine the phase angle and ratio errors for the rated burden and rated secondary current at 0.8p.f. lagging and 0.8 pf leading. Neglect the resistance and leakage resistance of secondary winding. (JNTU May 09)

6. a. Explain the constructional features used in potential transformers to reduce the ratio and phase angle errors.

b. Explain the characteristics of potential transformers in detail. (JNTU May 09)

7. a. Explain the constructional features of current transformers with the help of neat sketches.b. A 1000/5A, 50Hz current transformer has a secondary burden comprising a non inductive impedance

of 1.6Ω. The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load. The magnetizingmmf is100AT . (JNTU May 09)

8. a. Explain how a current transformer can be used for current and power measurements with the help of neat sketch. Indicate the errors that occur in current transformers.

b. A 100/5A, 50Hz current transformer has a bar primary and rated secondary burden of 12.5vA. The secondary winding has 190 turns and a leakage inductance of 0.96mH with a purely resistive burden at rated full load, the magnetization mmf is 16A and the loss excitation requires 12A. Find the ratio and phase angle errors. (JNTU May 09)

9. With a neat sketch explain the working and construction of electro resonance type power factor meters. Draw the phasor diagrams under different power factor conditions. (JNTU Nov 08)

10. a. Find the working current of the slide wire and the rheostat setting b. If the slide wire has divisions marked in mm and each division can be interpolated to one fifth,

calculate the resolution of the instrument. c. What is standardization and explain with an example, how it is obtained. (JNTU Nov 08)

11. a. Write short notes about dial type synchroscope. Electro dynameter power factor meter. b. Write explanatory notes on the frequency meters with illustrative sketches wherever necessary.

(JNTU Nov 08)

12. i. Obtain the differences between current transformer and potential transformer. ii. What are the major sources of errors in current transformers? Explain them in detail.iii. Draw the equivalent circuit of current transformer. (JNTU Feb 08, Nov 07)

13. Explain the effect of the following on the characteristics of potential transformers.i. Burden (VA) of secondary winding circuitii. Power factor of secondary winding circuitiii. Frequency andiv. Supply voltage. (JNTU Feb 08)

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14. i. Draw the phasor diagram of potential transformation.ii. Explain the design and constructional features used in potential transformers for reduction of ratio and

phase angle errors. (JNTU Feb 08, Nov 07)

15. i. Explain briefly about the characteristics of current transformers. What are the causes of errors in current transformers?

ii. A current transformer has a single turn primary and a 200 turns secondary winding. The secondary winding supplied a current of 5A to Non-inductive burden of 1ohm resistance. The requisite flux is set up in the core by an mmf of 80A. The frequency is 50Hz and the net cross section of the core is 1000mm? Calculate the ratio and Phase angle of the transformer. Also find the flux density in the core. Neglect the effects of magnetic leakage, iron losses and I2 R losses. (JNTU Feb 08)

16. i. Explain how a current transformer can be used for current and power measurements with the help of neat sketch. Indicate the errors that occur in current transformers.

ii. A 100/5A, 50Hz current transformer has a bar primary and rated secondary burden of 12.5vA. The secondary winding has 190 turns and a leakage inductance of 0.96mH with a purely resistive burden at rated full load, the magnetization mmf is 16A and the loss excitation requires 12A. Find the ratio and phase angle errors. (JNTU Feb 08)

17. i. What are the different methods of measurement of frequency in the power frequency range.ii. Explain the working and construction of a mechanical resonance type frequency meter using a neat

sketch. (JNTU Nov 07)

18. Explain the constructional details and working of a single phase electrodynamometer type of power factor meter. Prove that the special displacement of moving system is equal to the phase angle of the system. (JNTU Nov 07)

19. Explain the constructional details and working of a 3-phase electrodynamometer type of power factor meter. Explain why phase splitting is not necessary in this case while in a single phase power factor phase splitting has to be done by using R in one circuit and L in another circuit of the moving coils.

(JNTU Nov 07)

20. i. Describe the constructional details and working of a 3 ö electro dynamometer type of power factor meter.

ii. Describe why phase splitting is not necessary in this case while in a single phase power factor phase splitting has to be done by using ‘R’ in one circuit and ‘L’ in another circuit of the moving coils.

(JNTU Nov 07)

21. i. Explain the constructional features used in potential transformers to reduce the ratio and phase angle errors.

ii. Explain the characteristics of potential transformers in detail. (JNTU Feb 07, Nov 06)

22. i. Explain the errors in potential transformers and means of reducing the same.ii. Describe the following methods for testing of a current transformer :

i. Mutual inductance methodii. Silsbee‘s method (JNTU Feb 07)

23. i. Explain how po-wer can be measured by using instrument transformersii. The total resistance of the pressure coil circuit and the inductance of a wattmeter the 4000 and 6.5mH.

respectively Given the shunted capacitor method of compensating the inductance error and also determine across what portion of the series resistane a 0.1µF capacitor should be shunted to effect compensation. (JNTU Nov, Feb 07)

24. With a neat sketch explain the working and construction of electro resonance type power factor meters. Draw the phasor diagrams under di”erent power factor conditions. (JNTU Nov 06)

25. i. With neat sketch, explain how high currents and voltages can be measured with the help of instrument transformers. Describe the advantages of instrument transformers for extension of range of current and voltage on high voltage a.c. systems.

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ii. A current transformer with 5 primary turns has a secondary burden consisting of a resistance of 0.16 and an inductive resistance of 1.12“ . When the primary current is 200A, the magnetizing current is 1.5A and the iron loss current is 0.4A. Determine the expressions used, the number of secondary turns needed to make the current ratio 100:1 and also the phase angle under these conditions.

(JNTU Nov 06)

26. i. Explain Resonance type synchroscope.ii. In a deflection frequency meter working on the principle of electrical resonance, there are two parallel

circuits each consisting of an inductance and capacitance in series. One circuit has C1=1µF and is tuned to a frequency f1=60Hz. The other has C2=1.5µF and is tuned to a frequency, f2 below 50Hz.. The resistance of each circuit is R1=R2=100 ohms. What must be the inductance of the second circuit, and to what frequency must it be tuned, in order that the current in both the circuits shall be same at a frequency of 50Hz. (JNTU May 06)

27. Describe the constructional details and working of a 1ö electro dynamometer type of power factor meter. And also prove that special displacement of moving system is equal to the phase angle of the system. (JNTU May 06)

28. Write short notes on the following : i. Weston type frequency meter ii. Ratiometer type Frequency meter. (JNTU May 06)

29. i. Draw the equivalent circuit and phasor diagram of a potential transformer and derive the expressions for actual transformation ratio and phase angle.

ii. A current transformer of turns 1 : 199 is rated as 1000/5A, 25VA. The core loss and magnetizing component of the primary current are 4 and 7A under rated conditions. Determine the phase angle and ratio errors for the rated burden and rated secondary current at 0.8p.f. lagging and 0.8 pf leading. Neglect the resistance and leakage resistance of secondary winding. (JNTU Mar 06)

30. i. Draw the equivalent circuit and phasor diagram of a current transformer. Derive the expressions for transformation ratio and phase angle.

ii. A single phase potential transformer has a turns ratio of 3810/63. The nom inal secondary voltage is 63V and the total equivalent resistance and leakage reactance referred to the secondary side are 2 and 1 respectively. Calculate the ratio and phase angle errors when the transformer is supplying a burden of 100+j200. (JNTU Mar 06)

31. i. Derive the expressions for ratio and phase angle error of a current transformer. ii. A 1000/5A, 50 Hz current transformer has a Secondary burden comprising a non- inductive burdenof

1.6 ohm. The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load.

(JNTU Mar 06)

32. Describe the construction and working of a Weston type synchroscope. How is it assured that the i. Incoming machine has the same voltage as that of the bus bars and also whether they are in phase with

each other (or) noteii. Incoming machine has the same phase sequence as the busbars to which it has to be connected.iii. Frequency of the incoming machine is same as that of the busbars. iv. Incoming machine is Faster or slower than the bus bars. (JNTU Nov 05)

33. Write short notes about dial type Synchroscope. (JNTU Nov 03)

34. Write short notes on followingi. Resonance type frequency meter.ii. Advantages and disadvantages of Moving Iron power factor meter. (JNTU Nov 03)

35. List out the differences between instrument transformers and power transformers.(JNTU Nov 03)

36. i. Explain the construction and working of a MI type power factor meters.ii. Describe the construction and working of Weston type synchroscope. (JNTU May 02)

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37. i. Explain the construction and working of a MI type power factor meters.ii. Describe the construction and working of Weston type synchroscope. (JNTU May 02)

38. Describe a direct reading frequency meter for measuring a frequency of the order of either i. 50 cycles per second (or) ii. 500 cycles per second Suggest a suitable method for calibrating the instrument.

39. A 200/1 current transformer (CT) is wound with 200 truns on the secondary on a toroidal core. When it carries a current of 160 A on the primary, the ratio and phase errors of the CT are found to be-0.5% an 30 minutes respectively. If the number of secondary turns is reduced by 1 the new ratio error (%) and phase error (min) will be respectively.a. 0.0, 30 b. -0.5, 35 c. -1.0, 30 d. -1.0, 25 (GATE 06)

40. A 50 Hz, bar primary CT has a secondary with 500 turns. The secondary supplies 5 A current into a purely resistive burden of 1 ohm. The magnetizing ampere-turns is 200. The phase angle between the primary and secondary current is _ (GATE 04)

41. The core flux in the CT of above problem under the given operating condition is _ (GATE 04)

42. A 500A/5A, 50 Hz current transformer has a bar primary.Te secondary burden is apure resistance of 1 ohm and it draws a current of 5 A. If the magnetic core requires 250 At for magnetization, the percentage ratio error is _____ (GATE 03)

43. Describe the construction and working principle of a single phase electrodynamic power factor meter. Compare it working with a moving iron type power factor meter. (IES 01)

44. Draw a functional block diagram and explain the principle of working of a digital frequency meter(IES 96)

45. Give the constructional features and principles of working of a synchroscope. (IES 95)

46. i. Explain briefly about the characteristics of current transformers. What are the causes of errors in current transformers?

ii. A current transformer has a single turn primary and a 200 turns secondary winding. The secondary winding supplied a current of 5A to Non-inductive burden of 1 resistance. The requisite flux is set up in the core by an mmf of 80A. The frequency is 50Hz and the net cross section of the core is 1000mm? Calculate the ratio and Phase angle of the transformer. Also find the flux density in the core. Neglect the effects of magnetic leakage, iron losses and I2 R losses. (JNTU Apr 05)

47. What is ratio error? State its expression.

48. How to obtain actual transformation ratio? On which factor it depends?

49. What is phase angle error and on which factor it depends?

50. How to minimize the ratio error and phase angle error in the instrument transformers.

51. Compare power Transformer and instrument transformer?

52. Describe the comparison method using wattmeters for testing of potential transformers.

53. Explain the Absolute Null method for testing of potential transformers.

54. Explain the Mutual inductance method for testing of current transformers.

55. Explain the Silsbee’s method for testing of current transformers

56. Explain the Arnolds method for testing of current transformers.

57. Explain the disadvantages of shunts and multipliers when used for extension of range.

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58. Explain the Wilson compensation method for reduction of errors in current transformers.

59. Explain the effect of change of primary winding current on the performance of current transformers.

60. Explain the effect of change of frequency on the performance of current transformers.

61. Explain the effect of change of secondary circuit burden on the performance of current transformers.

62. Explain the effect of change of secondary winding current on the performance of potential transformers.

UNIT – III

1. a. Discuss the various types of errors and their methods of compensation in the dynamometer type wattmeter.

b. What are the differences between LPF and UPF wattmeters. (JNTU May 09)

2. a. Explain how do you measure reactive power in a 3-phase circuit with the help of only one wattmeter? Draw the relevant circuit and phasor diagrams.

b. Two wattmeters are connected to measure power in a 3-phase network. The two readings are 200 watts and 1000 watts respectively. If another wattmeter be connected such that its current coil is in one phase and the potential coil is across the other two phase terminals, what will it read? Also, estimate the reactive power of the network. (JNTU May 09)

3. a. Explain the errors in electrodynamometer type wattmeter in detail.b. Explain the constructional details of an electrodynamometer type wattemeter. Derive the expression

for torque when the instrument is used on A.C supply. (JNTU May 09)

4. a. Explain the construction and principle of operation of a dynamometer type Wattmeter. How it can be made to read d.c as well as A.C?

b. In a dynamometer type wattmeter the moving coil has 500 turns of mean diameter 3cm. Calculate the torque if the axis of the field and moving coils are ati. 300 ii. 600 iii. 900

when the flux density in the field coils is 15mWb/m2, the current in the moving coil is 0.5A and power being measured has a power factor of 0.866. (JNTU May 09)

5. a. Describe the construction & working of electro dynamo meter wattmeter. Derive the expression for torque when the instrument is used on a.c.

b. The pressure coil of an electro dynamo meter wattmeter has a resistance of 6600. When the voltage applied to the pressure coil is 120V and a current of 20A flows in the series coil, the deflection is 1600. What additional resistance must be connected in the pressure coil circuit to make the meter constant equal to 20W per degree. (JNTU May 09)

6. a. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro dynamometer wattmeter. (JNTU May 09)

b. Discuss the shape of scale of electro dynamometer wattmeters with the help of a neat sketch.

7. a. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro dynamometer wattmeter. (JNTU May 09)


8. Explain the following errors for electro dynamometer wattmeters. (JNTU May 09)a. Mutual inductance effects b. Errors due to connectionsc. Eddy currents d. Stray Magnetic fieldse. Vibration of Moving system f. Temperature errors

9. a. Explain how the power in a 3 phase system is measured by the use of i. only one wattmeter ii. two wattmeters. Indicate how the power factor is determined.

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b. A non inductive resistance is connected in series with a coil across a 230V, 50Hz supply. The current is 1.8A and the potential di_erence across the resistance and the coil is 80 & 171 volts respectively. Calculatei. resistance & inductive reactance of the coil ii. the supply power & pf (JNTU Nov 08)

10. a. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro dynamometer wattmeter. (JNTU Nov 08)


11. Explain the following errors for electro dynamometer wattmeters.a. Mutual inductance effects b. Errors due to connectionsc. Eddy currents d. Stray Magnetic fieldse. Vibration of Moving system f. Tempetature errors (JNTU Nov 08)

12. Write short notes on the following: i. Power measurements methods in 3-phase balanced and unbalanced circuits.ii. Extension of wattmeter range by instrument transformers.iii. Polyphase wattmeter. (JNTU Feb 08)

13. Write short notes on the following:i. Errors present in 1-phase electrodynamometer type wattmeter.ii. Extension of wattmeter range by instrument transformers.iii. Polyphase wattmeter. (JNTU Feb 08)

14. i. Explain the constructional details and working principle of Low power factor wattmeter (electrodynamometer type).

ii. A dynamometer wattmeter is used to measure the power factor of a 20 µF capacitor. The pressure coil of the wattmeter having a resistance 1000 ohms and an inductive reactance of 15 ohms is connected across a 50Hz supply. The current coil of the wattmeter, a variable resistor R and the capacitor are connected in series across the same supply. The wattmeter deflection is made zero by adjusting the value of R to 1.65ohms. If the current coil resistance is 0.1 ohms and inductance is negligible. Determine the power factor of the capacitor. (JNTU Feb 08)

15. i. Show that the power in a 3-phase system is measured by the use of a. only one watt meter and b. two wattmeters.Indicate how the power is determined. Comment on the accuracy of the measurements when the load is unbalanced and the supply is a four-wire system.

ii. Two wattmeters used to measure the power input in a 3-phase circuit indicate 1000w and 500w respectively. Find the powerfactor of the circuit.a. When both wattmeters readings are positiveb. When the latter is obtained by reversing the current coil connections. (JNTU Feb 08)

16. i. Explain the working of a 3 phase wattmeter with the help of a neat sketch. Describe how the mutual effects between the two elements of the wattmeter are eliminated.

ii. If the current in the pressure coil of a wattmeter lags 20 behind the voltage and instrument is accurate when cos0=1, find the percentage error when cos0=0.8, 0.6 and 0.4 respectively. (JNTU Feb 08)

17. i. Explain how power can be measured by using instrument transformers ii. The total resistance of the pressure coil circuit and the inductance of a wattmeter the 4000 ohms and

6.5mH. respectively Given the shunted capacitor method of compensating the inductance error and also determine across what portion of the series resistane a 0.1µF capacitor should be shunted to effect compensation. (JNTU Feb 08)

18. i. Describe the three ammeter method for measurement of power and power factor in a single phase circuit. Derive the expressions for power and power factor

ii. The power flowing in a 3 phase, 3 wire balanced load system is measured by two wattmeter method. The reading of wattmeter A is 7500W and of wattmeter B is 1500W What is the power factor of the system?

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iii. If the voltage of the circuit is 400V, what is the value of capacitance which must be introduced in each phase to cause the whole of the power measured to appear on wattmeter A. The frequency is 50Hz.

(JNTU Feb 08)

19. i. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro dynamometer wattmeter.

ii. Discuss the shape of scale of electro dynamometer wattmeters with the help of a neat sketch.(JNTU Feb 08)

20. i. Discuss the various types of errors and their methods of compensation in the dynamometer type wattmeter.

ii. What are the di”erences between LPF and UPF wattmeters. (JNTU Nov 07)

21. i. Explain how do you measure the total power in a 3-phase circuit with the help of two wattmeters only.ii. In a balanced three phase system power is measured by two wattmeter method and the ratio of two

wattmeter readings is 2:1. Determine the power factor of the system and deduce the relation used?(JNTU Nov 07)

22. Derive the torque equation for an electrodynamometer type wattmeter. Explain why it is necessary to make the potential coil circuit purely resistive? Comment upon the shape of scale if spring control is used. (JNTU Nov 07)

23. i. Show that the power in a 3-phase system is measured by the use of a. only one watt meter and b. two wattmeters.Indicate how the power is determined. Comment on the accuracy of the measurements when the load is unbalanced and the supply is a four-wire system.

ii. Two wattmeters used to measure the power input in a 3-phase circuit indicate 1000w and 500w respectively. Find the powerfactor of the circuit.a. When both wattmeters readings are positiveb. When the latter is obtained by reversing the current coil connections. (JNTU Nov 07)

24. i. Explain with the help of a neat circuit diagram, how the power and the power factor in a 3-phase circuit can be measured by two wattmeter method. Explain how the readings of the two wattmeters change with load p.f?

ii. A balanced load is supplied from a 3-phase, 400V, 3 wire system whose power is measured by two wattmeters. If the total power supplied is 26 KW at 0.75 pf lagging, find the readings of each of the two wattmeters. (JNTU Nov 07)

25. Explain the following methods of measurement of reactive power in three phase circuitsa. Two autotransformers method b. A single electrodynamometer type wattmeter method

(JNTU Nov 07)26. i. Describe the construction & working of electro dynamo meter wattmeter. Derive the expression for

torque when the instrument is used on a.c.ii. The pressure coil of an electro dynamo meter wattmeter has a resistance of 6600. When the voltage

applied to the pressure coil is 120V and a current of 20A flows in the series coil, the deflection is 1600. What additional resistance must be connected in the pressure coil circuit to make the meter constant equal to 20W per degree. (JNTU Feb 07, Mar 06)

27. Explain how the power in a 3 phase system is measured by the use ofi. Only one wattmeterii. Two wattmeters. Indicate how the power factor is determined. (JNTU Feb 07)

28. A non inductive resistance is connected in series with a coil across a 230V, 50Hz supply. The current is 1.8A and the potential difference across the resistance and the coil is 80 & 171 volts respectively. Calculatei. Resistance and inductive reactance of the coil ii. The supply power and pf (JNTU Feb 07)

29. i. Describe with a connection diagram, how would you standard ardize the wattmeter with the help of standard potentiometer. Mention all relevant precautions.

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ii. A voltage : 100 Sin.t + 40 cos (3.t-300)+50SinVt+6cos(5.t-1200)A. What will be the reading on the wattmeter? What percentage of this power is due to fundamental frequency? (JNTU Feb 07)

30. i. Explain the following methods of measurement of reactive power in three phase circuitsi. Two autotransformers methodii. A single electrodynamometer type wattmeter method

31. A dynamometer wattmeter measures power in a 50Hz, single phase circuit without error, at all power factors. The resistance of the voltage coil & its series resistance has a disturbed self capacitance equivalent to a shunt capacity of 20pf. What is the self inductance of the pressure coil?

32. Explain with the help of a neat circuit diagram, how the power & the power factor in a 3ö circuit can be measured by two wattmeter method. Explain how the readings of the two wattmeters change with load p.f?

33. A balanced load is supplied from a 3, 400V, 3 wire system whose power is measured by two wattmeters. If the total power supplied is 26 KW at 0.75 pf lagging, find the readings of each of the two wattmeters. (JNTU Nov 06, Mar 06)

34. Write short notes on the following :i. Errors in power measurements due to connections of wattmeter in different waysii. Two wattmeter method of measuring 3 phase poweriii. Extension of wattmeter range by instrument transformers (JNTU Nov 06, Mar 06)

35. i. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro dynamometer wattmeter.

ii. Discuss the shape of scale of electro dynamometer wattmeters with the help of a neat sketch. (JNTU Mar 06)

36. i. Explain the following errors for electro dynamometer wattmeters. i. Mutual inductance effectsii. Errors due to connections iii. Eddy currents iv. Stray Magnetic fields (e) Vibration of Moving system

(f) Tempetature errors. (JNTU Nov 05)

37. i. Explain the 3 voltmeter method of power measurement with the help of vector & connection diagrams ii. In a dynamometer wattmeter the moving coil has 500 turns of mean diameter 30mm. Estimate the

torque if the axes of the field & the moving coils are at i. 600 ii. 900 when the flux density produced by field coils is 15 x 10-3wb/m2, the current in moving coil is 0.05A & the power factor is 0.866.

(JNTU Nov 05)38. i. Explain the errors caused due to pressure coil inductance and pressure coil capacitance in electro

dynamometer wattmeter. ii. Discuss the shape of scale of electro dynamometer wattmeters with the help of a neat sketch.

(JNTU Apr 05)

39. i. Explain the construction and theory of operation of a single phase electrodynamometer type wattmeter.ii. A certain circuit takes 10A at 200V and the power absorbed is 1000W. If the wattmeters current coil

has a resistance of 0.15W and its pressure coil a resistance of 5000W and an inductance of 0.3H, find a. The error due to the resistance for each of the two possible methods of connectionb. The error due to the inductance if the frequency is 50Hz;c. Total error in each case. (JNTU Nov 04)

40. i. Explain with the help of a phasor diagram the error caused by the inductance of the pressure coil of a dynamometer wattmeter. Indicate the dependence of the error on load power factor and supply frequency.

ii. A 500V, 20A dynamometer instrument is used as a wattmeter. Its current coil has 0.1W resistance and pressure coil has 25KW resistance and 0.1H inductance. The meter was calibrated on dc supply. What is the error in the instrument if it is used to measure the power in a circuit with supply voltage 500v, load current 24A at 0.2 p.f. Assume that the pressure coil is connected across the load.

(JNTU Nov 03)

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41. The pressure coil of a dynamometer type wattmeter isa. highly inductive b. highly resistive c. purely resistive d. purely inductive (GATE 09)

42. Two wattmeters, which are connected to measure the total power on a three-phase system supplying a balanced load, read 10.5 KW and -2.5 KW, respectively. The total power and the power factor, respectively, are______ (GATE 05)

43. The circuit in figure is used to measure the power consumed by the load. The current coil and the voltage coil of the wattmeter have 0.02 ohm adn 1000ohm resistances respectively. The measured power compared to the load power will be ___ (GATE 04)

44. A single phase load is connected between R and Y terminals of a 415 V, symmeterucal, 3-phase, 4 wire system with phase sequence RYB. A wattmeter is connected in the system as shown in figure. The power factor of the load is 0.8 lagging. the wattmeter will read _____ (GATE 04)

45. A wattmeter reads 400 W when its current coil is connected in the R phase and is pressure coil is connected between this phase and the neutral of a symmetrical 3-phase system supplying a balanced star connected 0.8 pf inductive load. The phase sequence is RYB What will be the reading of this wattmeter if its pressure coil alone is reconnected between the B and Y phases, all other connections remaining as before? (GATE 04)

46. Describe a method of power measurement for a 3 phase 3 wire-unbalanced load. How can power factor of a balanced load be determined by the method? (IES 02)

47. What is power? Why wattmeter is essential?

48. Write a note on three phase wattmeter.

49. Explain the error in wattmeter reading due to method of connection.

50. Write a note on low power factor wattmeter.

51. Write about the shape of scale of dynamometer type wattmeter.

52. Explain Blondel’s theorem?

UNIT – IV

1. a. Explain the construction and working of a Merz price maximum demand indicator.b. A single phase induction type energy meter is adjusted to read correctly at unity power. It is observed

that at 1/4 th full load current at 0.5 lag p.f, the effective voltage magnet flux lags behind the current magnet flux by 270. Will it introduce any error in the measurement? If so, calculate the percentage error introduced? (JNTU May 09)

2. a. Draw the connection diagram of a 3-phase energy meter and explain its working. How do you correct it, if it is found to be moving fast?

b. A single phase energy meter makes 500 revolutions per kwh. It is found on testing as making 40 revolutions in 58.1sec at 5 kw full load. Find out the percentage error? (JNTU May 09)

3. Explain the functions of the following in a single phase induction type Energy meter.a. Shunt and series magnets b. Moving disc c. Permanent magnet d. Shading bands and holes in disc. (JNTU May 09)

4. a. Draw a neat sketch showing the construction of a single phase induction type energymeter. Give the theory & operation of the instrument.

b. An Energymeter is designed to make 200 revolutions of disc for one unit of energy. Calculate the number of revolutions made by it when connected to load carrying 80 A at 230v and 0.6 powerfactor for an hour. If it actually makes 500 revolutions, find the percentage error. (JNTU May 09)

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5. a. Draw a neat circuit diagram of a single phase watt hour meter and explain its working. What are the various sources of errors and how they are compensated? (JNTU May 09)

b. A large consumer has a KVA demand R a KVAh tariff measured by “Sine” R “cosine” watthour type meters each equipped with a Merz price demand indicator. The tariff is Rs.40 per month per KVA of demand plus 30 paise per KVAh. Determine the monthly bill for 30 days based upon the following readings: ‘Sine’ meter advances by 90,000 reactive KVAR demand indicator 150 KVAR, ‘cosine’ meter advances by 120,000 kwh & demand indicator by 200kw. What is the average monthly pf and the total cost per unit? (JNTU May 09)

6. a. Explain the theory & operation of single phase energy meters. Derive the expression for the total number of revolutions

b. A 220V, 5A d.c. energy meter is tested at its marked ratings. The resistance of the pressure coil is 8800 and that of current coil is 0.1. Calculate the power consumed when testing the meter with i. direct loading arrangementsii. phantom loading with current circuit excited by a 6V battery (JNTU May 09)

7. a. Explain the sources of errors in single phase induction type energy metersb. A single phase induction watthour meter, tested at its full load rating of 240V, 10A is 1% slow at unity

power factor & correct at a power factor 0.5 lagging. Assuming that the friction error is compensated at all power factors, estimate the error at rated VA when the power factor of the system isi. 0.8 lagging ii. 0.8 leading (JNTU May 09)

8. a. Draw a neat circuit diagram of a single phase watt hour meter and explain its working. What are the various sources of errors and how they are compensated?

b. A large consumer has a KVA demand R a KVAh tari_ measured by “Sine” R “cosine” watthour type meters each equipped with a Merz price demand indicator. The tari_ is Rs.40 per month per KVA of demand plus 30 paise per KVAh. Determine the monthly bill for 30 days based upon the following readings: ‘Sine’ meter advances by 90,000 reactive KVAR demand indicator 150 KVAR, ‘cosine’ meter advances by 120,000 kwh & demand indicator by 200kw. What is the average monthly pf and the total cost per unit? (JNTU Nov 08)

9. a. Draw a neat sketch showing the construction of a single phase induction type energy meter. Give the theory & operation of the instrument

b. An energy meter is designed to make 100 revolutions of the disc for one unit of energy. Calculate the no. of revolutions made by it when connected to a load carrying 20A at 230volts at 0.8 pf for an hour. If it actually makes 360 revolutions, find the percentage error. (JNTU Nov 08)

10. a. Explain how KVAh & KVA measurements can be done with the help of a trivector meter b. Explain the method of testing a.c. meters by phantom loading

11. a. Draw a neat sketch showing the construction of a single phase induction type energy meter. Give the theory & operation of the instrument

b. An energy meter is designed to make 100 revolutions of the disc for one unit of energy. Calculate the no. of revolutions made by it when connected to a load carrying 20A at 230volts at 0.8 pf for an hour. If it actually makes 360 revolutions, find the percentage error.

12. What is phantom loading? Explain with an example how is it more advantages than teating with direct loading?

13. The constant for a three phase, 3 element integrating energymeter is 0.12 revolution of disc per Kwh. If the meter is normally used with a potential transformer of ratio 22,000/110v and a current transformer of ratio 500/5A. Find the error expressed as a percentage of the correct reading from the following test results for the instrument only:Line voltage = 100V; Current =5.25 A; p.f=1 . Time to complete 40 revolutions=61sec.


14. What is creeping? How can it be prevented?

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15. A correctly adjusted, single phase, 240V Induction watt hour meter has a meter constant of 600 rev per Kwh. Determine the speed of the disc, for a current of 10 A at a power factor of 0.8 lagging. If the lag adjustment is altered so that the phase angle between voltage fluse and applied voltage is 860. Calculate the error introduced at a. unity p.f b. 0.5 p.f lagging. Give comments upon the results. (JNTU Feb 08, Nov 07)

16. Explain the construction and working of a single phase induction type energymeter. Show that the total number of revolutions made by its disc during a particular time is proportional to the energy consumed.

17. The disc of an energymeter makes 600 revolutions per unit of energy. When a 1,000 watt load is connected, the disc rotates at 10.2 rpm. If the load is on for 12 hours, how many units are recorded as error? (JNTU Feb 08)

18. Draw a neat sketch showing the construction of a single phase induction type energy meter. Give the theory and operation of the instrument

19. An energy meter is designed to make 100 revolutions of the disc for one unit of energy. Calculate the no. of revolutions made by it when connected to a load carrying 20A at 230volts at 0.8 pf for an hour. If it actually makes 360 revolutions, find the percentage error. (JNTU Feb 08, Nov 07)

20. Explain how the following adjustments are made in a single phase induction type energy meter.i. Lag adjustmentii. Adjustment for friction compensationiii. Creepiv. Overload compensation andv. Temperature compensation. (JNTU Nov 07)

21. Explain the working of the following with neat diagramsi. Maximum demand indicator.ii. Trivector meter. (JNTU Nov 07)

22. i. Explain how KVAh and KVA measurements can be done with the help of a trivector meterii. Explain the method of testing a.c. meters by phantom loading (JNTU Nov 07)

23. Draw a neat sketch showing the construction of a single phase induction type energy meter. Give the theory and operation of the instrument (JNTU Feb 07, Nov 06, 05, Mar 06)

24. An energy meter is designed to make 100 revolutions of the disc for one unit of energy. Calculate the no. of revolutions made by it when connected to a load carrying 20A at 230volts at 0.8 pf for an hour. If it actually makes 360 revolutions, find the percentage error. (JNTU Feb 07, Nov 06, 05, Mar 06)

25. What are the different factors which affect the precision measurement of medium resistances with wheat stone bridge? Explain how their effects are minimized/eliminated (JNTU Feb 07)

26. A wheat stone bridge is used for measuring the value of change of resistance of a strain gauge which forms one of the arms of the bridge. All the arms of the bridge including the strain guage have a resistance of 100“ each. The maximum allowable power dissipation from the strain gauge is 250 MW. Determine the value of maximum permissible current through the strain gauge and maximum allowable value of bridge supply voltage. Suppose a source of 20V is available, find the value of series resistance to be connected between the source and the bridge to limit the input voltage of the bridge to permissible level. (JNTU Feb 07)

27. Describe the construction & working of a Merz price maximum Demand indicator.(JNTU Feb 07)

28. A single phase induction type energy meter is adjusted to read correctly at unity pf. It is observed that 1/4 full load current at 0.5 lagging pf the effective voltage magnet flux lags behind the current magnet flux by 270, Will it introduce any error in the measurement? If so, calculate the percentage error introduced. (JNTU Feb 07)

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29. Draw a neat circuit diagram of a single phase watt hour meter and explain its working. What are the various sources of errors and how they are compensated?

30. A large consumer has a KVA demand and a KVAh tari_ measured by “Sine” and “cosine” watt hour type meters each equipped with a Merz price demand indicator. The tari_ is Rs.40 per month per KVA of demand plus 30 paise per KVAh. Determine the monthly bill for 30 days based upon the following readings: ‘Sine’ meter advances by 90,000 reactive KVAR demand indicator 150 KVAR, ‘cosine’ meter advances by 120,000 kwh & demand indicator by 200kw. What is the average monthly pf and the total cost per unit? (JNTU Nov 06, 05, Mar 06)

31. Explain the constructional details of 3 - ph energy meter. (JTNU Mar 06, Nov 05)

32. A correctly adjusted single phase 240Volts, induction watt hour meter has ammeter constant of 6000 revolution per kwh. Determine the speed of the disk, for a current of 10 Amps. At a power factor of 0.8 lagging If the lag adjustment is altered so that the phase angle between flux and applied voltage is 860. Calculate the error introduced it a. unit pf b. 0.5pf lagging. (JNTU Mar 06, May 03)

33. Explain the testing of energy meter using R.S.S. meter. (JNTU Nov 05)

34. The meter constant of a 230V, 10A, watt our meter is 1800 revolutions per Kwh. The meter is tested at half load and rated voltage and unity power factor. The meter is found to make 80 revolutions in 138 second. Determine the meter error at half load. (JNTU Nov 05)

35. What is energy meter testing? Explain phantom load testing. (JNTU Nov 05)

36. A 220V, 5A, DC energy meter is tested at its marked ratings. The resistance of pressure circuit is 8800W and that of current coil is 0.1W. Calculate the power consumed when testing the meter with phantom loading with current circuit excited by a 6 volts battery. (JNTU Nov 05)

37. A correctly adjusted single phase 240 volts, induction watt hour meter has ammeter constant of 6000 revolution per Kwh. Determine the speed of the disc, for a current of 10 Amps. At a power factor of 0.8 lagging. If the lag adjustment is altered so that the phase angle between flux and applied voltage

(JNTU Nov 05)

38. Describe the construction & working of two element Induction type energy meter(JNTU Nov 05)

39. The constant for a three phase, 3 element integrating wattmeter is 0.12 revolution of disc per kwh. If the meter is normally used with a potential transformer of ratio 22,000/110V & a current transformer of ratio 500/5A, find the error expressed as a percentage of the correct reading from the following test figures for the instrument only Line voltage = 100V; current = 5.25A; pf = 1 time to complete 40 revolutions = 61Sec. (JNTU Apr 05)

40. A dc A-h meter is rated for 15 A, 250 V. The meter constant is 14.4 A-sec/rev. The meter constant at rated voltage may expressed as _______ (GATE 04)

41. The effect of stray magnetic fields on the actuating torque of a portable instrument is maximum when the operating field of the instrument and the stray fields are ____ (GATE 03)

42. Explain the phenomena of ‘creeping’. If an energy meter disc makes 10 revolutions in 100 seconds when a load of 360W is connected to it determine the meter constant in revolutions / k. Wh.

(IES 02)

43. Write a note on trivector meter.

44. Explain the three element and two element three phase induction type energy meter.

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45. The constant for a three phase, 3 element integrating energy meter is 0.13 revolution of disc per Kwh. If the meter is normally used with a potential transformer of ratio 22,000/110v and a current transformer of ratio 600/6A. Find the error expressed as a percentage of the correct reading from the following test results for the instrument only:Line voltage = 100V; Current =5.25 A; p.f=1 . Time to complete 40 revolutions=61sec.

46. A large consumer has a KVA demand and a KVAh tari_ measured by “Sine” and “cosine” watthour type meters each equipped with a Merz price demand indicator. The tari_ is Rs.45 per month per KVA of demand plus 35 paise per KVAh. Determine the monthly bill for 30 days based upon the following readings: ‘Sine’ meter advances by 90,000 reactive KVAR demand indicator 160 KVAR, ‘cosine’ meter advances by 120,000 kwh & demand indicator by 20kw. What is the average monthly pf and the total cost per unit?

47. What is tarrif ?Explain the various type of tarrif used.

48. Describe the crossed phase method for measurement of VArh in 3 phase 3 wire circuits.

49. Explain the sources of errors in single phase induction type energy meter.

50. Explain the underlying principle for using different types of tariffs for different types of consumers.

51. Describe a VAR meter using bridge type rectifiers.

UNIT – V

1. Explain the following in A.C. potentiometer:a. Drysdale phase shifting Transformer. B. Transfer instrument (JNTU May 09)

2. Draw the circuit diagram of D.C. crompton’s potentiometer and explain its working. (JNTU May 09)

3. a. Find the working current of the slide wire and the rheostat setting.b. If the slide wire has divisions marked in mm and each division can be interpolated to one fifth,

calculate the resolution of the instrument?c. What is standardization and explain with an example, how it is obtained. (JNTU May 09)

4. a. Explain standardizing of A.C. potentiometers and use of transfer instruments in case of a.c. potentiometer.

b. Measurements for the determination of the impedance coil are made on a coordinate type of potentiometer. The results are: Voltage across 1 standard resistance in series with the coil + 0.952V on in phase dial and - 0.340 V on quadrate dial; voltage across 10:1 potential divider connected to the terminals of the coil: +1.35 V on inphase dial and + 1.28 V on quadrate dial. Calculate the resistance and reactance of the coil. (JNTU May 09)

5. Describe the construction, principle of operation of a duo-range potentiometer by drawing its circuit diagram. Also explain its advantages (JNTU May 09)

6. a. What is synchronizing? Describe under what condition a 3 phase alternator can be synchronized to 3 phase bus bars?

b. Explain the construction and working of the Weston type synchroscope. (JNTU May 09)

7. a. Explain the construction and working of a 3φ rotating field power factor meterb. Prove that the deflection of the moving system is equal to the phase angle of the system with respect to

the above meter. (JNTU May 09)

8. a. What is synchronizing? Describe under what condition a 3 phase alternator can be synchronized to 3 phase bus bars?

b. Explain the construction and working of the Weston type synchroscope. (JNTU May 09)

9. Describe the construction and working of a polar type potentiometer. How is it standardized? What are the functions of the transfer instrument and the phase shifting transformer? (JNTU Nov 08)

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10. i. Describe the steps when D.C. crompton’s potentiometer is used to measure an unknown resistance?ii. A basic slide wire potentiometer has a working battery voltage of 3 volts with negligible internal

resistance. The resistance of slide wire is 400 ohms and its length is 200 cm. A 200 cm scale is placed along the slide wire. The slide wire has 1 mm scale divisions and it is possible to read upto of a division. The instrument is standardized with 1.018 V standard cell with sliding contact at the 101.8 cm mark on scale. Calculate:a. Working current b. The resistance of series rheostatc. The measurement range and d. The resolution of the instrument. (JNTU Feb 08)

11. i. Explain how “time zero” is obtained in a crompton’s potentiometer? (JNTU Feb 08)ii. Explain the reasons why a separate “standard cell dial circuit” is provided in modern d.c.

potentiometer?

12. Explain the basic principle of operation of d.c. potentiometer with a neat sketch. Explain why a potentiometer does not load the voltage source whose voltage is being measured?

(JNTU Feb 08)

13. i. Draw the circuit diagram of a basic slide wire d.c. potentiometer. Explain its working?ii. A single range potentiometer has a 18 step dial switch where each step represents 0.1V, the dial

resistors are 10ohms. The slide wire of the potentiometer is circular and has 11 turns and a resistance of 11ohms each. The slide wire has 100 divisions and interpolation can be done to one fourth of a division. The working battery has a voltage of 6 volts and negligible internal resistance. Calculate:a. the measuring range of potentiometer b. the resolutionc. working current and d. setting of rheostat. (JNTU Feb 08)

14. i. Find the working current of the slide wire and the rheostat setting ii. If the slide wire has divisions marked in mm and each division can be interpolated to one fifth,

calculate the resolution of the instrument.iii. What is standardization and explain with an example, how it is obtained. (JNTU Feb 08)

15. i. Describe the construction and working of a co-ordinate type a.c. potentiometer. How is it standard? Explain how an unknown voltage can be measured with it.

ii. Discuss the source of errors with respect to a.c potentiometers. (JNTU Feb 08)

16. Explain the construction and working principal of a polar type potentiometer with a neat sketch.(JNTU Nov 07)

17. Explain the following:i. How would you apply a correction for thermo-emf in d.c. potentiometer measurement?ii. What is the difference between and A.C. potentiometer and a d.c. potentiometer?iii. What are the practical diculties associated with a.c. potentiometers?iv. How the d.c. potentiometer is standardized? (JNTU Nov 07)

18. i. Explain how an unknown voltage can be measured by using a polar type potentiometer?ii. Calculate the inductance of a coil from the following measurement on an a.c. potentiometer. Voltage

drop across a 0.1“ standard resistor connected in series with the coil = 0.613 1206’. Voltage across the test coil through a 100/1 volt-ratio box = 0.781 50048’ V. Frequency is 50 Hz. (JNTU Nov 07)

19. Explain the following:i. Standardization procedure of d.c. cropmtons potentiometer.ii. Applications of d.c. crompton potentiometer. (JNTU Nov 07)

20. Explain with the help of suitable diagrams, how a.c. potentiometers can be used fori. Calibration of voltmetersii. Calibration of ammetersiii. Calibration of wattmeters and energy metersiv. Measurement of reactance of a coil (JNTU Nov 07)

21. Describe the construction and working of a polar type potentiometer. How is it standardized? What are the functions of the transfer instrument and the phase shifting transformer?

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(JNTU Feb 08, 07, Nov 07, 06, 05)

22. i. Find the working current of the slide wire and the rheostat settingii. If the slide wire has divisions marked in mm and each division can be interpolated to one fifth,

calculate the resolution of the instrument.iii. What is standardization and explain with an example, how it is obtained.

(JNTU Feb 07, Nov 06, May 05)

23. Describe the construction, principle of operation of a duo-range potentiometer by drawing its circuit diagram. Also explain its advantages. (JNTU Feb 07)

24. i. Describe the working and construction of a potentiometer with the help of a diagram.ii. A basic slide wire potentiometer has a working battery voltage of 3.0V with negligible internal

resistance. The resistance of slide wire is 400“ and its length is 200cm. A 200cm scale is placed along the slide wire. The slide wire has 1mm scale divisions and it is possible to read up to 1/5 of a division. The instrument is standardized with 1.018V standard cell with sliding contact at the 101.8cm mark on scale calculatea. Working current b. The resistance of series rheostatc. The measurement range d. The resolution of instrument (JNTU Nov 06)

25. i. Explain the reasons why d.c. potentiometers cannot be used for a.c. measurement. Explain the modifications that are needed in a d.c. potentiometer to be used for a.c. applications.

ii. In the measurement of power by a polar potentiometer, the following readings were obtained : Voltage across a 0.2 standard resistance in series with the load = 1.46 |320V Voltage across a 200:1 potential divider across the line = 1.37560V. Estimate the current, voltage, power and power factor of the load.

(JNTU May 06)26. i. Explain the operation of any one type of AC potentiometer.

ii. Explain clearly how such a potentiometer can be employed for measurement of unknown inductance and unknown capacitance. (JNTU May 06, 05)

27. i. Explain the term “Standardization” of a dc potentiometer. (JNTU May 06)ii. With a neat circuit diagram explain salient features of self balancing poteniometer.

28. i. Explain how “true zero is obtained in a crompton‘s potentiometer.ii. What are the applications of potentiometers. (JNTU Nov 05)

29. i. Explain with neat sketch Gall Tinsley co-ordinate AC potentiometer to measure unknown voltage. Indicate clearly how it is standardized.

ii. Explain how the ration and phase angle error of a CT can be measured using AC potentiometer. (JNTU Nov 05)

30. i. Explain how “true zero is obtained in a crompton‘s potentiometer. (JNTU Nov 05)ii. What are the applications of potentiometers.iii. With a neat circuit diagram explain salient features of a self balancing potentiometers.

31. i. With a neat sketch, explain the measurement of resistance using a potentiometer.ii. Draw circuit diagram and explain the measurement of power using potentiometer. (JNTU May 04)

32. i. Explain how potentiometer is employed in measuring resistance, power and calibration of watt meter? ii. During the measurement of a low resistance using a potentiometer the following readings were

obtained. Voltage drop across the low resistance under test – 0.4221V voltage drop across the 0.1 standard resistance – 1.0235V. Calculate the value of unknown resistance, Current and power lost in it.

(JNTU May 03)

33. i. Draw the circuit diagram of Crompton’s potentiometer and explain its working. Describe the steps used when measuring an unknown resistance.

ii .Power is measured with an AC potentiometer. The voltage across a 0.1 standard resistance connected in series with the load is 0.35 – J 0.10V. The voltage across 300:1 potential divider connected to the supply is 0.8+J 0.15V. Determine the power consumed by the load and the PF. (JNTU May 03)

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34. Explain the term “Standardization of a potentiometer”. Describe the procedure for the standardization of a DC potentiometer. (JNTU Nov 03)

35. i. Write a circuit diagram to explain salient features of self balancing potentiometer.ii. Explain clearly the construction and working principle of “DRYSDALE” polar type AC potentiometer.

(JNTU Nov 03)

36. A slide wire potentiometer has a battery of 4V and negligible internal resistance. The resistance of slide wire is 100 Ohms and its length 200cm. A standard cell of 1.018V is used for standardizing the potentiometer and the Rheostat is adjusted so hat balance is obtained when the sliding contact is at 101.8 cm. Find the working current of slide wire and the rheostat setting. If the slide wire has division marked in mm and each division can be interpolated to one fifth, calculate the resolution of the instrument. (JNTU Nov 03)

37. A dc potentiometer is designed to measure up to about 2V with a slide wire of 800 mm. A standard cell of emf 1.18V obtains balance at 600 mm. A test cell is seen to obtain balance at 680mm. The emf of the test cell is_____ (GATE 04)

38. A 0-10000 micro ampere microammeter guaranteed to be 8.7 accurate needs to be calibrate using a 1.0 V DC potentiometer. Draw the circuit diagram and find the value of the standard resistance used and the least count of the potentiometer. (GATE 97)

39. The current taken by a small iron core choke coil is measured by a rectangular coordinate AC potentiometer. A 1.0 Ohm non inductive resistance is connected in series with the choke coil. The voltage measured across the resistance and the coil are (0.8 – j0.75) volt and (1.2 + j0.3)V respectively. Assuming sinusoidal voltage and current determine the core loss in the coil. (GATE 97)

40. A slide wire potentiometer of 150cm in length has resistance of 150 Ohms, the working battery has an emf of 4.2 V and negligible internal resistance. The galvanometer resistance is 20 Ohms. The standard cell has an emf of 1.018V and internal resistance of 1.5 Ohms. The rheostat in the circuit is adjusted so that the standard cell is in balance with the slide wire contact at 101.8 cm. Find the resistance of the rheostat. (GATE 97)

41. Calculate the inductance of a coil from the following measurements on an AC potentiometer. Voltage drop across a 0.3 Ohms standard resistor connected in series with the coil = 0.612ë12°6V voltage

(GATE 97)

42. The balance is obtained at a length of 60 cm when the emf of standard cell used for standardization is 1.0186 volts. Determine

i. The emf of the cell which balances at 75cmii. The current flowing through a standard resistance of 2 ohms if the Pd across it balances at 66 cm.iii. The voltage of a supply main which is reduced by a volt ratio box to one hundred and balance is

obtained at 84 cm. (GATE 97)

43. A Crompton’s potentiometer consists of a resistance dial having 15 steps of 10 Ohms each and a series connected slide wire of 10 Ohms which is divided into 100 division. If the working current of the potentiometer is 10 mA and each division of slide wire can be read accurately up to 1/5 of its span. Calculate the resolution of the potentiometer in volt. (GATE 97)

44. Explain true zero in potentiometer.

45. Write a note on simple potentiometer with calibrating circuit.

46. List the basic requirements of A.c potentiometer.

47. Write application of DC potentiometer.

48. Write application of AC potentiometer.

49. A basic slide wire potentiometer has a working battery voltage of 8.0V with negligible internal resistance. The resistance of slide wire is 400“and its length is 200cm. A 200cm scale is placed along

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the slide wire. The slide wire has 1mm scale divisions and it is possible to read up to 1/5 of a division. The instrument is standardized with 1.018V standard cell with sliding contact at the 101.8cm mark on scale calculatea. Working current b. The resistance of series rheostatc. The measurement range d. The resolution of instrument

UNIT – VI

1. a. What are the different difficulties encountered in the measurement of high resistances? Explain how these difficulties are overcome?

b. A highly sensitive galvanometer can detect a current as low 0.1 nano-Amperes. This galvanometer is used in a wheat-stone bridge as a detector. The resistance of galvanometer is negligible. Each arm of the bridge has a resistance of 1K. The input voltage applied to the bridge is 20V. Calculate the smallest change in resistance, which can be detected. The resistance of the galvanometer can be neglected as compared with the internal resistance of bridge. (JNTU May 09)

2. Explain the following:a. Why is Kelvin’s double bridge superior to the wheat-stone bridge for the purpose of low resistance

measurement?b. How the difficulties associated with the measurement of a very high resistance are over come? c. How the effects of contact resistance and resistance of the connecting leads are eliminated in the

measurement of resistance by Kelvin’s double bridge?d. Why is the Voltmeter-Ammeter method unsuitable for the precise measurement of the low resistance?

(JNTU May 09)

3. a. Draw the circuit diagram of wheat stone bridge. State its limitations. How these limitations can be overcome?

b. A Kelvin bridge is balanced with the following constants: outer ratio arm 100 and 1000; inner arms ratio 99.92 and 1000.6; Resistance of link, 0.1; standard resistance 0.00377. Calculate the value of unknown resistance. (JNTU May 09)

4. a. Derive the expression for bridge sensitivity for a Wheatstone bridge with equalarms. Find also the expression for current through the galvanometer for a small unbalance.

b. The four arms of a wheatstone bridge are as follows: AB=100; BC=1000; CD=4000 and DA=400. The galvanometer has a resistance of 100, a sensitivity of 100 mm/μA and is connected across AC. A source of 4V d.c. is connected across BD. Calculate the current through the galvanometer and its deflection if the resistance of arm DA is changed from 400 to 401 . (JNTU May 09)

5. a. What are the different difficulties encountered in the measurement of high resistances? Explain how these difficulties are overcome.

b. Explain in detail the use of guard circuit for measurement of high resistancec. Classify the resistances from the point of view of measurements. (JNTU May 09)

6. Describe the construction and working of a polar type potentiometer. How is it standardized? What are the functions of the transfer instrument and the phase shifting transformer? (JNTU May 09)

7. A moving coil galvanometer has a sensitivity of 4 cm per micro ampere, with a scale of 1 metre distant, and the time of free oscillation is 2.8 seconds If the galvanometer is dead beat when the total circuit resistance (coil and external circuit) is 2500 ohms, find the moment of inertia of the moving system. Prove the formula used (JNTU May 09)

8. What are the different problems associated with the measurement of low resistances. Explain the principle of working of a Kelvin‘s double bridge and explain how the effect of contact resistance and resistance of leads is eliminated (JNTU May 09)

9. What are the different problems associated with measurement of low resistances. Explain the principle of working a Kelvin’s Double Bridge and explain how the effect of contact resistance and resistance of leads is eliminated? (JNTU Feb 08)

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10. i. Explain the Ammeter-Voltmeter method of measurement of resistances. There are two ways in which the circuit of Ammeter Voltmeter method can be used.a. Ammeter connected to the side of unknown resistance andb. Voltmeter connected to the side of unknown resistance. Derive a condition, that decides which circuit is to be used for a particular set of Ammeter, Voltmeter and unknown resistance. Assume equal relative error in both the cases.

ii. In a laboratory a voltmeter of 200 ohm resistances and an ammeter of 0.02 ohm resistance are available. Calculate the value of resistance that can be measured by the Ammeter voltmeter method for which the two different circuit measurements give equal errors. (JNTU Feb 08)

11. i. Explain the loss of charge method for measurement of insulation resistance of cables.ii. A length of cable is tested for insulation resistance by the loss of charge method. An electrostatic

voltmeter of infinite resistance is connected between the cable conductor and earth, forming there with a joint capacitance of 600 pF. It is observed that after charging the voltage falls from 250V to 92V in 1 minute. Calculate the insulation resistance of the cable. (JNTU Feb 08)

12. i. Mention some of the difficulties in measuring of high resistance.ii. Derive an expression for insulation resistance of a single core cable. The conductor of a cable has a

diameter of 5 mm and the over all diameter of the cable is 35cm. If the insulation resistance of the cable is 16,000ohm/km, calculate the specific resistance of insulating matrial. (JNTU Feb 08)

13. i. What are the different difficulties encountered in the measurement of high resistances? Explain how these difficulties are overcome.

ii. Explain in detail the use of guard circuit for measurement of high resistanceiii. Classify the resistances from the point of view of measurements. (JNTU Feb 08)

14. Explain the loss of charge method for measuring high resistance. Mention the possible errors and suggest methods to minimize these. (JNTU Nov 07)

15. Explain the following: (JNTU Nov 07)i. Why is Kelvin’s double bridge superior to the wheat-stone bridge for the purpose of low resistance

measurement? ii. How the difficulties associated with the measurement of a very high resistance are over come?iii. How the effects of contact resistance and resistance of the connecting leads are eliminated in the

measurement of resistance by Kelvin’s double bridge?iv. Why is the Voltmeter-Ammeter method unsuitable for the precise measurement of the low resistance?

16. Explain what do you mean by low, medium and high resistances? Suggest various suitable methods for measuring them giving justification. Explain any method to measure a low resistance with accuracy?

(JNTU Nov 07)

17. i. Classify the resistances from the point of view of measurements. ii. Explain in brief the di”erent methods used for measurement of medium resistances.iii. A voltmeter of resistance 500 ohm and a milliammeter of 1ohm resistance are used to measure a

resistance by Ammeter-Voltmeter method. If the Voltmeter reads 20V and milli-Ammeter 100 mA, Calculate the value of measured resistance.a. If the Voltmeter is put across the resistance and the milli-Ammeter connected in series with the unknown resistance.b. If the voltmeter is put across the resistance with ammeter connected on the supply side.

(JNTU Nov 07)

18. i. What are the different factors which affect the precision measurement of medium resistances with wheat stone bridge? Explain how their effects are minimized/eliminated

ii. A wheat stone bridge is used for measuring the value of change of resistance of a strain gauge which forms one of the arms of the bridge. All the arms of the bridge including the strain guage have a resistance of 100“ each. The maximum allowable power dissipation from the strain gauge is 250 MW. Determine the value of maximum permissible current through the strain gauge and maximum allowable value of bridge supply voltage. Suppose a source of 20V is available, find the value of series resistance to be connected between the source and the bridge to limit the input voltage of the bridge to

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permissible level. (JNTU Nov 07)

19. i. Describe with a neat diagram the working of a Carey Foster Slide wire bridge method.ii. In a Carey Fosters bridge a resistance of 1.0125 ohms is compared with a standard resistance of 1.0000

ohm, the slide wire has a resistance of 0.250 ohm in 100 divisions. The ratio arms nominally 10ohm each are actually 10.05 ohm and 9.95 ohm respectively. How far (in scale divisions) are the balance positions from those which would obtain of arms ratio were true to their nominal value? The slide wire is 100cm long. (JNTU Feb 07, May 06)

20. Describe a method by which the insulation resistance to earth of each of a pair of live mains can be measured by a voltmeter of known resistance. Discuss the limitations of the method

(JNTU Feb 07)

21. The following readings were taken with a 250V, 1000“ per volt, voltmeter Between two mains ) 218 volts Positive main to earth) 188 volts Negative main to earth ) 10 volts Calculate the insulation resistance of each main. (JNTU Feb 07)

22. A moving coil galvanometer has a sensitivity of 4 cm per micro ampere, with a scale of 1 metre distant, and the time of free oscillation is 2.8 seconds If the galvanometer is dead beat when the total circuit resistance (coil and external circuit) is 2500 ohms, find the moment of inertia of the moving system. Prove the formula used (JNTU Nov 06)

23. Describe about the Kelvin double bridge for the comparison of small resistances. Explain the precautions followed for achieving highest prescision (JNTU Nov 06)

24. Draw the circuit of Kelvin double bridge used for measurement of low resistances. Derive the condition for balance. (JNTU Nov 06)

25. A highly sensitive galvanometer can detect a current as low as 0.1 nA. This galvanometer is used in a whetstone bridge as a detector. The resistance of galvanometer is negligible. Each arm of the bridge has a resistance of 1K. The input voltage applied to the bridge is 20V. Calculate the smallest change in the resistance which can be detected.

(JNTU May 06)

26. What are the various limitations of whetstone bridge for measurement of high and low resistances.(JNTU Nov 06)

27. The four arms of a whetstone bridge are as follows. AB = 100W, BC = 1000W, CD = 4000W and DA = 400W. The galvanometer has a resistance of 100W, a sensitivity of 100mm / Micro Amp. And is ohms connected across AC. A source of 4V DC is connected across BD. Calculate the current through the galvanometer. (JNTU May 03)

28. Describe any one method of measuring a very high value of resistance. (JNTU May 03)

29. A lissajous pattern on the oscilloscope is stationary and has 6 vertical maximum values and 5 horizontal maximum values. The frequency of horizontal Input is 1500Hz. Determine the frequency of vertical Input. (JNTU May 03)

30. How do you classify the resistances from the point of view of measurements. (JNTU May 03)

31. Describe the method of measurement of medium resistances by wheatstone bridge method derive the conditions for balance. (JNTU May 03)

32. Describe the construction and principle of operation of a Meggar with a neat sketch?(JNTU May 03)

33. Explain the construction and operation principle of vibration galvanometer. (JNTU May 03)

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34. A modified wheatstone bridge network is constituted as follows: AB is resistance P in parallel with resistance p; BC is a resistance Q in parallel with a resistance q; CD and DA are resistances R and S respectively. The nominal values of P, Q and S are each 10W. (JNTU May 03)

35. A Kelvin Double bridge has each of the ratio arms P = Q = p = q = 1000W. The emf of the battery is 100V and a resistance of 5W is included in the battery circuit. The galvanometer has a resistance of 500W and the resistance of the link connecting the unknown resistance to the standard resistance may be neglected. The bridge is balanced when the standard resistance S = 0.001W.

i. Determine the value of unknown resistance.ii. Determine the current (approximate value) through the unknown resistance R at balance.iii. Determine the deflection of the galvanometer when the unknown resistance, R, is changed by 0.1

percent from its value at balance. The galvanometer has a sensitivity of 200mm/mA.(JNTU May 03)

36. Why is wheatstone bridge unsuitable for measurements of very low resistances? (JNTU May 03)

37. Describe with a neat sketch, the Kelvin’s double bridge method of measuring low resistances. How does it overcome the defect of wheatstone bridge? (JNTU May 03)

38. Draw the circuit of Kelvin double bridge used for measurement of low resistances. Derive the condition for balance. (JNTU May 02)

39. A highly sensitive galvanometer can detect a current as low as 0.1nA. This galvanometer is used in a wheat stone bridge as a detector. The resistance of galvanometer is negligible. Each arm of the bridge has a resistance of 1KW. The input voltage applied to the bridge is 20V. Calculate the smallest change in the resistance, which can be detected. (JNTU May 02)

40. Give the meaning of the following terms:i. Precisionii. Accuracyiii. Standard deviation andiv. Probable error

Two resistors R1 and R2 are connected in series and then in parallel. The value of resistances are R1 = 100.0 0.1W R2 = 50 0.05 W (IES 94)Calculate the uncertainty in the combined resistance for both series and parallel arrangements.

41. The resistance of an unknown resistance is determined by wheat stone bridge. The solution for the unknown resistance is stated as,The limiting value of various resistance are R1 = 500+1%, R2 = 615+1%, R3 = 100+0.5%Calculate

i. The nominal value of the unknown resistanceii. Its limiting error in percentiii. Its limiting error in Ohms (IES 93)

42. A bridge circuit is shown in figure (IES 93)i. The output signal of the bridge is V0, Looking into this part find an expression for the Thevenin

equivalent resistance of the bridge.ii. If R1 = R(1-x), R4 = R(1+x) and R2 = R3, find an expression for the output voltage V0 in terms of E

and x. Take RS = 0 in this case.

43. What are the difficulties associated with measurement of low resistance? Describe how low resistance is measured accurately by Kelvin’s double bridge? (IES 92)

44. Describe the substitution method of measurement of medium resistance. List the factors on which the accuracy of the method depends.

45. Draw the circuit of a wheatstone bridge and derive the condition of balance.

46. Explain the loss of charge method for measurements of insulation resistance of cables.

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47. What is three terminal resistances? Explain its use.

48. How the bridge is used in the measurement of the parameters like stress , strain, temperature etc ?

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UNIT – VII

1. Draw the circuit diagrams and phasor diagram of the following bridges under balanced conditions. Also, derive the equations under balanced conditions.

a. D’sauty’s bridge b. Schering bridge and c. owen’s bridge. (JNTU May 09)

2. a. State the advantages and disadvantages of Anderson’s bridge.b. Draw the phasor diagram for Anderson’s bridge under balance conditions.c. A bridge consists of the following:

Arm ab - a choke coil having a resistance R1 and inductance L1Arm bc - a non-inductive resistance R3.Arm cd - a mica condenser C4 in series with a non-inductive resistance R4.Arm da - non-inductive resistance R2.When this bridge is fed from a source of 500 Hz, balance is obtained under following conditions.R2=2410; R . 3=750; C . 4=0.35 μF ; R4 = 64.5. The series resistance of capacitor is 0.4. Calculate the resistance and inductance of the choke coil. The supply is connected between a and c and the detector is between b and d. (JNTU May 09)

3. a. Draw the circuit diagram of Hay’s bridge. Also, draw the pahsor diagram under balance conditions.b. Define Quality factor of a coil? Why is Hay’s bridge suited for measurement of inductance of high Q

coils?c. State the advantages and dis-advantages of Hay’s bridge? (JNTU May 09)

4. a. Derive the equations for balance in the case of Maxwells inductance bridge for the measurement of self Inductance

b. Arm ab consists of a coil with inductance L1 and resistance r1 in series with a non inductive resistance R. Arm bc and ad are each a non-inductive resistance of 100Ω. Arm ad consists of standard variable inductor L of resistance 32.7Ω. Balance is obtained when L2=47.8mH and r=1.36Ω. Find the resistance and inductance of the coil in arm ab (JNTU May 09)

5. a. What are the different sources of errors in a.c. bridges? Explain the precautions taken and the techniques used for elimination/minimization of these errors.

b. Explain the function and working of wagner Earth devices. (JNTU May 09)

6. a. Discuss in detail about high voltage schering bridge b. The Four arms of a bridge are :

arm ab : an imperfect capacitor C1 with an equivalent series resistance of rarm bc : a non inductive resistance R3

arm cd : a non-inductive resistance R4,arm da : an imperfect capacitor C2 with an equivalent resistance of r2 series with a resistance R2. A supply of 450Hz is given between terminal a and c and the detector is connected between b and d. At balance : R2=4.8, R3=2000, R4=2850 and C2=0.5µF and r2=0.4. Calculate the value of C1 and r1 and the dissipating factor. (JNTU May 09)

7. a. Describe the working Carey foster Bridge; Heydweiller Bridge and give its applications with neat diagram.

b. A modified Carey-foster‘s bridge, is used for measurement of capacitance. Arm ab contains the secondary winding a mutual inductance of 18.35mH and a total non-reactive resistance of 200Ω. The inductance of secondary of mutual inductor in arm ab is 40.6mH., Arm ad is short circuited Arm bc contains the unknown capacitor in series with a resistance of 119.5Ω. Arm cd comprises of a resistor of 100Ω resistance. The detector is across bd. Determine the capacitance and its equivalent series resistance. (JNTU May 09)

8. a. In Maxwell‘s Inductance-capacitance bridge the dial of variable capacitor can be made to read the value of unknown inductance directly? How is it done?

b. A Maxwell‘s inductance capacitance bridge is used to measure an unknown inductance in comparison with capacitance. The various values at balance : areR2 of arm ad =400ΩR3 of arm bc = 600 ΩR4 and C4 of arm Cd = 1000 Ω, 0.5 µ

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Calculate the values of R1 and L1 arm ab calculate also the value of storage (Φ) factor of coil if frequency is 1000Hz. (JNTU Nov 08)

9. a. Explain why Maxwell‘s inductance - capacitance bridge is useful for measurement of coils having storage factor between 1 and 10.

b. An ac bridge circuit is working at 1000Hz. Arm ab is 0.2µF pure capacitance, arm bc is a 500 pure resistance, arm cd contains an unknown impedance and arm da has a 300 resistance in parallel with a 0.1µF capacitor. Find the R and C (or) L constants of arm cd considering it as a series circuit.

(JNTU Nov 08)

10. a. Discuss advantages and disadvantages of D‘Sauty Bridge (JNTU Nov 08)b. Describe the working of a low voltage schering bridge. Derive the equations for capacitance and

dissipation Factor. Draw the phasor diagram of the bridge under balanced conditions.

11. a. Describe how an Inductance can be measured in terms of capacitance, by using owen‘s bridge. Draw the phasor diagram and explain

b. Give the advantages and disadvantages of owen‘s bridge. (JNTU Nov 08)

12. i. What are the limitations of L.V. schering bridge?ii. Define dissipation factor? Derive the equation for dissipation factor in case of L.V. schering bridge?iii. In a Low-voltage schering bridge designed for the measurement of permittivity, the branch ab consists

of two electrodes between which the specimen under test may be inserted; arm bc is a non-reactive resistor R3 in parallel with a standard capacitor C3; arm CD is a non-reactive resistor R4 in parallel with a standard capacitor C4; arm da is a standard air capacitor of capacitance C2. Without the specimen between the electrodes, balance is obtained with the following values, C3 = C4 = 120 pF, C2 = 150 PF, R3 = R4= 5000ohms. With the specimen inserted, these values become C3 = 200 PF; C4 = 1000 pF; C2 = 900 pF, and R3 = R4 = 5000ohms In each test w = 5000 rad/sec. Find the relative permittivity of the specimen. (JNTU Feb 08, Nov 07)

13. i. Draw the circuit diagram of Maxwell’s Inductance Capacitance Bridge. Also, draw the phase figure under balance conditions.

ii. State the advantages and disadvantages of the above bridge. iii. A Maxwell’s bridge shown in figure.1 has the following constants: Arm ab consists of a coil with

inductance L1 and resistance r1 in series with a noninductive resistance R. Arm bc and cd each are a non-inductive resistance of 100ohms. Arm ad consists of standard variable inductor L of resistance 32.7ohms. Balance is obtained when L2 = 47,8mH and R=1/36ohms. Find the resistance and inductance of the coil in arm ab. (JNTU Feb 08)

14. i. In a Maxwell’s Inductance-Capacitance bridge the dial of variable capacitor can be made to read the value of unknown inductance directly. How is it done?

ii. Explain why Maxwell’s Inductance-Capacitance bridge is useful for measurement of inductance of coils having quality factor between 1 and 10.

iii. The four arms of a Maxwell’s capacitance bridge at balance are: arm ab, an unknown inductance L1, having an inherent resistance R1; arm bc, a noninductive resistance of 1000 ohms. Derive the equation of balance for the bridge and determine the value of R1 and L1. Draw the phasor diagram of the bridge under balance conditions. (JNTU Feb 08)

15. i. What is the difference between L.V. schering bridge and H.V. schering bridge?ii. Draw the circuit diagram of H.V. schering bridge.iii. A capacitor bushing forms arm ab of a schering bridge and a standard capacitor of 500 pF capacitance

and negligible loss, forms arm ad. Arm bc consists of a noninductive resistance of 300 ohms. When the bridge is balanced arm cd has a resistance of 72.6 ohms in parallel with a capacitance of 0.148 µF. The supply frequency is 50 Hz. Calculate the capacitance and dielectric loss angle of capacitor. Derive the equations for balance and draw the phasor diagram under conditions of balance. (JNTU Feb 08)

16. i. Derive the general equations for balance of an a.c. bridge. Prove that “For balance in an a.c. bridge, both magnitude and phase have to be satisfied unlike a d.c. bridge where in only the magnitude condition is to be satisfied”.

ii. Describe the sources and the null detectors that are used for a.c. bridges. (JNTU Feb 08)

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17. i. Derive the equations for balance in the case of Maxwell’s Inductance capacitance bridge. Give its advantages. Draw the phasor diagram for balanced conditions.

ii. An a.c bridge circuit is working at 1000Hz. Arm ab is 0.2µF pure capacitance, arm bc is a 500ohms pure resistance, arm cd contains an unknown impedance and arm da has a 300ohms resistance in parallel with a 0.1µF capacitor. Find the R and C (or) L constants of arm cd considering it as a series circuit. (JNTU Feb 08, 07)

18. i. Discuss the advantages and disadvantages of Anderson‘s bridge. ii. The arms of Five node bridge are as follows :

arm ab : an unknown impedance (R1, L1) in series with anon-inductive variable resistor x1arm bc : a non inductive resistor R3 = 100ohmsarm cd : a non inductive resistor R4=200ohmsarm da : a non inductive resistor R2=250ohmsarm de : a non inductive variable resistor rarm ec : a loss-less capacitor C=1 µF,and arm be : a detector An a.c. supply is connected between a and c. Calculate the resistance and inductance R1,L1, when under balanced conditions r1=43.1ohm and r=229.7ohm.(JNTU Feb 08)

19. Describe the working of Hay‘s bridge for measurement of inductance. Derive the equations for balance and draw the phasor diagram under conditions of balance. Why is this bridge suited for measurement of Inductance of high Q coils. (JNTU Feb 08, Nov 07, May 06)

20. Explain the following:i. Why is schering bridge particularly suitable for measurement at high voltage?ii. Why a spark is connected across resistance arms in a schering bridge?iii. Why is vibration galvanometer widely used as detector for operation of A.C. bridges?iv. Why is wagner’s earthing device used in measurements by A.C. bridges? (JNTU Nov 07)

21. i. Explain the method of measuring the dielectric loss of the capacitor at high voltage and high frequency. Derive the condition of balance for the bridge. Also, explain the precautions to be taken to ensure accuracy. Draw the phasor diagram under balance conditions.

ii. In an Anderson bridge for measurement of inductance Lx and Resistance Rx in the arm AB, the arm CD and DA have resistances of 600 ohms each and the arm CE has a capacitor of 1µ F capacitor with A.C. supply at 100 Hz supplied across A and C, balance is obtained with a resistance of 400 ohms in arm DE and 800 ohms in the arm BC. Calculate the value of Lx and Rx. (JNTU Nov 07)

22. i. In Maxwell‘s Inductance-capacitance bridge the dial of variable capacitor can be made to read the value of unknown inductance directly? How is it done? (JNTU Nov 07)

ii. A Maxwell‘s inductance capacitance bridge is used to measure an unknown inductance in comparison with capacitance. The various values at balance : areR2 of arm ad =400 ohms, R3 of arm bc = 600 ohms, R4 and C4 of arm Cd = 1000 ohms, 0.5 µ Calculate the values of R1 and L1 arm ab calculate also the value of storage factor of coil if requency is 1000Hz.

23. i. What are the different sources of errors in a.c. bridges? Explain the precautions taken and the techniques used for elimination/minimization of these errors.

ii. Explain the function and working of wagner Earth devices. (JNTU Nov 07)

24. i. Explain why Maxwell‘s inductance - capacitance bridge is useful for measurement of coils having storage factor between 1 and 10.

ii. An ac bridge circuit is working at 1000Hz. Arm ab is 0.2µF pure capacitance, arm bc is a 500ohms pure resistance, arm cd contains an unknown impedance and arm da has a 300 ohms resistance in parallel with a 0.1µF capacitor. Find the R and C (or) L constants of arm cd considering it as a series circuit. (JNTU Nov 07)

25. i. Discuss advantages and disadvantages of D‘Sauty Bridge (JNTU Feb 07)ii. Describe the working of a low voltage schering bridge. Derive the equations for capacitance and

dissipation Factor. Draw the phasor diagram of the bridge under balanced conditions.

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26. i. What are the different sources of errors in a.c. bridges? Explain the precautions taken and the techniques used for elimination/minimization of these errors.

ii. Explain the function and working of wagner Earth devices. (JNTU Nov 06)

27. i. What are the usual errors encountered in a.c. bridges and how are they eliminatedii. Explain how capacitance of an imperfect capacitor is measured using A.C. bridge and draw the phasor

diagram for the balanced bridge. (JNTU Nov 06)

28. i. Describe how relative permittivity of a specimen of insulating material can be determined using a schering bridge.

ii. A sheet of bakelite 4.5mm thick is tested at 50Hz between electrodes 0.12 m in diameter. The schering bridge employs a standard air capacitor C2 of 106 PF capacitance, a non-reactive resistance R4 of 1000/ð ohms in parallel with a variable capacitor C4, and a non-reactive variable resistance R3. Balance is obtained with C4=0.5µF and R2=260“. Calculate the power factor, capacitance and relative permittivity of sheet. (JNTU Nov 06)

29. i. Give advantages and disadvantages of Hays bridge in detailsii. A bridge consists of arm ab, a choke coil having a resistance R1 and inductance L1. arm bc a non -

inductive resistance R3. When this bridge is fed from a source of 500Hz, balance is obtained under following conditions: R2=2410ohms, R3=750ohms, C4=0.35µF, R4=64.5ohms. The series resistance of capacitance is = 0.4“. Calculate the resistance and inductance of the choke coil. The supply is connected between a and c and the detector is between b and d. (JNTU Nov 06)

30. i. Explain what is meant by sliding balance. How is this condition avoided by choosing variables for manipulation of balance i.e. why variables are so chosen that the two equations for balance are independent of each other?

ii. Why is it preferable in bridge circuits, that the equations for balance are independent of Frequency? Explain. (JNTU May 06, Nov 05)

31. i. Explain how mutual inductance is measured in terms of self inductance. ii. Explain Heaviside mutual inductance bridge with the help of circuit and vector diagrams. Obtain

balance equations. (JNTU May 06)

32. i. Discuss in detail about high voltage schering bridgeii. The Four arms of a bridge are : arm ab : an imperfect capacitor C1 with an equivalent series resistance

of rarm bc : a non inductive resistance R3 arm cd : a non-inductive resistance R4, arm da : an imperfect capacitor C2 with an equivalent resistance of r2 series with a resistance R2 A supply of 450Hz is given between terminal a and c and the detector is connected between b and d. At balance : R2=4.8, R3=2000, R4=2850 and C2=0.5µF and r2=0.4. Calculate the value of C1 and r1 and the dissipating factor. (JNTU May 06)

33. i. Explain how mutual inductance is measured in terms of self inductance. ii. Explain Heaviside mutual inductance bridge with the help of circuit and vector diagrams Obtain

balance equations. (JNTU May 06)

34. i. Discuss the advantages and disadvantages of Anderson‘s bridge. ii. The arms of Five node bridge are as follows : arm ab : an unknown impedance (R1, L1) in series with a non-inductive variable resistor x1

arm bc : a non inductive resistor R3 = 100A arm cd : a non inductive resistor R4=200A arm da : a non inductive resistor R2=250 arm de : a non inductive variable resistor arm ec : a loss-less capacitor C=1 µF, and arm be : a detector An a.c. supply is connected between a and c. Calculate the resistance and inductance R1,L1, when under balanced conditions r1=43.1and r=229.7. (JNTU May 05)

35. i. Give advantages and disadvantages of Maxwell‘s Inductance capacitance bridgeii. The four arms of a Maxwell‘s capacitance bridge at balance are : arm ab, an unknown inductance L1,

having a resistance R1, arm bc, a non-inductive resistance of 1000, arm cd, a capacitor of 0.5µF in parallel with a resistance of 1000, arm da, a resistance of 1000. Find the inductance L1 of arm ab.

(JNTU May 05)

36. i. Derive the equations for balance in the case of Maxwells inductance bridge for the measurement of self Inductance

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ii. Arm ab consists of a coil with inductance L1 and resistance r1 in series with a non inductive resistance R. Arm bc and ad are each a non-inductive resistance of 100. Arm ad consists of standard variable inductor L of resistance 32.7. Balance is obtained when L2=47.8mH and r=1.36. Find the resistance and inductance of the coil in arm ab. (JNTU May 05)

37. i. Explain what is meant by sliding balance. How is this condition avoided by choosing variables for manipulation of balance i.e. why variables are so chosen that the two equations for balance are independent of each other?

ii. Why is it preferable in bridge circuits, that the equations for balance are independent of frequency? Explain. (JNTU May 05)

38. The four arms of a bridge are:Arm ab: an imperfect capacitor C1 with an equivalent series resistance of R1

Arm bc: a non-inductive resistance R3 cd: a non-inductive resistance R4

Arm da: an imperfect capacitor C2 with an equivalent resistance of R2 in series with a resistance R2. A supply of 450 Hz is given between terminal a and c and the detector is connected between b and d. At balance:R2 = 4.8Wm, R3 = 2000W, R4 = 2850W and C2 = 0.5mF and R2 = 0.4W.Calculate the value C1 and r1 and also of the dissipating factor for this capacitor. (JNTU May 04)

39. i. Derive the equations of balance for an Anderson’s bridge. Draw the phasor diagram for conditions under balance. Discuss advantages and disadvantages of the bridge.

ii. In an Anderson bridge for the measurement of inductance the arm AB consists of an unknown impedance with inductance L and R, a known variable resistance in arm BC, fixed resistance of 600W each in arms CD and DA, a known variable resistance in arm DE and a capacitor with a fixed capacitance of 1mF in the arm CE. The AC supply of 100Hz is connected across A and C and the detector is connected between B and E. If the balance is obtained with a resistance of 400W in the arm DE and a resistance of 800W in the arm BC calculate the values of unknown R and L.

(JNTU May 03)40. i. Explain the difference between balance conditions for DC and AC bridges.

ii. An AC bridge circuit working at 1000Hz, have its arms as follows Arm AB is 0.2 Micro Farad capacitance. Arm BC is a 500 ohms resistance; arm CD contains an unknown impedance and arm DA has a 300resistance in parallel with a 0.1 Micro Farad capacitor. Find the R and L or C constants of arm CD considering it as a series circuit. (JNTU May 03)

41. The four arms of Maxwell’s capacitance bridge at balance are: arm ab, an unknown inductance L1, having an inherent resistance R1; arm bc, a non-inductive resistance of 1000W; arm cd, a capacitor of 0.5mF in parallel with a resistance of 1000W; arm da, resistance of 1000W. Derive the equations of balance for the bridge and determine the value of R1 and L1. Draw the phasor diagram of the bridge.

(JNTU May 03)

42. i. Describe how an unknown capacitance can be measured with the help of D’Sauty’s bridge. What are the limitations of this bridge? (JNTU May 02)

43. Describe the working of a low voltage Schering bridge. Derive the Equations for capacitance and dissipation factor. (JNTU May 01)

44. The ac bridge shown in the figure is used to measure the impedance Z. if the bridge is balanced for oscillator frequency f=2kHz, then the impedance Z will be (GATE 08)a. (260 + j0) Ω b. (0 + j200) Ωc. (260 + j200) Ω d. (260 + j200) Ω

45. R1 and R4 are the opposite arms of a Wheatstone bridge as are R3 and R2. The Source voltage is applied across R1 and R2. The source voltage is applied across R1 and R3. Under balanced conditions which one of the following is true? (GATE 06)a. R1=R3R4/R2 b. R1=R2R3/R4 c. R1=R2R4/R3 d. R1=R2+R3+R4

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46. A reading of 120 is obtained when a standard inductor was connected in the circuit of a Q - meter and the variable capacitor is adjusted to a value of 300 pF. A lossless capacitor of unknown value Cx is then connected in parallel with the variable capacitor and the same reading was obtained when the variable capacitor is readjusted to a value of 200 pF. The value of Cx in pF is _______ (GATE 03)

47. Figure Shows a bridge for measuring the resistance and inductance of a choke.i. Write down the condition for bridge balance and obtain expressions for R and Lii. If the resistors R1, R2 and R3 can have a variation of ±0.2% and C a variation of ±0.1% from their

nominal values, estimate the percentage error in the evaluation of R and L. (GATE 91)

48. In a Hay bridge, the four arms are R1 – L1, R2, R3 – C3 R4 connected in clockwise order. Show that, under the ‘phase-null’ condition, Q of the coil is given by (IES 02)

49. The items in Group I represent the various types of measurements to be made with a reasonable accuracy using a suitable bridge. The items in Group II represent the various bidges available for this purpose. Select the correct choice of the item in Group II for the corresponding item in group I from the following Group I Group IIP Resistance in the m Ohm range . 1. Wheat stone bridge.Q. Low values of capacitance 2. Kelvin double bridgeR. Comparison of resistances which are nearly equal 3. Schering Bridge.S. Inductance oa coil with a large time-constant 4. Weins bridge.

5. Hay’s bridge6. Carey-Foster Bridge

50. How can frequency can be determine using a bridge? Draw this bridge and derive condition for balance. Why and how are two resistances and capacitances made equal? (IES 01)

51. What is Wein-bridge? What are it uses? Show how variable frequency oscillator can be built using an operational amplifier with bridge. Derive an expression for frequency of oscillation of the circuit.

(IES 99)52. List the factors that may load to inaccuracies in measurement by AC bridges.

The four arms of a bridge are:Arm ab : an imperfect capacitor C1 with an equivalent series resistance of r2Arm bc : a non inductive resistance R3Arm cd : a non inductive resistance R4Arm da : an imperfect capacitor C2 with an equivalent resistance r2 in series with a

resistance R2.A supply of 450 Hz is given between terminals a and c and a detector is connected between b and d.At balance R2 = 5 ohms, R3 = 2000 ohms, R4 = 29050 ohms, C2 = 0.5mF and r2 = 0.4 ohm. Calculate the values of C1 and r1 and also the dissipating factor for this capacitor. Derive the relations used. If any. (IES 95)

53. Figure shows a schering bridge circuit used for measuring the power loss in the dielectrics. The specimens are in the form of discs 0.3 cm thick and have a dielectric constant of 2.3. The area of each electrode 314 cm2 and the loss angle is 9’ for a frequency of 50 Hz. e0 = 8.855 x 10-12 F/m. The fixed resistors of the network has a value of 1000 Ohm and the fixed capacitance is 50mF. Find the values of variable resistor and capacitor required at balance. Derive the expression used, if any.

(IES 94)

54. Explain with help of circuit diagram, the principle of working of a Q-meter. (IES 94)

55. How can frequency be determined using a bridge? Draw this bridge and derive condition for balance. Why and how are two resistances and capacitances made equal? (IES 94)

56. The arms of an Anderson’s bridge are as follows:Arm AB : An unknown impedance (R1, L1) in series with a non – inductive resistor R1Arm BC : A non inductive resistor R3 = 100WArm CD : A non inductive resistor R4 = 150WArm DA: A non inductive resistor R2 = 200W

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Arm DE ; A variable non inductive resistor rArm EC : A loss less capacitor C = 1mFAC supply is connected across A and C, and the detector is connected between B and E. Deduce conditions of balance and calculate R1 and L1 under balance conditions when R1 = 40W and r = 220

(IES 93)

57. Describe the Wien-bridge method for measuring unknown frequencies in the audio range. What are the other applications of this bridge?

(IES 93)

58. An a.c. bridge ABCD has the following four arms taken in sequence:Arm AB : A capacitance with series loss effect resistance R in seies with the primary of a mutual inductance M.Arm BC : Resistance R2

Arm CD : Resistance R3

Arm DA: Loss – less capacitance CAThe primary of mutual inductance has self-inductance L and negligible resistance. The secondary of mutual inductance is connected in series with detector across BD. The source of angular frequency w is connected across AC. Determine the capacitance C and associated loss angles if the bridge is balance with w = 103, M = 0.0015 H, R2 = R3 = 104W, L = 0.0045 H and C4 = 0.15mF, derive the balance conditions and there from the expressions used. Comment on the source of error in measurement. (IES 92)

UNIT – VIII

1. Prove that in a ballistic galvanometer, the charge is proportional to first swing of the moving coil. (JNTU May 09)

2. a. Derive an expression for equation of motion of a ballistic galvanometer?b. A flux meter is connected to a search coil having 500 turns and a mean area of 500 mm2. The search

coil is placed at the center of a solenoid 1 metre long, wound with 800 turns. When a current of 5A is reversed, there is a deflection of 25 scale divisions. Calculate the flux linkages per scale division.

(JNTU May 09)

3. Explain the method for determination of B-H curve of a magnetic material using method of reversals. (JNTU May 09)

4. Explain the constructional features of flux meter with a neat diagram. Show that for a flux meter Nφ = K (θ2 − θ1) Where N is the number of turns in the search coil used, φ is the change in flux, θ1 is the initial reading in the flux meter and θ2 is the final reading in the flux meter and K is a constant.

(JNTU May 09)

5. Describe a method of experimental determination of flux density in a specimen of magnetic material using a ballistic galvanometer (JNTU May 09)

6. a. What are the advantages of using ring specimens for testing of magnetic properties?b. A coil of 1000 turns is wound uniformly over an annular ring former of mean diameter 1 meter. A

second shorter coil is mounted inside the first, co-axially with it. The coil has 50 turns and a mean diameter of 25mm. A ballistic galvanometer is connected to this second coil. The total resistance of the second coil circuit is 2300 ohms. When a current of 5A through the first coil is reversed, the galvanometer is deflected through 100 divisions. Neglecting damping, calculate the constant of galvanometer. (JNTU May 09)

7. a. Describe briefly the different types of tests that are used for testing of magnetic materials.b. Explain the principle of operation of Ballistic galvanometer with neat circuit diagram?

(JNTU May 09)

8. a. The iron loss in a sample is 300W at 50Hz. with eddy current loss component 5 times as big as the hysteresis loss component. At what frequency will the iron loss be double if the flux density is kept the same.

b. Briefly explain about iron loss curves. (JNTU May 09)

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9. Describe a method of experimental determination of flux density in a specimen of magnetic material using a ballistic galvanometer (JNTU Nov 08)

10. Explain the following:i. Why are magnetic measurements more in accurate than other types of measurements?ii. Why is a ballistic galvanometer usually light damped?iii. How does a flux meter differ from ballistic galvanometer?iv. Flux measurement with flux meter. (JNTU Feb 08)

11. i. Why are ring specimens preferred over rods or strips for magnetic testing?ii. Explain with the help of a neat diagram, a method for the determination of B-H curve of a magnetic

sample. Point out the various sources of errors and the methods of minimizing them?(JNTU Feb 08, Nov 07)

12. i. Compare the relative merits of Ballistic galvanometer and flux meter as means of making magnetic measurements.

ii. A flux meter is connected to a search coil having 1000 turns and a mean area of 4 cm2. The search coil is placed at the center of a solenoid 1.2 meters long wound with 1200 turns. When a current of 5A is reversed, there is a deflection of 25 scale divisions on the flux meter. Determine the flux meter constant. (JNTU Feb 08)

13. i. Describe briefly the different types of tests that are used for testing of magnetic materials.ii. Explain the principle of operation of Ballistic galvanometer with neat circuit diagram?

(JNTU Feb 08)

14. i. What are the differences between flux meter and Ballistic galvanometer?ii. The coil of a ballistic galvanometer has 115 turns of mean area 25 × 10 mm2. The flux density in the

air gap is 0.12 W/m2 and the moment of Inertia is 0.5×10-6 kg-m2. The stiffness constant of springs is 45 ×10-6 Nm/rad. What current must be passed to give a deflection of 1000 and what resistance must be added in series with the movement to give critical damping? (JNTU Feb 08, Nov 07)

15. Explain the construction and working principle of flux meter with a neat diagram.(JNTU Nov 07)

16. i. Derive an expression for equation of motion of a ballistic galvanometer? ii. A flux meter is connected to a search coil having 500 turns and a mean area of 500 mm2. The search

coil is placed at the center of a solenoid 1 metre long, wound with 800 turns. When a current of 5A is reversed, there is a deflection of 25 scale divisions. Calculate the flux linkages per scale division.

(JNTU Nov 07)

17. Explain the methods of seperation of iron losses into their two components: eddy current and hysteresis losses. If the maximum value of flux density is maintained constant and

i. frequency is varied keeping the form factor constant.ii. form factor is varied keeping the frequency constant. (JNTU Nov 07)

18. i. Give advantages of Burrow’s permeameter with respect to others. (JNTU Feb 08, 07)ii. A ring having a mean diameter of 0.3m and a cross-sectional area 400mm 2 has a primary winding of

80 turns wound uniformly. The secondary winding of 30 turns is connected to a fluxmeter having a constant of 0.12x10-3 weber turn per division. A deflection of 46 divisions is observed when a current of 2A is reversed in the primary winding. Calculate the relative permeability of iron.

19. Describe a method of experimental determination of flux density in a specimen of magnetic material using a ballistic galvanometer (JNTU Feb 08, 07, Nov 07)

20. Explain the methods of separation of iron losses into their two components: eddy current and hysteresis losses. (JNTU Feb 07)

21. i. Explain in detail about Ewing double bar permeameter.ii. Explain in detail about Fahy‘s simplex p. (JNTU Feb 07)

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22. Describe a method of experimental determination of flux density in a specimen of magnetic material using a ballistic galvanometer (JNTU Nov 06, May 06)

23. i. Explain in detail how measurement of leakage factor can be done using flux meter?(JNTU Nov 06)ii. In loss tests on a sample of iron laminations the following results were recorded:

a. 60hz,250v total iron loss=200w b. 40hz,100v, total iron loss=40w. Calculate the eddy current and hysteresis loss for each test. The Stienmetzindex is 1.6.

24. i. Explain in detail about Ewing double bar permeameter.ii. Explain in detail about Fahy‘s simplex permeameter. (JNTU Nov 06)

25. i. Explain with neat diagram the principle of operation of a grassot flux meter.ii. How is the range of meter extended? What are its applications? (JNTU May 06)

26. i. The iron loss in a sample is 300W at 50Hz. with eddy current loss component 5 times as big as the hysteresis loss component. At what frequency will the iron loss be double if the flux density is kept the same.

ii. Briefly explain about iron loss curves. (JNTU May 06)

27. i. Explain with neat diagram the principle of operation of a grassot flux meter. ii. How is the range of meter extended? What are its applications? (JNTU May 05)

28. Describe the Lloyd Fisher square for measurement of Iron losses in a specimen of laminations. Describe how correction for resistance of wattmeter pressure coil and resistance of secondary winding are applied. How is the true value of flux density obtained in the laminations determined?

(JNTU May 05)

29. i. Describe briefly the different types of tests that are used for testing of magnetic materials.ii. Explain the principle of operation of Ballistic galvanometer with neat circuit diagram?

(JNTU Nov 05) 30. A ballistic galvanometer gives a first swing of 60o for a discharge of 1000mc. Find the quantity of

electricity to producei. A swing of 90o in the instrumentii. A spot deflection of 20mm on a scale 1 m away. (JNTU May 04)

31. i. Describe with a diagram a method of getting the relative permeability of the bar specimen using a flux meter.

ii. In a test on a specimen of total weight 13Kg the measured values of iron loss at a given value of flux density were 17.2 watts at 40 Hz and 28.9 watts at 60w. Estimate the values of hysterisis and eddy current losses at 50 Hz for the same value of peak flux density. (JNTU May 04)

32. i. Describe the step by step method of getting B-H curve of a ring specimen using ballistic galvanometer?ii. An iron ring has a mean diameter of 0.15m and a cross sectional area of 34.5 sq.mm. It is wound with

a magnetizing winding of 330 turns and a secondary winding of 220 turns. On reversing a current of 12 Amps in the magnetizing winding a ballistic galvanometer gives a throw of 272 scale division. With a HMS with 10 turns and flux of 0.00025wb. gives a reading of 102 scale division. Other conditions remaining the same find the relative permeability of the specimen. (JNTU May 04)

33. Explain with suitable diagram the working of Ballistic galvanometer in the magnetic measurement. Show that the instrument is proportional to the total charge. (JNTU May 03)

34. i. With a suitable diagram explain the working of ballistic galvanometer. (JNTU May 03)ii. Show that by using flux meter the leakage factor can be measured in the specimen.

35. i. Describe the method of obtaining hysterisis loop of a ring specimen using flux meter.ii. The mutual inductance between magnetizing winding and a search coil wound on a specimen is 9mH.

The search coil has 20 turns and the specimen has a cross sectional area of 5000Sq.mm reversal of current of 3 amps in magnetizing winding produces galvanometer through of 60 divisions. Calculate

138


the value of the flux density in the specimen if the reversal of current in the magnetizing winding produces a galvanometer deflection of 3 divisions. (JNTU May 03)

36. Write a short notes on the following:i. Loss of energy due to hysteresisii. Measurement of permeability (JNTU Nov 03)

37. i. Describe the construction and working of a moving coil ballistic galvanometer.ii. Describe the method of experimental measurement of flux density in a specimen of magnetic material

using ballistic galvanometer. (JNTU May 02)

38. Write the short notes on the following:i. Shunted flux meterii. Hibberts Magnetic standard and its applications. (JNTU May 02)

39. Briefly explain the following instruments:i. Lloyd Fisher square ii. Flux meteriii. PF Meter iv. Megger (JNTU May 02)

40. Describe the method of reversal used for the determination of B-H loop of a sample material. State the advantages of this method over step by step method. How do you calculate hysterisis loss in this specimen. (JNTU May 01)

41. Discuss the construction and working principle of a flux meter. (JNTU May 01)

42. Explain the principle of electrostatic focusing of electron beam in a CRO. Calculate the maximum velocity of the beam of electrons in CRT having a cathode anode voltage of 1000 V. Assume the electrons to live the cathode with zero velocity. Charge of electron = 1.6 x 10-19C; and mass of electron = 9.1 x 10-31 Kg. (IES 95)

43. Explain with the help of functional block diagram, the principle of working of an X-Y recorder.(IES 92)

44. Describe a method of experimental determination of flux density in a specimen of magnetic material using a ballistic galvanometer. Explain how the correction for flux in the air space between the specimen and the coil is applied.

45. Explain how the value of AC permeability of magnetic materials is determined through the use of: i. Maxwell’s Bridge ii Campbell’s Bridge.

46. Describe briefly the different types of tests that are used for testing of magnetic materials.

47. Describe how magnetizing and loss components of no load current of a transformer to determined by using an AC potentiometer.

48. A solenoid 30 cm long of radius 2 cm is wound uniformly with 4,500 turns of wire. A current of 2A flows through the coil.

i. What is the solenoid current density?ii. What is the value of B on the axis at the center?iii. What is the value of B on the axis at the end?iv. What is the flux through one end?v. What is the flux at the middle?

Derive any formula used.

49. The discharge of a capacitor through a ballistic galvanometer produces a frequency of oscillations 0.125 hz and successive maximum deflections of 12,9.6 and 7.68 cm. Determine the value of the logarithmic decrement. Derive any formulae used.

139


50. The coil of a ballistic galvanometer has 115 turns of mean area 2.5 x 4 cm2. The flux density in the air gap is 0.12 Wb/m2 and the moment of inertia is 5 x 10-7 kg.cm2. The stiffness is 4.5 x 10-5 N-m per radian. What current must be passed to give a deflection of 100° and what resistance must be added in series with the movement to give critical damping?

51. A ballistic galvanometer, connected to a search coil for measuring flux density in a core, gives a throw of 100 scale divisions on reversal of flux. The galvanometer coil has a resistance of 180 Ohms. The galvanometer constant has 100 mC per scale division. The search coil has an area of 50 cm2 with 100 turns having a resistance of 20 Ohms Calculate the flux density in the core.

52. An iron ring specimen of 4 cm2 cross section area and a mean length of 1.0 m is wound with 200 turns. A secondary coil of 100 turns is wound over and connected to a Ballistic galvanometer for measurement of permeability of the specimen. The Ballistic galvanometer gives a throw of 100 scale divisions on current reversal of 5A in the coil. Calculate the permeability. Assume galvanometer constant = 1mC/division and resistance of measuring circuit = 1,000 Ohms.

53. A ballistic galvanometer of resistance 2,500 Ohms gives a throw of 75 division when the flux through the search coil to which it is connected, is reversed. If the flux density is 0.1T, the search coil has.

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5. SUBJECT DETAILS

5.3 POWER SYSTEMS - II

5.3.1 Objective and Relevance

5.3.2 Scope

5.3.3 Prerequisites

5.3.4 Syllabus

i. JNTU

ii. GATE

iii. IES


5.3.6 Websites


5.3.8 Journals


5.3.10 Session Plan



i. JNTU

ii. GATE

iii. IES

141


142



This subject covers Transmission lines, design, performance, maintenance, and operation. The main aim of studying this subject is to design a 100% efficient transmission lines in between generating stations and consumers. The complexity in design of transmission lines is more due to increasing power demand. So, to increase the efficiency of a transmission line, we should not only consider efficient design but also other parameters like power factor and voltage regulation. So, in this subject student will learn different types of power factor improvement equipment, cables and insulators.

5.3.2 SCOPE

This subject covers wide spectrum of electrical power systems (transmission lines) and deals with the electrical and mechanical design, performance, maintenance, and operation. There is a wide scope of development and research in the power systems. New trends of implementation of Power electronics and HVDC brought a major change in the improvement of power quality has been improved. The basic of this subject is required for the implementation of computers in the Power systems.

5.3.3 PREREQUISITES

This subject requires the basic understanding of power system modeling and various types of generation, transmission and distribution parameters. A basic course in mathematics, applications of network theorems and matrix analysis are essential. It also requires knowledge of Power systems, Network theory, rigorous but clear treatment of mechanical design of transmission lines, mathematical approach, salvation of differential equations.

5.3.4.i. SYLLABUS – JNTU

UNIT – I OBJECTIVE

This unit deals with calculation of transmission line parameters for various conductor configurations. This unit gives a overview of calculation of resistance, inductance and capacitance of various types of overhead transmission lines.

SYLLABUS

Types of conductors - calculation of resistance for solid conductors- calculation of inductance for single phase and three phase, single and double circuit lines, concept of GMR and GMD, symmetrical and asymmetrical conductor configuration with and without transposition, numerical problems.

Calculation of capacitance for 2 wire and 3 wire systems, effect of ground on capacitance, capacitance calculations for symmetrical and asymmetrical single phase and three phase, single and double circuit line and numerical problems.

UNIT – II OBJECTIVE

The main objective of this unit is to learn the various concepts of OH lines. A OH lines are subjected to certain weather conditions and other external interferences, this calls for use of proper mechanical factor for safety in order to ensure the continuity of the operation of the line

SYLLABUS

Classification of transmission Lines- Short, medium and long line and their model representations, Nominal-T, Nominal-pie and A, B, C, D constants for symmetrical and asymmetrical Networks, Numerical problems. Mathematical Solutions to estimate regulation and efficiency of all type lines, numerical problems

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UNIT – III OBJECTIVE

The objective of this unit is to understand classification of transmission lines and give an overview of difference between short medium and long transmission lines. It also covers the concept of regulation using nominal Pie, Nominal T and ABCD parameters calculation methods

SYLLABUS

Long Transmission lines, rigorous solution, evaluation of A,B,C,D constants, Interpretation of the long line equations, Incidents, reflected and refracted waves, Surge Impedance and SIL of Long lines, wave length and velocity of propagation of the waves, representation of long lines, equivalent-T and equivalent Pie network models and numerical problems

UNIT – IV OBJECTIVE

The objective of this unit is to study different types of transients that may occur in power systems. It also deals with the concept of termination of lines with different types of conditions and Bewley’s lattice diagram.

SYLLABUS

Types of system transients: Traveling or propagation of surges, attenuation, distortion, reflection and Refraction coefficients, termination of lines with different types of conditions, open circuited Line, short circuited line, T-junction, lumped reactive junctions numerical problems. Bewely’s lattice diagrams for all the cases mentioned with examples.

UNIT – V OBJECTIVE

The objective of this unit is to understand different types of effect that may occur in OH lines and its effects. It deals with Skin effect, Proximity effect, Ferranti effect and factors affecting these phenomenons.

SYLLABUS

Skin and Proximity effects: description and effect of resistance on solid conductors. Ferranti effect: charging current, effect on regulation of the transmission line, shunt compensation.Corona: description of the phenomenon, factors affecting corona, critical voltage and power loss, radio Interference.

UNIT – VI OBJECTIVE

The objective of this unit is to understand study and analysis of the effects of the overhead insulators in transmission system. It deals with overhead insulators, string efficiency, different types of grading of insulators.

SYLLABUS

Types of insulators, string efficiency and methods of improvement, Numerical problems, voltage distribution, calculation of string efficiency, capacitance grading and static shielding.

UNIT – VII OBJECTIVE

The main objective of this unit is to learn the mechanical concepts of OH lines. It deals with sag and tension calculations of various types of towers with equal heights and unequal a heights. Introduction to Stringing chart and sag template and its applications.

144


SYLLABUS

Sag and Tension calculations with equal and unequal heights of towers, effect of wind and ice on weight of conductor, Numerical problems. Stringing chart and sag template and its applications.

UNIT – VIII OBJECTIVE

The objective of this unit is to understand the types of cables and insulating materials and calculation of insulations resistance and capacitance of the cables. It also deals with introduction to 3 core belted cables and capacitance grading and intersheath grading.

SYLLABUS

Types of cables, construction, types of insulating materials, calculation of insulation resistance and stress in insulation and numerical problems. Capacitance of single and three core belted cables, numerical problems.

Grading of cables, capacitance grading, numerical problems, description of inter, sheath stress.

5.3.4.ii. SYLLABUS- GATE

UNIT – I Steady state performance of overhead lines.

UNIT – II Transmission line models and performance.

UNIT – III Transmission line models and performance.

UNIT – IV Not covered.

UNIT – V Corona and radio interference.

UNIT – VI Transmission line Insulators.

UNIT – VII Not covered.

UNIT – VIII Cable performance.


UNIT – I Power transmission lines.

UNIT – II Modeling and performance characteristics.

UNIT – III Not covered.

UNIT – IV Power system transients.

UNIT – V

145


Not covered.

UNIT – VI Not covered.

UNIT – VII Not covered.

UNIT – VIII Not covered.


TEXT BOOKS T1 A Text Book on Power System Engineering by M.L.Soni, P.V.Gupta, U.S.Bhatnagar,, A.Chakrabarthy,

Dhanpat Rai&Co Pvt.Ltd.

T2 Electrical Power Systems-C.L. Wadhwa, New Age International (P) Limited Publishers, 1998.

REFERENCE BOOKS

R1 Principles of Power Systems, V.K.Mehta, Rohit Mehta, S.Chand Publishers, New Edition.R2 Power System Analysis, John J Grainger and William D Stevenson, 4th Edn, Tata McGraw Hill

Company.R3 Electrical Power System Design by Deshpande, Tata McGraw Hill R4 Modern Power System Analysis, I.J. Nagarath and D.P. Kothari, 2nd Edn, Tata McGraw Hill

5.3.6 WEBSITES

1. www.ntu.ac.sg2. www.utoronto.ca3. www.ee.washington.edu4. www.esca.com5. www.ne.ac.sg6. www.iitm.ac.in7. www.iitb.ac.in8. www.iitk.ac.in9. www.annauniv.edu10. www.vjti.ac.in.11. www.ieeecss.org12. www.ieee.com13. www.iee.com14. www.google.com


REGIONAL 1. Name : Prof. M Sydulu

Designation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering,

NIT-Warangal – 506004.Phone No. : +91-870-2431616(O)Email : [email protected]

146


2. Name : Prof. D.M.Vinod KumarDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone No. : +91-870-2431616(O)Email : dvmk @nitw.ac.in

3. Name : Dr. Bhagwan K.MurthyDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone No. : +91-870-2431616(O)Email : [email protected]

4. Name : V.T. SomashekharDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone No. : +91-870-2453416 (O) Email : [email protected], [email protected]

5. Name : Dr. A.D.RajkumarDesignation : ProfessorDepartment : Electrical EngineeringOffice Address : Department of Electrical Engineering, University College of Engineering

Osmania University, Hyderabad-500007Phone No. : +91-040-27682382 (O)Email : [email protected]

6. Name : Dr. M. VijayakumarDesignation : Associate ProfessorDepartment : Electrical EngineeringOffice Address : Department of Electrical Engineering, JNTU College of Engineering

Ananthapur, A.PEmail : www.jntu.ac.in

7. Name : Prof. ShankarramDesignation : ProfessorDepartment : Electrical EngineeringOffice Address : Department of Electrical Engineering, JNTU College of Engineering

Kukatpally, HyderabadEmail : www.jntu.ac.in

NATIONAL

1. Name : D.P. KothariDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

Dy. Director (Administration.), IIT - Delhi,Hauzkhas, New Delhi - 110016.

Phone No. : +91-11-26591250 (O) , Fax : 91-11-26862037,Email : [email protected], [email protected]

147


2. Name : Dr. S.V. Kulkarni,Designation : Associate Professor,Department : Electrical and Electronics EngineeringOffice address : IIT, Bombay, Powai, Mumbai - 400076, India,Phone No. : +91- 22-25671098,Email : [email protected]

3. Name : Dr.J K Chatterjee Designation : Professor & Head of Department Department : Electrical and Electronics engineering

Office Address : Room No. II/211, IIT Delhi Phone No. : +91 11 2659 1094 ,91 11 2659 1886


4. Name : Dr. Sivaji ChakravortiDesignation : Professor,Department : Electrical and Electronics engineeringOffice Address : Jadavpur University Kolkatta - 700032, IndiaEmail : [email protected], [email protected]

INTERNATIONAL1. Name : Gary S. Mary

Designation : ProfessorDepartment : School of Electrical EngineeringOffice address : Georgia Institute of Technology, USA.Email : [email protected]

2. Name : Dr. Clayton R Paul, Designation : ProfessorDepartment : Electrical and Computer Engineering,Office Address : School of Engineering, Mercer University, Macom, Georgia-31207,Phone No. : (912) 301-2213,website : www.faculty.mercer.paul_cr

3. Name : Jushan ZhangDesignation : Associate ProfDepartment : Dept. of Electrical EngineeringOffice address : Ira A.Fulton School of Engineering, Arizona State University. Tempe, AZPhone No. : 85287-7206Email : Jushan Zhang @ee.gatech.edu

4. Name : Dr. Edward Wai-Chau Lo, Designation : Honorary Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice address : Department of Electrical and Electronics Engineering

University of Hongkong, Hongkong.Phone No. :Email : [email protected]

5.3.8 JOURNALS

1. Name of the Journal : IEEE Transactions on energy conversionPublisher : IEEE Publications

2. Name of the Journal : IEEE Transactions on Power SystemsPublisher : IEEE Publications

3. Name of the Journal : IEE Proceedings: Part-C [Generation, Transmission & Distribution]

Publisher : IEEE Publications

148


4 Name of the Journal : IEEE Transactions on Industrial ElectronicsPublisher : IEEE Publications

5. Name of the Journal : IEEE Transactions on Industrial ApplicationsPublisher : IEEE Publications

6. Name of the Journal : IEEE Transactions on Automatic ControlPublisher : IEEE Publications

7. Name of the Journal : Electrical engineering update.Publisher : Institution of Engineers (India) Publishers

8. Name of the Journal : Electrical IndiaPublisher : Chary Publications Pvt Ltd.

9. Name of the Journal : Journal of Institution of Engineers, India.Publisher : Institution of Engineers (India) Publishers

10. Name of the Journal : Elector-India ElectronicsPublisher : Century Publications Pvt Ltd

11. Name of the Journal : E-PowerPublisher : EFY Enterprises Pvt Ltd



1. Title : “Vibration of Bundled Conductors Following Ice Shedding”.Author : Kollar, L.E.; Farzaneh, MJournal : Power Systems, IEEE Transactions on”Year, Vol. & Page No. : 2008,Volume:23, Issue:2,page(s):1097-1104

2. Title : “Small Corona Cage for Wideband HVac Radio Noise Studies: Rationale and Critical Design”.

Author : Urban, R.G. ;Reader, H.C.; Holtzhausen, J.P.Journal : Power Systems, IEEE Transactions on”Year, Vol. & Page No. : Aug. 2008,Volume: 23, Issue: 2, Page(s): 1150-1157

3. Title : “Electric Fields on AC Composite Transmission Line Insulators”.Author : Phillips, A.J.; Kuffel, J.; Baker, A.; Burnham, J.; Carreira,

Farzaneh, M.; GemignaniJournal : Power Systems, IEEE Transactions.”

Year, Vol. & Page No. : Aug. 2008, Volume: 23, Issue: 2, Page(s): 823-830

4. Title : “The Integrity of ACSR Full Tension Splice Connector at Higher Operation Temperature”.

Author : Wang, J.J.-A.; Lara-Curzio, E.; King, T.; Graziano, J.; Chan, J.Journal : Power Systems, IEEE Transactions on”Year, Vol. & Page No. : Aug. 2008, Volume: 23, Issue: 2, Page(s): 1158-1165

5. Title : “Application of Differential Evolution Algorithm for Transient Stability Constrained Optimal Power Flow”.

Author : Cai, H.R.; Chung, C.Y.; Wong, K.P.Journal : Power Systems, IEEE Transactions on”Year, Vol. & Page No. : Aug. 2008, Volume: 23, Issue: 2, Page(s): 719-728

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http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=4282002&isYear=2007

http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=59










6. Title : “Continuous-Wavelet Transform for Fault Location in Distribution Power Networks: Definition of Mother Wavelets Inferred From Fault Originated Transients”.

Author : Borghetti, A.; Bosetti, M.; Di Silvestro, M.; Nucci, C.A.; Paolone, M.Journal : Power Systems, IEEE Transactions on”Year, Vol. & Page No. : Aug. 2008, Volume: 23, Issue: 2, Page(s): 380-388

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5.3.10 SESSION PLAN

Sl.No.

JNTU Syllabus Topics Modules and Sub-modulesLecture

No.Suggested Books with

Page Nos.Remarks

UNIT-I—TRANSMISSION LINE PARAMETERS (No. of Lectures-8)

1

Types of conductors. Calculations of resistance for solid conductors. Calculation of Inductance for single phase circuit lines

Introduction to types of conductors,Resistance of overhead transmission line, Calculation of resistance for solid conductors.Inductance, calculation of inductance for single phase circuit lines

L1

T1-Ch2(P:162-163)T2-Ch2 (P: (13-15)R1-Ch9 (P: (194-195)R2-Ch4 (P:141-146)R3-Ch1 (P:1-4)R4-Ch2 (P:45-46)

2

calculation of inductance for three phase, single and double circuit lines, concept of GMR and GMD, Symmetrical and asymmetrical conductor configuration with and without transposition, numerical problems.

Derivation of Inductance for three phase single and double circuit lines.Concept of GMR and GMD.

L2

T1-Ch2(P:166-173)T2-Ch2 (P:28-33)R1-Ch9 (P:199-205)R2-Ch4 (P:156-157)R3-Ch1(P:6-8)R4-Ch2 (P:54-72)

Problems on the calculation of inductance for single and three phase circuit lines

L3

T1-Ch2(P:166-173)T2-Ch2 (P:28-33)R1-Ch9 (P:199-205)R2-Ch4 (P:156-157)R3-Ch1 (P:6-8)R4-Ch2 (P:54-72)

Difference between symmetrical and unsymmetrical spacing of conductors and calculation of the inductance for both the configurations.

L4


3

Capacitance of transmission lines,Calculation of capacitance for 2 wire and 3 wire systems, Capacitance calculations for symmetrical and asymmetrical single phase and three phase, single and double circuit line and numerical problems.

Calculation of capacitance for 2 wire and 3 wire systems derivations.Effect of ground on capacitance

L5


Calculation of capacitance for symmetrical and unsymmetrical spacing of single phase lines and problems for both single and double circuit lines

L6


Calculation of capacitance for symmetrical and unsymmetrical spacing of Three phase lines for both single and double circuit lines

L7T1-Ch2(P:183-184)T2-Ch3 (P:46-49)R2-Ch5 (P:183-186)R4-Ch3 (P:83-87)

Calculation of capacitance for symmetrical and unsymmetrical spacing of Three phase lines for both single and double circuit lines

L8

T1-Ch2(P:183-184)T2-Ch3 (P:46-49)R2-Ch5 (P:183-186)R4-Ch3 (P:83-87)

151


UNIT-II—PERFORMANCE OF SHORT AND MEDIUM LENGTH TRANSMISSION LINES (No. of Lectures-4)

4

Classification of overhead transmission Lines- Short, medium and long line and their model representationsNominal-T, Nominal-Pie Mathematical solutions to estimate the regulations and efficiency to all types of lines.

Classification of transmission Lines:Short Transmission Lines Medium Transmission Lines Long Transmission Lines

L9

T1-Ch3 (194-215)T2-Ch4 (P:55-75)R1-Ch10 (P:219-220)R2-Ch6 (P:193-207)R3-Ch2 (P:31-35)R4-Ch5(P:128-147)

GATEIES

Short- transmission Line: equilent.ckt and phasor diagram.Medium transmission Lines:Nominal-T representation Mathematical solutions to estimate the regulations and efficiencyNumerical problems

L10

T1-Ch3(P:194-208)T2-Ch4 (P:55-75)R1-Ch10 (P:220-245)R2-Ch6 (P:195-209)R3-Ch2 (P:33-47)R4-Ch5(P:129-142)

Nominal Pie Representation Mathematical solutions to estimate the regulations and efficiencyNumerical problems

L11

T1-Ch3(P:P:194-208)T2-Ch4 (P: (55-75)R1-Ch10 (P:220-245)R2-Ch6 (P:195-209)R3-Ch2 (P:33-47)R4-Ch5(P:129-142)

5Generalized circuit constants of a Tr:line, Numerical problems

A,B,C,D constants for symmetrical and asymmetrical networksMathematical solutions to estimate the regulations and efficiencyNumerical problems

L12


UNIT-III— PERFORMANCE OF LONG TRANSMISSION LINES (No. of Lectures-6)

6

Long Transmission lines-Rigorous solution, evaluation of A,B,C,D constants

Introduction to long Transmission linesRigorous Solution methodsCalculation of A,B,C,D constants

L13


GATEIES

7

Interpretation of the Long Line equations,Incidents, reflected and refracted waves

Interpretation of the Long Line equations,Introduction to Incidents reflected and refracted waves in long transmission lines.

L14

T1-Ch3(P:209-210)T2-Ch4(P:71-75)R2-Ch6(P:205-207)R4-Ch5(P:143-145)

8

Surge Impedance and SIL of Long lines, wave length and velocity of propagation of the waves

Introduction to surge impedance SIL of long lines

L15

T1-Ch3(P:207-208)R2-Ch6(P:205-207)R3-Ch2(P:33-34)R4-Ch5(P:143-145)

wave length and velocity of propagation of the waves

L16

T1-Ch3(P:207-208)R2-Ch6(P:205-207)R3-Ch2(P:33-34)R4-Ch5(P:143-145)

152


9

Representation of long linesEquivalent-T and equivalent Pie network models and numerical problems

Representation of long linesequivalent-T representationNumerical problems

L17

T1-Ch3(P:206-210)T2-Ch4(P:79-85)R2-Ch6(P:212-2157)R3-Ch2(P:33-34)R4-Ch5(P:152-154)

Representation of long linesEquivalent Pie representationNumerical problems

L18


UNIT-IV— POWER SYSTEM TRANSIENTS (No. of Lectures-7)

10

Types of system transients Traveling or propagation of surges, Attenuation, Distortion, reflection and Refraction coefficients

Types of system transients Traveling or propagation of surges Attenuation coefficient

L19T2-Ch12(P:256-265)R2-Ch6(P:222-226)

IES

Distortion, reflection and Refraction coefficients

L20R2-Ch5(P:179-180)R4-Ch6(P:218-220)

11

Termination of lines with different types of conditions : Open circuited line, short circuited line

Termination of lines with different types of conditions - Open circuited Line, short circuited line

L21T2-Ch12(P:269-277)R2-Ch6(P:222-226)R4-Ch6(P:218-220)

12T-junction, lumped reactive junctions numerical problems

T-junction, lumped reactive junctionsnumerical problems

L22L23

T2-Ch12(P:269-284)R2-Ch6(P:222-226)R4-Ch6(P:218-220)

13Bewely’s lattice diagrams for all the cases mentioned with examples.

Introduction to Bewely’s lattice diagrams for all the cases mentioned with examples.

L24 L25

T2-Ch12(P:269-284)R2-Ch6(P:222-226)R4-Ch6(P:218-220)

UNIT-V—VARIOUS FACTORS GOVERNING THE PERFORMANCE OF TRANSMISSION LINE (No. of Lectures-6)

14

Skin and Proximity effects: Description and effect of resistance on solid conductors.

Definition of Skin effect and proximity effect and their description.Effect of the above factors in Solid conductors

L26

T1-Ch2(P:190-191)T2-Ch2(P:33-35)R1-Ch9(P:196-197)R2-Ch4(P:143-146)R3-Ch1(P:1-3)R4-Ch2(P:70-72)

15

Ferranti effect : Charging current Effect on regulation of the transmission lineShunt compensation.

Introduction to Ferranti effectcharging current due to the above effectEffect of Ferranti effect on Regulation of transmission lines

L27


Shunt compensation to improve the regulation of the line

L28


16

Corona : Description of the PhenomenonFactors affecting coronaCritical voltage and power loss Radio Interference.

Phenomenon of Corona. Theory of Corona Formation.Factors affecting Corona

L29


GATECritical voltage calculations and numerical problems

L30


Power loss, radio Interference.Numerical problems

L31


153


UNIT-VI—OVERHEAD LINE INSULATORS (No. of Lectures-7)

17overhead Line Insulators,String efficiency

Types of InsulatorsPin typeSuspension typeShackle type String efficiency and its calculation

L32


18Methods of improvementNumerical problems

Methods to improve string efficiencyProblems on string efficiency

L33L34

T1-Ch5(P:286-287)T2-Ch8(P:172-177)R1-Ch8(P:160-162)

19Voltage distribution, calculation of string efficiency,

Voltage distribution in string of insulators and derivations related to that.

L35T1-Ch5(P:286-288)T2-Ch8(P:177-183)R1-Ch8(P:160-165)

20 Capacitance grading and static shielding.

Methods to improve string efficiency Capacitance grading and static shielding

L36T1-Ch5(P:286-288)T2-Ch8(P:177-183)R1-Ch8(P:160-165)

GATE

Numerical problems on calculations of string efficiency

L37,L38

T1-Ch5(P:286-288)T2-Ch8(P:177-183)R1-Ch8(P:160-165)

UNIT-VII—SAG AND TENSION CALCULATIONS (No. of Lectures-7)

21 Sag and tension Calculations with equal heights

Sag in overhead Lines.

Calculation of the sag, effect of ice and wind loading on e the line. Derivation of related formulae

L39,

L40

T1-Ch8(P:310-313)T2-Ch7(P:150-162)

R1-Ch8(P:178-181)

R3-Ch3(P:94-96)

GATE

Problems on Sag calculations with Equal heights

L41

T1-Ch8(P:310-313)T2-Ch7(P:150-162)R1-Ch8(P:178-181)

R3-Ch3(P:94-96)

22 Sag and tension Calculations with unequal heights

Sag and tension calculations with equal heights

L42

T1-Ch8(P:310-313)T2-Ch7(P:150-162)R1-Ch8(P:178-181)

R3-Ch3(P:94-96)

GATE

Problems on Sag and tension calculations with unequal heights

L43,

L44

T1-Ch8(P:310-313)T2-Ch7(P:150-162)R1-Ch8(P:178-181)

R3-Ch3(P:94-96)

23String charts and sag template

Stinging chart use and Sag template

L45

T1-Ch8(P:313-314)T2-Ch7(P:162-167)R1-Ch8(P:191-193)

R3-Ch3(P:96-98)

UNIT-VIII—UNDERGROUND CABLES (No. of Lectures-10)

25 Types of cables

Introduction to underground cables:

Types of Cables:

i) Belted Cables

ii) Screened cables

iii) Pressure cables

L46T1-Ch9(P:326-327)T2-Ch9(P:184-188)R1-Ch11(P:254-256)

GATE

154


26 Insulating materials

Insulating materials used for underground cables:

Rubber, Vulcanized Indian rubber, Impregnated paper, PVC, Introduction to construction of the cable

L47

L48

T1-Ch9(P:326-327)T2-Ch9(P:184-188)

R1-Ch11(P:254-256)

27Calculation of the insulation resistance

Insulation resistance of single core cable and problems related to it

L49

T1-Ch9(P:327-329)T2-Ch9(P:199-200)

R1-Ch11(P:262-263)

28Stress and capacitance calculations

Capacitance in the cables:

Capacitance calculations in Single core cable and Di-electrical stress in Single core cable

L50

T1-Ch9(P:327-334)T2-Ch9(P:199-202)

R1-Ch11(P:277-279)

29Single and multi core cables

Grading of cables

Most economical size of conductor in cable;

Grading of cables:

Capacitance grading

L51

T1-Ch9(P:327-334)T2-Ch9(P:190-195)

R1-Ch11(P:277-279)

Inter sheath grading related problems

L52

T1-Ch9(P:327-334)T2-Ch9(P:199-202)

R1-Ch11(P:277-279)

Capacitance of 3-phase core cables

L53

T1-Ch9(P:327-334)T2-Ch9(P:199-202)

R1-Ch11(P:277-279

30Power factor and charging current; thermal characteristics of cables

Heating of cables:

Power factor improvement

Variation dielectric power factor with voltage

L54

T1-Ch9(P:327-334)T2-Ch9(P:199-202)

R1-Ch11(P:277-279)

31 Sheath current and lossesSheath loss and sheath circuit currents

L55

T1-Ch9(P:327-334)T2-Ch9(P:199-202)

R1-Ch11(P:277-279)

155



1. Title : “Congestion-Driven Transmission Planning Considering the Impact of Generator Expansion”

Author : Tor, O.B.; Guven, A.N.; Shahidehpour, M.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : Nov. 2007,Volume: 22, Issue: 4, Page(s): 781-789

2. Title : “Foreword Special Section on Transmission Investment, Pricing, and Construction”.

Author : Conejo, A. J.; Hobbs, B. F.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : Nov. 2007,Volume: 22, Issue: 4, , Page(s): 1392-1393

3. Title : “Modeling Weather-Related Failures of Overhead Distribution Lines”.

Author : Zhou, Y.; Pahwa, A.; Yang, S.-S.Journal : Power Systems, IEEE Transactions onYear, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s): 1683 - 1690

4. Title : “Bolted Connectors for Stranded Aluminum Power ConductorsAuthor : Runde, M.; Magnusson, N.; Lenes, A.Journal : Power Systems, IEEE Transactions on,Year, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s):523 - 530

5. Title : “Small Corona Cage for Wideband HVac Radio Noise Studies: Rationale and Critical Design

Author : Urban, R.G.; Reader, H.C.; Holtzhausen, J.P.Journal : Power Systems, IEEE Transactions on,Year, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s): 1150-1157

6. Title : “The Integrity of ACSR Full Tension Splice Connector at Higher Operation Temperature”.

Author : Wang, J.J.-A.; Lara-Curzio, E.; King, T.; Graziano, J.; Chan, J.Journal : Power Systems, IEEE Transactions on,Year, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s): 1158-1165

7. Title : “Comparative Laboratory Evaluation of Premolded Joints for Medium Voltage Cables”.

Author : Yaroslavskiy, V.; Walker, M.; Katz, C.; Keefe, R.J.Journal : Power Systems, IEEE Transactions on,Year, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s): 516-522

8. Title : “Analytical Formula to Estimate the Maximum Inrush Current”.Author : Yunfei Wang; Abdulsalam, S.G.; Wilsun XuJournal : Power Systems, IEEE Transactions on,Year, Vol. & Page No. : Nov. 2008,Volume: 23, Issue: 2 , Page(s): 1266-1268

156



UNIT – I

1. a. Explain the effect of ground on capacitance calculations.b. Calculate the inductance of a single-phase circuit comprising of two parallel conductors of 6 mm in

diameter spaced 1 meter apart. If the material of the conductor isi. Copper and ii. Steel with a relative permeability of 50. (JNTU May 09)

2. a. State the factors which governs the capacitance of a transmission line.b. Calculate the capacitance per phase of a three-phase, three-wire system by considering ground effect,

when the conductors are arranged in a horizontal plane with spacing D12= D23=3.5m, and D31=7m. The conductors are transposed and each has a diameter of 2.0 cm. Assume that the transmission line is 4m above the ground level. (JNTU May 09)

3. a. Derive potential difference between two conductors of a group of charged conductors.b. Calculate the capacitance of a conductor to neutral in a single-phase transmission line having two

parallel conductors spaced 3 m apart. The diameter of each conductor is 1.2 cm. (JNTU May 09)

4. a. Derive an expression for the inductance per phase for a 3-phase overhead transmission line when conductors are unsymmetrical placed but lines are untransposed.

b. Calculate the inductance and reactance of each phase of a three-phase 50Hz overhead high-tension line (HTL) which has conductors of 2.5cm diameter. The distance between the three-phases are i. 5m between A and B, ii. 4m between B and C andiii. 3m between C and A as shown in Figure 1(b)iii. Assume that the phase conductors are transposed regularly. (JNTU May 09)

5. A 3-phase,50Hz transmission line has resistance, inductance and capacitance per phase of 10ohms, 0.1H and 0.9µF respectively and delivers a load of 35 MW at 132 kV and 0.8 p.f laging. Determine the efficiency and regulation of the line using

a. nominal T method b. nominal πmethod. (JNTU May 09)

6. Find the ABCD parameters of a 3-phase, 80Km, 50Hz transmission line with series impedance of (0.15 + j 0.28 ) ohms per Km and a shunt admittance of j 5x10-4 ohm per Km for the both off and T networks. (JNTU May 09, Nov 08)

7. a. Derive the ABCD constants for long transmission lines. (JNTU May 09)b. Explain briefly classification of transmission lines based on line lengths with neat diagrams.

8. a. What do you understand by the constants of an over head line? (JNTU May 09)b. Derive an expression for the loop inductance of a single phase line. Also calculate loop inductance per

km if distance between conductors is 1.5 mtr and radius of each conductor 1.2 cm.

9. a. Explain briefly classification of transmission lines based on line lengths with neat diagrams. Derive approximate voltage drop for shortline

b. Define Voltage regulation of a transmission line and explain clearly the Ferranti effect with a phasor diagram. (JNTU Nov 08)

10. a. Briefly discuss the various types of conductor material used for over head transmission linesb. A single phase, two wire transmission line 20km long, is made up of round conductors each 0.9cm in

diameter, separated from each other by 45cm. Calculate the equivalent diameter of a fictitious hollow, thin-walled conductor having the same inductance as the original line. What is the value of this inductance? (JNTU Nov 08)

157


11. a. How can the inductance of a bundled conductor line be calculated? Derive expressions for geometric mean radii of duplex, triplex and quadruplex arrangement.

b. Calculate the inductance per phase of a three-phase, double circuit line as shown in Figure 1b. The diameter of each conductor is 1.5 cm. (JNTU Nov 08)

12. a. Show that the inductance per loop meter of two wire transmission line using solid round conductors is given by L = 4 × 10-7 log D/r’ henries where D is the distance between the conductors and r′ is the GMR of the conductors.

b. A single phase overhead line 32km long consists of two parallel conductors each 1cm diameter, 3 meters apart. If the line voltage be 25kV at 50Hz. Determine the charging current with the line open circuited. (JNTU Nov 08)

13. a. Derive an expression for the inductance per phase for a 3-phase overhead transmission line when conductors are symmetrically placed.

b. Calculate the inductance per phase of a three-phase transmission line as shown in Figure. The radius of the conductor is 0.5 cm. The lines are untransposed. (JNTU Nov 08)

14. i. What is bundled conductor and why it is used?ii. A 3-phase, 50 Hz, 66 kV overhead transmission line has its conductors arranged at the corners of an

equilateral triangle of 3m sides and the diameter of each conductor is 1.5 cm. Determine the inductance and capacitance per phase, if the length of line is 100 km. And also calculate the charging current.

(JNTU Feb 08)

15. i. Determine the capacitance of a three-phase double circuit line when conductors are placed flat vertical unsymmetrical spacing.

ii. Three conductors of a 3-phase line are arranged at the corners of a triangle of sides 2m, 3.2m and 4m.The diameter of each conductor is 2.5cm; calculate the inductance per km of the line.

(JNTU Feb 08)

16. i. Explain the merits and demerits of bundled conductors.ii. Calculate the capacitance of a single-phase overhead line consisting of a pair of parallel wires 12mm in

diameter and spaced uniformly 2.5 m apart. If the line is 30 km long and its one end is connected to 50 kV, 50 Hz system, what will be charging current when the other end is open circuited?

(JNTU Feb 08)

17. i. Explain briefly classification of transmission lines based on line lengths with neat diagrams. Derive approximate voltage drop for short line

ii. Define Voltage regulation of a transmission line and explain clearly the Ferranti effect with a phasor diagram. (JNTU Feb 08)

18. i. What are bundled conductors? Discuss the advantages of bundled conductors, when used for overhead lines.

158


ii. Calculate the capacitance (phase-to-neutral) of a three-phase 100 km long double circuit line shown in Figure 1b, with conductors of diameter 2.0 cm each arranged at the corners of an hexagon with sides measuring 2.1 m. (JNTU Nov 07)

19. Calculate the inductance per phase of a 400 kV, three-phase single circuit line that utilizes a bundled conductor arrangement as shown in Figure 1b. The space between the two phases is 15m in a horizontal formation. The sub-conductors of a phase are at the corners of a square of sides 0.5m, each sub-conductor having a diameter of 3cm. (JNTU Nov 07)

20. i. Distinguish between AC and DC resistances of a conductor? Why the two differ?ii. Calculate the capacitance of a conductor per phase of a three-phase 400 km long line, with the

conductors spaced at the corners of an equilateral triangle of side 4 m and the diameter of each conductor being 2.5cm. (JNTU Nov 07)

21. i. What is bundled conductor and why it is used?ii. A 3-phase, 50 Hz, 66 kV overhead transmission line has its conductors arranged at the corners of an

equilateral triangle of 3m sides and the diameter of each conductor is 1.5 cm. Determine the inductance and capacitance per phase, if the length of line is 100 km. And also calculate the charging current.

(JNTU Nov 07)

22. Input to a single-phase short line is 2000kW at 0.8 lagging power factor. The line has a series impedance of (0.4 + j 0.4 ) ohms. If the load voltage is 3kV, find the receiving end power factor and supply voltage. (JNTU Nov 07)

23. Derive an expression for the inductance per phase for a 3-phase overhead transmission line when i. Conductors are symmetrically placedii. Conductors are unsymmetrically placed but the line is completely transposed. (JNTU Nov 07)

24. i. Derive from first principles the capacitance per km to neutral of a 3-phase overhead transmission line with unsymmetrical spacing of conductors assuming transposition.

ii. A single phase overhead line 32km long consists of two parallel conductors each 1 cm diameter, 3 meters apart. If the line voltage be 25kV at 50HZ, determine the charging current with the line open circuited. (JNTU Apr 05)

25. i. Derive from basic considerations an expression for the capacitance and charging current per km length of a single phase line made up of two solid round conductors of radius meters and spaced at D meters. Neglect the effect of ground.

ii. Determine the capacitance per km of a pair of parallel conductors 1.5cm in dia and spaced informing 65 cm apart in air. Also find charging current per km 1cm if line is working at 110KV.

(JNTU Apr 05)

26. i. A 3 phase 50km long single circuit 66Kv, 50 Hz transposed overhead line has horizontal spacing with 3 meters between adjacent conductors and 6 meters between outer conductor. The conductor diameter is 2 cm. Find the capacitive admittance and the chagrining current per phase when he line is energized at 66 KV.

159


ii. Explain the method of images for finding the capacitance of transmission line with ground.(JNTU Apr 05)

27. Determine the inductance per phase per km of a double circuit 3-phase line. The radius of each conductor is 20mm and the conductors are placed on the circumference of an imaginary circle of radius 7m forming a regular hexagonal figure. (JNTU Apr 05)

28. i. Distinguish between a.c. and d.c. resistance of a conductor. Why the two differ? Explain fully.ii. Show that the inductance per loop meter of two-wire transmission line using solid round conductors is

given by L = 4 × 10-7 loge, (D/r) Henries. Where D is the distance between the conductors and is the G.M.R. of the conductors. (JNTU Apr 05)

29. i. Prove that the inductance of a groups of parallel wires carrying current can be represented in terms of their geometric distances. Explain the meaning of the term self G.M.D and mutual G.M.D.

ii. A conductor is composed of seven identical copper strands each having a radius or. Find the GMR of the conductor. (JNTU Apr 05)

30. Find the loop inductance and reactance per km of a single phase overhead line consisting of two conductors each 1.213 cm diameter. The spacing between conductors is1.25 m and frequency is50 Hz.

(JNTU Nov, June 03)

31. i. Derive an expression for line to neutral capacitance for a 3 phase line when conductors are symmetrically placed.

ii. What is transposition? Explain the method of transposition of 3 phase line over length. (JNTU Nov 03)

32. i. How do we find line to neutral capacitance in a 3-phase system?ii. The three conductors R, Y and B of a 3-phase line are arranged in a horizontal plane with Dry =1.5m;

Dyb = 2m and DBR=2m and DBR=3.5m. Find line to neutral capacitance per km if dia of each conductor is 1.2cm. The conductors are transposed at regular intervals. Also calculate line capacitance per km length. (JNTU Nov 03)

33. i. Write a short notes on overhead line conductors.ii. What is bundled conductor? Why it is used? Give the few configurations commonly employed.ii. Find the loop inductance and reactance of single phase OH line consisting of two conductors, each

1.3Cm diameter. The spacing between conductors is 1.4m and frequency is 50 Hz (JNTU Nov 03)

34. What is symmetrical and asymmetrical spacing of conductors? What is the significance of symmetrical spacing of conductors? (JNTU Jun 03)

35. i. What factors must be taken into account while calculating the resistance of Overhead line conductors? How are these factors accounted for?

ii. What is equivalent spacing of a 3-phase line? What is its significance?iii. A 3-phase 50km long single circuit 66KV transposed overhead line has horizontal spacing with 3

meters between adjacent conductors and 6 meters between outer conductors. The conductor diameter is 2cm. Find the inductance per phase. (JNTU Jun 03)

36. i. How can the inductance of a two-conductor bundled conductor single phase line be calculated? Derive expressions for GMR and GMD of the arrangement.

ii. A 3-phase transposed line has conductors of diameter 2cm and spaced at distance of 3, 5 and 8 meter between the centers. Calculate the inductance per phase per km of line length. (JNTU Jun 03)

37. Derive an expression for line to neutral capacitance for a 3-phase line when conductors are:i. Symmetrically placed ii. Unsymmetrically placed but transposed (JNTU Jun 03)

38. i. Develop an expression for the inductance of a single phase transmission line taking into account the internal flux linkages. Assume the conductors are solid.

ii. Calculate the inductance per km per phase of a 3-phase transposed line. With distance between any two conductors being 4m, 4m and 8 meter respectively. (JNTU Jun 03, Nov 02)

160


39. What is method of images? Derive an expression for the capacitance per unit length of a 3-phase line completely transposed. What is the effect of earth on the capacitance of the line? (JNTU Nov 02)

40. i. Clearly explain what you understand by GMR and GMD of a transmission line.ii. Derive the expression for inductance per km of a 3 phase line with marginal spacing between the

conductors.iii. Calculate the inductance /km/ph for a 3 phase transmission live with Dab=Dbc=4mand Dca=8m.The

radius of the conductor is 0.25m.The line is transposed. (JNTU Nov 02)

41. i. Derive the expression for capacitance of a 3-phase, uncomposed transmission line with an equal spacing section the conductors.

ii. What do you understand by transposition of lines. What is its effect on the performance of the lines? (JNTU Nov 02)

42. i. Explain the concept of G.M.R and G.M.D.ii. A 3-phase, 50 Hz overhead transmission line has each conductor of 3 cm diameter. The distance

between the three phases are: between A and B is 6 meters, B and C is 5 meters and C and A is 4 meters. Calculate the inductance of each line. If the lines are transposed regularly, determine the inductive reactance per km. (JNTU Jun N.R. 02)

43. i. Derive an expression for the capacitance of a three phase transmission line with unequal spacing assuming uniform transposition.

ii. A 110 KV double circuit line has its conductors place on the vertices of a regular hexagon of side 4.5 m with the conductors of same phase being placed diametrically opposite. If the radius of each conductor is 1 cm, what is the charging current per km of line length? (JNTU Jun 01)

44. Derive the formula for Inductance for loop meter of a two-wire transmission line using solid round conductors. (JNTU Nov 01)

45. For a fixed value of complex power flow in a transmission line having a sending end voltage V, the real power loss will be proportional to a. V b. V2 c. 1/V2 d. 1/V (GATE 09)

46. Consider a long, two-wire line composed of solid round conductors. The radius of both conductors is 0.25 cm and the distance between their centers is 1m. If this distance is doubled, then the inductance per unit length.i) doubles ii) halvesiii) increases but does not double iv) decreases but does not halve (GATE 02)

47. A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum electric stress occurs at i) the upper surface of the conductor

ii) the lower surface of the conductoriii) the ground surface iv) midway between the conductor and ground (GATE 02)

48. The conductors of a 10 km long, single phase, two wire line are separated by a distance of 1.5m. The diameter of each conductor is 1 cm. If the conductors are of copper, the inductance of the circuit isi) 50.0 mH ii) 45.3 mH iii) 23.8 mH iv) 19.6 mH (GATE 01)

49. The load carrying capability of a long AC transmission line is:i) always limited by the conductor size ii) limited by stability considerationsiii) reduced at a low ambient temperaturesiv) decreased by the use of bundled conductors of single conductors (GATE 99)

50. A 6.6 kV, 50 Hz, single core lead-sheathed cable has the following data: Conductor diameter: 1.5 cm, length:4 kmInternal diameter of the sheath: 3 cm Resistivity of insulation: 1.3 x 1012 n-m Relative permittivity of insulation: 3.5 Calculate:i) the insulation resistance ii) the capacitance andiii) the maximum electric stress in the insulation (GATE 99)

161


51. Bundled conductors are employed to improve the (GATE 97)i) appearance of the transmission line ii) mechanical stability of the lineiii) decreases system stability iv) increases the short circuit current

52. Show that the inductance per unit length of an overhead line due to internal flux linkages is constant and is independent of size of conductor.

53. Derive expressions for the inductance of a 3-phase line with conductors untransposed. What is the significance of imaginary term in the expression for inductance ? Hence derive the expression for inductance for a completely transposed line.

54. Derive an expression for the flux linkages of one conductor in a group of n conductors carrying currents whose sum is zero. Hence derive an expression for inductance of composite conductors of a 1-phase line consisting of m strands in one conductor and n strands in the other conductor.

55. A single circuit 3-phase line operated 50 Hz is arranged in form of triangle with equally spaced of 1.5 m apart. The conducted diameter is 0.6 cm determine the inductance and inductive reactance per km. Prove the formula used.

56. What do you understand by the constants of an overhead transmission line.

57. Find the expression for the flux linkages.i. Due to a single current carrying conductor ii. In parallel current carrying conductors

58. What do you understand by electric potential? Derive an expression for electric potential at a charged single conductor.

59. i. Why do we find line to neutral capacitance in a 3-phase system?ii. Will capacitance of a transmission line depend upon the ground effect?

UNIT – II

1. a. Define regulation of a short 3-phase transmission system and develop an expression for approximate voltage regulation.

b. A balanced 3-phase load of 30MW is supplied at 132kV, 50Hz and 0.85 p.f. lagging by means of a transmission line. The series impedance of a single conductor is (20 + j52) ohms and the total phase-neutral admittance is 315 × 10-6 mho. Using nominal-T method, determine:i. The A, B, C and D constants of the line,ii. Sending end voltage,iii. Regulation of the line. (JNTU May 09)

2. a. Derive the expressions for the ABCD constants for the nominal-π circuit of a medium transmission line. (JNTU May 09)

b. The following data refers to a 50 Hz, three-phase transmission line: length 10 km; sending-end voltage =11 kV; load delivered at receiving end 100 kW at 0.8 p.f. lag; resistance of each conductor = 0.4 ohms/ km; reactance per phase = 0.45 ohms / km. Findi. receiving-end voltage ii. line current and iii. efficiency of transmission.

3. a. What is a nominal-circuit representation? Find ABCD constants for nominal T circuit of a transmission line.

b. A single-phase, 11 kV line with a length of 15 km is to transmit 500 kVA. The inductive reactance of the line is 0.6Ω per km and the resistance is 0.25 Ω per km. Calculate the efficiency and regulation for a p.f of 0.75 lead. (JNTU May 09)

4. A balanced 3-phase load of 35 MW is supplied at 110 kV, 50Hz and 0.8 p.f lag by means of a transmission line. The series impedance of a single conductor is (15+j35) ohms and the total phase-neutral admittance is 300 × 10-6 mhos. Use nominal - T method to determinei. A, B, C, D constants of the line, ii. Vs

iii. regulation of the line and iv. efficiency. (JNTU May 09)

162


5. a. Give brief description of corona phenomenon. (JNTU May 09)b. Derive the expression for potential gradient at the surface of a conductor of 1-phase transmission line.

6. Find the voltage distribution and string efficiency of three unit suspension insulator string if the capacitance of the link pins to earth and to the line are respectively 20% and 10% of the self capacitance of each unit. If a guard ring increases the capacitance to the line of lower link pin to 35% of the self capacitance of each unit, find the redistribution of voltage and string efficiency.

(JNTU May 09)

7. a. What is critical disruptive voltage? Derive the expression for it. b. Give brief description about the factors a_ecting the critical disruptive voltage. (JNTU May 09)

8. a. Derive an expression for the capacitance between conductors of a single phase line. Deduce the expression for line to neutral capacitance. Discuss the approximation involved in deriving the above expressions.

b. A 400 KV, 3-phase single circuit bundled conductor line with two sub-conductors per phase has a flat configuration. The center to center distance between adjacent phases is 4m and distance between sub-conductors of phase is 45 cm. The radius of each sub-conductor is 1.6 cm . Find the capacitance per phase per km. (Given D12=D23=D31=4m). (figure 2b). (JNTU May 09)

9. a. Determine the critical disruptive voltage and corona loss for a 3-phase line space operating at 110kV which has conductors of 1.25cm diameter arranged in a 3.05m delta spacing. Assume air density factor of 1.07 and the dielectric strength of air to be 21kV/cm.

b. Explain in brief the disadvantages of corona and different methods of reducing corona loss.(JNTU Nov 08)

10. a. List various methods of improving string efficiency. b. In a string of three insulator units the capacitance of each unit is C, from each conductor to ground is

C/3, and from each connector to the line conductor is C/5. Calculate the voltage across each unit as a percentage of the voltage. To what value the capacitance between the connector of the unit and the linehas to be increased by a guard ring to make the voltage across it equal to that across the next higher unit? (JNTU Nov 08)

11. a. What is critical disruptive voltage? Derive the expression for it. b. Give brief description about the factors affecting the critical disruptive voltage. (JNTU Nov 08)

12. a. Show how regulation and transmission efficiency are determined for medium lines using end condenser method and illustrate your answer with suitable vector diagram.

b. A three phase transmission line is 135 km long. The series impedance is Z=0.04 + j 0.95 ohms per phase per km, and shunt admittance is Y=j 5.1×10-6 mhos per phase per km. The sending end voltage is 132 kV, and the sending end current is 154 A at 0.9 power factor lagging. Determine the voltage, current and power at the receiving end and the voltage regulation using medium line-T model.

(JNTU Nov 08)

13. a. What do you understand by the terms ‘nominal-T’ and ‘nominal-π’ circuits. b. A 220 kV, 50 Hz, three-phase transmission line is 50 km long. The resistance per phase is 0.15

ohms/km and the inductance per phase is 1.33 mH per km and the shunt capacitance is negligible. Use the short line model to determine i. the voltage and power at the sending end,ii. voltage regulation and efficiency when the line is supplying a three-phase load of 400 MVA, 220 kV at a power factor of 0.8 lagging. (JNTU Nov 08)

14. a. What do you understand by medium transmission lines? How capacitance effects are taken into account in such lines?

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b. A three phase transmission line is 140 km long. The resistance per phase is 0.04 ohms per km and the inductance per phase is 0.95 mH per km. The shunt capacitance is 0.0105 nF per km. The receiving end load is 90 MVA with 0.85 power factor lagging at 110 kV. Determine the voltage, powers at the sending end, voltage regulation and efficiency by using nominal - π model. (JNTU Nov 08)

15. a. Draw the phasor diagram for a nominal-T circuit of a transmission line and derive expressions for sending end voltage and current.

b. A three-phase, 50Hz, 11kV transmission line delivers a load of 2400kW at power factor of 0.8 lag over a distance of 20km. The line conductors are placed at the corners of an equilateral triangle of 2m side. The line losses are 10%. Calculate the sending end power factor. (JNTU Nov 08)

16. Show how regulation and transmission efficiency are determined for medium lines using nominal- method and illustrate your answer with suitable vector diagram.

17. An overhead 1-phase delivers a load of 1.5kW at 33kV at 0.9 p.f. lagging. The total resistance and inductance of the over head transmission line is 8ohms and 15ohms respectively. Determine the following: (JNTU Feb 08)a. Percentage of voltage regulation b. Sending end power factor c. Transmission efficiency.

18. Define regulation of a short 3-phase transmission system and develop an expression for approximate voltage regulation.

19. A balanced 3-phase load of 30MW is supplied at 132kV, 50Hz and 0.85 p.f. lagging by means of a transmission line. The series impedance of a single conductor is (20 + j52) ohms and the total phase-neutral admittance is 315 × 10-6 mho. Using nominal-T method, determine:a. The A, B, C and D constants of the line,b. Sending end voltage,c. Regulation of the line. (JNTU Feb 08, Nov 07)

20. i. How do you classify transmission lines?ii. A short transmission line has impedance of (0.2+j0.45) ohm/per phase. The sending-end voltage being

3.3 kV (L-L) and the load at the receiving end being 250 kW per phase at a p.f of 0.8 lagging, calculate a. the receiving-end voltage b. the line current, and c. efficiency. (JNTU Feb 08)

21. Define A, B, C and D constants of a transmission line? What are their values in short lines?

22. A 3-phase, 3km long line delivers 3000kW at a power factor of 0.8 lagging to a load. If the voltage at the supply end is 11kV, determine the voltage at the load end, percentage regulation, sending end power factor and the efficiency of transmission. The resistance and reactance per km of each conductor are 0.4 ohm and 0.3 ohm respectively. (JNTU Feb 08)

23. Explain the physical significance of the generalized circuit constants A, B, C and D of a transmission line? Find the values of A, B,C and D in the nominal method in terms of Z and Y. (JNTU Nov 06)

24. A 3-phase overhead line has a resistance of 2 ohms per phase and a reactance of 6 ohms per phase. It supplies a load of 10MVA at a p.f. of 0.8 leading at 33kV between lines at far end. Find:a. Sending end voltage; b. Percentage regulation;c. Sending end power factor; d. Transmission efficiency. (JNTU Nov 06)

25. i. Explain the effect of power factor on regulation and efficiency. ii. A single-phase, 11 kV line with a length of 15 km is to transmit 500 kVA. The inductive reactance of

the line is 0.6 ohms per km and the resistance is 0.25ohms per km. calculate the efficiency and regulation for a p.f of 0.75 lag. (JNTU Nov 06)

26. Find the ABCD parameters of a 3-phase, 80Km, 50Hz transmission line with series impedance of (0.15 + j 0.28) ohms per Km and a shunt admittance of j 5x10-4 ohm per Km for the both and T networks.

(JNTU Feb 08, 07, Nov 07, 06, 05, 03)

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27. i. Input to a single-phase short line is 200kW at 0.8 lagging power factor. The line has a series impedance of (0.4 + j 0.4) ohms. If the load voltage is 3kV, find the receiving end power factor and supply voltage.

ii. Derive the equivalent ABCD parameters considering nominal T network. (JNTU Nov 06)28. Using the nominal π method, find the sending end voltage and voltage regulation of a 250Km, 3-phase,

50Hz, transmission line delivering 25MVA at 0.8 power factor to a balanced load at 132kV. The line conductors are spaced equilaterally 3m apart. The conductor resistance is 0.11ohms/Km and its effective diameter is 1.6cm.Neglect leakage. (JNTU Mar 06)

29. A 3-phase, 50Hz transmission line has resistance, inductance and capacitance per phase of 10ohms, 0.1H and 0.9µF respectively and delivers a load of 35 MW at 132 kV and 0.8 p.f lagging. Determine the efficiency and regulation of the line using

i. Nominal T method ii. Nominal PI method (JNTU Nov 05)

30. Determine the sending end voltage, current, power factor of a 1-phase, 50Hz, 76.2kV transmission line delivering a load of 12 MW at 0.8 pf lagging. The line constant are R=25ohms, L=200mH and Capacitance between lines 2.5µF. Also determine the regulation and efficiency of transmission. Use nominal p method. Draw phasor diagram. (JNTU Nov 05)

31. i. Derive the ABCD parameters of a nominal T represented medium length transmission line with neat phasor diagram. (JNTU Feb 08, Nov 05, 04)

ii. Find the ABCD parameters of a 3-phase, 100 Km, 50 Hz transmission line with series impedance of (0.10 + j 0.3) ohms per Km and a shunt admittance of j 4 x 10-4 mho per Km.

32. A 3-phase, 50Hz transmission line has resistance, inductance and capacitance per phase of 1ohms, 0.3H and 0.01µF respectively and delivers a load of 35 MW at 132 kV and 0.8 p.f lag. Determine the efficiency and regulation of the line using nominal PI method. (JNTU Nov 04)

33. Discuss why equivalent circuit of a long line is preferred over the equivalent T circuit.

34. A three phase 50Hz transmission line is 150 km long and delivers 25MW at 0.85 power factor lagging and at 110KV. The resistance and reactance of the line per conductor per km are 0.3 ohms and 0.9 ohms respectively. The line charging admittance is 0.3 x 10 -6 mho per km per phase. Compute by applying the nominal method the voltage regulation and transmission efficiency

(JNTU Nov, Jun 03)

35. i. Why transmission lines are of three phase three wire type and distribution lines are of three phase four wire type?

ii. Differentiate between a nominal T and equivalent T representation of a transmission line.iii. Input to a single phase short line is 2000KW at 0.8pf lagging. The line has a series impedance of 0.4 +

j0.4 ohms. If the load voltage is 3KV, find the load and receiving end power factor. Also find supply voltage and supply power factor (JNTU Nov 03)

36. i. Discuss the effect of load power factor on voltage regulation and efficiency of a transmission line.ii. A 10km long 3 phase line delivers 1 MW at 0.8 lagging power factor. The series impedance of the line

is 0.5 +j0.56 ohms per km per phase. The ending end voltage is 11KV. Find the line current, receiving end voltage and transmission efficiency. (JNTU Nov 03)

37. i. Discus why the receiving end voltage of a unloaded long line may be more than the sending end voltage.

ii. A single phase transmission line 100Km long has the following constants R/phase=0.25 ohms and X/phase=0.8 ohms. Susceptance per Km is 14 micro ohms. Receiving end voltage is 66kV. Assuming that the total capacitance of the line is localized at the receiving end only, Determine sending end V, I, regulation, efficiency, power factor. The line is delivering 15MW at 0.8 lagging power factor. Draw the vector diagram to illustrate your calculations. (JNTU Jun 03, Nov 02)

38. A 345 KV 3 phase transmission line is 130km long. The resistance per phase =0.036ohm/km and inductance per phase =0.8mH/km. The shunt capacitance per phase is 0.0112 micro Farad/km. the receiving end load is 270MVA with 0.8 pf lagging at 325kV. Find the voltage regulation and power at

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sending end. Use Nominal –T method, Nominal Pie method and ABCD Constants. Compare the result. (JNTU Jun 03)

39. i. Draw the phasor diagram of a medium transmission lines represented by a T model and derive the expression for voltage regulation.

ii. Determine the efficiency and regulation of a 3 phase, 50 Hz transmission line having resistance, inductance and capacitance of 10 ohms, 0.1 H and 0.9 micro farads respectively. The line delivers a load of 35MW at 132 KV and 0.8 p.f. lag. Use nominal T method. (JNTU Jun 03)

40. i. How do you classify the transmission lines?ii. A 220KV, 3 phase transmission line is 40 km long. The resistance per phase is 0.15 ohms/ km and the

inductance per phase is 1.3263 mH per km. The shunt capacitance is negligible. Use the short line model to find the voltage and power at the sending end and the voltage regulation and efficiency when the line is supplying a 3 phase load of:a. 381 MVA at 0.8 power factor lagging at 220 KV.b. 381 MVA at 0.8 power factor leading at 220 KV. (JNTU Jun 03)

41. The generalized circuit constants of a transmission line are A = 0.93 + j0.016 B = 20+j140The load at the receiving end is 60 MVA, 50Hz, 0.8 power factor lagging. The voltage at the supply end is 220KV. Calculate the load voltage. (JNTU Nov 02)

42. i. Draw the vector diagrams of nominal and nominal T models.ii. A single phase 50 Hz generator supplies an inductive load of 5MW at a power factor 0.707 by means

of an overhead line of 20km long. The line resistance and inductance are 0.0195 ohms and 0.63 mH per Km respectively. The voltage at the receiving end is to be kept at 10KV. Findi. Voltage regulation and ii. Efficiency of the transmission (JNTU Nov 02)

43. i. Explain the physical significance of the generalized constants A, B, C & D.ii. The sending end voltage and receiving end voltages of the 3 phase Tr. Line are maintained at 70 KV

and 66kV respectively. The line impedance per phase is 20+ j60 ohms. Calculate the Max power obtaining at receiving end. (JNTU Jun 02)

44. A 10km long 3 phase line delivers 1 MW at 0.8 lagging power factor. The series impedance of the line is 0.5 +j0.56 ohms per km per phase. The sending end voltage is 11KV. Find the line current, receiving end voltage and transmission efficiency? (JNTU Jun 02)

45. Explain the physical significance of the generalized constants A, B, C and D. (JNTU Jun 01)

46. The sending end and receiving end voltages of a 3-phase transmission line are maintained at 70 kV and 66 kV respectively. The line impedance per phase is (20 + j60) ohms. Calculate the maximum power obtained at the receiving end. (JNTU Jun 01)

47. A 50 Hz three phase transmission line is 280 km long. It has a total series impedance of 35 + j140 ohms and a shunt admittance of 930 X 10-6 ohm. It delivers 40 Mwatt 220 kV 90% power factor lagging. Find the sending end voltage, voltage regulation, transmission efficiency by nominal T method approximation. (JNTU Jun 01)

48. The A, B, C, D constants of a 220kV line are : A = D = 0.94∟10, B = 130∟730, C = 0.001∟900. If the sending end voltage of the line for a given load delivered at nominal voltage is 240 kV, then % voltage regulation of the line is a. 5 b. 9 c. 16 d. 21 (GATE 06)

49. Consider the model shown in Fig. of a transmission line with a series capacitor at its mid-point. The maximum voltage on the line is at the location

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a) P1 b) P2 c) P3 d) P4 (GATE 01)

50. Using the nominal Pie method, find the sending end voltage, and voltage regulation of a 250 KM, 3-ph, 50 Hz, transmission line, delivering 25 MVA at 0.8 lagging power factor to a balanced load at 132 KV. The line conductors spaced equilaterally 3m apart. The conductor resistance is 0.11/Km and its effective dia is 1.6 cm. (GATE 00)

51. Input to a single phase short line shown below is 2000KW at 0.8 lagging p.f. The line has a series impedance of (0.4 + j0.4) . If the load voltage is 3KV, find the load and receiving end power factor. Also find the supply voltage. (GATE 99)

52. A 66 kV, 3 phase, 50 Hz, 150 km long overhead transmission line is open circuited at the receiving end. Each conductor has a resistance of 0.25 Ohm/Km, an inductive reactance of 0.52 Ohm/Km and a capacitive admittance to neutral of 0.04 x 10-4 S/km.

i. Draw the nominal Pie equivalent circuit and indicate the value of each parameter.ii. Calculate the receiving end voltage if the sending end voltage is 66 kV. (GATE 99)

53. A 220 kV, 20 km long, 3-phase transmission line has the following A, B, C, D constants. A = D = 0.96∟3°, B = 55∟65°ohm/phase, C = 0.5E - 04∟80°S/phase. Its charging current per phase is:i) b) 11A c) 220A d) (GATE 99)

54. A 220 KV, 20 KM long 3-phase transmission line has the following A, B, C, D constants: A = D = 0.9∟63o; B = 55∟65o phase; C = 0.5∟0.48o siemens/phase. What is the charging current/phase? (IES 97)

55. The ABCD constants of a nominal? Network representing a three phase transmission line are A=D=0.950∟1.27°, B =92.4∟76.87° Ohm and C = 0.0006∟90°S Find steady state limit if both the sending end and the receiving end voltages are held at 130 KV, I) with the given ABCD constants and ii) with series resistance and shunt admittance neglected. (IES 97)

56. The sending end voltage and receiving end voltages of the 3 phase Tr. Line are maintained at 110 KV and 66kV respectively. The line impedance per phase is 10+ j10 ohms. Calculate the Max power obtaining at receiving end______ (GATE 92)

57. Determine the efficiency and regulation of the three phase 100 km line delivering 20Mw at a p.f. of 0.8 lagging and 66kV to a balance load. The conductors are of copper, each having resistance 0.1 ohm per km, outside dia, soaced equilaterally 2 meters between centers. Use nominal T method

58. Discuss the terms voltage regulation and transmission efficiency as applied to transmission line.

59. What do you understand by medium transmission lines? How capacitance effects are taken into account in such lines?

60. Calculate A,B,C,D constants of 3 phase 50Hz transmission line 160 km long having the following distributed parameters: R=0.15ohm/km, L=1.20 mH/km, C=8 nanoF/km,G=0

UNIT – III

1. a. Explain the physical significance of the generalized constants A,B,C and D. b. A=D=0.936+j 0.016; B=33.5+j138 ohms; C=(-5.18+j914) 10-6mhos. The load at the receiving end is

50 MW at 220 kV with a power factor of 0.9 lagging. Find the sending end voltage and regulation of line. (JNTU May 09)

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2. a. Discuss why Ferranti effect is significant only in medium and long lines. (JNTU May 09)b. In a 3-phase line with 132 kV at the receiving end, the ABCD constants are A=D=0.98∟30,

B=110∟750ohms; C=0.0005∟880ohms.If the load at the receiving end is 40MVA at 0.8 lagging p.f, determine i. The sending end voltage.ii. The loading MVAr for this load at the receiving end if the sending end voltage is 140kV.

3. a. Derive equivalent parameters of two transmission lines when they are connected in parallel.b. A three - phase overhead transmission line has series impedance per phase of 150∟80 0 ohms and a

total shunt admittance of 0.001∟900 siemen per phase. The line delivers a load of 150MW at 0.707 pf lagging and 220kV between the lines. Calculate the sending-end voltage and current by the rigorous meth (JNTU May 09)

4. a. Derive the equivalent ABCD constants of a transmission line connected in series with an impedances at both ends.

b. The per-unit-length parameters of a 215kV, 400km, 60Hz, three phase long transmission line are y = j3.2 × 10-6 mhos per km per phase and z = (0.1 + j 0.5) ohm/km. The line supplies a 150 MW load at unity power factor. Determinei. the voltage regulationii. the sending-end power andiii. the efficiency of transmission. (JNTU May 09)

5. a. What is a sag template? Explain how this is useful for loading of towers and stringing of power conductors. (JNTU May 09)

b. A transmission line has a span of 200m between level supports. The conductor has a cross-section area of 130mm2, weights 1.2 kgf/m and has a breaking stress of 40kgf/mm2. Calculate the sag for a factor of safety of 5, allowing for a maximum wind pressure of 125kgf/m2 of projected surface.

6. a. Derive expressions for sag and tension in a power conductor strung between two supports at equal heights taking into account the wind and ice loadings also.

b. An overhead transmission line has a span of 220m between level supports. Calculate the maximum sag if the conductor weights 700kgf/km and has a breaking strength of 6880kgf. Allow a factor of safety of 3. Neglect wind and ice loading. (JNTU May 09)

7. An overhead line at a river crossing is supported from two towers at heights of 50m and 85m above water level, the horizontal distance between the towers being 450m. If the maximum tension is 3980 kgf and the conductor weighs 1.726 kgf/m, find

a. the minimum clearanceb. the clearance between the conductor and the water level at a point midway between the towers.c. the clearance between the conductor and water at appoint 200m from the lower. (JNTU May 09)

8. a. Discuss the effect of load power factor on voltage regulation and efficiency of a transmission line.b. What is skin and proximity effects?c. A 10km long 3 phase line delivers 1 MW at 0.8 lagging power factor. The series impedance of the line

is 0.5 +j0.56 ohms per km per phase. The ending end voltage is 11 KV. Find the line current, receiving end voltage and transmission efficiency. (JNTU May 09)

9. A transmission line has a span of 180m between level supports. The conductor has a cross-section area of 129mm2, weights 1.17 kgf/m and has a breaking stress of 42kgf/mm2. Calculate the sag for a factor of safety of 5, allowing for a maximum wind pressure of 125kgf/m2 of projected surface.

(JNTU Nov 08)

10. An overhead line is supported between two towers having heights of 30m and 70m from the datum level. If the horizontal distance between them is 300m, find the height of the conductor from the datum level between the supports. Assume maximum tension of 1720kgf and weight per meter run is 0.727kgf. (JNTU Nov 08)

11. An overhead line has a conductor of cross section 2.5 cm2 hard drawn copper and a span length of 150 m. Determine the sag which must be allowed if the tension is not to exceed one fifth of the ultimate strength of 4175 kg/cm2.

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a. in still air, andb. with a wind pressure of 1.3kg/m and an ice coating of 1.25cm. Determine also the vertical sag in the

latter case. (JNTU Nov 08)

12. a. Explain the evaluation of transmission line constants. b. A three - phase overhead transmission line has series impedance per phase of 250 ∟ 800 ohms and a

total shunt admittance of 0.0019 ∟900 siemen per phase. The line delivers a load of 100MW at 0.8 pf lagging and 200kV between the lines. Calculate the sending-end voltage and current by the rigorous method. (JNTU Nov 08)

13. a. Explain surge impedance loading.b. A three-phase, 50 Hz, 160 km long transmission line has three conductors each of 0.75 cm radius

spaced at the corners of triangle of sides 2.5 m, 3m and 3.5m. The resistance of each conductor is 0.3 ohms per km and the line delivers 30 MVA at 132 kV and at a lagging p.f. of 0.95. Determine ABCD constants as i. long line (both real and complex angle methods) andii. Parameters of equivalent T representations of long lines. (JNTU Nov 08)

14. a. Starting from the first principles, deduce expressions for ABCD constants of a long line in terms of its parameters.

b. A three-phase, 50 Hz, 150 km long transmission line has three conductors each of 0.7 cm radius spaced at the corners of triangle of sides 2 m, 3.5m and 4.5m. The resistance of each conductor is 0.4 ohms per km and the line delivers 50 MVA at 132 kV and at a lagging p.f. of 0.85. Determine ABCD constants as long line (both real and complex angle methods) (JNTU Nov 08)

15. a. Starting from first principles derive an expression for the sending end voltage and current of a long transmission line interms of the line parameters and receiving end voltage and current.

b. A three - phase overhead transmission line has series impedance per phase of 120 ∟ 750 ohms and a total shunt admittance of 0.002∟ 900 siemen per phase. The line delivers a load of 125MW at 0.85 pf lagging and 132kV between the lines. Calculate the sending-end voltage and current by the rigorous method. (JNTU Nov 08)

16. i. Derive the equivalent ABCD constants of a transmission line connected in series with impedances at both ends.

ii. The per-unit-length parameters of a 215kV, 400km, 60Hz, three phase long transmission line are y = j3.2 × 10-6 mhos per km per phase and z = (0.1+ j 0.5) ohm/km. The line supplies a 150 MW load at unity power factor. Determine (JNTU Feb 08)a. the voltage regulation b. the sending-end power and c. the efficiency of transmission.

17. A three-phase, 200 km long transmission line has the following constants. Resistance/ ph/ km = 0.15 ohm, reactance / ph/km = 0.20 ohm, shunt admittance/ph/km = 1.2×10-6 mho. Calculate by rigorous method, the sending end voltage and current when the line is delivering a load of 20 MW at 0.8 p.f lagging. The receiving-end voltage is kept constant at 110 kV. (JNTU Feb 08)

18. What is an equivalent T circuit of a long line? Derive an expression for parameters of this circuit in terms of line parameters.

19. The line constants of a three-phase long line are: A = 0.85 /__2.30; B = 180/__750; C = 0.0014/__900. Determine the sending-end voltage, the current and power factor when the open-circuit voltage at receiving end of the line is 220kV. (JNTU Feb 08)

20. Using rigorous method, derive expressions for sending end voltage and current for a long transmission line.

21. A 3-phase transmission line is 480km long and serves a load of 400MVA, 0.8p.f lag at 345kV. The ABCD constants of the line are A=D=0.818 /__1.30; B=172.2 /__84.20; C=0.001933 /__90.40 mhos.a. Determine the sending end line to neutral voltage, the sending end current and the percent voltage drop at full load.b. Determine the receiving end line to neutral voltage at no load, the sending end current at load and the voltage regulation. (JNTU Feb 08)

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22. i. Derive equations which represent the performance of a long transmission line with its electrical parameters uniformly distributed along its length.

ii. The per-unit-length parameters of a 132kV, 350km, 50Hz, three phase long transmission line are y=j2.5×10-6 mhos per km per phase and z = (0.2 + j 0.4) ohm/km. The line supplies a 130 MW load at 0.8 power factor lagging. Determinea. the voltage regulation, b. the sending-end power and c. the efficiency of transmission.

(JNTU Nov 07)

23. i. Prove that the impedance at any point of transmission line is proportional to the hyperbolic tangent of the position angle.

ii. A 400kV, 3-phase transmission line has impedance per phase of (50+j100) ohms and an admittance of 0+j002mho. Using the convergent series method determinea. the sending end voltage andb. the sending end current when the receiving end current is 150Amps at 0.8 p.f lagging.

(JNTU Nov 07)

24. i. Derive the expressions for voltage and current distribution over a long line. Explain the significance of characteristic impedance loading in connection with the long lines. Deduce the above voltage and current relations in the hyperbolic form and obtain the element values of an equivalent to represent the long lines.

ii. Determine the auxiliary constants of a 3-phase, 50Hz. 200km long transmission line having resistance, inductance and capacitance per phase per km of 0.15 ohm, 3.5mH and 0.009µF respectively.

(JNTU Nov 07)

25. i. When the transmission line is terminated by the capacitive load, how do you find out the expressions of reflected voltage and current wave.

ii. An under ground cable having an inductance of 0.3mH per km and a capacitance of 0.4µF per km is connected in series with an overhead line having an inductance of 2.0mH per km and a capacitance of 0.014µF per km. Calculate values of reflected and transmitted wave of voltage and current at junction due to a voltage surge of 110kV travelling to a junction along the cable. (JNTU Nov 07)

26. Derive the equivalent ABCD parameters considering nominal T network. (JNTU Nov 07)

27. The ABCD constants of a 3-phase transmission line are A = D = 0.936 |0.980, B = 142 |76.40 ohms and C = (-5.18 + J914)x10-6mhos. The load at the receiving end is 50 MW at 220 kV with a power factor of 0.9 lagging. Find the magnitude of the sending end voltage and the voltage regulation also draw the vector diagram. (JNTU Nov 07)

28. A series capacitor bank is to be installed at the mid point of the 300 Km line. The ABCD constants for 150 Km of the line are A = D = 0.9534 |0.30 B = 90.33 |84.10 ohms, and C = 0.001014 |90.10 mhos. The ABCD constants of the series capacitor bank are A = D = 1 |0 0,B = 146.6 |-900ohms, C = 0. Determine the equivalent ABCD constants of the series combination of the line-capacitance-line.

(JNTU Nov 07, 05)

29. i. Derive the ABCD constants for long transmission lines. ii. Explain briefly classification of transmission lines based on line lengths with Neat diagrams.

(JNTU Nov 05, 04)

30. Derive the equivalent ABCD parameters when two different transmission lines are connected is Cascade. (JNTU Nov 04)

31. Discuss why equivalent Pie circuit of a long line is preferred over the equivalent T circuit (JNTU Jun 03)

32. A three phase 50Hz transmission line is 150 km long and delivers 25MW at 0.85 power factor lagging and at 110KV. The resistance and reactance of the line per conductor per km are 0.3 ohms and 0.9 ohms respectively. The line charging admittance is 0.3 x 10-6 mho per km per phase. Compute by applying the nominal “ method the voltage regulation and transmission efficiency

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(JNTU Jun 03)

33. A 3 phase 50 Hz , 100 Km long Transmission line delivers a load of 20000kW at 110kV 0.9 p.f. Lagging The copper conductors of the line are 1.2 cm in diameter and are spaced equilaterally , so that the distance between them is 2 m. Using Nominal Pi method, Calculate the sending end voltage, current, power factor, regulation & efficiency of line. Neglect the leakage (JNTU Jun 03)

34. i. What is an equivalent Π circuit of a long line? Derive the expression for the parameters of the circuit in terms of line parameters?

ii. A 60 Hz short line has a resistance of 0.5 ohm/ph and inductance of 90 mH/ph. the line supplies to the star connected load at 100kW at 0.9 pf lag and at 215Kv. Calculate the sending end voltage

(JNTU Jun 01)

35. Match the items in List-I with the items in List-II and selet the correct answer using the codes give below the lists.

List 1 List IITo Use

a. improve power factor 1. shunt reactorb. reduce the current ripples 2. shunt capacitorc. increase the power flow in line 3. series capacitord. reduce the Ferranti effect 4. series reactor

a. a→2, b→3, c→4, d→1 b. a→2, b→4, c→3, d→1c. a→4, b→3, c→1, d→2 d. a→4, b→1, c→3, d→2 (GATE 09)

36. A lossless transmission line having surge Impedance Loading (SIL) of 2280 MW is provided with a uniformly distributed series capacitive compensation of 30%. Then, SIL of the compensated transmission line will be a. 1835 MW b. 2280 MWc. 2725 MW d. 3257 MW (GATE 08)

37. Two transmission lines are connected in cascade, whose ABCD parameters are respectively. Find the resultant ABCD parameters.i) A 100 MVA generator with 10% reactance and a 200 mVA generator with 8% reactance (reactance’s on their own bases) are connected as shown in Figure. The fault level on bus 1 is to be restricted to 1500 MVA. Calculate, on 100 MVA base. (GATE 2000)ii) The reactance of bus bar reactor X.iii) Fault level of Bus 2iv) MVA rating of circuit breaker C.

38. With reference to long transmission lines, give physical interpretation of the terms ‘characteristics impedance’ and ‘propagation constant’. What is meant by “surge impedance”? (IES 98)

39. A 50 Hz transmission line 300 km ling has a total series impedance of 40+ j125 ohms and a total shunt admittance of 10-3 mho. The receiving-end load is 50 MW at 220 kv with 0.8 lagging power factor. Find the sending-end voltage, current, power and power factor using short line approximation method.

40. A 50 Hz transmission line 300 km ling has a total series impedance of 40+ j125 ohms and a total shunt admittance of 10-3 mho. The receiving-end load is 50 MW at 220 kv with 0.8 lagging power factor. Find the sending-end voltage, current, power and power factor using nominal Pie method.

41. A 50 Hz transmission line 300 km ling has a total series impedance of 40+ j125 ohms and a total shunt admittance of 10-3 mho. The receiving-end load is 50 MW at 220 kv with 0.8 lagging power factor. Find the sending-end voltage, Current, power and power factor using exact transmission line equations

42. A single circuit 50Hz 3 phase transmission line has the following parameters R=0.2 ohm, L=1.3mH, C=0.01micro F. the voltage at the receiving end is 132kV. If the line is open at the receiving end, find the rms value and phase angle of the following i. the incident voltage to neutral at the receiving end the reflected voltage to neutral at the receiving end.

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43. A single circuit 50Hz 3 phase transmission line has the following parameters R=0.2 ohm, L=1.3mH, C=0.01micro F. Determine the efficiency of the line if the line is 120 km long and delivers 40 MW at 132 kV and 0.8 p.f. lagging.

44. A single circuit 50 Hz 3 phase transmission line has the following parameters R=0.2 ohm, L=1.3mH, C=0.01micro F. If the line is 120 km and receiving end voltages 132kv determine ABCD parameters of the line.

45. Determine the sending end voltage current, power and power factor for a 160 km section of 3-phase line delivering 50 MVA at 132 kV and p.f. 0.8 lagging. Also find the efficiency and regulation of the line. Resistance per line 0.1557 ohm per km, spacing 3.7 m, 6.475 m, 7.4 m transposed. Evaluate the A,B, C, D parameters also. Diameter 1.956 cm.

46. What is meant by “Natural loading “of lines? Explain with reasons whether the economic loading for (i) overhead, and (ii) underground lines are more/less than their natural loadings.

47. Derive for a long line the sending end voltage and current relations in terms of receiving end voltage and current and the parameters of the line.

48. Derive equivalent parameters of two transmission lines when they are connected in tandem and parallel.

49. Determine A,B,C,D parameters of the line 400 km long having per unit impedance and admittance as (0.15+j0.78) ohm/km and j5.0 micro mho per km. Assuming line could be represented by nominal Pie or nominal T.

50. Determine A, B, C, D parameters of the line 400 km long having per unit impedance and admittance as (0.15+j0.78) ohm/km and j5.0 micro mho per km. Assuming exact representation of line.

51. A 3-phase overhead transmission line has a total series impedance per phase of 200 at an angle of 800 ohms and a total shunt admittance of 0.0013 at an angle of 900 siemen per phase. The line delivers a load of 80 MW at 0.8 p.f. lagging and 220kv between the lines. Determine the sending end line voltage and current by rigorous method.

52. Derive the formulae for sending end voltage and current of long transmission line using rigorous method.

53. What do you understand by long transmission lines? How capacitance effects are taken into account in such lines?

54. What do you understand by generalised circuit constants of a transmission line? What is their importance?

55. Evaluate the generalised circuit constants for long transmission line.

56. A long transmission line is open circuited at the receiving end. Will there be any current in the line at the sending end? Explain your answer.

57. A 3-phase transmission line 200 km long has the following constants: Resistance/phase/km is 0.16 ohms, Reactance/phase/km is 0.25 ohms, Shunt admittance/phase/km is 1.5 micro siemens. Calculate by rigorous method the sending end voltage and current when the line is delivering a load of 20 MW at 0.8 p.f. lagging. The receiving end voltage is kept constant at 110kv.

UNIT – IV

1. a. When the transmission line is terminated by the capacitive load, how do you find out the expressions of reflected voltage and current wave.

b. An under ground cable having an inductance of 0.3mH per km and a capacitance of 0.4µF per km is connected in series with an overhead line having an inductance of 2.0mH per km and a capacitance of 0.014µF per km. Calculate values of reflected and transmitted wave of voltage and current at junction due to a voltage surge of 110kV travelling to a junction along the cable. (JNTU May 09)

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2. a. Develop an equivalent circuit at the transition points of transmission lines for analyzing the behavior of travelling waves.

b. A cable has an inner conductor of radius 1 cm inside a sheath of inner radius 0.75cm. Findi. the inductance per meter lengthii. capacitance per meter length,iii. surge impedance,iv. velocity of propagation, if the permittivity of insulation is 4 (JNTU May 09)

3. a. Derive the travelling wave equations in a lossless transmission line.b. The ends of two long transmission lines, A and C are connected by a cable B, 1km long. The surge

impedances of A, B, C are 400, 50 and 500 ohms respectively. A rectangular voltage wave of 25 kV magnitude and of infinite length is initiated in A and travels to C, determine the first and second voltages impressed on C. (JNTU May 09)

4. a. What is the outcome of the transient in the transmission lines? Develop the differential equation for the transient in the transmission system.

b. A 500 kV, 2 µsec, duration rectangular surge passes through a line having surge impedance of 350Ω and approaches a station at which the concentrated earth capacitance is 3×10 3 pF. Calculate the maximum value of surge transmitted to the second line. (JNTU May 09)

5. a. A single core cable has an inner diameter of 5cms and a core diameter of 1.5cm. Its paper dielectric has a working maximum dielectric stress of 60 kV/cm. Calculate the maximum permissible line voltage when such cables are used on a 3-phase power system.

b. A 66kV concentric cable with two inter sheaths has a core diameter 1.8 cm. Dielectric material 3.5 mm thick constitutes the three zones of insulation. Determine the maximum stress in each of the three layers if 20kV is maintained across each of the inner two layers. (JNTU May 09)

6. a. Derive the formula for dielectric stress in an UG cable. b. Single-core, lead covered cable is to be designed for 66kV to earth. Its conductor radius is 10mm and

its three insulating materials A,B and C have relative permittivities of 5,4 and 3 respectively and corresponding maximum permissible stresses of 3.8, 2.6 and 2.0 kV/mm (rms) respectively. Find the minimum diameter of the lead sheath. (JNTU May 09, Nov 08)

7. An overhead line at a river crossing is supported from two towers at heights of 50m and 85m above water level, the horizontal distance between the towers being 450m. If the maximum tension is 3980 kgf and the conductor weighs 1.726 kgf/m, find

a. the minimum clearanceb. the clearance between the conductor and the water level at a point midway between the towers.c. the clearance between the conductor and water at appoint 200m from the lower supporting tower.

(JNTU May 09)

8. In a 5 insulator disc string capacitance between each unit and earth is 1/6 of the mutual capacitance. Find the voltage distributions across each insulator in the string as percentage of voltage of the conductor to earth. Find string efficiency. How is this efficiency affected by rain.

(JNTU May 09)

9. a. Derive the formula fpr insulation resistance of aUG cable. b. In a coaxial cable the conductor diameter is 10 mm and the inner shath diameter is 50mm. There are

two layers of insulation, the inner layer of dielectric constant 4 and a maximum working gradient of 6kV/mm has a radial thickness of 4.6 mm; the outer layer has dielectric constant 2.5 and maximum voltage gradient 5kV/mm. Calculate the maximum working voltage for the cable. (JNTU Nov 08)

10. a. What is the relation between the conductor diameter and breakdown potential of a cable while voltage of the cable and its overall diameter are fixed? Derive the same.

b. The capacitance per kilometer of a 3-phase belted cable is 0.25µF between the two cores with the third core connected to the lead sheath. Calculate the charging current taken by five kilometers of this cable when connected to a 3-phase, 50Hz, 11kV supply. (JNTU Nov 08)

11. a. Give merits anddemerits of UG scales.

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b. The test results for 1km of a 3-phase metal sheathed belted cable gave a measured capacitance of 0.7µF between one conductor and the other two conductors bunched together with the earth sheath and 1.2µF measured between the three bunched conductor and the sheath. Find i. the capacitance between any pair of conductors, the sheath being isolated andii. the charging current when the cable is connected to 11kV, 50Hz supply. (JNTU Nov 08)

12. a. Starting from first principles show that surges behave as travelling wave. (JNTU Nov 08)b. An over head line with inductance and capacitance per km length of 1.24 mH and 0.087 µF

respectively is connected in series with an ungrounded cable having inductance and capacitance of 0.185 mH / km and 0.285 µF / km respectively. Calculate the values of reflected and refracted waves of voltage and current at the junction due to a voltage surge of 110 kV traveling to the junctioni. along the line towards the cable, and ii. along the cable towards the line.

13. a. Explain the surge phenomena.b. A voltage having a crest value of 3000 kV is traveling on a 750 kV line. The protective level is 1700

kV and the surge impedance of the line is 300Ω. Calculatei. the current in the line before reaching the arresterii. current through the arresteriii. the value of arrester resistance for this conditioniv. reflect voltage. Verify the reflection and refraction coefficient. (JNTU Nov 08)

14. a. Develop an equivalent circuit for the analysis of the behavior of traveling waves at transition points on a transmission line.

b. The ends of two long transmission lines, A and C are connected by a cable B, km long. The surge impedances of A, B, C are 500, 70 and 600 ohms respectively. A rectangular voltage wave of 20 kV magnitude and of infinite length is initiated in A and travels to C. Determine the first and second voltages impressed on C. (JNTU Nov 08)

15. a. What is the outcome of the transient in the transmission lines? Develop the differential equation for the transient in the transmission system.

b. A 500 kV, 2 µsec, duration rectangular surge passes through a line having surge impedance of 350Ω and approaches a station at which the concentrated earth capacitance is 3×10 3 pF. Calculate the maximum value of surge transmitted to the second line. (JNTU Nov 08)

16. a. Deduce expressions for surge impedance and velocity of propagation.b. A 200 kV surge travels on line of 400ohms surge impedance and reaches a junction where two branch

lines of serge impedances of 500ohms and 300ohms are connected with the transition line. Find the surge voltage and current transmitted into each branch line. Also find the reflected voltage and current.

(JNTU Feb 08)

17. Discuss the wave length and velocity of propagation. Show that a traveling wave moves with a velocity of light on the overhead line and its speed is proportional to 1/ r. on a cable with dielectric material of permittivity r.

18. Two stations are connected together by an underground cable having a surge impedance of 60 ohms joined to an overhead line with a surge impedance of 400 ohms. If a surge having a maximum valve of 100 kV travels along the cable towards the junction with the overhead line, determine the value of thereflected and transmitted wave of voltage and current at the junction. (JNTU Feb 08)

19. Explain the surge phenomena. (JNTU Nov 07)

20. A voltage having a crest value of 3000 kV is traveling on a 750 kV line. The protective level is 1700 kV and the surge impedance of the line is 300ohms. Calculate

i. the current in the line before reaching the arresterii. current through the arresteriii. the value of arrester resistance for this conditioniv. reflect voltage. Verify the reflection and refraction coefficient. (JNTU Nov 07)

21. Starting from first principles show that surges behave as traveling wave. (JNTU Nov 07)

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22. An over head line with inductance and capacitance per km length of 1.24 mH and 0.087 µF respectively is connected in series with an ungrounded cable having inductance and capacitance of 0.185 mH / km and 0.285 µF / km respectively. Calculate the values of reflected and refracted waves of voltage and current at the junction due to a voltage surge of 110 kV traveling to the junction

i. along the line towards the cable, andii. along the cable towards the line. (JNTU Nov 07)

23. Derive reflection and refraction coefficient of transmission line when receiving end is open circuited. (JNTU Nov 07)

24. An overhead line has a surge impedance of 450 ohms. A surge voltage V=250(e0.05t -e-t) kV, where t is in msec, travels along the line. The termination of the line is connected to two parallel overhead line transformer feeders. The surge impedance of the feeder is 350 ohms. These two transformers are protected by surge diverters each of surge impedance being 40 ohms. Determine the maximum voltage which would initially appear across the feeder end windings of each transformer due to the surge. Assume the transformer to have infinite surge impedance. (JNTU Nov 07)

25. Staring from first principle show that surges behaves as traveling wave. (JNTU Nov 07)

26. An overhead line is connected to a terminal apparatus through a length of single phase cable, the characteristic impedance being 300 and 60 ohms respectively. A traveling wave of vertical front and infinite tail of 110kV magnitude originates in the overhead line and travels towards the junction with the cable. Determine the energy transmitted into the cable during a period of 3µ Sec after the arrival of the wave at the junction. What voltage is reflected back into the line. (JNTU Nov 07)

27. Starting from first principles show that surges behave as traveling waves. Find expressions for surge impedance and wave velocity. (JNTU Nov 07)

28. A step wave of 110 kV travels through a line having a surge impedance of 350 ohms. The line is terminated by an inductance of 5000 µH. Find the voltage across the inductance and reflected voltage wave. (JNTU Nov 07)

29. When the transmission line is terminated by the capacitive load, how do you find out the expressions of reflected voltage and current wave. (JNTU Nov 07)

30. An under ground cable having an inductance of 0.3mH per km and a capacitance of 0.4µF per km is connected in series with an overhead line having an inductance of 2.0mH per km and a capacitance of 0.014µF per km. Calculate values of reflected and transmitted wave of voltage and current at junctiondue to a voltage surge of 110kV traveling to a junction along the cable. (JNTU Nov 07)

31. Given an RL circuit with a sudden 50 Hz sinusoidal voltage applied where R=20 ohms, L=0.36 H and voltage V=220V.

i. The switch is closed at such a time as to permit maximum transient current . What is the instantaneous value of voltage upon closing the switch?

ii. What is the maximum values of current in part (i)?iii. Let the switch be closed so as to yield minimum transient current. What instantaneous values of V and

x correspond to this instant of closing the switch?

32. Determine the relative attenuation occurring in two cycles in the over voltage surge set up on a 132KV cable fed through an air blast breaker when the breaker opens on a system short circuit. The breaker uses critical resistance switching. The network parameters are R=10 ohms, L=8 mH and C=0.8 μF.

33. Explain with neat diagrams two different theories of charge generation and separation in a thunder cloud.

34. Explain with neat sketches the mechanism of lightning discharge.

35. Differentiate between a hot lightning stroke and a cold lighting stroke.

36. Explain the variation of current and voltage on an overhead line when one end of the line is

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i. short-circuited, and ii. Open-circuited and at the other end a source of constant e.m.f. V is switched in.

37. What is a traveling wave ? Explain the development of such a wave on an over-head line.

38. An overhead transmission line with surge impedance 400 ohms is 300 km long. One end of this line is short-circuited and at the other end a source of 11kv is suddenly switched in. Calculate the current at the source end 0.005sec after the voltage is applied.

39. Explain why a short length of cable is connected between the dead end tower and the terminal apparatus in a station. An overhead line with surge impedance 400 ohms is connected to a terminal apparatus through a short length of cable of surge impedance 40 ohms.

40. An overhead line with surge impedance 400 ohms bifurcates into two lines of surge impedance 400 ohms and 40 ohms respectively. If a surge of 20KV is incident on the overhead line, determine the magnitudes of voltage and current which enter the bifurcated lines.

41. A long overhead line has a surge impedance of 500 ohms and an effective resistance of 6 ohms per km. If a surge of 400 KV enters the line at a certain point, calculate the magnitude of this surge after it has traversed 100km and calculate the power loss and heat loss of the wave over this distance. Assume velocity of wave as 3*108m/sec.

42. A rectangular surge of 2 μsec duration and magnitude 100kv travels along a line of surge impedance 500 ohms. The latter is connected to another line of equal impedance through an inductor of 500 μH. Calculate the maximum value of surge transmitted to the second line.

43. The effective inductance and capacitance of a faulted system as viewed from the contacts of a breaker are 2.5 mG and 600 pF respectively. Determine the restricting voltage across the breaker contacts when a fault current of 150 amps is chopped.

44. What is arcing ground? Explain its effect on the performance of a power system.

45. What is “capacitance switching”? Explain its effect on the performance of the circuit breaker.

46. Derive an expression for the restricting voltage across the circuit breaker contacts. The system consists of an unloaded alternator with neutral solidly grounded.

47. Explain clearly the variation of current and impedance of an alternator when a 3-phase sudden short circuit takes place at its terminals.

48. An overhead line with inductance and capacitance per km of 1.24 mH and 0.087 MF respectively is connected in series with an underground cable having inductance and capacitance of 0.185 mH/km and 0.285 mF/km. Calculate the values of transmitted and reflected waves of voltage and current at the junction due to a voltage surge of 110 kv traveling to the junction(i) along the line towards the cable, and (ii) along the cable towards the line.

49. A dc source of 120V with negligible resistance is connected through a switch S to a lossless transmission line having Ze=30 ohm. If the line is terminated in a resistance of 90 ohm, plot vR versus time until t=5T where T is the time for a voltage wave to travel the length of the line.

50. Draw the lattice diagram for current and plot current versus time at the sending end of the transmission line terminated in open circuit.

51. Draw the lattice diagram for current and plot current versus time at the sending end of the transmission line terminated in short circuit.

52. Explain briefly transients and simple circuit elements.

53. A 3-phase transmission line has conductors 1.5 cms in diameter spaced 1 metre apart in equilateral formation. The resistance and leakage reactance negligible, Calculate

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i. The natural impedance of the lineii. the line current if a voltage wave of 11 kv travels along the line iii. The rate of energy absorption, the rate of reflection and the state and the form of reflection if the line is terminated through a star connected load of 1000 ohm per phase.

54. A 3-phase transmission line has conductors 1.5 cms in diameter spaced 1 metre apart in equilateral formation. The resistance and leakage reactance negligible, Calculate i. The value of the terminating resistance for no reflection.ii. The amount of reflected and transmitted power if the line is connected to a cable extension with inductance and capacitance per phase per cm of 0.05 nanoH and 1 pico F respectively.

55. A surge of 15 kv magnitude travels along a cable towards its junction with an overhead line. The inductance and capacitance of the cable and overhead line are respectively 0.3 mH, 0.4 micro F and 1.5 mH, 0.012 micro F per km. Find the voltage rise at the junction due to the surge.

56. A surge of 100 kv traveling in a line of natural impedance 600 ohms arrives at a junction with two lines of impedances 800 ohms and 200 ohms respectively. Find the surge voltages and currents transmitted into each branch line.

57. A 500 kv 2 microsec rectangular surge on a line having a surge impedance of 350 ohms approaches a station at which the concentrated earth capacitance is 3000 pF. Determine the maximum value of the transmitted wave.

UNIT -V

1. a. Derive the electrical stress of single phase two wire system.b. A 3-phase line has conductors 2.5 cm in diameter spaced equilaterally 3m part. If the dielectric

strength of air is 21.21 kV (rms) per cm, find the disruptive critical voltage for the line. Take air density factor δ=0.953 and irregularity factor m0 = 0.92. (JNTU May 09)

2. a. Write a short notes on radio interference due to corona.b. Determine the disruptive critical voltage and the visual critical voltages for local and general corona on

a 3-phase overhead transmission line consisting of three stranded copper conductors spaced at 2.5 meters apart at the corners of an equilateral triangle. Air temperature and pressure are 210C and 73.5 cm of Hg respectively. Conductor diameter is 1.8 cm, irregularity factor (m0) 0.85, and surface factors (mv) is 0.7 for local and general corona are 0.7 and 0.8 respectively. Breakdown strength of air is 21.1 kV (r.m.s) / cm. (JNTU May 09)

3. a. What is corona and what are the factors affecting corona loss? Discuss them briefly.b. An overload transmission line operates at 210 kV between phases at 50 Hz. The conductors are

arranged in a 3.5 metre delta formation. What is the maximum diameter of conductor that can be used for no corona loss under fair weather conditions? Assume an air density factor of 0.9 and irregularity factor of 0.82. The critical voltage is 230 kV. Find also the power loss under storm conditions.

(JNTU May 09)

4. a. What is corona? What are its effects and how are they reduced? (JNTU May 09)b. Find the disruptive critical voltage and visual voltage of a 3-phase transmission line operating at 132

kV, the conductors being 1.5 cm in diameter and arranged in delta with spacing of 4 m. The surrounding air is at a temperature of 320C and barometric pressure 74 cm of mercury. The various factors are irregularity factor = 0.85, surface factor for local corona = 0.7, surface factor for decided corona = 0.80, Breakdown strength of air = 21.21 kV/cm, assume fair weather condition.

5. a. Why is their a phase difference between voltage and current in an ac circuit? Explain the concept of power factor?

b. Derive an expression for most economical power factor which may be attained by a consumer? c. Explain, why a consumer having low power factor is charged at higher rates?

(JNTU May 09, Nov 08)

6. a. What is the effect of 3-φ induction motor operation on supply power factor? Discuss?

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b. The load on an installation is 800KW,0.8 lagging which works for 3000 hours per annum. The tariff is Rs 100 per KVA plus 20 paise per KWh. If the power factor is improved to 0.9 lagging by means of loss-free capacitors costing Rs 60 per KVAR, calculate the annual saving effected. Allow 10% per annum for interest and depreciation on capacitors. (JNTU May 09)

7. a. Explain how a phase shifting transformer is used simultaneously both for power factor and voltage control . Explain them with neat sketches .

b. How can an individual consumer of 1-φ f and 3-φtype would control the power factor at the load side effectively? Explain your answer with respect to different types of consumers . (JNTU May 09)

8. a. What is a sag-template? Explain how this is useful for location of towers and stringing of power conductors.

b. What is a stringing chart? Explain clearly the procedure adopted for stringing the power conductors on the supports. (JNTU May 09)

9. a. Explain the phenomenon of corona? How can the corona loss be minimized in transmission lines.b. Determine the disruptive critical voltage and the critical voltages for local and general corona on a 3-

phase overhead transmission line, consisting of three stranded copper conductors, spaced 3 meters apart at the corners of an equilateral triangle. Air temperature and pressure are 21oC and 73.5 cm of mercury respectively. Conductor diameter is 2.2 cm. Take air density factor 3.92 b/(273 + t), irregularity factor (m) = 0.82 and surface factors (mv) for local and general corona = 0.7 and 0.8 respectively. Break down strength of air is 21.21 kV (r.m.s) per cm. (JNTU Nov 08)

10. a. Write a short notes on radio interference due to corona.b. Determine the disruptive critical voltage and the visual critical voltages for local and general corona on

a 3-phase overhead transmission line consisting of three stranded copper conductors spaced at 2.5 meters apart at the corners of an equilateral triangle. Air temperature and pressure are 210C and 73.5 cm of Hg respectively. Conductor diameter is 1.8 cm, irregularity factor (m0) 0.85, and surface factors (mv) is 0.7 for local and general corona are 0.7 and 0.8 respectively. Breakdown strength of air is 21.1 kV (r.m.s) / cm. (JNTU Nov 08)

11. a. Describe the phenomenon of corona? Discuss the factors which affect corona loss.b. A 3-phase line has conductors of radius 1.0 cm, spaced at the corners of an equilateral triangle of side

2.5 m apart. If the dielectric strength of air is 30kV/cm, determine the disruptive critical voltage at which corona will occur. Take relative air density factor δ =0.96 and irregularity factor m0 = 0.94.

(JNTU Nov 08)

12. a. What is corona loss? Why is it different in different weather conditions? How can it be estimated?b. A 132kV overhead line conductor of radius 1cm is built so that corona takes place if the line voltage is

210 kV (r.m.s). If the value of voltage gradient at which ionization occurs can be taken as 21.21 kV (r.m.s) per cm, determine the spacing between the conductors. (JNTU Nov 08)

13. a. Explain the effect of shunt compensation on transmission lines. b. A 110 kV, 3 Phase, 50 Hz transmission line, 175 km long consists of three 1 cm diameter stranded

copper conductors spaced in 3 m delta arrangement. Temperature taken at 260C and barometric pressure as 74 cm. Assume surface irregularity factor m= 0.85 (Roughness factor) mv for local corona= 0.72 and mv for general corona=0.82. Findi. Disruptive voltage (JNTU Feb 08)ii. Visual corona voltage for local coronaiii. Visual corona voltage for general corona andiv. Power loss due to corona using Peek’s formula under fair weather and wet conditions.

14. a. Derive an equation for calculating the maximum electric intensity on the conductor surface of a 3-phase single circuit horizontal configuration line with two sub-conductors per phase.

b. In a 3-phase overhead line, the conductors have an overall diameter of 3.0 cm each and are arranged in delta formation. Assuming a critical disruptive voltage of 250 kV between lines and an air density factor of 0.90 and m0 =0.95, find the minimum spacing between conductors allowable, assume fairweather conditions. (JNTU Feb 08)

15. a. Explain the surge phenomena.

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b. A voltage having a crest value of 3000 kV is traveling on a 750 kV line. The protective level is 1700 kV and the surge impedance of the line is 300ohms. Calculatei. the current in the line before reaching the arresterii. current through the arresteriii. the value of arrester resistance for this conditioniv. reflect voltage. Verify the reflection and refraction coefficient. (JNTU Feb 08)

16. a. What is corona and what are the factors affecting corona loss? Discuss them briefly.b. An overload transmission line operates at 210 kV between phases at 50 Hz. The conductors are

arranged in a 3.5 metre delta formation. What is the maximum diameter of conductor that can be used for no corona loss under fair weather conditions? Assume an air density factor of 0.9 and irregularityfactor of 0.82. The critical voltage is 230 kV. Find also the power loss under storm conditions.

(JNTU Nov 07)

17. a. What is meant by the disruptive critical voltage and visual critical voltage? State the effects of conductor size, spacing and condition of the surface of conductors on these voltages.

b. A certain 3-phase equilaterally spaced transmission line has a total corona loss of 55 kW at 110 kV and a loss of 110 kW at 120 kV. What is the disruptive critical voltage between lines? What is the corona loss at 125 kV?

18. a. Explain the effect of shunt compensation on transmission lines. (JNTU Nov 07)

19. a. What is corona loss? Give the Peaks corona loss formula and specify the terms. (JNTU Nov 07)b. Determine the corona loss for a 3-phase 110kV, 50Hz, 160km long line, with conductor diameter

1.036cm, 2.44m delta spacing, air temperature 26.670C and pressure of 73.15cm. (JNTU Nov 07)

20. a. What is critical disruptive voltage? Derive the expression for it.b. Give brief description about the factors affecting the critical disruptive voltage. (JNTU Nov 07)

21. i. Determine the critical disruptive voltage and corona loss for a 3-phase line space operating at 110kv which has conductors of 1.25cm diameter arranged in 3.05m delta spacing. Assume air density factor of 1.07 and the dielectric strength of air to be 21kv/cm.

ii. Explain in brief the disadvantages of corona and different methods of reducing corona loss. (JNTU Feb 07, Nov 07, 05)

22. i. Give brief description of corona phenomenon.ii. Derive the expression for potential gradient at the surface of a conductor of 1-phase transmission line.

(JNTU Feb 08, Mar 06, Nov 07, 06, 05, 04)

23. i. What do you mean by critical visual disruptive voltage?ii. Find the critical disruptive voltage and the critical voltages for local and general corona on a 3-phase

overhead transmission line, consisting of three stranded copper conductors spaced 2.5m apart at the corners of an equilateral triangle. Air temperature and pressure are 210C and 73.6 cm Hg respectively. Take conductor dia 10.4mm, irregularity factor 0.85, local and general surface factors 0.7 and 0.8 respectively. (JNTU Nov 07, 05)

24. Discuss the effect of load power factor on voltage regulation and efficiency of a transmission line. What are skin and proximity effects? (JNTU Nov 05)

25. A single phase overhead line has two conductors of dia 1 cm with a spacing of 1m between centers. If the dielectric strength of air is 21kV/cm, determine the line voltage for which corona will commence on the line. Derive the formula used. (JNTU Jun 04)

26. Define Voltage regulation of a transmission line and explain clearly the Ferranti effect with a phasor

diagram. (JNTU Nov 04)

27. i. What is Proximity effect? (JNTU Nov 07, Jun 03)ii. Why transmission lines are transposed? Explain the procedure of Transposition?

28. i. Discuss why Ferranti effect is significant only in medium and long lines?ii. What are tuned power lines? (JNTU Jun 03)

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29. What is Skin effect? (JNTU Jun 03)

30. How a corona formation does affect the efficiency of the line? Give Peterson’s formula to determine the power loss due to corona? (JNTU Nov 03)

31. Explain the phenomena of corona. How it is influenced by atmospheric conditions and conductor geometry

32. 3 phase 220KV 50 Hz transmission line has equivalent triangular spacing of side 1.38m. The conductor diameter is 3.2cm. the air density factor and irregularity factor are 0.95 & 0.83 respectively. Find the critical disruptive voltage and corona loss per Km. assume required data (JNTU Apr 02)

33. i. Define disruptive critical voltage?ii. A 110kv, 3 hase, 50 Hz transmission line, 175km long consists of three 1cm diameter stranded copper

conductors spaced in 3m delta arrangement. Temperature taken at 260C and barometric pressure as 74 cm. Assume surface irregularity factor m=0.85,(roughness factor) mV for local corona=0.72 and mV for general corona=0.82. Findi. Disruptive voltageii. Visual corona voltage for local coronaiii. Visual corona voltage for general coronaiv. Power loss due to corona using Peek’s formula under fair weather and wet conditions.v. Power loss due to corona using Peterson’s formula under fair weather and wet conditions.

(JNTU Nov 02)34. i. Describe the phenomena of corona.

ii. Find the disruptive critical voltage and visual corona voltage (local corona as well as general corona) for a 3 phase 220KV line consisting of 22.26mm diameter conductors spaced in a 6m delta configuration. The following data can be assumed. Temperature 250C, Pressure 73cm of mercury, surface factor 0.84, irregularity factor for local corona 0.72, irregularity factor for general corona 0.82.

(JNTU Nov 02)

35. i. Explain ‘Corona’.ii. A certain 3 phase equilaterally spaced transmission line conductor has a total corona loss of 53 Kw at

106 KV and a loss of 98 Kw at 110KV. What is the disruptive critical voltage between lines? What is the corona loss at 113KV? (JNTU Nov 02)

36. i. What are the disadvantages of corona? Explain how corona considerations affect the design of a line?ii. Find the critical disruptive voltage 7 visual voltage for a 3 phase line having 10mm dia conductors

spaced in delta arrangement spaced at 3 m. Assume temperature of 25 Deg. Centigrade and pressure of 70 cm of mercury . Assume surface irregularity factor 0.72 and 0.82 for general corona.

(JNTU Aug 01)

37. Bundled conductors are mainly used in high voltage overhead transmission lines toa) reduce transmission line losses b) increase mechanical strength of the linec) reduce corona d) reduce sag (GATE 03)

38. The corona loss on a particular system at 50 Hz is IkW/km per phase. The corona loss at 60 Hz would bea) IkW/km per phase b) 0.83kW/km per phasec) 1.2kW/km per phase d) 1.13kW/km per phase (GATE ‘00)

39. Corona losses are minimized when (GATE 99)a) Conductor size is reduced b) smooth conductor is reducedc) sharp points are provided in the line hardware d) current density in conductors is reduced

40. Derive an expression for disruptive critical (corona) voltage of single – phase overhead line. Show that the result can be extended to a 3 phase line. Explain how bundle conductors help to raise disruptive critical voltage of transmission line. (IES 94)

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41. Determine the corona characteristics of a 3-phase, 50 Hz, 132kV transmission line 100 km long running through terrain at an altitude of 600 meters, temp. Of 300C and barometric pressure 74cm. The conductors are 1.5 cm diameter and spaced with equilateral spacing of 2.75 meters. Assume surface irregularity factor of 0.9 and mv=0.75.

42. A 3-phase, 50 Hz, 132kV transmission line consists of conductors of 1.17 cm dia and spaced equilaterally at a distance pf 3 meters. The line conductors have smooth surface with value for m=0.96. The barometric pressure is 72 cm of Hg and temperature of 200C. Determine the fair and foul weather corona loss per km per phase.

43. A 3-phase, 50 Hz, 138 kv transmission line has conductors in equilateral formation spaced 2.5 meters apart. The conductor diameter is 1.04cm and the surface factor is 0.85. The air pressure and temperature are 74cm of Hg and 210C respectively. Determine the critical visual voltage for corona and the corona loss per km per phase of the line, mv=0.72.

44. Estimate the corona loss for a three-phase, 110 kv, 50Hz, 150 km long transmission line consisting of

three conductors each of 100 mm diameter and spaced 2.5 m apart in an equilateral triangle formation. The temperature of air is 300C and the atmospheric pressure is 750 mm of mercury. Take irregularity factor as 0.85. Ionization of air may be assumed to take place at a maximum voltage gradient of 30 kV/cm.

45. Taking the dielectric strength of air to be 30 kV/cm, calculate the disruptive critical voltage for a 3-phase line with conductors of 1 cm radius and spaced symmetrically 4 m apart.

46. A 3-phase, 220 kV, 50Hz transmission line consists of 1.2cm radius conductors spaced 2 m at the corners of an equilateral triangle. Calculate the corona loss per km of the line. The condition of the wire is smoothly weathered and the weather is fair with temperature of 200C and barometric pressure of 72.2 cm of Hg.

47. What is corona? What are the factors which affect corona?

48. Discuss the advantages and disadvantages of corona.

49. Explain the following terms with reference to corona:i. Critical disruptive voltageii. Visual critical voltageiii. Power loss due to corona.

50. Explain clearly the “Ferranti effect “with a phasor diagram.

51. Explain clearly the “Skin effect” and “proximity effect” when referred to overhead lines.

52. What are bundled conductors? Discuss the advantages of bundled conductors when used for overhead lines.

UNIT – VI

1. a. Explain how the electrical breakdown can occur in an insulators.b. Each conductor of a 33 kV, 3-phase system is suspended by a string of 3 similar insulators. The

capacitance between each insulator pin and earth is 13% of self capacitance of each insulator. Findi. The distribution of voltage over three insulatorsii. String efficiency. (JNTU May 09)

2. a. Explain why suspension type of insulators are preferred for high voltage overhead lines. Sketch a sectional view of one unit of the suspension type insulator and describe the construction.

b. An insulator string containing five units has equal voltage across each unit by using disc of different capacitances. If the top unit has a capacitance of C and pin to tower capacitance of all units is 20 percent of the mutual capacitance of top unit. Calculate mutual capacitance of each disc in a string.

(JNTU May 09)

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3. a. Explain the use of grading rings and arcing horns on suspension insulators. (JNTU May 09)b. A string consisting of seven suspension discs is fitted with a grading ring. Each pin to earth capacitance

is C. If the voltage distribution is uniform, determine the values of line to pin capacitance.

4. What are the various methods of voltage control in a power system, explain with neat sketches and vector diagrams. (JNTU May 09)

5. a. Explain the method of intersheath grading of cables.b. A single core lead covered cable is to be designed for 66 kv to earth. Its conductor radius is 0.5 cm and

its three insulating materials A, B, C have relative permittivities of 4,4,2.5 with maximum permissible stresses of 50, 40, 30 kv/cm respectively. Find the minimum internal diameter of the lead sheath.

(JNTU May 09)

6. Describe the synchronous condenser method of voltage control in a transmission line. Illustrate your answer with a neat sketch and vector diagram. Where are its locations in a Power system network, show with neat sketches. (JNTU Nov 08)

7. What are the various methods of voltage control in a power system, explain with neat sketches and vector diagrams. (JNTU Nov 08)

8. a. Explain why the potential distribution is not, in general, uniform over the string in suspension type of insulators.

b. A string of suspension insulator consists of four units and the capacitance to ground is 12 percent of its mutual capacitance. Determine the voltage across each unit as a fraction of the operating voltage. Also determine the string effciency. (JNTU Nov 08)

9. a. List the characteristics which the insulator should posses.b. Each conductor of a 3-phase high voltage transmission line is suspended from cross arm of steel tower

by a string of 4 suspension type disc insulators. If the voltage across the second unit is 13.2 kV and that across the third unit is 20 kV. Calculate the voltage between the conductors. (JNTU Nov 08)

10. a. List the advantages of suspension type insulators over pin type insulators.b. A string of 5 insulator units has a self-capacitance equal to 11 times the pin to earth capacitance. Find

the string efficiency? (JNTU Nov 08)

11. a. What do you mean by string efficiency? How can it be improved?b. A 3-phase overhead transmission line is being supported by three discs suspension insulators. The

potential across the first and second insulators are 11 kV and 13.2kV respectively. Calculatei. the line voltage and ii. string efficiency. (JNTU Nov 08)

12. a. What is guard ring which is being used in the suspension string type insulator? Deduce the relation for determining the capacitance formed by the ring.

b. A three phase over head line is being supported by tree discs suspension insulators, the potential across the first and second insulators are 12 and 18 kV respectively. Calculatei. the line voltage,ii. the ratio of capacitance between pin and earth to self-capacitance of each unit,iii. the string efficiency. (JNTU Feb 08)

13. a. Write a short notes on different types of insulators used for overhead lines and their applications.b. Find the potential difference across each unit of over head suspension insulator connecting of four

similar units. The potential between the line conductors and the earth is 58 kV and the ratio of capacity of each insulator to the capacity relative to earth, of each intermediate section of connecting work is 6:1. It is assumed that no leakage takes place. Also find the string efficiency. (JNTU Feb 08)

14. a. Give reasons for unequal potential distribution over a string of suspension insulators.b. Each line of a 3-phase system is suspended by a string of 3 similar insulators. The voltage across the

unit nearer to the line conductor is 12 kV. Calculate the line to neutral voltage. Assume the shunt capacitance between each insulator and earth is 1/6 capacitance of the insulator itself. Also find the sting efficiency. (JNTU Feb 08)

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(JNTU Feb 08)

16. a. Define string efficiency. Why is it necessary to have high string efficiency? How can it be achieved?b. A string of suspension insulators consists of 5 units each having capacitance C. The capacitance

between each unit and earth is 1/8 of C. Determine the voltage distribution across each insulator in the string as a percentage of voltage of conductor to earth .If the insulators in the string are designed to withstand 36 kV maximum, calculate the operating voltage of the line where 5 suspension insulator strings can be used. (JNTU Nov 07)

17. a. Explain why the voltage across the insulator string is not equal and describe practical methods to improve them.

b. A three phase over head transmission line is suspended by a suspension type insulator which consists of three units. The potential across top unit and middle unit are 7 kV and 10 kV respectively. Calculatei. The ratio of capacitance between pin and earth to the self capacitance of the each unitii. The line voltage andiii. String efficiency. (JNTU Nov 07)



(JNTU Nov 07)

19. a. Discuss the method of grading the string unit in insulations?b. In a 33 kV over head line there are three units in the string of insulators. The capacitance between each

insulator pin and earth is 13% of self capacitance of each insulator. Findi. The distribution of voltage over three insulators ii. String efficiency. (JNTU Nov 07)

20. i. List various methods of improving string efficiency.ii. In a string of three insulator units the capacitance of each unit is C, from each conductor to ground is

C/3, and from each connector to the line conductor is C/5. Calculate the voltage across each unit as a percentage of the voltage. To what value the capacitance between the connector of the unit and the line has to be increased by a grading to make the voltage across it equal to that across the next higher unit?

(JNTU Feb 08, 07, Nov 06)

21. A string of suspension insulator consists of four units. The capacitance between each pin and earth is one tenth of the self capacitance of the unit. The voltage between the line conductor and earth is 100 kV. Fine the voltage distribution across the each unit and string efficiency.

(JNTU Feb 07, Nov, Mar 06)

22. i. What are overhead line insulators? Explain briefly different types of insulators based on their applications and operating voltage levels with neat diagram.

ii. Each conductor of a three phase overhead line is suspended from a cross arm of a steel tower by a string of 4 suspension insulators. The voltage across the second unit is 13.2kV and across the third 19.5kV. Find the voltage between the conductors and the string efficiency. (JNTU Feb 08, 07)

23. i. Give brief description of corona phenomenon.ii. Derive the expression for potential gradient at the surface of a conductor of 1-phase transmission line.

(JNTU Nov 06)24. i. What are the basic tests to be carried out on insulators?

ii. A three-phase overhead transmission line is being supported by three-disc suspensions insulators, the potentials across the first and second insulator are8 KV and 11 KV respectively. Calculate

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i. line voltageii. ratio of the capacitance between pin and earth to self-capacitance of each unit andiii. the string efficiency. (JNTU Mar 06)

25. Find the voltage distribution and string efficiency of three unit suspension insulator string if the capacitance of the link pins to earth and to the line are respectively 20% and 10% of the self capacitance of each unit. If a guard ring increases the capacitance to the line of lower link pin to 35% of the self capacitance of each unit, find the redistribution of voltage and string efficiency.

(JNTU Feb 08, Mar 06)

26. i. Mention different types of insulating materials used in underground cables. Give brief explanation. ii. Determine the economical size of a single core cable working on 220kV, 3-phase system. The

maximum permissible stress in the dielectric is not to exceed 250kV/cm. (JNTU Mar 06)

27. i. Each conductor of a 33 KV, 3-phase system is suspended by a string of three similar insulators; the capacitance of each disc is nine times the capacitance to ground. Calculate the voltage across each insulator. Determine the string efficiency.

ii. A string of eight suspension insulators is to be graded to obtain uniform distribution of voltage across the string. If the capacitance of the top unit is 10 times the capacitance to ground of each unit, determine the capacitance of the remaining seven units. (JNTU Nov 05)

28. Each conductor of a three phase overhead line is suspended from a cross arm of a steel tower by a string of 4 suspension insulators. The voltage across the second unit is 14.2kV and across the third 20kV. Find the voltage between the conductors and the string efficiency. (JNTU Apr 05)

29. An overhead line is supported between two towers having heights of 30m and 70m from the datum level. If the horizontal distance between them is 300m, find the height of the conductor from the datum level between the supports. Assume maximum tension of 1720kgf and weight per meter run is 0.727kgf. (JNTU Nov 04)

30. i. Explain different methods of improving voltage distribution across the insulating disc.ii. A string of suspension insulator consists of four units. The capacitance between each pin and earth is

one tenth of the self capacitance of the unit. The voltage between the line conductor and earth is 100kV. Find i) The Voltage distribution across the each unit ii) the string efficiency. (JNTU Nov 04)

31. i. Explain the reason why the insulating disc nearer to the conductor is more stressed? ii. What is string efficiency of overhead line insulators? Give its significance. (JNTU Apr 04)

32. A string of eight suspension insulators is to be graded to obtain uniform distribution of voltage across the string. If the capacitance of the top unit is 10 times the capacitance to ground of each unit, determine the capacitance of the remaining seven units? (JNTU Nov 03)

33. A string of suspension insulators consists of 8 units. If the maximum peak voltage per unit is 33KV. Calculate i. The maximum voltage for which this string can be usedii. The string efficiency. Assume capacitance between each link pin and earth as 15 percent of the self capacitance of each unit (JNTU Nov 03)

34. In a 5 insulator disc string capacitance between each unit and earth is 1/6 of the mutual capacitance. Find the voltage distributions across each insulator in the string as percentage of voltage of the conductor to earth. Find string efficiency. How is this efficiency affected by rain? (JNTU Jun 03)

35. Each conductor of a 33KV, 3-phase system is suspended by a string of three similar insulators; the capacitance of each disc is nine times the capacitance to ground. Calculate the voltage across each insulator. Determine the string efficiency? (JNTU Nov 02)

36. A three phase overhead Transmission line is supported on 4 disc suspension insulators. The voltages across the second and third discs are 13.2kv and 18KV respectively. Calculate the line voltage and mention the nearest standard voltage in practice (JNTU Nov 02)

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37. i. What are the advantages and disadvantages of suspension type insulators over pin type insulators?ii. Determine the voltage across each disc of suspension insulators as a percentage of the line voltage to

earth. The self and capacitance to ground of each disc is C and 0.2C respectively. The capacitance between link pin and the guard ring is 0.1C. If the capacitance to the line of the lower link pin were increased to 0.3C by means of guard ring, determine the distribution of voltage. Also determine the string efficient in each case. (JNTU Nov 02)

38. i. Explain grading methods of string insulators?ii. Each conductor of a 3-phase H.V. transmission line is separated by a string of 4 insulator discs. If the

potential difference across the second from to is 13.2KV and across 3rd from top is 18KV, determine the voltage between conductors. (JNTU Nov 02)

39. A 3 phase overhead transmission line is being supported by 3 disc suspension insulators. The potentials across the first and second insulator are 8KV and 11KV respectively.Calculate: i. the line voltage ii. String efficiency. (JNTU Nov 01)

40. i. A string of 6 insulators unit has a self capacitance of 10 times the pinto-earth capacitance. Find the string efficiency.

ii. Discuss the method of grading of string unit in insulators (JNTU Jun 01)

41. i. Show that the voltage distribution across the units of string insulator is not uniformii. What is string efficiency? Explain the methods of improving the same (O.R. 02)

42. In a transmission line each conductor is at 20 kV and is supported by a string of 3 suspension insulators. The air capacitance between each cap-pin junction and tower is one fifth of the capacitance C of each insulator unit. A guard ring, effective only over the line-end insulator unit is fitted so that the voltages on the two units nearest the line-end are equal.i. Calculate the voltage on the line end unit.ii. Calculate the value of capacitance CS required. (GATE 01)

43. Determine the voltage across each disc of suspension insulators as a percentage of the line voltage to earth. The self and capacitance to ground of each disc is C and 0.2C respectively. The capacitance between the link pin and the guard ring is 0.1C.

44. Determine the voltage across each disc of suspension insulators as a percentage of the line voltage to earth. The self and capacitance to ground of each disc is C and 0.4C respectively. If the capacitance to the line of the lower link pin were increased to 0.3C by means of a guard ring, determine the redistribution of voltage. Also determine the string efficiency in each case.

45. Each line of a 3-phase system is suspended by a string of 3 similar insulators. If the voltage across the line units is 17.5 kV, calculate the line to neutral voltage and string efficiency. Assume that shunt capacitance between each insulator and earthed metal work of tower to be 1/10th of the capacitance of 10 insulators.

46. The three bus-bar conductors in an outdoor sub-station are supplied by units of post insulators. Each unit consists of a stack of 3-pin insulators fixed one on the top of the other. The voltage across the lowest insulator is 8-45 kV and that across the next is 7.25 kV. Find the bus-bar voltage of the station.

47. A string of suspension insulators consists of three units. The capacitance between each link pin and earth is one - sixth of the self-capacitance of each unit. If the maximum voltage per unit is not to exceed 35 kV, determine the maximum voltage that the string can withstand. Also calculate the string efficiency.

48. A string 4 insulators has self-capacitance equal to 4 times the pin-to-earth capacitance. Calculate (i) the voltage distribution across various units as a percentage of total voltage across the string and (ii) string efficiency.

49. A string of four suspension insulators is connected across a 285 kV. line. The self-capacitance of each unit is equal to 5 times pin to earth capacitance. Calculate:i. the potential difference across each unit ii. the string efficiency

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50. What is a strain insulator and where is it used? Give a sketch to show its location.

51. Give reasons for unequal potential distribution over a string of suspension insulators.

52. Define and explain string efficiency. Can its value be equal to 100%?53. A string of four insulators has a self-capacitance equal to 5 times pin to earth capacitance. Find (i) the

voltage distribution across various units as a percentage of total voltage across the string and (ii) string efficiency.

54. The self capacitance of each unit in a string of three suspension insulators is C. The shunting capacitance of the connecting metal work of each insulator to earth is 0.15 C while for line it is 0.1C. Calculate (i) the voltage across each insulator as a percentage of the line voltage to earth and (ii) string efficiency.

UNIT – VII

1. a. What is sag template? What is its use?b. An overhead line has a span of 160 m of copper conductor between level supports. The conductor

diameter is 1.5 cm and has a breaking stress of 35 kg/mm. Calculatei. the deflecting sagii. the vertical sag. The line is subjected to a wind pressure of 40 kg/m2 of projected area and

radial ice coating of 9.53 mm thickness. The weight of ice is 913.5 kg/m3. Allow a factor of safety of 2 and take the density of copper as 8.9 g/cm3. (JNTU May 09)

2. a. Write a short note on conductor vibrations.b. A transmission line conductor has an effective diameter of 19.5 mm and weighs 1.0 kg/m. If the

maximum permissible sag with a horizontal wind pressure of 39 kg/m2 of projected area and 12.7 mm radial ice coating is 6.3m. Calculate the permissible span between two supports at the same level allowing a safety factor of 2. Finally, strength of the conductors is 800kg and weight of ice is 910 kg/m3. (JNTU May 09)

3. a. What are the drawbacks of loose span?b. An over head transmission line at a river crossing is supported from two towers at a height of 25 m and

75 m above water level. The horizontal distance between the towers is 250 m. If the required clearance between the conductors is 45m and if both of towers are on the same side of the point of the maximum sag of the parabolic configuration. Find the stringing tension in the conductor. The weight of the conductor is 0.70kg/m. Also find the span of allowable for the same maximum sag if the supporters were level. (JNTU May 09)

4. a. Explain the factors affecting the mechanical design.b. An over head line with stranded copper conductor is supported on two poles 200 meters apart having a

difference in level of 10 m the conductor diameter is 2 cm and weighs 2.30 kg/m square meter of the projected area and the factor of safety is 4. The maximum tensile strength of the copper is 4220 kg/square meter. (JNTU May 09)

5. a. What is a network reduction technique and how will it be useful in manipulating the symmetrical fault analysis .

b. Consider a system which consists of an alternator supplying power to the load through a step down transformer and a feeder .Derive the fault current expression , if a 3-φ short circuit fault occurs at the far end of the feeder .Assume the literal number data if necessary . (JNTU May 09)

6. a. What is the importance of base KVA in short circuit calculations? b. A generating station has four bus bar sections .Each section is connected to tie bar through 20%

reactors rated at 200MVA.Generators of total capacity 100MVA and 20% reactance are connected to each bus bar section. Calculate the MVA fed to a fault under short circuit condition on two of the bus bars. (JNTU May 09, Nov 08)

7. a. Derive the relationship between the symmetrical component voltages and the unbalanced phase voltages. (JNTU May 09)

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b. The line to line voltages in an unbalanced three phase supply are Vab=1000∟00, Vbc=866.0254∟ - 1500,and Vca=500∟1200. Determine the symmetrical components for line and phase voltages.

8. a. What is a phase advancer? For which application this is used?b. Explain in detail the operation of a phase advancer. c. A factory load consists of the following

i. an Induction Motor of 40 HP, with 0.8 p.f. and efficiency 0.85ii. a synchronous motor of 25 HP, with 0.9 p.f. leading and efficiency 0.9iii. Lighting load of 10 KW at 0 p.f.Find the annual electrical charges if the tariff is Rs. 100 per KVA of maximum demand per annum plus 150 paise per KWH, assuming the load to be steady for 2000 hours in a year. (JNTU May 09)

9. a. What are the different symmetrical faults and which one is more severe describe your answer.b. A 3-φtransmission line operating at 15KV and having a resistance of 2 and reactance of 5 is connected

to the generating station bus-bars through 5MVA step-up transformer having a reactance of 5%.The bus-bars are supplied by a 10MVA alternator having 10% reactance. Calculate the short circuit KVA fed to symmetrical fault between phases if it occurs simultaneously at the low voltage and high voltage terminals of the transformer. (JNTU Nov 08)

10. a. Why do you use a single line diagram for power system representation. What are the assumptions that are being made while drawing a single line diagram.

b. A transmission line of inductance 0.1H and resistance of 5 is connected to a source of V=100sin(ω t+150),f=50HZ at one end and other end is suddenly short circuited at t=0 at the bus-bar end .Write the expression for short circuit current i(t).Find approximately the value of the first current maximum.

(JNTU Nov 08)

11. a. Explain the necessity of a stringing chart for a transmission line and show how such a chart can be constructed.

b. Two towers of height 40 and 90 meters respectively support a transmission line conductor at a water crossing. The horizontal distance between the towers is 500 m. If the allowable tension in the conductor is 1600kg, find the minimum clearance of the conductor and the clearance of the conductor mid-way between the supports. Weight of the conductor is 1.1kg/m. Bases of the towers can be considered to be at the water level. (JNTU Nov 08)

12. a. Show that the sag on level supported line conductor of span L, weight per unit length W kgs, and

minimum tension in the line conductor T0 is given by; . What will be the sag if level

difference is of h meters?b. An overhead line has the following data: span length 185 m, difference in levels of supports 6.5 m,

conductor diameter 1.82 cm, weight per unit length of conductor 1.5kg/m, wind pressure 39 kg/m 2 of projected area. Maximum tensile strength of the conductor is 4250 kg/cm2, factor of safety is 5. Calculate the length of the lower support. (JNTU Nov 08)

13. a. Describe the vibration of power conductors and explain the methods used to damp out these vibrations.b. Determine the sag of an overhead line for the following data: span length 160 meters, conductor

diameter 0.95 cm, weight per unit length of the conductor 0.65 kg/meter. Ultimate stress 4250 kg/cm2, wind pressure 40 kg/cm2 of projected area, Factor of safety 5. (JNTU Nov 08)

14. a. Prove transmission line conductor between two supports at equal heights takes the form of a catenary.b. A transmission line conductor at a river crossing is supported by two towers at heights of 50 and 80

meters above water level. The horizontal distance between the towers is 300 meters. If the tension in the conductor is 2000 kg, determine the clearance between the conductors and water at a point midwaybetween the towers. (JNTU Nov 08)

15. a. Assuming that the shape of an overhead line can be approximated by a Parabola, deduce expressions for calculating sag and conductor length. How can the effect of wind and ice loadings be taken into account.

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b. A transmission line has a span of 150m between level supports. The line conductor has a cross-sectional area of 1.25 sq.cm and it weighs 120 kg per 100 meters. If the breaking stress of the copper conductor is 4220 kg per sq.cm. Calculate the maximum sag for a safety factor of 4. Assume a maximum wind pressure of 90 kg per square meter of projected surface. (JNTU Feb 08)

16. a. What are the factors affecting sag?b. A transmission line conductor at a river crossing is supported from two towers at heights of 60 and 80

meters above water level. The horizontal distance between the towers is 300m. If the tension in the conductor is 2000kg, find i. the maximum clearance between the conductor and water,ii. the clearance between the conductor and water at a point mid way between the towers. Weight of conductor is 0.844 kg/m. Assume that the conductor takes the shape of a parabola. (JNTU Feb 08)

17. a. What are the various types of line supports? Discuss the suitability of each with reference to system voltage and span.

b. Determine the maximum sag of an overhead line conductor having a diameter of 19.5 mm weighs 0.85 kg/m. The span length is 275 meters, wind pressure is 40 kg/m2 of projected area with ice coating of 13 mm. The ultimate strength of the conductor is 8000 kg, the factor of safety is 2 and ice weighs 910 kg/m3. (JNTU Feb 08)

18. What is a stringing chart? Explain clearly the procedure adopted for stringing the power conductors on the supports (JNTU Feb 08)

19. A transmission line conductor at a river crossing is supported from two towers at heights of 50m and 75m above sea level. The span length is 275m. Weight of the conductor 0.75kg/m. Determine the clearance between the conductor and water at a point midway between towers if the tension in the conductor is 2000 kg. (JNTU Feb 08)

20. a. Discuss the consideration which govern the selection of span and conductor configuration of a high voltage line.

b. An overhead transmission line has a span of 220 meters, the conductor weighing 804 kg/km. Calculate the maximum sag if the ultimate tensile strength of the conductor is 5,758 kg. Assume a safety factor of 2. (JNTU Nov 07)

21. Derive an equation to calculate the conductor tension under erection conditions if the conductor tension and loading under bad weather conditions are known. (JNTU Nov 07)

22. A transmission line has a span of 150 m between supports, the supports being at the same level. The conductor has a cross-sectional area of 2 cm2. The ultimate strength is 5,000 kg/cm2. The specific gravity of the material is 8.9 gm/cm3. If the coating of ice is 1.0 cm, calculate the sag at the center of the conductor if factor of safety is 5. (JNTU Nov 07)

23. a. Explain how the effect ice and wind can be included in sag calculations of transmission lines.b. An overhead line has a span of 250 metres. Find the weight of conductor if the ultimate strength is

5758kg, sag is 1.5 metres and factor of safety is 2. (JNTU Nov 07)

24. An overhead transmission line conductor on a hill side is supported between two points separated by a horizontal distance of 400m and at heights of 1150m and 900m above sea level respectively. The weight of the conductor is 1.492kgf/m and the tension is 3935kgf. Determine the vertical clearance between the conductor and a point on the hill side at a height of 970m and a horizontal distance of 175m from the lower support. Assume parabolic configuration. (JNTU Nov 07)

25. i. Describe the vibration of power conductors and explain the methods used to damp out these vibrations.ii. An overhead line at a river crossing is supported from two towers of heights 30metresand 90 meters

above water level with a span of 300 metres. The weight of the conductor is 1 Kg/metre and the working tension is 2000 Kg. Determine the clearance between the conductor and the water level midway between the towers. (JNTU Mar 06)

26. In a transmission line the line conductor has an effective diameter of 19.53mm, weights 844kgf/km, and has an ultimate breaking strength of 7950kgf. Calculate the height above the ground at which a

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conductor with a span of 275m must be supported in order that the total tension shall not exceed half the ultimate strength and with a 12.7mm radial coating of ice and a horizontal wind pressure of 380N/m2 of projected area. The ground clearance required is 6.7m. Weight of ice is 913.5kgf/m3.

(JNTU Nov 07, Mar 06)

27. An overhead line has a span of 160m of copper conductor between level supports. The conductor diameter is 1.0cm and has a breaking stress of 35kgf/mm2. Calculate

a. The deflecting sag b. The vertical sag. The line is subjected to a wind pressure of 40kgf/m2 of Projected area and radial ice

coating of 9.53 mm thickness. The weight of ice is 913.5kgf/m3. Allow a factor of safety of 2 and take the density of copper as 8.9g/cm3. (JNTU Feb 08, Mar 06)


(JNTU Feb 08, Mar 06, Nov 05)



30. Calculate maximum sag of a line with copper conductor 7/0.295 cm size, are 0.484 sq.cm, overall diameter 0.889 cm, weight 428 kg/km and breaking strength 1,975kg. Assume factor of safety 2. Span 200 meters. Level supports:i. Due to weight of the conductor (JNTU Nov 05)ii. Due to additional weight of ice loading of 1cm thicknessiii. Due to both i) and ii) plus wind acting horizontally at a pressure of 39 kg per sq.m.

31. A transmission line conductor at a river crossing is supported from two towers at heights of 45m and 75m above sea level. The span length is 300m. Weight of the conductor 0.85kg/m. Determine the clearance between the conductor and water at a point midway between towers if the tension in the conductor is 2050 kg. (JNTU Feb 08, Nov 05)

32. i. What is a sag template? Explain how this is useful for loading of towers and stringing of power conductors.

ii. A transmission line has a span of 200m between level supports. The conductor has a cross-section area of 130mm2, weights 1.2 kgf/m and has a breaking stress of 40kgf/mm2. Calculate the sag for a factor of safety of 5, allowing for a maximum wind pressure of 125kgf/m2 of projected surface.


33. An overhead line has the following data: span length 185m, difference in levels of supports 6.5m, conductor dia 1.82cm, weight per unit length of conductor 2.5kg/m, wind pressure 49kg/m2 of projected area. Maximum tensile stress of the conductor 4250kg/cm2. Factor of safety 5. Calculate the allowable sag in meters at the lower support. (JNTU Apr 05)

34. An overhead transmission line conductor on a hill side is supported between two points separated by a horizontal distance of 400m and at heights of 1150m and 900m above sea level respectively. The weight of the conductor is 1.492kgf/m and the tension is 3935kgf. Determine the vertical clearance between the conductor and a point on the hill side at a height of 970m and a horizontal distance of 175m from the lower support. Assume parabolic configuration. (JNTU Apr 05)

35. An overhead transmission line has a span of 240m between level supports. Calculate the maximum sag if the conductor weights 727kgf/km and has a breaking strength of 6880kgf. Allow a factor of safety of 2. Neglect wind and ice loading. Derive the formula used. (JNTU Apr 05)

36. An overhead line has a span of 160m of copper conductor between level supports. The conductor diameter is 1.0cm and has a breaking stress of 35kgf/mm2. Calculate

i. The deflecting sag

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ii. The vertical sag. The line is subjected to a wind pressure of 40kgf/m2 of projected area and radial ice coating of 9.53 mm thickness. The weight of ice is 913.5kgf/m3. Allow a factor of safety of 2 and take the density of copper as 8.9g/cm3. (JNTU Nov 04)

37. An overhead line has a conductor of cross section 2.5 cm2 hard drawn copper and a span length of 150 m. Determine the sag which must be allowed if the tension is not to exceed one fifth of the ultimate strength of 4175 kg/cm2 a) in still air, and b) with a wind pressure of 1.3kg/m and an ice coating of 1.25cm. Determine also the vertical sag in the latter case. (JNTU Nov 04, Jun 03)

38. An overhead conductor consists of 7 strands of silicon-bronze having an ultimate strength of 10000 kg/cm2 and an area of 2.5 cm2 when erected between supports 650m apart and having a 20m difference in level, determine the vertical sag which must be a allowed so that the factor of safety shall be 5. Assume the wire weights 2kg/m, ice loading 1 kg/m and wind loading is 1.75kg/m

(JNTU Nov 04)

39. What is a sag-template? Explain how this is useful for location of towers and stringing of power conductors. (JNTU Nov 03)

40. What is a stringing chart? Explain clearly the procedure adopted for stringing the power conductors on the supports. (JNTU Nov 03)

41. Derive the expressions for sag and tension when the supports are at unequal heights.(JNTU Nov 03)

42. Calculate maximum sag of a line unit copper conductor 7/0.295cm size, are 0.484sq.cm, overall diameter 0.889cm, weight 428kg/km and breaking strength 1,975kg. Assume factor of safety 2. Span 200 meters. Level supports:

i. Due to weight of the conductor ii. Due to additional weight of ice loading of 1 cm thickness Due to both i. and ii. plus wind acting

horizontally at a pressure of 39kg per sq. metre. (JNTU Nov 03)

43. A transmission line conductor having a dia of 19.5mm weighs 0.85kg/m. The span is 275 meters. The wind pressure is 40kg/m2 of projected area with ice coating of 13mm. The ultimate strength of the conductor is 8000Kg. Calculate the maximum sag, if the factor of safety is 2 and ice weighs 91 Okg/m3. (JNTU Jun 03)

44. i. Deduce expressions for calculating sag and conductor length for an OH line when the supports are at same level.

ii. What is sag template? What is its use? (O.R. 02)

45. i. Develop the expression for sag of a transmission line assuming the line configuration to a parabola. Take the supports to be at the same level.

ii. A Transmission line has a span of 120m between the line supports. The line conductors have a cross sectional area of 1.25 sq.cm. each and weight of 100 kg/ 100 m . The breaking stress of the copper conductor is 4220 kg per sq.cm. Calculate the maximum sag for the safety factor of 4. Assume max. Wind pressure of 100kg/sq.m. of projected area (JNTU Nov 01)

46. Find the critical disruptive voltage and the critical voltages for local and general corona on a 3-phase over head transmission line, consisting or three standard copper conductors spaced 2.5m apart at the corners of an equilateral triangle. Air temperature and pressure are 21oC and 13.6Cm Hg respectively. The conductor diameter, irregularity factor and surface factors are 10.4mm, 0.85, 0.7 and 0.8 respectively. (IES 98)

47. A transmission line conductor is supported from two towers at heights of 70 m above water level. The horizontal distance between the towers is 300 m. If the tension in the conductors is 1500 kg. find the clearance at a point mid-way between the towers. The size of the conductor is 0.9 cm2 and density of conductor material is 8.9 gm/cm3.

48. An overhead line has a span of 260 m, the weight of the line conductor is 0.68 kg per meter run. Calculate the maximum sag in the line. The maximum allowable tension in the line is 1550 kg.

190


49. A transmission line has a span of 150m between level supports. The cross-sectional area of the conductor is 1.25 cm2 and weights 100 kg per 100 m. The breaking stress is 4220 kg/cm2. Calculate the factors of safety if the sag of the line is 3.5 m. Assume a maximum wind pressure of 100 kg per sq. metre.

50. A transmission line has a span of 150 m between the level supports, the supports being at the same level. The conductor has a cross-sectional area of 1.29 cm2. The ultimate strength is 4220 kg/cm2 and factor of safety is 2. The wind pressure is 40 kg/cm2. Calculate the height of the conductor above ground level at which it should be supported if a minimum clearance of 7m is to be kept between the ground and the conductor.

51. A transmission line has a span of 150 m between level supports. The conductor has a cross-sectional area of 2 cm2. The ultimate strength is 5000 kg/cm2. The specific gravity of the material is 8.9 gm/cm3. If the wind pressure is 1.5 kg/m length of the conductor, calculate the sag if factor of safety is 5.

52. Two towers of height 40 m and 30 m respectively support a transmission line conductor at water crossing. The horizontal distance between the towers is 300 m. If the tension in the conductor is 1590 kg, find the clearance of the conductor at a point mid-way between the supports. Weight of conductor is 0.8 kg/m. Bases of the towers can be considered to be at the water level.

53. What is corona? What are the factors which affect corona?

54. Discuss the advantages and disadvantages of corona?

55. Explain the following terms with reference to corona:i. Critical disruptive voltageii. Visual critical voltageiii. Power loss due to corona

UNIT – VIII

1. a. Derive a formula for the electric stress in a single core cable. Where is the stress maximum? Where it is minimum?

b. The inner and outer diameters of a cable are 3 cm and 8cm. The cable is insulated with two materials having permittivity of 5 and 3.5 with corresponding stresses of 38kV/cm and 30 kV/cm. Calculate the radial thickness of each insulating layer and the safe working voltage of the cable. (JNTU May 09)

2. a. What are sheath eddies in a cable? Why are sheaths bounded? How are sheath losses controlled in a cable.

b. A 3 phase, 3 core, 8 km long belted cable tested for capacitance between a pair of cores with the third is earthed give a result of 0.6µ F/km. Calculate the charging current of the cable when connected to 33 kV, 3-phase, 50 Hz supply. (JNTU May 09)

3. a. How can the current rating of a cable be determined? What factors affect this rating?b. A 66 kV concentric cable with two inter sheaths has a core diameter of 2.3 cm dielectric material 3.5

mm thick constitutes three zones of insulation. Determine the maximum stress in each of the three layers, if 22 kV is maintained across each of the inner two layers. (JNTU May 09)

4. a. Describe briefly some commonly used insulating materials for cables.b. A 12.5 kV single-core cable has an outside diameter of 8 cm. Determine the radius of the core and the

electric field strength that must be withstand by the insulating material in the most economical (optimal-ratio) configuration. (JNTU May 09)

5. a. Obtain the expressions for sequence impedances of a 3-φ , 3 wire un transposed transmission line. Also draw the sequence impedance networks. Assume that the transmission line is having mutual impedance from phase to phase .

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b. Obtain the expressions for sequence impedances of a 3-φ, 3 wire transposed transmission line. Also draw the sequence impedance networks. Assume that the transmission line is having mutual impedance from phase to phase. (JNTU May 09)

6. a. Derive the expression for the fault current and the terminal voltages for a line to ground fault which occurs at the terminals of an unloaded 3-φ alternator. Assume that the alternator neutral is grounded through reactance xn. (JNTU May 09)

b. A 20MVA, 11KV, 3-φ 50HZ generator has its neutral earthed through a 5% reactor .It is in parallel with another identical generator having isolated neutral. Each generator has a positive sequence reactance of 20%, Negative sequence reactance of 10% and zero sequence reactance of 15%. If a line to ground short circuit occurs in the common bus-bar ,determine the fault current.

7. a. Derive the expression for fault current and terminal voltages of three different phases of an alternator, when a double line to ground fault occurs on the Y phase. Assume that the alternator neutral is grounded through reactance of xn. (JNTU May 09)

b. A 3-φ, 11KV , 25MVA generator with x0=0.05 p.u.,x1=0.2 p.u. is grounded through a reactance of 0.3Ω . Calculate the fault current for a double line to ground fault through reactance 0.0 Ω. Also calculate the terminal voltage of the faulted phase with respect to ground.

8. a. Explain the need for per unit method in power system calculations.b. Explain how base quantities can be selected and derive the formula for base impedance.c. A 3-phase unbalanced system currents are read as IR=150 A; IY =0 A; and IB=80 A. The phase sequence

is RYB. Find all the three symmetrical components for the case. (JNTU May 09)

9. a. Draw the positive ,negative and zero sequence impedance diagrams for five different 3-φ transformer winding connections.

b. Draw the positive , negative and zero sequence networks for the system described as follows. The system consists of a 3-φ star connected alternator is supplying power to the 3-φ star connected synchronous motor through a delta-star step up transformer, a transmission line and a star- delta step down transformer .The neutral points of the machine and transformer windings are grounded through the impedance Zn. (JNTU Nov 08)

10. a. Derive the expression for fault current and terminal voltages of three different phases of an alternator,

when there is a double line to ground fault occurs on the Y phase through fault reactance xf . Assume that the alternator neutral is grounded through reactance xn .

b. A 3-φ, 11KV , 25MVA generator with x0=0.05 p.u.,x1=0.2 p.u. is grounded through a reactance of 0.3Ω . Calculate the fault current for a double line to ground fault through reactance 0.2 Ω. Also calculate the terminal voltage of the faulted phase with respect to ground . (JNTU Nov 08)

11. a. A 3-φ alternator is supplying power to the star connected load through a feeder. The alternator per phase impedance is equal to ZS and the load impedances are ZR , ZY , and ZB in R,Y and B phases respectively . Neglect the feeder impedance. Derive the expressions for phase currents and phase voltages at the load end, when there is a double line fault. Assume both neutrals are solidly grounded.

b. A 3-φ , 400V , 1MVA alternator has per phase reactance of 3 and negligible resistance is supplying power to a star connected load having reactances 10, 20, and 15 in R, Y, and B phases respectively. Calculate the fault current and phase voltages at the load side , when there is a double line fault occurs at the middle of the feeder .Assume both neutrals are solidly grounded . (JNTU Nov 08)

12. a. Derive the expression for fault current and the terminal voltages of a 3-φ alternator ,when a line to line fault occurs at the far end of the alternator. Assume that the generator neutral is earthed through a reactance of xn . (JNTU Nov 08)

b. A 20MVA, 11KV, 3-f 50HZ generator has its neutral earthed through a 5% reactor .It is in parallel with another identical generator having neutral earthed through a 5% reactor. Each generator has a positive, Negative, and Zero sequence reactance are 20%, 10%, and 15% respectively. If a line to ground short circuit occurs through a 10% reactor in the common bus bar , determine the fault current .

(JNTU Nov 08)

13. a. Derive the formula for insulation resistance of a cable.b. Determine the economical core diameter of a single core cable working on 22 kV, single phase system.

The maximum permissible stress in the dielectric is not to exceed 33 kV/cm. (JNTU Nov 08)

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14. a. Derive a formula for capacitance of a single core cable.b. Determine the economical core diameter of a single core cable working on 210 kV, 3-phase system.


15. a. Derive a relation between the conductor radius and inside sheath radius of a single core cable so that the electric stress of the conductor surface may be minimum.

b. A cable has been insulated with two insulating materials having permittivity of 6 and 4 respectively. The inner and outer diameter of a cable is 3 cms and 7 cms. If the dielectric stress is 50 kV/cm and 30 kV/cm, calculate the radial thickness of each insulating layer and the safe working voltage of the cable.

(JNTU Nov 08)

16. a. What are the causes of cable breakdown? What are voids? How are they formed? Why do voids lead to cable failure?

b. A single core lead sheathed cable is graded by using two dielectrics of relative permittivity 3.8 (inner) and 2.8 (outer), the thickness of each being 0.75cm. The core diameter is 1 cm; system voltage is 66 kV, 3-phase. Determine the maximum stress in two dielectrics. (JNTU Nov 08)

17. a. Show that for the same dimensions of a cable with an intersheath can withstand a working voltage of 33% higher than a non-intersheath cable. Assume same homogeneous dielectric and most economical designs for both cables.

b. A 3-phase, single core 66 kV cable has a conductor diameter of 3 cm and a sheath of inside diameter 6 cm. If two intersheaths are introduced in such a way that the stress varies between the same maximum and minimum in the three layers. Findi. Positions of intersheathsii. voltage on the intersheathsiii. Maximum and minimum stress. (JNTU Feb 08)

18. a. Compare the merits and demerits of underground system and overhead system.b. Determine the thickness of insulation and operating voltage of a single core cable if the maximum and

minimum stress in the dielectric is 38 kV/cm (r.m.s) and 12 kV/cm (r.m.s) respectively and the diameter of core is 3 cm. (JNTU Feb 08)

19. a. Discuss the methods of grading of cables. Why are they not used generally?b. A three-phase, single core, lead covered cable has radius of core 0.5 cm and internal diameter of sheath

6 cm. Its 3 insulating materials A, B, and C have relative permittivity of 4, 4, and 2.5 with maximum permissible stress of 50, 40, and 30 kV/cm respectively. Find the operating voltage of the cable.

(JNTU Feb 08)

20. a. What do you understand by grading of cable? Explain why grading is more of theoretical interest than practical? What is the modern practice adopted to avoid grading?

b. Determine the maximum and minimum stress in the insulation of a 33 kV single core cable which has a core diameter of 1.5 cm and a sheath of inside diameter 5 cm. (JNTU Feb 08, Nov 07)

21. a. Derive the formula for insulation resistance of a UG cable. b. In a coaxial cable the conductor diameter is 10 mm and the inner sheath diameter is 50mm. There are

two layers of insulation, the inner layer of dielectric constant 4 and a maximum working gradient of 6kV/mm has a radial thickness of 4.6 mm; the outer layer has dielectric constant 2.5 and maximum voltage gradient 5kV/mm. Calculate the maximum working voltage for the cable.


22. a. Derive a formula for capacitance of a single core cable.b. Determine the economical core diameter of a single core cable working on 210 KV, 3-phase system.


23. a. Show that in a three core belted cable the neutral capacitance to each conductor Cu is equal to CS+3CC where CS and CC are capacitance of each conductor to sheath and to each other respectively.

b. A single core 11 kV, 50Hz , 5 km long cable has a core diameter of 1.5 cm and diameter of under sheath 3.0 cm. The relative permittivity of the insulating material is 2.5. The power factor on open circuit is 0.04. Determine

193


i. the capacitance of the cableii. charging per conductoriii. dielectric lossiv. The equivalent insulation resistance. (JNTU Nov 07)

24. a. Derive a formula for calculating the current rating of a cable.b. Single core, lead covered cable is to be designed for 66 kV to earth. Its conductor radius is 10 mm and

its three insulating materials A, B, and C have relative permittivity of 6, 5, and 4 respectively and the corresponding maximum permissible stress of 4.0, 3.0, and 2.0 kV/ mm respectively. Find the maximum diameter of the lead sheath. (JNTU Nov 07)

25. a. Explain briefly intersheaths grading of an UG cable.b. A circuit, 10km long, consists of three single core cables is connected to a 33kV, 3-phase, 50 Hz

supply. The core of each cable is 10 mm diameter and the dielectric of relative permittivity 2.25, has a radial thickness of 6mm. If the total dielectric loss in the circuit is 10.5 kW and the capacitance to neutral of each cable is 2.55 µF, determine the loss angle of the dielectric. (JNTU Nov 07)

26. i. Give the list of various types of UG cables. ii. Determine the operating voltage of a single core cable of diameter 2 cm and having three insulating

material of permittivites 5, 4, 3. The overall diameter of the cable is 5cm and the maximum working stress is 40kV/cm. Compare the operating voltage with the voltage if the cable were not graded and thematerial with same working stress was used. (JNTU Nov 06)

27. i. Give merits and demerits of UG cables.ii. The test results for 1km of a 3-phase metal sheathed belted cable gave a measured capacitance of 0.7µF

between one conductor and the other two conductors bunched together with the earth sheath and 1.2µF measured between the three bunched conductor and the sheath. Find i. the capacitance between any pair of conductors, the sheath being isolatedii. the charging current when the cable is connected to 11kV, 50Hz supply (JNTU Nov 06)

28. i. What do you mean by grading of cables? Explain briefly different types of grading of cablesii. A conductor of 1 cm diameter passes centrally through a porcelain cylinder of internal diameter 2cms

and external diaeter 7cms. The cylinder is surrounded by a tightly fitting metal sheath. The permittivity of porcelain is 5 and the peak voltage gradient in air must not exceed 34kV/cm.

Determine the maximum safe working voltage.(JNTU Nov 06)

29. i. A single core cable has an inner diameter of 5cms and a core diameter of 1.5cm. Its paper dielectric has a working maximum dielectric stress of 60kV/cm. Calculate the maximum permissible line voltage when such cables are used on a 3-phase power system.

ii. A 66kV concentric cable with two inter sheaths has a core diameter 1.8 cm. Dielectric material 3.5mm thick constitutes the three zones of insulation. Determine the maximum stress in each of the three layers if 20kV is maintained across each of the inner two layers. (JNTU Feb 08, Nov 07, 06, Mar 06)

30. What are the limitations of solid type cables? How are these overcome in pressure Cables?(JNTU June 06, 03, Nov 03)

31. i. What is the relation between the conductor diameter and breakdown potential of a cable while voltage of the cable and its overall diameter are fixed? Derive the same.

ii. The capacitance per kilometer of a 3 phase belted cable is 0.25µF between the two cores with the third core connected to the lead sheath. Calculate the charging current taken by five kilometers of this cable when connected to a 3 phase, 50Hz, 11kV supply. (JNTU Mar 06)

32. A single core lead covered cable is to be designed for 66kV to earth. Its conductor radius is 0.5cm and its three insulating material A,B and C have relative permitivities 4, 4.5 and 2.5 with maximum permissible stresses of 50,40 and 30 kV/cm respectively. Find the minimum internal diameter of the lead sheath. (JNTU Mar 06)

33. Determine the economical size of a single core cable working on 220kV, 3-phase system. The maximum permissible stress in the dielectric is not to exceed 250kV/cm. (JNTU Mar 06)

194


34. i. Explain with neat sketch, the general construction of a 3-conductor cable.ii. Test results on a 25 km, 2-core single-phase metal-sheathed cable are as follows.

i. Capacitance per km between the cores bunched and the sheath is 100 µF.ii. With the sheath insulated, capacitance per km between the cores is 0.5µF.

i. Calculate the core-to-core capacitance assuming equal capacitance between each core and the sheath.ii. Also estimate the total charging current required for the cable when connected to 1 kw, 50 Hz supply mains. (JNTU Mar 06)

35. A single core cable has an inner diameter of 5cms and a core diameter of 1.5cm. Its paper dielectric has a working maximum dielectric stress of 60 kV/cm. Calculate the maximum permissible line voltage when such cables are used on a 3-phase power system. (JNTU Nov 05, 04)

36. i. What are the different types of losses taking place in Cables? Give brief account of them.ii. A single-core cable 5km long has an insulation resistance of 0.4 MW. The core diameter is 20 mm and

the diameter of the cable over the insulation is 50mm. Calculate the resistivity of the insulating material. Derive the formula used. (JNTU Nov 05)

37. With a neat diagram, show the various parts of a high voltage single core cable. (JNTU Nov 03, 05)

38. A 66kV concentric cables with two inter sheaths has a core diameter 1.8 cm. Di-electric material 3.5 mm thick constitutes the three zones of insulation. Determine the maximum stress in each of the three layers if 20kV is maintained across each of the inner two layers. (JNTU Feb 08, May 05)

39. A single core cable has an inner diameter of 5cms and a core diameter of 1.5cm. Its paper dielectric has a working maximum dielectric stress of 60 kV/cm. Calculate the maximum permissible line voltage when such cables are used on a 3-phase power system. (JNTU Feb 08, Nov 04)

40. i. Derive the formula for dielectric stress in an UG cable.ii. Single-core, lead covered cable is to be designed for 66kV to earth. Its conductor radius is 10mm and

its three insulating materials A,B and C have relative permittivities of 5,4 and 3 respectively and corresponding maximum permissible stresses of 3.8, 2.6 and 2.0 kV/mm (rms) respectively. Find the minimum diameter of the lead sheath. (JNTU Feb 08, Nov 04)

41. Single-core, lead sheathed cable joint has a conductor of 10mm diameter and two layers of different insulating materials, each 10mm thick. The relative permittivities are 3(inner) and 2.5(outer). Calculate the potential gradient at the surface of the conductor when the potential difference between the conductor and the lead sheathing is 60kV. (JNTU Nov 04)

42. i. Explain the factors which decides the rating of a cable. ii. Classify the under ground cables according to various parameters. (JNTU Nov 04)

43. Find the diametral dimensions for the I-core, metal-sheathed cable giving the greatest economy of insulating material for a working voltage of 85 kv, if a dielectric stress of 60 kv per cm can be allowed.

(JNTU Nov 03)44. i. A single core cable has conductor diameter of 40mm and the internal diameter of the lead sheath of

90mm. The cable is provided with two different insulating materials having relative permittivity 4.5 (inner), and 3.5 (outer) respectively. The corresponding maximum permissible electric stresses are 4.5 and 3.5 kv/mm.

ii. Determine the radial thickness of the insulating materials required to confirm with the above specifications. Also find the safe operating voltage of the cable. (JNTU Nov 03)

45. Derive the expression for the insulation resistance of a single core cable. A 11kv, 50Hz, single-phase cable has a diameter of 10mm and an internal sheath radius of 15mm. If the dielectric has a relative permittivity of 24, determine for a 2.5 km length cable (i) the capacitance (ii) the charging current.

(JNTU Nov 03)

46. Derive an expression for the capacitance of a single core cable. (JNTU Nov 03, 02)

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47. The insulation resistance of a single core cable is 495M Ohms/km. If the core diameter is 2.5cm and resistivity of insulation is 4.5x1014 Ohm-cm. Find the insulation thickness. (JNTU Nov 03)

48. i. What are all insulating materials used in UG cables? Explain in detail about the different kinds of insulating materials

ii. Determine the economical size of a single core cable working on 220 KV, 3 phase system, the maximum permissible stress in dielectric is not to exceed 250kV/cm (JNTU Jun 03)

49. i. What is the relation between the conductor diameter and break down potential of a cable while voltage of the cable and its overall diameter are fixed? Prove the same.

ii. The capacitance per Km of a 3 phase belted cable is 0.25 micro farads between the two core with the third core connected to the lead sheath. Calculate the charging current taken by five Km of the cable when connected to a 3 phase, 50 Hz supply. (JNTU Jun 03)

50. Derive expression for insulation resistance in the cables? (NR 03)

51. i. Classify the underground cables according to various parameters.ii. A 3-core, 11 kV Cable supplies a load of 1500 KW at 0.85 pf lag for 280 days in a year at an average

of 9 hours per day. The capital cost per KM of the cable is Rs 8000a+20000. The resistance per Km of a cable of cross sectional area of 1 sq. cm is 0.173 ohms. If the energy loss cost per unit is 2 paisa and the rate of interest and depreciation is 12%.Calculate the most economical current density and dia of conductor. (JNTU Jun 03)

52. A single core cable is to be designed for 66kV to earth. Its conductor radius is 0.5 cm and its three insulating materials A, B and C have relative permittivity of 4, 4.5 and 2.5 with max. Permissible stresses of 50, 40 and 30 kV/cm respectively. Find the min internal diameter of the lead sheath.

(JNTU Jun 03)

53. i. Describe with neat sketch the construction of 3-core belted cable. Discuss the limitation s of such a cable.

ii. A 66 kV single core cable has a conductor diameter of 2.5cm and a sheath of inside diameter 6cm. Calculate the max stress. It is desired to reduce this stress by using two inter sheaths. Determine their best positions, the maximum stress and voltage on each. (JNTU Nov 02)

54. i. Prove that for a concentric cable of given dimension and given maximum potential gradient in the dielectric, the maximum permissible voltage between the core and the sheath is independent of the permittivity of the insulating material.

ii. A single core 66kV cable working on a 3 phase system has a conductor diameter of 2 and a sheath inside diameter 5.5 cm. If the two inter sheath are introduced in such a way that the varies between the same maximum and minimum in the three layer find:i. Positions of the inter sheathii. Voltage on the inter sheathiii. Maximum and minimum sheath (JNTU Nov 02)

55. i. Derive the expression for capacitance in the 3 phase cable?ii. cable has insulated with two insulating materials having permittivity of 6 and 4 respectively. The inner

and outer dia of the cable are 3 and 7 cms. The dielectric stresses of 58 KV/cm and 28 KV/cm. Calculate the radial thickness of each insulating material and the safe working voltage of the cable

(JNTU Nov 02)

56. i. Find the expression for capacitance and dielectric stress of a single core cable?ii. Derive expression for power in 3 phase in a 3 phase circuit using symmetrical components?

(JNTU Nov 02)

57. i. Discuss the various methods of grading of single core cable with their limitations in practical application.

ii. a 66 KV single core cable is graded by using two dialectical of relative permittivity 5 and 3 respectively. Thickness of each being 1 cm .The core diameter is 2 cm. Determine the maximum stress in two dielectrics.

58. Explain the Grading of cables and Importance of Grading? (JNTU Jun 01)

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59. Explain different types of Under ground cables with neat diagrams? 60. The L/C ratio for 132 KV and 400 KV lines are tropically 160 x 103 and 62.5 x 103 respectively. That

the natural 3-phase loading for the two lines? (GATE 01)

61. A 6.6kV, 50 hz single core lead-sheath cable has the following data:Conductor diameter: 1.5 cm, length : 4 kmInternal diameter of the sheath : 3 cmresistivity of insulation : 1.3x1012 ohm-mRelative permittivity of insulation : 3.5Calculate i. insulation resistance ii. the capacitanceiii. The maximum electric stress in the insulation (GATE 99)

62. An overhead line is having a surge impedance of 400 ohm is connected in series with an underground cable having a surge impedance of 100 ohm. If a surge of 50KV travels from the line end towards the line cable junctions, the value of transmitted voltage at the junction is? (GATE 99)

63. The cable has the following characteristics L=0.201 micro H/m and C=196.2pF/m. The velocity of the wave propagation through the cable is (GATE 98)

64. Why shunt capacitors are preferred over series capacitors for improvement of power factor in distribution systems? (IES 03)

65. Two long overhead transmission lines A and B having surge impedances of 400 ohms and 420 ohms respectively, are connected by a short underground cable C of surge impedance 50 ohms. A rectangular surge of magnitude 100 kV and of infinite length travels along A towards the cable C. Find out the surge voltage which is transmitted into the cable at the junction of A and C when the first reflected wave from the junction of C and B reaches the former junction. (IES 02)

66. A single core cable has an inner diameter of 5 cm and core diameter of 1.5 cm it’s paper dielectric has a working maximum dielectrical stress of 60 kv per cm . calculate maximum permissible line voltage when such cables are used on 3-phase power system.

67. Show that for concentric cable of given dimensions and given maximum potential gradient in dielectric, the maximum permissible voltage between core and sheath is independent of of insulating material

68. What is void formation in a cable ? How does it effect the performance of a cable ? What steps are taken to prevent the formation of these voids?

69. A 33 kV, single-core cable has a conductor diameter of 1 cm and insulation of 1.5 cm. Find the maximum and minimum stress in the insulation.

70. Find the economic size of a single-core cable working on 220 kV, 3-phase system. The maximum permissible stress in the dielectric is not to exceed 250 kV/cm.

71. The inner conductor of a concentric cable has a diameter of 3 cm with insulation of diameter 8.5 cm. The cable is insulated with two materials having relative permittivities of 5 and 3 with corresponding safe working stresses of 38 kV/cm and 26 kV/cm. Calculate the radial thickness of insulating layers and the safe working voltage of the cable.

72. The Murray loop test is used to locate an earth fault on one core of a two-core cable. The other core is used to complete the loop. When the network is balanced, the resistance connected to the faulty core has a value of 3.2 ohm. The other resistance arm has a value of 11.8 ohm. The fault is 42.7 m from the test end. Find the length of the cable.

73. Murray loop test is performed to locate an earth fault on one core of a 2-core cable 100 m long. The other core is healthy and used to form the loop. At balance, the resistance connected to the faulty core

197


was 4 ohm. The other resistance arm has a value of 16 ohm. Calculate the distance of the fault from the test end.

74. The Varley loop test is used to find the position of an earth fault on a line of length 40 km. The resistance/km of a single line is 28 ohm. The fixed resistors have resistances of 250 ohm each. The fault is calculated to be 7 km from the test end. To what value of resistance was the variable resistor set?

75. Prove that gmax/gmin in a single-core cable is equal to D/d.

76. Find an expression for the most economical conductor size of a single core cable.

77. Derive an expression for the thermal resistance of dielectric of a single-core cable.

78. What do you mean by permissible current loading of an underground cable?

198


5. SUBJECT WISE DETAILS

5.4 POWER ELECTRONICS


5.4.2 Scope

5.4.3 Prerequisites

5.4.4 Syllabus

i. JNTU

ii. GATE

iii. IES


5.4.6 Websites

5.4.7 Expert Details

5.4.8 Journals


5.4.10 Session Plan



i. JNTU

ii. GATE

iii. IES

199


200



Power electronics is an interdisciplinary area using members of thyristor family, control electronics to control the switch ON and OFF processes of the devices and the principle of control theory. The market demands on industry for productivity and quality are increasing. This results in the increasing demand for automation in production processes and hence for the use of variable speed drives. Today, power electronics is an indispensable tool in any advanced country’s industrial economy, saving energy is an important aspect of power electronic Applications. Power electronics permits generation of electric power from environmentally clean photovoltaic, fuel cell and wind energy sources.

5.4.2 SCOPE

Power electronics is that field of electronics which deals with conversion, control and switching of electrical energy for power applications and playing a major role in revolutionizing the Industrial controls. The market demands an Industry for productivity and quality are increasing. This results in the increasing demand for automation in production processes and hence for the use of variable speed drives. To day power electronics is an indispensable tool in any advanced countries Industrial economy. Saving energy is an important aspect of power electronics applications.

5.4.3 PREREQUISITES

The students must have basic knowledge of the following subjects Network theory and various theorems, Basic electronics, semiconductors and their characteristics, Basic electrical Machines 5.4.4.i SYLLABUS - JNTU


This unit deals with power semiconductor devices and circuits in terms of their terminal characteristics and functionality. It briefly describes the switching characteristics of SCR.

SYLLABUS

Thyristors, silicon controlled rectifiers (scr’s), bjt, power mosfet, power igbt and their characteristics and other thyristors, basic theory of operation of scr, static characteristics, turn on and turn off methods, dynamic characteristics of SCR, turn on and turn off times, salient points.


This unit deals with triggering circuits, protection circuit for SCR, ratings and series - parallel connection of SCRs. It also describes the various commutation methods.

SYLLABUS

Two transistor analogy, SCR, UJT firing circuit, series and parallel connections of SCR’s, snubber circuit details, specifications and ratings of scr’s, BJT, IGBT, numerical problems, line commutation and forced commutation circuits.


This unit discusses all possible configurations of half controlled converters with various loads along with their mathematical analysis as well as performance factors.

201


SYLLABUS

Phase control technique, line commutated converters-midpoint and bridge connections, half controlled converters with resistive, RL and rle loads, derivation of average load voltage and current, active and reactive power inputs to the converters with and without free wheeling diode, numerical problems


This unit discusses all possible configurations of full controlled converters with various loads along with their mathematical analysis as well as performance factors.

SYLLABUS

Fully controlled converters, Midpoint and bridge connections with resistive, RL and RLE Loads, Derivation of Average load voltage and current, Line commutated inverters, Active and reactive power inputs to the converters with and without free wheeling diode, Effect of source inductance, derivation load voltage and current, numerical problems.


This unit discusses the three pulse, six pulse and dual converters with wave forms and the effect of source inductance on the performance of these converters.

SYLLABUS

Three phase converters, three pulse and six pulse converters, midpoint and bridge connections, average load voltage with r & RL loads, effects of source inductance, dual converters (both single phase and three phase), waveforms, numerical problems.


This unit discusses the characteristics of AC regulators with different types of loads and also introduces cyclo converters, their characteristics and applications.

SYLLABUS

ac voltage controllers, single phase two scr’s in anti parallel with r and rl loads, modes of operation of triac, triac with resistive and RL loads, derivation of rms load voltage, current and power factor wave forms, firing circuits, problems, cyclo converters, single phase mid point cyclo converters, with resistive and inductive load (principle of operation only), bridge configuration of single phase cyclo converter (principle of operation only) wave forms and numerical problems.


This unit discusses the principle of operation of chopper in DC to DC conversion along with their control techniques and its configurations.

SYLLABUS

Choppers, time ratio control and current limit control strategies, step down choppers, derivation of load voltage and current with r, rl and rle loads, step up chopper load, voltage expression, morgan’s chopper, jones chopper and oscillation chopper (principle of operation only) wave forms, ac chopper, problems.

202



This unit is a comprehensive treatment of DC - AC inverters in which the various voltage fed and current fed inverters are discussed.

SYLLABUS

Inverters, single phase inverter, basic series inverters, basic parallel capacitor inverter, bridge inverter, wave forms, simple forced commutation circuits for bridge inverters, McMurray and McMurray Bedford inverters, voltage techniques for inverters, pulse width modulation techniques, numerical problems.


UNIT – I

Semiconductor power devices, diodes, transistors, thyristors, triacs, GTO’s, MOSFET, IGBT’s, static characteristics and principle operation.

UNIT – II

Triggering circuits.

UNIT – III

Phase controlled rectifiers, Bridge converters - Half controlled.

UNIT – IV

Bridge converters - Fully controlled.

UNIT – V

Bridge converters - Fully controlled and Half controlled.

UNIT – VI

AC voltage Regulators.

UNIT – VII

Principles of Choppers.

UNIT – VIII

Principles of Inverters.


UNIT – I

Power semiconductor devices, Power transistors, thyristors, GTO’s, MOSFET’s characteristics and operation.

UNIT – II Not covered.

UNIT – III AC to DC converters, single phase half controlled converters.

203


UNIT – IV Single phase fully controlled converters.

UNIT – V Three phase converters.

UNIT – VI AC regulators, Thyristor controlled reactors.

UNIT – VII DC to DC converters, switched mode power supplies.

UNIT – VIII Inverters - Single phase and three phase, PWM, sinusoidal modulations with uniform sampling.


TEXT BOOKS

T1 Power Electronics, M.D. Singh and K.B. Khanchandani, Tata McGraw Hill Publishing Company, 1998.

T2 Power Electronics, V.R. Murthy, 1st Edn., Oxford university press, 2005.

REFERENCE BOOKS

R1 Power Electronics, devices, converters and applications, G. Tulsi Ram Das, B S publications.R2 Power Electronics Circuits Devices and Applications, M.H. Rashid, 2nd Edn., Prentice Hall of India,

1998.R3 Power Electronics, Vedam Subramanyam, New Age International (P) Ltd., Publishers.R4 Power Electronics, C.W. Lander, 2nd Edn., McGraw Hill Companies, 1993.R5 Power Electronics Principles and Applications, J. Vithayathil, McGraw Hill Companies, 1995.R6 Power Electronics, PC Sen, Tata McGraw Hill Publishing Company.R7 Thryistorised Power Controllers, J.K. Dubey, S.R. Dorada, A. Joshi and R.M.K. Sinha, New Age

International Pvt Ltd. Publishers, 1996R8 “Modern power electronics : Evolution, Technology and Applications”, B.K. Bose, Jaico Publishing

House, 1999.R9 A text book on power electronics, Harish C Rai, 3rd Edn., Galgotia Publications.

5.4.6 WEB SITES

1. www.powerelectronics.com2. www.powerdesigns.com3. www.cdpowerelectronics.com4. www.magnetekpower.com5. www.micro-power.com6. www.iitm.ac.in7. www.iitd.ac.in8. www.iitk.ac.in9. www.iitb.ac.in10. www.iitg.ernet.in11. www.iisc.ernet-in

204

http://www.iisc.ernet-in/

http://www.iitg.ernet.in/

http://www.iitb.ac.in/

http://www.iitk.ac.in/

http://www.iitd.ac.in/

http://www.iitm.ac.in/

http://www.micro-power.com/

http://www.magnetekpower.com/

http://www.cdpowerelectronics.com/

http://www.powerdesigns.com/

http://www.powerelectronics.com/



REGIONAL

1. Name : Dr. Bhagwan K.MurthyDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering,

NIT-Warangal – 506004.Phone No. : +91-870-2431616(O)Email : [email protected], [email protected]

2. Name : V.T. SomashekharDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering,




NATIONAL


Dy. Director (Administration.), IIT - Delhi, Hauzkhas, New Delhi - 110016.Phone No. : +91-11-26591250 (O) , Fax : 91-11-26862037,Email : [email protected], [email protected]

2. Name : Dr. S.V. Kulkarni,Designation : Associate Professor,Department : Electrical and Electronics EngineeringOffice address : IITBombay, Powai, Mumbai - 400076, India,Phone No. : +91- 22-25671098,Email : [email protected]


Office Address : Room No. II/211, IIT Delhi Phone No. : +91 11 2659 1094 ,91 11 2659 1886


4. Name : Dr. Sivaji ChakravortiDesignation : Professor,Department : Electrical and Electronics engineering, Office Address : Jadavpur University, Kolkatta - 700032, IndiaPhone No. :Email : [email protected], [email protected]

205

mailto:[email protected]










INTERNATIONAL

1. Name : Gary S. MaryDesignation : Professor

Department : School of Electrical EngineeringOffice address : Georgia Institute of Technology, USA.Phone No. :Email : [email protected]

2. Name : Dr. Clayton R Paul, Designation : ProfessorDepartment : Electrical and Computer Engineering,Office Address : School of Engineering, Mercer University, Macom, Georgia-31207,Phone Number : (912) 301-2213,website : www.faculty.mercer.paul_cr

3. Name : Jushan ZhangDesignation : Associate Prof

Department : Dept. of Electrical EngineeringOffice address : Ira A.Fulton School of Engineering, Arizona State University. Tempe, AZPhone No. : 85287-7206Email : Jushan Zhang @ee.gatech.edu

4. Name : Dr. Edward Wai-Chau Lo, Designation : Honorary Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice address : Department of Electrical and Electronics Engineering,

University of Hongkong, Hongkong.Email : [email protected]

5.4.8 JOURNALS



3. Name of the Journal : IEEE Transactions on power electronicsPublisher : IEEE Publications







10. Name of the Journal : Elector-India Electronics

206



http://www.faculty.mercer.paul_cr/



Publisher : Century Publications Pvt Ltd



5.4.9. RECENT FINDINGS AND DEVELOPMENTS

1. Title : A Novel Three-Phase Three-Leg AC/AC Converter Using Nine IGBTs

Author : Liu, C.; Wu, B.; Zargari, N. R.; Xu, D.; Wang, J. R.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1151-1160

2. Title : Solid State Voltage and Frequency Controller for a Stand Alone Wind Power Generating System

Author : Ecklebe, A.; Lindemann, A.; Schulz, S.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1173-1181

3. Title : A Multipulse-Structure-Based Bidirectional PWM Converter for High-Power Applications

Author : Xu, A.; Xie , S.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1233-1242

4 Title : Single-Phase Multilevel PWM Inverter Topologies Using Coupled Inductors

Author : Salmon, J.; Knight, A. M.; Ewanchuk, J.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1259-1266

5. Title : Improved Direct Power Control of Grid-Connected DC/AC Converters

Author : Zhi , D.; Xu, L.; Williams, B. W.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1280-1292

6. Title : Common-Mode Ripple Current Estimator for Parallel Three-Phase Inverters

Author : Chen, T.-P.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1330-1339

7. Title : Means of Eliminating Electrolytic Capacitor in AC/DC Power Supplies for LED Lightings

Author : Gu, L.; Ruan, X.; Xu , M.; Yao , K.Journal : IEEE Transactions on power electronicsYear, Vol. & page No. : May 2009, Volume: 24, Issue 5, Page(s): 1399-1408

8. Title : Uncertainty Management in the Unit Commitment ProblemAuthor : Ruiz, P. A.; Philbrick, C. R.; Zak, E.; Cheung, K. W.; Sauer, P. W.Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 642-651

207



9. Title : Sensitivity Methods in the Dispatch and Siting of FACTS Controllers

Author : Fang, X.; Chow, J. H.; Jiang, X.; Fardanesh, B.; Uzunovic, E.; Edris, A.-A.

Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 713-720

10. Title : Evaluation of Network Equivalents for Voltage Optimization in Multi-Area Power Systems

Author : Phulpin, Y.; Begovic, M.; Petit, M.; Heyberger, J.-B.; Ernst, D.Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 729-743

11. Title : An Improved OPA Model and Blackout Risk AssessmentAuthor : Mei, S.; He, F.; Zhang, X.; Wu, S.; Wang, G.Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 814-823

208





5.4.10 SESSION PLAN

Sl. No

JNTU syllabusTopics

Modules and Sub modulesLecture

NoSuggested Books

With page NumbersRemarks

UNIT – I - POWER SEMI CONDUCTOR DEVICES (No. of Lectures - 09)

1Thyristors, Silicon Controlled Rectifiers (SCR’s)

Power Electronics- Introduction, advantages, applicationsThyristor- family details

L1L2

T1-Ch1 (P:1-3)T2-Ch1 (P:1-7)R2-Ch1 (P:1-2)R2-Ch7 (P:190-193)R3-Ch2 (P:16-18)R3-Ch1 (P:1-2)

GATEIES

2Thyristors, basic theory of operation of SCR-Characteristics

Operation ,Static characteristics

L3


3Turn on and Turn off methods of SCR, Turn on and Turn off times

Dynamic characteristics,Turn on and Turn off methods ,Switching characteristics during Turn-on, and Turn-off

L4L5

T1-Ch1 (P:19-21)T2-Ch (P:19-48)R3-Ch1 (P:3-5)R2-Ch7 (P:192-195)

4BJT, Power MOSFET Characteristics

BJT- characteristics,MOSFET-Characteristics,

L6L7

T1-Ch10 (P:601-677)T2-Ch1 (P:79-90)R2-Ch8 (P:262-295)R8-Ch1 (P:14-22)R3-Ch2 (P:80-96)

5IGBT and their characteristics

IGBT- Characteristics, GTOL8L9

T1-Ch10 (P:684-694T2-Ch1 (P:65-79)R2-Ch7 (P:108)R3-Ch1 (P:70-79)R9-Ch5 (P:104-158)

UNIT-II - DEVICES AND COMMUTATION CIRCUITS (No. of Lectures - 09)

6 Two transistor analogy Two transistor analogy L10


GATEIES

7 UJT Firing circuit

Features of firing circuit

L11


UJT-Basic structure , Circuit Symbol & V-I Characteristics

Synchronized UJT Triggering L12


8Series and Parallel connections of SCR’s

Series operation of SCR,Parallel operation of SCR, problems

L13L14

T1-Ch3 (P:110-122)T2-Ch1 (P:45-48)R2-Ch4 (P:114-119)R3-Ch2 (P:55-63) R6-Ch1 (P:104-110)

209


9 Snubber circuit details Thyristor protection circuits,Design of Snubber circuit, Problems

L15

T1-Ch11 (P:755-765)T2-Ch1 (P:55-64)R2-Ch4 (P:102-105)R3-Ch2 (P:54-55) R6-Ch2 (P:166-172)

10Specifications and ratings of SCR’s, BJT,IGBT

Specifications and ratings of SCR’s ,BJT,IGBT

L16

T1-Ch1 (P:8-10)T1-Ch10 (P:604-606)T2-Ch1 (P:48-55)R9-Ch2 (P:11-15)

11Line commutation and Forced commutation circuits

Different thyristor commutation techniques

L17L18


UNIT-III – SINGLE PHASE HALF CONTROLLED CONVERTERS (No. of Lectures - 06)

12 Phase control technique Phase controlled rectifiers – introductionPrinciple of phase control

L19

T1-Ch4 (P:132-133)T2-Ch2 (P:122-124)R2-Ch1 (P:12-13)R2-Ch6 (P:193)R3-Ch3 (P:121-125)

GATEIES

13

Line commutated converters, Midpoint and bridge connections, Half controlled converters with resistive, RL and RLE Loads

Single phase half controlled mid point circuit and bridge ciruit with R, RL and RLE load with and without freewheeling diode

L20L21L22


14

Derivation of Average load voltage and current, Active and reactive power inputs to the converters with and without free wheeling diode, Numerical Problems

Derivation of average load voltage and current,Active and Reactive power inputs to converters,Numerical Problems

L23L24

T1-Ch4 (P:140-145) T2-Ch2 (P:126-127)R3-Ch3 (P:146-160)R9-Ch11 (P:325)

UNIT-IV - SINGLE PHASE FULLY CONTROLLED CONVERTERS (No. of Lectures - 06)

15

Fully controlled converters, Midpoint and bridge connections with resistive, RL and RLE Loads

Single phase Fully controlled mid point circuit & bridge circuit with R, RL & RLE load with & without freewheeling diode

L25L26


GATEIES

16

Line commutated inverters, Derivation of Average load voltage and current, Active and reactive power inputs to the converters with and without free wheeling diode, Effect of source inductance, derivation load voltage and current, numerical problems.

Operation of full converter as inverterDerivation of average load voltage & currentCalculations of Active and Reactive power inputs to convertersEffect of source inductance on performance of full converterNumerical Problems

L27L28L29L30


210


UNIT-V - THREE PHASE LINE COMMUTATED CONVERTERS (No. of Lectures - 06)

17

Three phase converters, Three pulse and six pulse converters, Midpoint and Bridge connections, average load voltage with R & RL Loads

Three phase full converter with R & RL Load (Mid pt and Bridge connections)

L31L32L33

T1-Ch4 (P:168-193) T2-Ch2 (P:134-193)R2-Ch (P:206-218)R3-Ch3 (P:222-226)

GATEIES

Three phase Half converter with R & RL Load(Mid pt and Bridge connections)Calculation of average load voltageNumerical Problems

18

Effects of source inductance, Dual converters (both single phase and three phase) Waveforms, Numerical Problems

Effect of source inductance on the performance of three phase full converter L34

L35L36

T1-Ch8 (P:513-520)T1-Ch4 (P:200-209)T2-Ch2 (P:206-255)R2-Ch6 (P:233-234)R3-Ch3 (P:479-485)

Single phase dual converter

Three phase dual converter

Numerical Problems

UNIT-VI - AC VOLTAGE CONTROLLERS & CYCLO CONVERTERS (No. of Lectures - 06)

19

AC voltage controllers Single phase two SCR’s in anti parallel with R and RL loads

AC Voltage Controller-principal of operation

L37L38


IESTypes of control – Integral cycle control & phase control

One phase voltage controller with R load & RL load

20Modes of operation of TRIAC, TRIAC with resistive and RL loads

TRIAC – circuit symbol & V-I characteristics

L39

T1-Ch10 (P:590-596)T2-Ch1 (P:66-68)R6-Ch1 (P:133-136)R7-Ch2 (P:77-79)R8-Ch1 (P:8-10)R9-Ch5 (P:108-112)

Operation of TRIAC with R & RL load

21

Derivation of RMS load voltage, Current and power factor wave forms- Firing circuits- problems

Derivation of RMS Load voltage, current & power factor with R & RL load L40


Gating signal requirements

problems

22

Cyclo converters, single phase mid point cyclo converters, with resistive and inductive load (principle of operation only)

cyclo converters – step up & step down

L41


Single phase midpoint cyclo converter with R and RL load-continuous & Discontinuous conduction

23

Bridge configuration of single phase cyclo converter (principle of operation only) wave forms and numerical problems.

Single phase bridge cyclo converter with R & RL Load

L42

T1-Ch7 (P:476)T2-Ch6 (P:549-551)R2-Ch6 (P:218-225)R3-Ch4 (P:510-520)

Problems

211


UNIT-VII – CHOPPERS (No. of Lectures - 06)

24Choppers, Time ratio control and current limit control strategies

Principal of chopper operation (step down)

L43

T1-Ch6 (P: 386-396)T2-Ch3 (P:277-286)R2-Ch9 (P:303-310)R3-Ch6 (P:602-622)R9-Ch-12 (P:341-345)

GATEIES

Control strategies-Time ratio control & current limit control

25

Step down choppers, Derivation of load voltage and current with R, RL and RLE loads, Step up chopper, load voltage Expression

Derivation of load voltage and current with R, RL and RLE loads for step down chopperOperation of step up chopperDerivation of load voltage expression for step up chopper

L44L45


26Morgans chopper jones chopper, Oscillation Chopper, Ac chopper

Principle of operation and wave forms ,problems

L46L47L48

T1-Ch6 (P:432-440)T2-Ch3 (P:313-318)T2-Ch4 (P:354-360)R3-Ch6 (P:630)R9-Ch12 (P:356-359)

UNIT-VIII - INVERTERS (No. of Lectures - 07)

26

Inverters, Single Phase inverter, Basic Series inverters, Basic Parallel capacitor inverter

Inverters –principle of operation & Classification

L49L50

T1-Ch5 (P:265-281)T2-Ch5 (P:414-425)R2-Ch10 (P:356-360)R3-Ch7 (P:652-670)R9-Ch10(273-274) GATE

IES

Analysis of inverter with R, RL & RLC Load

Series Inverter

Parallel capacitor Inverter

27

Bridge inverter, Wave forms, Simple forced commutation circuits for bridge inverters, McMurray and McMurray Bedford inverters

Single phase Bridge Inverter with R & RL load

L51L52

T1-Ch5 (P:290-310)T2-Ch5 (P: 425-455)R2-Ch10 (P:360-363)R3-Ch7 (P:671-680)R9-Ch10 (P:274-291)

Mc Murray Inverter

Modified Mc Murray Inverter

28

Voltage techniques for inverters, Pulse width modulation Techniques, Numerical problems

External control of DC output voltage & ac output voltage,Single pulse modulation,Multiple Pulse modulation,Sinusoidal pulse modulation,Problems

L53L54L55

T1-Ch5 (P:329-340)T2-Ch5 (P:464-474) R2-Ch10 (P:372-390)R3-Ch7 (P:710-712)R9-Ch10 (P:292-295)


1. Title : Space Vector Modulation for Low Switching Frequency Current Source Converters With Reduced Low-Order Noncharacteristic Harmonics

Author : Lopes, L.; Naguib, M.F.Journal : IEEE Transactions on power electronicsYear, Vol. & Page No. : Apr 2009, Volume: 24, Issue 4, Page(s): 903-910

2. Title : A Single-Phase Active Filter Using an H-Bridge PWM Converter With a Sampling Frequency Quadruple of the Switching Frequency

Author : Fujita, H.Journal : IEEE Transactions on power electronicsYear, Vol. & Page No. : Apr 2009, Volume: 24, Issue 4, Page(s): 934-941

212


3. Title : Dual-Current Pump Module for Transient Improvement of Step-Down DC–DC Converters

Author : Pang-Jung Liu; Yu-Kang Lo; Huang-Jen Chiu; Yi-Jan Emery ChenJournal : IEEE Transactions on power electronicsYear, Vol. & Page No. : Apr 2009, Volume: 24, Issue 4, Page(s): 985-990

4. Title : Optimal Variable Switching Frequency Scheme for Reducing Switching Loss in Single-Phase Inverters Based on Time-Domain Ripple Analysis

Author : Xiaolin Mao; Ayyanar, R.; Krishnamurthy, H.K.Journal : IEEE Transactions on power electronicsYear, Vol. & Page No. : Apr 2009, Volume: 24, Issue 4, Page(s): 991-1001

5. Title : Feasible Strategy for Allocating Cost of Primary Frequency Regulation

Author : Chu, W.-C.; Chen, Y.-P.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : May 2009, Volume: 24, Issue 2, Page(s): 508-515

6. Title : An Advanced IPFC Model to Reuse Newton Power Flow CodesAuthor : Bhowmick, S.; Das, B.; Kumar, N.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : May 2009, Volume: 24, Issue 2, Page(s): 525-532

7. Title : A Method for the Calculation of Frequency-Dependent Transmission Line Transformation Matrices

Author : Fan, S.; Li, Y.; Li, X.; Bi, L.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : May 2009, Volume: 24, Issue 2, Page(s): 552-560

8. Title : Frequency-Adaptive Power System Modeling for Multiscale Simulation of Transients

Author : Gao, F.; Strunz, K.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : May 2009, Volume: 24, Issue 2, Page(s): 561-571

9. Title : Unit Commitment for Systems With Significant Wind PenetrationAuthor : Tuohy, A.; Meibom, P.; Denny, E.; O'Malley, M.Journal : IEEE Transactions on Power SystemsYear, Vol. & Page No. : May 2009, Volume: 24, Issue 2, Page(s): 592-601

10. Title : Reactive Power and Voltage Control in Distribution Systems With Limited Switching Operations

Author : Liu, M. B.; Canizares, C. A.; Huang, W.Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 889-899

11. Title : A Direct Load Control Model for Virtual Power Plant ManagementAuthor : Ruiz, N.; Cobelo, I.; Oyarzabal, J.Journal : IEEE Transactions on Power Systems Year, Vol. & page No. : May 2009, Volume: 24, Issue 2, Page(s): 959-966

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UNIT – I

1. Explain the SCR firing circuits in detail with the help of circuits and waveformsa. Resistance firing circuits b. RC firing circuit. (JNTU May 09)

2. A string of Thyristor connected in series to withstand a d.c. voltage of V s= 15KV. The max. leakage current and recovery charge difference of thyristor are 10mA and 150 µC respectively. A derating factor of 20% is applied for the steady state and transient voltage sharing is 1000V. Determine

a. Steady state voltage sharing resistance R for each thyristorb. The transient voltage capacitance. (JNTU May 09)

3. Explain in detail various voltage ratings and current ratings of a thyristor. (JNTU May 09)

4. a. Explain the operation of series connected and parallel connected SCRs with neat circuit diagrams and their characteristics.

b. Derive the static equalizing and dynamic equalizing circuit parameters with respect to series operation of SCR. (JNTU May 09)

5. Ten thyristors are used in a string to withstand a d.c. voltage of 12KV. The max. leakage current and recovery charge difference of SCRs is 10mA and 50µC respectively. The values of R for steady state equalizing circuit is 40k ohms and value of capacitance C of dynamic equalizing circuit is 0.2µF. Find the steady state and transient derating factor. (JNTU May 09)

6. a. Draw the equivalent circuit of a UJT and explain its working. (JNTU May 09)b.Describe the VI characteristics of a UJT. Clearly explain its negative resistance nature.

7. Explain the V-I Characteristics of Thyristors with elaborating the following :a. Latching current b. holding currentc. on-state and off-state condition d. turn-on and turn-off timese. finger voltage (JNTU May 09)

8. Explain in detail various voltage ratings and current ratings of a thyristor. (JNTU May 09)

9. a. Explain the necessity of series and parallel connection of SCRs.b. What is String efficiency in series and parallel connections.c. What are the problems arising in series and parallel connections. (JNTU Nov 08)

10. a. What are the three regions of operation for power BJTs. Explain in detail.b. What are turn-on and turn-off times of BJTsc. What are base drive techniques for increasing switching speeds of BJTs.d. What is secondary breakdown of BJT. (JNTU Nov 08)

11. Explain the SCR firing circuits in detail with the help of circuits and waveformsa. Resistance firing circuits b. RC firing circuit. (JNTU Nov 08)

12. A rectangular pulse of 30V with 10μs duration is applied at the gate. The average gate power dissipation of the thyristor is 0.5W and a peak gate drive power is 5W. Calculate the values of the series resistance to be connected in the gate circuit, the frequency and duty cycle of the triggering pulse. (JNTU Nov 08)

13. A 200A thyristor operates in parallel with a 300A thyristor. Their ON state voltage drops are respectively 1.5V and 1.0V. calculate the value of the resistance to be inserted in series with each thyristor so that they share a load of 500A in proportion to their respective current ratings.

(JNTU Nov 08)

14. Explain in detail various voltage ratings and current ratings of a thyristor. (JNTU Nov 08)

15. Explain the SCR firing circuits in detail with the help of circuits and waveforms

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a. Resistance firing circuits b. RC firing circuit (JNTU Feb 08)

12. Ten thyristors are used in a string to withstand a d.c. voltage of 12KV. The max. leakage current and recovery charge difference of SCRs is 10mA and 50µC respectively. The values of R for steady state equalizing circuit is 40k ohms and value of capacitance C of dynamic equalizing circuit is 0.2µF. Find the steady state and transient derating factor (JNTU Feb 08)

13. The latching current of a thyristor with d.c. voltage source of 100V is 50mA. Calculate the value of minimum width of the gate pulse current when connected to a pure inductive load of 1H. Compute the effect, if a resistance of 10 ohms is connected in series with the load (JNTU Feb 08, Nov 08, 05)

14. The specifications of a Thyristor operating from a peak supply of 400V is as follows Repetitive Peak current Ipk = 200A,(di/dt)max = 15A/us , (dv/dt)max = 108V/us.Choosing a factor of safety of 2 for Ipk, (di/dt)max and (dv/dt)max, design a suitable snubber circuit, if the minimum loads (RLmin) be 10 ohms resistive (JNTU Feb 08)

15. Explain in detail various voltage ratings and current ratings of a thyristor. (JNTU Feb 08)

16. A string of Thyristor connected in series to withstand a d.c. voltage of Vs= 15KV. The max. leakage current and recovery charge difference of thyristor are 10mA and 150 µC respectively. A derating factor of 20% is applied for the steady state and transient voltage sharing is 1000V. Determine

a. Steady state voltage sharing resistance R for each thyristorb. The transient voltage (JNTU Feb 08)

17. a. Explain the transfer and output characteristics of MOSFETs.b. Why does the concept of saturation differ in BJTs and Power MOSFETs.c. What are the differences between enhancement type MOSFETs and depletion type MOSFETs.


18. Derive the Static equalizing and dynamic equalizing parameters in case of series and parallel connected SCRs (JNTU Nov 07)

19. a. What is the importance of Surge current rating of a thyristor, explain in detail.b. A thyristor has half-cycle surge current rating of 1000mA for a 50Hz supply.Calculate its one-cycle

surge current rating and I2t rating. (JNTU Nov 08, 07)

20. Explain the V-I Characteristics of Thyristors with elaborating the following :i. Latching current ii. holding currentiii. on-state and off-state condition iv. turn-on and turn-off timesv. finger voltage (JNTU Feb 07,Nov 07, 06, 05)

21. Ten thyristors are used in a string to withstand a d.c. voltage of 12KV. The maximum leakage current and recovery charge difference of SCRs is 10mA and 50µC respectively. The values of R for steady state equalizing circuit is 40k ohms and value of capacitance C of dynamic equalizing circuit is 0.2µF. Find the steady state and transient derating factor. (JNTU Nov 05)

22. Describe the different modes of operation of a thyristor with the help of its V-I characteristics?(JNTU May 04)

23. i. Explain the operation of SCR using the schematic diagram and explain the importance of junctions. ii. Sketch the static V-I Characteristics of SCR and discuss the importance of

i. Holding current ii. Latching current iii. Reverse breakdown voltage.(JNTU Nov 03)

24. i. Define holding and latching currents.ii. Describe various modes of operation of thyristor with the help of V-I characteristics.

(JNTU Jun 03)

25. i. What are the necessary conditions for turning on of an SCR. (JNTU Jun 03)

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ii. Define turn on and turn off times of SCR.

26. Draw thyristor gate V-I characteristics indicating clearly the gate drive limits. Explain, with the help of these characteristics, the selection of an operating point and the choice of gate circuit parameters.

(JNTU Jun 03)

27. i. Describe the dynamic characteristics of SCRii. Discuss how SCRs suffer from unequal voltage distribution across them during their turn-on and turn-

off process. (JNTU Jun 03)

28. Explain the turn-on and turn-off methods of SCR, BJT and Power MOSFET with neat waveforms.(JNTU May 02)

29. a. Explain the necessity of series and parallel connection of SCRs.b. What is String efficiency in series and parallel connections.c. What are the problems arising in series and parallel connections (JNTU Nov 05)

30. Describe the different modes of operation of a thyristor with the help of its V-I characteristics(JNTU Jun 03)

31. An SCR is considered to be a semi-controlled device becausea. it can be turned OFF but not ON with a gate pulseb. it conducts only during one half-cycle of an alternating current wavec. it can be turned ON but not OFF with a gate pulsed. it can be turned ON only during one half-cycle of an alternating voltage wave (GATE 09)

32. The circuit shows an ideal diode connected to a pure inductor and is connected to a purely sinusoidal 50Hz voltage source. Under ideal conditions the current waveform through the inductor will look like

a. b.

c. d. (GATE 09)

33. Match the switch arrangements on the top row to the steady-state V-I characteristics on the lower row. The steady state operating points are shown by large black dots.

a. A-I, B-11, C-m, D-IV b. A , B-IV, C-I, D-I11

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c. A-IV, B-111, C-I, D-11 d. A-IS', B-111, C-11, D-I (GATE 09)

In the ciruit shown in the figure, the switch is operated at a duty cycle of 0.5 A large capacitor is connected across the load. The inductor current is assumed to be continuous. (GATE 08)

a. 10V, 2A b. 10V, 8A c. 40V, 2A d. 40V, 8A

34. “Six MOSFETs connected in a bridge configuration (having no other power device) MUST be operated as a Voltage Source Inverter (VSI)”. This statement is

(GATE 07)a. True, because being majority carier devices, MOSFETs are voltage drivenb. true, because MOSFETs have inherently antiparallel diodesc. False, because it can be operated both s Current Source Inverter (CSI) or VSId. False, because MOSFETs can be operated as excellent constant current sources in the saturation region.

35. What is IGBT? Give the cross-section and the equivalent circuit for IGBT. Make comparative assessment between BJT, MOSFET and IGBT. (IES 00)

36. Discuss the turn-off process in a GTO with relevant voltage and current waveforms. Enumerate the advantages and disadvantages of a GTO as compared to a conventional thyristor. (IES 00)

37. What is IGBT? Sketch the cross section and equivalent circuit of an IGBT. Discuss its advantages and disadvantages. (IES 97)

38. Why does a thyristor not conduct when possitive voltage is applied to it. Explain how gate pulse make it conducting.

39. Describe the events that take place when a thyristor a subjected to a slowly increasing reverse voltage.40. Explain the difference in construction of a inverter grade thyristor over a conventional one.

41. Explain how a thyristor gets triggered with a high dv/dt.

42. Describe the different modes of operation of a thyristor with the help of its static V–I characteristic.

43. Describe the holding current and latching current as applicable to an SCR with the help of its static V–I characteristic.

44. With the help of a neat diagram, explain the two transistor analogy of an SCR. Also discuss the triggering conditions of SCR.

45. Give constructional details of an SCR. Sketch its schematic diagram and the circuit symbol.

46. Explain why i. The inner two layers of an SCR are lightly doped and are wide. ii. The inner n layer of an SCR is doped with gold.iii. IH is less than IL.

47. Explain in detail the turn-off mechanism of an SCR.

48. Explain the various types of triggering methods of SCR briefly. Which is the universal method and why?

49. What are the different signals which can be used for turning on an SCR by gate control? Compare them.

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50. Draw the gate characteristic of an SCR and explain it.

51. Draw the turn-off characteristic of an SCR and explain the mechanism of turn-off

52. a. What is the thyristor? How has this term been coined? Name the most popular thyristor.b. Give constructional details of a typical thyristor. Sketch its schematic diagram and the circuit symbol.c. describe the different modes of operation of a thyristor with the help of this static V – I characteristics.

53. Enumerate the various mechanisms by which thyristor can be triggered into conduction. Discuss briefly the techniques which result in random turn-on. But the other/others leading to relable turn-on of thyristors should be described in detail.

UNIT – II

1. Explain the operation of single phase half controlled bridge converter with R load and derive the load voltage and load current with circuit diagram and necessary waveforms for α= 300.

(JNTU May 09)

2. A single phase fully controlled converter connected to 230V, 50Hz supply through source reactance, is supplying dc load current of 25A. If commutating angle is 80 calculate the value of source inductance.

(JNTU May 09)

3. Derive the expressions for the following performance factors of single phase fully controlled bridge converter

a. input displacement factor b. input power factorc. voltage ripple factor d. active power inpute. Reactive power input (JNTU May 09)

4. a. Describe the operation of a single phase two pulse mid point converter with relevant waveforms. Derive an expression for average output voltage.

b. A single phase fully controlled bridge converter is supplied at 230V, 50Hz, with source inductance of 2mH. Neglecting resistance voltage drop, when the converter is operating at a firing angle of 450 and the load current is constant at 10A. Determine also the load voltage. (JNTU May 09)

5. Explain the operation of a singe phase half wave converter for R-load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for α = 300

(JNTU May 09)

6. Explain the working of single phase fully controlled bridge converter with RL loads for rectifying and inverting modes of operation and also sketch the transfer characteristics. (JNTU May 09)

7. Single phase half controlled bridge converter feeds an inductive load. Determine the average load voltage and load current for a firing angle of 300 and 1200 respectively. The input a.c. voltage is 230V and load resistance is 10 ohms and inductance is 10mH. (JNTU May 09)

8. Explain the operation of a singe phase half wave converter for R-load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for α = 300.

(JNTU May 09)

9. Single phase dual converter is operated from 230V, 50Hz supply and the load resistance 10 ohms. The circulating inductance is LC = 40mH, firing angles are α1 = 600 and α2 = 1200. Calculate the peak circulating current, peak currents of converter 1 and converter 2. Also compute the load current.

(JNTU Nov 08)

10. Explain the operation of a single phase full wave mid-point converter with R-load with the help of circuit and output waveforms with respect to supply voltages. Derive the output voltage for α= 450.

11. a. What are the features of Half -controlled converters over full controlled converters.b. Bring out the features of Free-wheeling diode used in converters. (JNTU Nov 08)

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12. A single phase fully controlled converter is connected to a lod comprised of 2 ohms resistance and 0.3H inductance. The supply voltage is 230V at 50Hz. Estimate the average load voltage, average load current and input power factor for a firing angle of 200. Assume continuous and ripple free load current, draw load voltage waveform. (JNTU Nov 08)

13. Explain the operation of a single phase half wave converter for R-Load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for α = 300.

(JNTU Nov 08)

14. i. Compare mid-point converters and bridge type converters and bring out important features. ii. Compare discontinuous and continuous current modes of operation of converters and bring out salient

features. (JNTU Nov 08)

15. Explain the operation of a singe phase half wave converter for R-load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for α = 300.


16. Explain the operation of a single phase full wave mid-point converter with R-load with the help of circuit and output waveforms with respect to supply voltages. Derive the output voltage for α= 450.


17. Explain the working of single phase half-controlled bridge converter with RL loads for discontinuous and continuous current mode of operations with circuit and wave-forms for α = 450

(JNTU Feb 08)

18. Discuss the effect of source-inductance on the performance of a single phase fully controlled converter, indicating clearly the conduction of various thyristors during one cycle. Derive an expression for its output voltage in terms of Vm, α and µ (JNTU Feb 08)

19. Explain the operation of single phase dual converter for RL loads with non-circulating current modes with circuit and necessary voltage and current waveforms (JNTU Feb 08)

20. Explain the operation of a single phase full wave mid-point converter with R-load with the help of circuit and output waveforms with respect to supply voltages. Derive the output voltage for α= 45 0.

(JNTU Nov 07)

21. A single phase fully controlled bridge is used for obtaining a regulated converter dc output voltage. The rms value of ac input voltage is 230V and firing angle is maintained at 600, so that the load current is 4A.

a. Calculate the d.c. output voltage and active and reactive power input.b. Assuming load resistance remains same and if free-wheeling diode is used at the output, calculates dc

output voltage. The firing angle is maintained at 600. (JNTU Nov 07)

22. A rectangular pulse of 30V with 10 us duration is applied at the gate. The 1.average gate power dissipation of the thyristor is 0.5W and a peak gate drive power is 5W. Calculate the values of the series resistance to be connected in the gate circuit, the frequency and duty cycle of the triggering pulse. (JNTU Feb 07, Mar 06)

23. Explain the operation of class -C commutation circuit and also give its application with neat circuit. (JNTU Feb 07)

24. Ten thyristors are used in a string to withstand a d.c. voltage of 12KV. The max. leakage current and recovery charge difference of SCRs is 10mA and 50µC respectively. The values of R for steady state equalizing circuit is 40k ohms and value of capacitance C of dynamic equalizing circuit is 0.2µF. Find the steady state and transient derating factor. (JNTU Feb 07)

25. The voltage and current ratings of a particular circuit are 3.3KV and 750 amps. SCRs with rating of 800V and 175 amps are available. The recommended minimum derating factor is 15%. Calculate min. series and parallel units required. Also calculate the values of resistance and capacitance to be used in the static and dynamic equalizing circuits if the max. forward blocking current for the SCRs is 25mA

219


and DQmax is 50µC. Where DQmax is max. charge stored in thyristor. (JNTU Nov 06, Mar 06)

26. i. Explain the necessity of series and parallel connection of SCRs.ii. What is String eciency in series and parallel connections.iii. What are the problems arising in series and parallel connections. (JNTU Nov 06, 05)

27. Discuss the operation of class - A and class-B commutation circuits. Also mention their application with the help of neat circuit diagram. (JNTU Mar 06)

28. i. Draw the equivalent circuit of a UJT and explain its working.ii. Describe the VI characteristics of a UJT. Clearly explain its negative resistance nature.

(JNTU Mar 06)

29. i. The SCR is rated to give an average power dissipation of 0.5W. Its gate voltage varies from 2.5V to 10V. Keeping average gate power dissipation constant, plot allowable gate characteristics of SCR. For a triggering gate pulses of duty cycle 0.6. Calculate the value of average gate dissipation.

ii. Explain the gate characteristics of a Thyristor. (JNTU Mar 06)

30. i. What is the importance of Surge current rating of a thyristor, explain in detail. ii. A thyristor has half-cycle surge current rating of 1000mA for a 50Hz supply. Calculate its one-cycle

surge current rating and I2t rating. (JNTU Nov 05)

31. Explain Thyristor gate characteristics with neat diagrams. (JNTU Nov 04, May 04)

32. i. What is derating factor with reference to SCR’s.ii. Twenty thyristors each of 500 V, 500 A are used in five columns and four rows in a circuit of 200 V

and 1800 A. Calculate voltage and current derating factors. (JNTU Nov, May 04)

33. .i. Describe the various anode voltage rating as applicable to an SCR. Indicate these voltage ratings on a relevant voltage waveform.

ii. Discuss how SCRs suffer from unequal voltage distribution across them during their turn on- and then-off process. (JNTU Nov 04)

34. i. Discuss the DC and UJT triggering circuits for SCR turn on.ii. Discuss the significance of and in SCR’s. (JNTU Nov 04)

35. Explain the Ramp firing circuit and Ramp and Pedest al firing circuits for SCR, with the help of circuit and waveforms. (JNTU Nov 04)

36. i. Describe class B self commutation by an LC circuit employed for a thyristor circuits. ii. A two thyristor class C turn off circuit is required to be designed for use as a blinker to turn on and off

a lamp of constant resistance of 10 W from a DC supply of 100V. If the SCR used are converter grade with turnoff time 50µsec, find the value of commutation capacitor so that the commutation failure may not occur. (JNTU Nov 04, 03, Jun 03)

37. i. Discuss with relevant waveforms of class A self commutation by resonating the load, employed for thyristor circuits.

ii. For the class C commutation circuit, the DC source voltage Edc=120V and current through R1 and R2 is 20A.The turnoff time of both the SCR is 60 µSec. Calculate the value of commutating capacitance for successful commutation. (JNTU Nov 04, 03)

38. i. Distinguish clearly between voltage commutation and current commutation in thyristor circuits.ii. Discuss how the voltage across the commutating capacitance is preserved in a commutating circuit. iii. A circuit employing resonance pulse commutation has C=20µF and L=3µ H the initial capacitor

voltage = source voltage, Vs=230V DC. Determine conduction time for auxiliary thyristor and circuit turnoff time for main thyristor in case constant load current is 300A. (JNTU Nov 04, 03)

39. Explain the need of commutation in thyristor Circuits. What are the different methods of commutation scheme? Explain Class A commutation with neat diagram. (JNTU May 04)

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40. i. With neat circuit Diagram and waveforms explain the operation of a class D auxiliary commutation employed for thyristor circuits.

ii. Circuit employing class B commutation has C=20µF and L=5µH.Initial voltage across capacitor is 230V. For a constant load current of 250A . Calculate:i. Conduction time for auxiliary SCRii. Voltage across the main SCR when it gets commutated. (JNTU May 04)

41. A two thyristor class C turn off circuit is required to be designed for use as a blinker to turn on and off a lamp of constant resistance of 10 & 20 from a DC supply of 100V. If the SCR used are converter grade with turnoff time 50µsec, find the value of commutation capacitor so that the commutation failure may not occur. (JNTU May 04)

42. For the class C commutation circuit, the DC source voltage Edc=120V and current through R1 and R2 is 20A.The turnoff time of both the SCR is 60 µSec. Calculate the value of commutating capacitance for successful commutation (JNTU May 04)

43. Draw the power circuit diagram of a current commutated chopper. Explain the working of a chopper by dividing its commutation process interval into well-defined modes. (JNTU May 04)

44. A thyristor string is made up of a number of SCR’s connected in series and parallel. The string has voltage and current ratings of 11 KV and 4 KA respectively. The voltage and current ratings of available SCR’s are 1800V and 1000A. For a string efficiency of 90%, calculate the number of series and parallel connected SCR’s. (JNTU May 04)

45. A thyristor string with 5 SCR’s in series is supplied with 4KV. The maximum permissible blocking voltage of each SCR is 1000V. Calculate the value of static equalizing resistance of each SCR, if maximum leakage current is 10mA. (JNTU May 04)

46. Calculate the number of SCR’s each with rating of 500V, 75A required in each branch of a series and parallel combination for a circuit with the total voltage and current rating of 7.5KV and 1000A. Assume derating factor of 14%. (JNTU May 04)

47. SCR’s with a rating of 1000V and 200A are available to be used in a string to handle 6KV and 1KA. Find number of series and parallel SCR’s required. If derating factor (i.) 0.1 (ii). 0.2. (JNTU May 04)

48. What is complementary impulse commutation? Describe this type of commutation with a circuit diagram and appropriate waveforms. Derive expressions for current through and voltage across commutating capacitor. Find also the circuit turnoff times for the complementary Thyristors

(JNTU Jun, May 03)

49. i. Describe the operation of class E commutation circuit with appropriate waveforms. ii. For a class D commutation circuit Vs=230V, L=20µH and C=40µF .For a constant load current of 120

A calculate the circuit turnoff times for main and auxiliary thyristors. (JNTU Jun 03)

50. Explain the series operation of SCR’s and derive resistance used for static voltage equalization for a series connected string. (JNTU Jun 03)

51. Describe the operation of voltage-commuted chopper with relevant circuit and voltage waveforms. (JNTU May 03)

52. i. Explain the need of commutation in thyristor circuits. What are the different commutation schemes? Explain class-A commutation with neat diagrams.

ii. A circuit employing parallel resonance turn off (Class B commutation) circuit has C=50mF L=20mH V=200V and initial voltage across the capacitor is 200V. Determine the circuit turnoff time for main thyristor for load R=1.5W. (JNTU May 02)

53. A circuit employing resonance pulse commutation has C=20mF and L=3mH the initial capacitor voltage is equal to source voltage, Vs=230V DC. Determine conduction time for auxiliary thyristor and circuit turnoff time for main thyristor in case constant load current is 300A. (JNTU May 02)

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54. Discuss the various current ratings of SCR (JNTU May 02)

55. Explain the necessity of snubber circuit for SCR and give its operation. Derive the expression for snubber circuit parameters connected for SCR (JNTU May 02)

56. A single phase bridge converter is used to change a battery of 200V having an internal resistance of 0.2Ω as shown in figure. The SCRs are triggered by a constant dc signal. If SCR 2 gets open circuited, then what will be the average charging current? (GATE 06)

a. 23.8A b. 15A c. 11.9A d. 3.54A57. An SCR having a trun ON time of 5 μsec., latching current of 50 mA and holding current of 40mA is

triggered by a short duration pulse and is sued in the circuit shown in figure. The minium pulse width required to turn the SCR ON will be (GATE 06)

a. 251 μsec b. 150μsec c. 100μsec d. 5μsec58. Consider the thyristor circuit of figure below. The thyristor is given a triggering pulse after every 10

ms. Calculate the duration for which the thyrisor remains ON after each triggering pulse. Assume ideal devices and explain briefly the basis. (GATE 95)

59. What is an Unijunction transistor? Draw a basic UJT pulse trigger circuit with typical waveforms and explain its operation. (IES 03)

UNIT – III

1. Explain the operation of 3-phase dual converter fed to RL loads for non-circulating current mode. With neat circuit diagram and waveforms. (JNTU May 09)

2. A three phase, six pulse fully controlled converter is connected to three phase ac supply of 440V and 50Hz and operates with a firing angle of π/5 radians. The load current is maintained constant at 5 Amps and load voltage is 440V. Calculate load resistance, source inductance and overlap angle.

(JNTU May 09)

3. a. Explain the operation of three phase, half controlled bridge converter with R load and associated waveforms.

b. Derive the expression for average load voltage for α = 300. (JNTU May 09)

4. A 3-phase, full wave converter is connected to a 3-phase ac supply of 400V, 50Hz and operates with a firing angle of π/4 rad. The load current is maintained constant at 10 amps and load voltage is 360 V. Calculate source inductance and overlap angle. (JNTU May 09)

5. A three phase fully controlled bridge converter supplies a dc voltage source of 400V having an internal resistance of 1.8 ohm. Assume highly inductive load with a constant load current of 20A. The supply RMS load voltage per phase is 230V and source inductance in each phase is 0.005H. Compute the following by ignoring the source resistance

a. firing angle for an output voltage of 436V b. overlap angle (JNTU May 09)

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5. Explain the operation of three phase half-wave controlled converter with resistive load, and inductive load. Sketch the associated waveforms. (JNTU May 09)

6. A 3-phase, full wave converter is connected to a 3-phase ac supply of 400V, 50Hz and operates with a firing angle of π/4 rad. The load current is maintained constant at 10 amps and load voltage is 360 V. Calculate source inductance and overlap angle. (JNTU May 09)

7. The three phase dual converter is operated from a three phase Y-connected 220V, 60Hz supply and load resistance, R = 10 ohms. The circulating inductance, Lr = 5mH and the firing angles are α1 = 600 and α2 = 1200. Calculate the peak circulating current and peak current of converters.

(JNTU May 09)


(JNTU May 09)

9. Explain the operation of three phase fully controlled bridge converter with RL loads. Describe in detail with discontinuous conduction mode with associated waveforms. (JNTU Nov 08)

10. A three phase semi converter is operated from a three phase star connected 220V, 60Hz supply. The load current is continuous and has negligible ripple. The average load current is I dc = 150A and commutating inductance per phase is Lc = 0.5mH. Determine the overlap angle ifa. α=π/6 b. α=π/3 (JNTU Nov 08)

11. A three phase, half wave converter is supplying a load with a continuous constant current of 40A over a firing angle from 00 to 750. What will be the power dissipated by the load at these limiting values of firing angle? The supply voltage is 415V (line). (JNTU Nov 08)

12. Explain the operation of three phase half-wave controlled converter with resistive load, and inductive load. Sketch the associated waveforms. (JNTU Nov 08)

13. A three phase, half wave controlled converter is connected to a 380V (line) supply. The load current is constant at 32A and is independent of firing angle. Find the average load voltage at firing angle of 00 and 450, given that the thyristors have a forward voltage drop of 1.2V. What value of current and peak reverse voltage rating will the thyristor require and what will be the average power dissipation in each thyristor. (JNTU Nov 08, 07)

14. A three phase, fully controlled converte is connected to a resistive load. Show that the average output voltage is given by

for 0 < α < П / 3 and

for П / 3 < α < 2П / 3 (JNTU Nov 08)


(JNTU Feb 08)

16. A 3-phase, full wave converter is connected to a 3-phase ac supply of 400V, 50Hz and operates with a firing angle of π/4 rad. The load current is maintained constant at 10 amps and load voltage is 360 V. Calculate source inductance and overlap angle (JNTU Feb 08)

17. The three phase half wave converter is operated from a three phase star connected 220V, 60Hz supply and load resistance is R = 10 ohms. If the average output voltage is 25% of max. possible average output voltage, calculate the

a. firing angleb. rms and average output currentsc. average and rms thyristor currents

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d. input power factor (JNTU Feb 08)

18. A six pulse thyristor converter connected on the secondary of the 6.6KV/415V, 50Hz transformer is supplying to 460V, 200A a.c, load. Calculate

a. Converter firing angleb. DC power delivered by the converterc. ac terminal powerd. ac line current (JNTU Feb, Nov 08)

19. A three phase semi converter is operated from a three phase star connected 220V,60Hz supply. The load current is continuous and has negligible ripple. The average load current is Idc = 150A and commutating inductance per phase is Lc = 0.5mH.Determine the overlap angle if

a. α=π/6b. α=π/3 (JNTU Feb 08)

20. Derive an expression for output voltage of a three phase, fully controlled bridge converter by conducting the following factors: overlap angle and source inductance continuous and has negligible ripple. If the average load current Idc= 150A and commutating inductance Lc = 0.1mH, determine the overlap angle when (a) α = 100 (b) α = 300 and (c) α = 600 (JNTU Nov 07)

21. Explain the operation of three phase fully controlled bridge converter with RL loads. Describe in detail with discontinuous conduction mode with associated waveforms (JNTU Nov 07)

22. Explain the operation of a singe phase half wave converter for R-load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for a = 300.


23. Explain the operation of three phase half-wave controlled converter with resistive load, and inductive load. Sketch the associated waveforms. (JNTU Nov 06, 05, Mar 06)

24. Explain the operation of single phase half controlled bridge converter with R load and derive the load voltage and load current with circuit diagram and necessary waveforms for á= 300. (JNTU Mar 06)

25. A three phase, half wave converter is supplying a load with a continuous constant current of 40A over a firing angle from 00 to 750. What will be the power dissipated by the load at these limiting values of firing angle? The supply voltage is 415V (line). (JNTU Mar 06)

26. i. What are the features of Half -controlled converters over full controlled converters.ii. Bring out the features of Free-wheeling diode used in converters. (JNTU Mar 06, Nov 05)

27. i. Draw the circuit diagram of a single phase half controlled converter and derive the equation for average current in case of RL load and discontinuous conduction.

ii. Explain the effects of source inductance and freewheeling diode on the performance of converters. (JNTU Nov 04)

28 i. Draw the circuit diagram of a three phase Half controlled converter and obtain an expression for the average load voltage across a resistive load.

ii. A three phase full converter is operated from a three phase 400V, 50Hz supply. The load resistance is 10 ohms. Calculate the firing angle for an average output voltage of 60% of the maximum possible mean output voltage. Calculate also the RMS value of load current. (JNTU Nov 04)

29. Explain with suitable circuit diagrams and wave forms the principle of operation of single phase semi-converter bridge operation with R-L load. (JNTU Nov 04)

30. For a single phase semi-converter bridge using 2 SCRs and 2 diodes the supply is fed from a single phase source of 230V,50Hz. The load consists of R=20 ohms, E=100volts and a large inductance so as to render a load current level. For a firing delay angle of 600 determine :

i The average output voltage

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ii. The average output current iii. The input power factor (JNTU Nov 04)

31. Explain clearly the difference between half-wave converter and semi-converter. (JNTU May 04)

32. i. Derive the expressions for output voltage of single phase Half controlled converter in its various modes of operation when feeding to R-L load.

ii. In a single phase mid point converter, turns ratio is 1.25. The source voltage is 130V, 50Hz. For a resistive load of R=2 ohms, determinei. Maximum possible values of positive and negative voltages across SCRs ii. Maximum output voltage and current and the corresponding firing and conduction angles.iii. The value of firing angle for load voltage of 100V. (JNTU Nov 03)

33. Draw and explain the operation of a 3-phase semi-converter with relevant waveforms at firing angle of 600 Obtain an expression for average output voltage. (JNTU Nov 03)

34. i. Derive an expression for the average output voltage of a single phase semi-converter.ii. What are semi-controlled converters? Explain how freewheeling takes place in these converters.

(JNTU Jan 01)

35. A Single phase half controlled converter shown in the figure is feeding power to highly inductive load. The converter is operating at a firing angle of 600. (GATE 08)

36. If the firing pulses are suddenly removed, the steady state voltage (v0) waveform of the converter will become

a. b.

c. d.

37. A single phase full-wave half-controlled bridge converter feeds an inductive load. The two SCR’s in the converter are connectd to a common DC bus. The converter has to have a freewheeling diode.

a. because the converter inherently does not provide for free-wheelingb. because the converter does not prvide for free-wheeling for high values fo triggering angles.c. or else the free-wheeling action of the converter will cause shorting of the AC supply.d. or else if a gate pulse to one of the SCRs is missed, it will subsequently cause a high load current int eh

other SCR. (GATE 07)

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38. A single-phase half wave uncontrolled converter circuit is shown in figure. A 2-winding transformer is used at the input for isolation. Assuming the load current to be constant and v-Vmsinwt, the current waveform through diode D2 will be (GATE 06)

a. b.

c. c.

39. The single phase half controlled AC to DC bridge converter of Figure below supplies a 10 Ohm resistor in series with a 100 V back emf load. The firing angle of the thyristors is set to 60°.

i. Find the average current through the resistor.ii. What will be the new average current through the resistor, if a very large inductor is connected in series

with the load? (GATE 95)

40. Why input power factor of a single phase half controlled bridge rectifier is higher than that for a fully controlled bride rectifier supplying an RL load for the same firing angle? (IES 02)

41. A single-phase semi converter feeds RLE load such that load current is constant for a firing angle of 230 degree. Sketch waveforms for source voltage, load voltage, load current, source current, one SCR current and freewheeling diode current for firing angle of 30 degree. Prove that the input PF for the above semi converter for firing angle 90 degree is 0.63 (IES 01)

42. A single phase bridge converter with a free wheeling diode feeds an R-L load. The load resistance is 7.5 ohms and inductance is very large providing ripple free load current. The converter is supplied by 120 V, single phase supply at a frequency of 50 Hz. Determine the average value of load current, device currents, power factor at a firing angle of 600.

43. A three pulse converter is fed from a 220 V, 3-phase, 50 Hz supply. If feeds an RL load with a diode across it. The load resistance is 10 ohms and inductance provides perfect smoothing. It is required to obtain 50% of the maximum possible dc voltage at the load terminals. Determine i. the firing angle ii. rms and average values of load current iii. values of device currents iv. power factors.

44. A single phase half controlled bridge converter has a ripple free load current. Draw the waveforms of voltages and currents. Using the Fourier analysis of the input current waveform, determine the expressions for displacement factor, distortion factor, harmonic factor.

45. A two pulse midpoint converter feeding an R-L load has a freewheeling diode connected across the load. The load has a sufficiently large inductance to cause perfect smoothing. The value of resistance is Rd=7.5 ohms. The converter transformer has secondary voltage of 120V. The firing angle is a = 600. Determine the following.i. Average value of load voltage ii. Average value of load currentiii. Displacement factor iv. Distortion factorv. The thyristor currents and voltages vi. The diode current.

46. The two pulse half controlled bridge converter is connected to a 200V, 50 Hz supply. The converter supplies R-L load with perfect smoothing. The source is ideal. Draw the waveforms of device currents, load current, line current.

226


47. A two half controlled bridge converter feeds a load consisting of a resistance = 5 ohms and a large inductance which makes the current ripple free. There is a back emf of 80 V. The converter is supplied form a 220 V, 50Hz supply. For a = 600, 1500, Determine

i. The average value of load voltageii. The average value of load currentiii. The power delivered to loadiv. The reactive power.

48. A two pulse half controlled converter feeds an R-L-E load with R = 10 ohms, L = 10 H and E = 50 V. The supply is 250 V, 50 Hz.

i. Determine the voltage and current waveforms.ii. What is the Fourier series of output voltage?iii. What is the lowest order harmonic in the current and its rms value ?

49. Draw the diagrams of two types of half controlled converters possible with two pulse bridge converters.

50. What are the advantages of half controlled converters over the converters with free wheeling diode.

51. Discuss how the power factor improvement is possible in half controlled converters.

52. Explain why inversion is not possible in half controlled converters.

53. A single-phase, half-wave rectifier with an ac voltage of 150 V has a pure resistive load of 9 ohms. The firing angle a of the thyristor is pi/2. Determine the i. rectification efficiency, ii. form factor, iii. transformer derating factor, iv. peak inverse voltage of the SCR, and v. ripple factor of the output voltage. Assume that the transformer ratio is 2:1.

54. The half-controlled rectifier has on input supply voltage of 115 V (RMS) at 50 Hz. Also R = 6 ohms and L = 0.3 H. If the firing angle of the thyristors is kept at 650, i. draw the load voltage and load current waveforms, ii. complete the RMS and dc magnitude of the load voltage, and iii. determine the magnitude of the dc load current.

55. i. Show that the performance of a single phase full converter is effected by source inductance and obtain the dc equivalent circuit

ii. A one phase full converter is connected to ac supply of 330sin314t at 50Hz. it operates with a firing angle alpha= 450. The total load current maintained constant at 5A and the load voltage is 140V. calculate the source inductance angle of overlap and the load resistance

56. The half controlled rectifier has a input supply voltage of 115 volts (RMS) at 50hz. Also R= 6ohms and L=0.3 H. if the firing angle of the thyristors is kept at 65 degrees. a) Draw the load voltage and load current wave forms, b) compute the RMS and dc magnitude of the load voltage and c) determine the magnitude of the dc load current.

57. A single phase, half wave rectifier is operated with extinction angle control with =60 degrees. the ac supply voltage is 200 volts (RMS) and a load resistance is 25 ohms. . Determine the i. distortion factor ii. input power factor iii. average load voltage, and iv. average load current

UNIT – IV

1. An a.c. voltage controller supplies power to a resistive load of 20 ohms. The rms of input voltage is 220V at 50Hz. The thyristors are switched ON for 30 cycles and OFF for 70 cycles. Calculate the values of a. the rms output voltage b. input power factorc. the average and rms values of thyristor currents (JNTU May 09)

2. The ac voltage controller uses on-off control for heating a resistive load of R = 4 ohms and the input voltage is Vs = 208V, 60Hz. If the desired output power is P0 = 3KW, determine thea. duty cycle δ b. input power factorc. sketch waveforms for the duty cycle obtained in (a) (JNTU May 09)

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3. Derive the output rms voltage, output rms current and source power factor for a single phase ac voltage controller fed to R-L load. (JNTU May 09)

4. A single phase ac voltage controller controls the load power. The input to the controller is 230V, 50Hz sinusoidal. The load circuit consists of R = 3 ohms and wL = 4 ohms. Determinea. The control range of firing angle b. the max. value of RMS load currentc. the max. power and power factor (JNTU May 09)

5. A 1-Φ 230V, 50HZ source connected to as anti parallel connected thyrister circuit; controlling power to the following loads, when _ = 900. Calculate output voltage and output current and load power factor for a. R=10 OHMS; L=0 H b. R=10 OHMS; L=60mH. (JNTU May 09)

6. The single phase ac full wave controller supplies an R load. The input voltage Vs = 120V at 60Hz. The load is such that R = 5 ohms. The delay angles of thyristors T1 and T2 are equal and α = 600. Determine the

a. conduction angles of thyristor T1

b. rms output voltagec. rms output current and thyristor currentd. input power factor (JNTU May 09)

7. Derive the output rms voltage, output rms current and source power factor for a single phase ac voltage controller fed to R-L load. (JNTU May 09)

8. Explain the operation of a single phase ac voltage controller with neat circuit diagram and output waveforms with respect to source voltage waveforms at α = 600 for Resistive load.

(JNTU May 09)

9. A single phase full wave ac voltage controller has a resistance load of a. 10 ohms and b. 5 ohms.

The input ac voltage is 230V, 50Hz. For a delay angle of 900, determine the rms load voltage, rms load current, rms thyristor current and input power factor for above two loads. (JNTU May 09)

10. Two SCRs are connected back-to-back have a load resistance of 400 ohms and a supply of 110V ac. If firing angle is 600, finda. the rms output voltage b. average power. (JNTU Nov 08)

11. A single phase full wave ac voltage controller has a resistance load of a. 10 ohms and b. 5 ohms. (JNTU Nov 08)

12. The input ac voltage is 230V, 50Hz. For a delay angle of 900, determine the rms load voltage, rms load current, rms thyristor current and input power factor for above two loads. (JNTU Nov 08)

13. A single phase ac voltage controller feeds power to a resistive load of 4 ohms from 230V, 50Hz source. Determine

a. The max. values of average and rms thyristor currents for any firing angle α.b. The minimum circuit turn-off time for any firing angle α.c. The max. value of di / dt occurring in the thyristors. (JNTU Nov 08)

14. Explain the operation of a single phase ac voltage controller with neat circuit diagram and output waveforms with respect to source voltage waveforms at α = 600 for Resistive load (JNTU Nov, Feb 08)

15. The ac voltage controller uses on-off control for heating a resistive load of R = 4 ohms and the input voltage is Vs = 208V, 60Hz. If the desired output power is P0= 3KW, determine the

a. duty cycle δb. input power factorc. sketch waveforms for the duty cycle obtained in (a) (JNTU Nov, Feb 08)

16. a. Explain the principle of ON-OFF control used in a.c. voltage controller.

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b. Derive the expression for the input power factor in an a.c. voltage controller using ON-OFF controlc. Explain its application with the help of a circuit and waveforms (JNTU Feb 08)

17. For a singe phase ac voltage controller feeding a resistive load, draw the waveforms of source voltage, gating signals, output voltage, source and output currents and voltage across SCRs. Describe its working with reference to the waveforms drawn (JNTU Feb 08)

18. A single phase ac voltage controller is connected to a resistive load of 10 ohms. The supply voltage is 230V, 50Hz. Determine the rms load voltage, rms load current and input power factor for a trigger angle of 600. Sketch the output waveforms (JNTU Feb 08)

19. A single phase full wave controller supplies an R load of R = 5 ohms. The input rms value of voltage is 220V at 50Hz. The delay angle of thyristors are equal as α1 = α2 = 900. Calculate

a. the conduction angle of thyristor 1b. the rms value of output voltage and currentc. the rms and average value of thyristor currentsd. input power factor (JNTU Feb 08)

20. a. Explain the principle of ON-OFF control used in a.c. voltage controller.b. Derive the expression for the input power factor in an a.c. voltage controller using ON-OFF control.c. Explain its application with the help of a circuit and waveforms. (JNTU Feb 08, Nov 07)

21. A single phase, 220V, 1 KW electric room heat is connected across 220V supply through a Triac. For a delay angle of 900 calculate

a. the power dissipated by the heater elementb. find the value of a for output voltage of 0.25V (JNTU Feb 08)

22. Derive the output rms voltage, output rms current and source power factor for a single phase ac voltage controller fed to R-L load. (JNTU Nov 07)

23. Explain the operation of a single phase full wave mid-point converter with R-load with the help of circuit and output waveforms with respect to supply voltages. Derive the output voltage for a= 450.

(JNTU Feb 07)

24. Derive the expressions for the following performance factors of single phase fully controlled bridge converter

i. input displacement factorii. input power factoriii. voltage ripple factoriv. active power inputv. Reactive power input (JNTU Nov 06, Mar 06)

25. A single phase fully controlled bridge converter is operated from a single phase 220V, 50Hz supply. The load current is continuous and has negligible ripple. The average load current is Idc= 50A and commutating inductance per phase is LC = 0.5mH. Determine the overlap angle if i. = 300 ii. = 600

(JNTU Nov 05)

26. Explain the operation of single phase fully-controlled bridge converter with RL loads for discontinuous and continuous current modes. Draw circuit and necessary waveforms for = 600. (JNTU Nov 05)

27 i. Derive the expression for the input power factor of single phase fully controlled bridge rectifier.ii. Explain the effect of freewheeling diode in detail. Also, justify the statement “Freewheeling diode

improves the power factor the system”. (JNTU Nov, May 04)

28. i. Describe the operation of a single phase two pulse mid point converter with relevant waveforms. Derive an expression for average output voltage.

ii. A single phase fully controlled bridge converter is supplied at 230V, 50Hz, with source inductance of 2mH. Neglecting resistance voltage drop, when the converter is operating at a firing angle of 450 and the load current is constant at 10A. Determine also the load voltage. (JNTU Nov 04)

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29. i. Show that the effect of source inductance on the performance of single phase fully controlled converter is to present an equivalent resistance of Ls ohms in series with the internal rectifier voltage

ii. A single phase fully controlled converter is supplied at 220V,50Hz. Determine the average load voltage for the following cases when the firing angle is 450 for purely resistive load. (JNTU Nov 04)

30. A 1-Ø fully controlled bridge converter is supplied at 230 V, 50 Hz with source inductance of 2 mH. Neglecting resistance drop, when the converter is operating at a firing angle of 450 and the load current is constant at 10A. Determine the load voltage. (JNTU May 04)

31. 3-Ø fully controlled bridge converter supplies a de voltage source of 400 V having an air internal resistance of 1.8. Assume highly inductive load with a constant load current of 20 A. The supply RMS load voltage per phase is 230 V and source inductance in each phase is 0.005 H. Compute the following by ignoring the source resistancei. Firing angle for an output voltage of 436 V ii. Overlap angle (JNTU May 04)

32. A single phase fully controlled bridge converter is supplied at 230V, 50Hz, with source inductance of 2mH. Neglecting resistance voltage drop, when the converter is operating at a firing angle of 450 and the load current is constant at 10A. Determine also the load voltage. (JNTU May 04)

33. i. Describe the working of single phase fully controlled bridge converter in the following two modes: a. rectifying mode b. inversion mode

ii. Sketch the following waveforms of single phase fully controlled converter for firing angles 450 and 1200.a. Load voltage and current waveformsb. Thyristor voltage and current waveformsc. Supply voltage and current waveforms (JNTU Nov 03)

34. In a 1Ø midpoint converter, turns ratio is 1.25. The source voltage is 130 V, 50 Hz for a resistive load of R=2 ohms, Determine.

i. Maximum possible values of positive and negative voltage across SCRs.ii. Maximum output voltage and current and the corresponding firing and conduction angles.iii. The value of firing angle at load voltage of 100V. (JNTU May 03)

35. A Single phase fully controlled bridge converter supplies a load drawing constant and ripple free load current. If the triggering angle is 300, the input power factor will be a. 0.65 b. 0.78 c. 0.85 d. 0.866 (GATE 08)

36. A single phase fully controlled converter bridge issued for electrical braking of a separately excited dc motor. The dc motor load is represented by an equivalent circuit as shown in the figure.

230


a. 440 b. 510 c. 1290 d. 1360 (GATE 08)

37. A single phase fully controlled thyristor bridge ac-dc converter is operating at a firing angle of 25 0 and an overalp angle 100 with constant dc output current of 20A. The fundamental power factor (displacement factor) at input ac mains is a. 0.78 b. 0.827 c. 0.866 d. 0.9 (GATE 07)

38. The phase controlled mid point converter is operating at firing angle of 45 degree and the load current at steady state is constant at Id. Neglecting source impedance.

i. Draw the output voltageii. Device currentsiii. Voltage across the thyristor. (GATE 94)

39. Show that the performance of a single phase full converter is effected by source inductance and obtain the d.c. equivalent circuit.

40. A single phase full converter is connected to a.c. supply of 330sin314t at 50Hz. It operates with firing angle α=PI/4 radians. The total load current is maintained constant at 5A and the load voltage is 140V. Calculate the source inductance , angle of overlap and the load resistance.

41. Describe the working principle of a single phase full converter in the rectifier mode with RLE load. Discuss how one pair of SCR’s is commutated by an incoming pair of SCR’s. Illustrate your answer with waveforms for source voltage E, output voltage and current, source current, current through and voltage across one thyristor. Assume continuous conduction

42. A single phase full converter feeding RLE load has the following data Source voltage 230 V, 50 Hz, R = 2.5 ohms, E = 100 V, Firing angle = 300. For a constant load current compute the i. average value of load voltage ii. load current iii. input power factor.

43. A pulse phase controlled midpoint converter feeds an R-L load. The load inductance is infinitely large to cause perfect smoothing. The load resistance is 10 ohms. The secondary voltage of the converter transformer is 230-V. Assuming the transformer and thyristors to be ideal, determine the average values of load voltage and load current for firing angles of a = 300, 600,. Determine the ratings of thyristor.

44. A single phase bridge converter feeds an R-L load having a resistance of 5.5 ohms and an inductance of a very large value causing perfect smoothing. The converter is fed from a 400 V, 50 Hz single phase supply. For a firing angle of a = 750 determine.i. the average value of output current ii. the rms value of output currentiii. the average and rms thyristor currents iv. the power factor of the ac source

45. A single phase bridge converter feeding an R-L load with perfect smoothing is supplied from a 230 volts 50 Hz single phase supply via a 2:1 transformer. The source including transformer offers an inductive reactance of 0.5 ohms. If the load resistance is 2.45 ohms, determine for a firing angle of a = 600.i. the average value of load voltage ii. the average value of load currentiii. the overlap angle iv. thyristor ratings.

46. A two pulse bridge converter supplies power to load comprising a large inductance in series with a resistance of 1.5 ohm. The large inductance is responsible for perfect smoothing. If an additional dc

231


source of 120-V is available in series with RL load, determine the value of firing angle to cause a current of 40 A in the load. The supply to the converter is at 120-V and 50 Hz. The source inductance amount to 0.75mH. Determine the overlap angle.

47. A two pulse bridge rectifier feeds an RL load. The load current is ripple free. The load resistance is 2.5 ohms and L is very large. The source inductance is 2.5 mH. The rectifier is supplied at 50 Hz, the supply voltage being 110V. For a firing angle of 450, determine the displacement factor, average value of load current. The rectifier elements are ideal.

48. A two pulse single phase mid point converter feeds and R-L load having sufficiently large inductance to smooth the dc load current perfectly. Determine the fundamental of the input current. Determine the reactive volt amperes of converter.

49. A single-phase fully controlled bridge rectifier supplies an RL Eb load. The data are Vs1 = 230 V (RMS), Eb = 130 V, L1d = 12 mH, a = 300, and frequency of ac supply = 50 Hz. (a) what value will the load resistance be if the conduction is required to be just continuous? (b) Determine the average values of the load voltage and load current. (c) Sketch the waveforms of the load voltage and load current.

50. Find the rectifier efficiency for a single-phase bridge rectifier for which the data are Vs = 120 V (RMS) at 50 Hz, a = 400, R1d = 12 ohms, L1d = 50 mH. Sketch the voltage across a thyristor and the current through it. Also calculate the ripple factor of the output voltage.

51. Find the mean values of load voltage and current for a centre-tapped type of rectifier with the following data: Vs1 = Vs2 = 135 V (RMS) at 50 Hz, Eb = 98 V, R1d=3.5 ohms, L1d = 14.5 mH, a = 500. Also calculate the ripple factor of the output voltage.

52. Find the mean values of the load voltage and current for a centre tapped type of rectifier with the following data Vs1=Vs2=135V (RMS) at 50 Hz, Eb=98volts, R1d=3.5ohms, L1d=14.5mh, =50degrees. Also calculate the ripple factor of the output voltage.

53. Find the mean values of the load voltage and current for a centre tapped type of rectifier with the following data Vs1=Vs2=125V (RMS) at 50 Hz, Eb=88volts, R1d=3ohms, L1d=11.5mh, =50degrees. Also sketch the wave forms.

54. Explain with the help of neat power-diagram and associated waveforms, theoperation of a single-phase half-wave controlled converters with i. Resistive load ii. Inductive load

55. Derive and expressions for the i. Average load voltage ii. Average load current iii. RMS load voltage, for single-phase half-controlled converter with resistive load and inductive load.

56. Explain the effective of freewheeling diode in details. Also, justify the statement “Freewheeling diode improves the power factor of the system”.

UNIT – V

1. Discuss the working of a single phase bridge type cyclo converter with RL loads and for discontinuous operations with relevant output waveforms and circuit diagram for f0 = 1/2 fs. (JNTU May 09)

2. Explain the operation of single phase midpoint cyclo converter with R-L load s for continuous conduction with relevant circuit diagram nd necessary output waveforms for f0 = 1/3 fs.

(JNTU May 09)

3. Discuss the working of single phase midpoint cycloconverter when feeding R and RL loads with neat circuit diagram and relavent output waveforms. (JNTU May 09)

232


4. For a single phase mid-point cyclo-converter, explain the operation of the circuit when fed to R-load with the help of neat circuit diagram and relevant output waveforms for α = 30 0 and α = 1200 for f0 = 1/4 fs. (JNTU May 09)

5. a. What is a cyclo converter?b. What are the varieties of single phase cyclo converters.c. What are the salient features of cyclo converters.d. What are the major limitations of cyclo converters (JNTU May 09)

6. Explain the operation of single phase bridge type cyclo converter when fed form 230V, 50Hz source and controlling power to resistive load with the help of neat circuit diagram and output voltage and current waveforms for α = 450 and α = 1600 for f0 = 1/5 fs. (JNTU May 09)

7. Discuss the working of a single phase bridge type cyclo converter with RL loads and for discontinuous operations with relevant output waveforms and circuit diagram for f0 = 1/2 fs. (JNTU Nov, Feb 08)

8. Explain the operation of single phase bridge type cyclo converter when fed form 230V, 50Hz source and controlling power to resistive load with the help of neat circuit diagram and output voltage and current waveforms for α = 450 and α = 1600 for f0 = 1/5 fs. (JNTU Nov 08)

9. Discuss the working of a single phase midpoint cyclo converter with RL loads and for continuous conduction with relevant circuit diagram and necessary output waveforms for f0 = 1/3 fs.

(JNTU Nov 08)

10. Discuss the working of a single phase midpoint cyclo converter with RL loads and for discontinuous conduction with relevant circuit diagram and necessary output waveforms for f0 = 1/3 fs.

(JNTU Nov 08)

11. For a single phase mid-point cyclo-converter, exlain the operation of the circuit when fed to r-load with the help of neat circuit diagram an drelevant output waveforms for α=300 and α=1200 for f0=1/4 fs.

(JNTU Nov 08)

12. For a single phase mid-point cyclo-converter, explain the operation of the circuit when fed to R-load with the help of neat circuit diagram and relevant output waveforms for α = 30 0 and α = 1200 for f0 = 1/4 fs. (JNTU Feb 08, Nov 07)

13. Discuss the working of a single phase mid point cyclo converter with R-L loads and for discontinuous operation with neat circuit diagram and output rms voltage and current waveforms for f0=1/3 fs.


14. Explain the operation of single phase bridge type cyclo converter when fed form 230V, 50Hz source and controlling power to resistive load with the help of neat circuit diagram and output voltage and current waveforms for α = 450 and α = 1600 for f0 = 1/5 fs. (JNTU Nov 07)

15. Explain the operation of 3-phase dual converter fed to RL loads for non-circulating current mode. With neat circuit diagram and waveforms. (JNTU Feb 07, Mar 06)

16. A three phase, six pulse fully controlled converter is connected to three phase ac supply of 440V and 50Hz and operates with a firing angle of pi/5 radians. The load current is maintained constant at 5 Amps and load voltage is 440V. Calculate load resistance, source inductance and overlap angle.


17. A three phase, fully controlled converter is connected to a resistive load. Show that the average output voltage is given by (JNTU Feb 07)

18. A three phase, half wave converter is supplying a load with a continuous constant current of 40A over a firing angle from 00 to 750. What will be the power dissipated by the load at these limiting values of firing angle? The supply voltage is 415V (line). (JNTU Nov 06)

233


19. A three phase, fully controlled bridge converter is supplying dc load of 400V, 60A from a three phase 50Hz, 660V (line) supply. If the thyristors have a voltage drop of 1.2V when conducting, then neglecting overlap, compute

i. firing angle of thyristorii. RMS value of thyristor currentsiii. mean power loss in thyristors (JNTU Nov 06)

20. Single phase dual converter is operated from 230V, 50Hz supply and the load resistance 10 ohms. The circulating inductance is LC = 40mH, firing angles are á1 = 600 and á2 = 1200. Calculate the peak circulating current, peak currents of converter 1 and converter 2. Also compute the load current.


21. A six pulse thyristor converter is connected to the mains through a transformer of 6% reactance. If the rms value of the voltage at the secondary of the transformer is 415V, calculate the voltage regulation. Neglect resistance in converter. The full load dc current is 200A. What is the value of commutation angle. (JNTU Nov 05)

22. i. Describe the effect of source inductance on the performance of a 3-phase full converter with the help of phase voltage waveforms. Indicate the sequence of conduction of various thyristors and sketch load current waveforms for both positive and negative group of thyristors.

ii. For the purpose of delivering energy from dc source to 3-phase system, the firing angle of the 3-phase converter has been increased to 1500. For the same value of DC source current of 10A, compute the output ac line voltage. (JNTU May, Nov 04)

23. i. Describe in detail the operation of dual converter in non- circulating current mode.ii. Two three phase full converters are connected in anti parallel to form a three phase dual converter of

the circulating current type. The input to the dual converter is 3 phase, 400V, 50Hz. If the peak value of the circulating current is to be limited to 20A, find the value of inductance needed for the reactor for firing angle of 60°. (JNTU Nov 04)

24. i. For a 3-phase full converter, explain how output voltage wave, for a firing angle of 300, is obtained by using i. phase voltages and ii. line voltages.

ii. A resistive load of 10 ohm is connected to a 3-phase full converter. The load takes 5 kW for a firing angle delay of 700. Find the magnitude of per phase input supply voltage. (JNTU Nov 04)

25. A three phase fully controlled bridge converter supplies a dc voltage source of 400V having an internal resistance of 1.8 ohm. Assume highly inductive load witha constant load current of 20A. The supply RMS load voltage per phase is 230V and source inductance in each phase is 0.005H. Compute the following by ignoring the source resistance.i. Firing angle for an output voltage of 436V ii. overlap angle (JNTU Nov 04)

26. i. Explain the line commutated inverter operation of a 3-phase full converter.ii. A naturally commutated three phase bridge inverter is used for power transfer from a 300V battery to a

3-phase 230V, 50Hz ac supply. Devices used in the bridge inverter circuit may be considered as ideal. A large filter inductor having 10 ohms resistance is included on the dc side. Calculate the power transferred and the power factor if i. = 90° and ii. =120°. (JNTU Nov 04)

27. i. Explain the operation of dual converter in circulating current mode. List the advantages and disadvantages of the scheme.

ii. Calculate the peak value of the circulating current for the 3 phase circulatory current type dual converter consisting of two three phase fully controlled bridges for a the given data: per phase supply RMS voltage = 230V, Frequency, f = 15 Hz, L=0.015 H, 1 =60°, 2= 120° (JNTU Nov 04)

28. i. Derive the expression for peak value of the circulating current in a dual converter.ii. A single phase fully controlled double bridge converter is operated from a 120V, 60 Hz supply and the

load resistance is 10 ohms. The circulating inductance is 40mH. Firing delay angle for converter I and II are 600 and 1200 respectively. Calculate the peak circulating current and the current through converters. (JNTU Nov 04)

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29. For a 3-Ø full converter, explain how output voltage wave for a firing angle of 300 is obtained by using

i. phase voltage ii. line voltage of 600. (JNTU May 04)

30. Two three phase full converters are connected in anti parallel to form a three phase dual converter of the circulating current type. The input to the dual converter is 3 phase, 400V, 50Hz. If the peak value of the circulating current is to be limited to 20A, find the value of inductance needed for the reactor for firing angle of 60°. (JNTU May 04)

31. A resistive load of 10 ohm is connected to a 3-phase full converter. The load takes 5 kW for a firing angle delay of 700. Find the magnitude of per phase input supply voltage. (JNTU May 04)

32. A three phase full converter is operated from a three phase 400V, 50Hz supply. The load resistance is 10 ohms. Calculate the firing angle for an average output voltage of 60% of the maximum possible mean output voltage. Calculate also the RMS value of load current. (JNTU Nov 03)

33. A three phase fully controlled bridge converter supplies a dc voltage source of 400V having an internal resistance of 1.8 ohm. Assume highly inductive load with a constant load current of 20A. The supply RMS load voltage per phase is 230V and source inductance in each phase is 0.005H. Compute the following by ignoring the source resistancei. firing angle for an output voltage of 436V ii. Overlap angle (JNTU May 03)

34. Explain the operation of dual converter in circulating mode. List the advantages and disadvantages of the scheme (JNTU May 03)

35. A 3Ø full converter is operated from a 3Ø 400 V, 50 Hz supply, the load resistance is 10 ohms. Calculate the firing angle for an average output voltage of 60% of the maximum possible mean output voltage. Calculate also the RMS. Value of load current. (JNTU May 03)

36. A three-phase Bridge is used to provide rectified output from a 400 V 50 Hz 3 phase supply to a RL load with 10Ohm resistance and 300 mH inductance. Determine the

i. DC level of the output voltage ii. RMS value of the diode currentiii. RMS value of source current iv. Apparent power drawn from the mains (GATE 99)

37. A 3 phase fully controlled thyristor converter is operated from an ac supply of 400 V rms line to line. When the converter is operated in the rectifier mode at a control angle of 30 degree, the overlap angle due to the line reactance is 15 degree. Calculate the reduction in dc output voltage due to overlap, if the converter operates in the inverter mode with firing angle of 1200 and without any change in the dc load current, what will be the overlap angle. (GATE 93)

38. A line commutated ac to dc converter is operated from a 3 phase, 50 Hz, 580 V (line to line) supply .it supplies a load current of 346A. Assume load current to be ripple free and neglect source inductance.

i. calculate the delay angle of the converter if its average output voltage is 648V.ii. calculate the power delivered to the load R in KW.iii. Sketch the waveform of the supply current.iv. Calculate fundamental reactive power drawn by converter from the supply in KVAR. (GATE 92)

39. In a 3-phase rectifier circuit, thyristor number 1, 2 and 3 are connected to R, Y, B phases of star connected transformer respectively. When the current is being commutated from thyristor 1 to 2, the effect of transformer leakage and the A.C system inductance will be such that it will

i. prolong the conduction in No.1 and delay the turn on of No.2 correspondingly ii. stop the conduction in No.1 at the scheduled time but the delay turn on of No.2.iii. produce conduction in both No.1 and No.2 in parallel for an overlapping period through transient.iv. double the voltage output through commutation transient. (IES 97)

40. What are the effects of source reactance in converter circuits? (JNTU Nov 03)

41. Explain the principle of operation of a 3-phase fully controlled rectifier with neat circuit diagram and waveforms. (JNTU Nov 03)

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42. A phase fully controlled rectifier is operated from a 3-phase Y connected 220V, 50Hz supply. It is required to obtain an average output voltage of 50% of maximum possible output voltage. Calculate i. delay angle, ii. average current, iii. input power factor. Give load resistance 10 ohms.

(JNTU Jun 02)43. A 3 phase converter feeds an RL-Load .Draw the wave forms of out put current and load voltages for

both continuous and discontinuous conduction. (JNTU Jan 01)

44. A three phase fully controlled bridge converter is fed from a 400V, 50Hz, 3-phase supply .It feeds a pure resistive load at 12 ohms for a firing angle of 600. Calculate average of output voltage and RMS output current. (JNTU Aug 00)

45. Explain the operation of a 3 phase fully controlled bridge converter with RL load. Draw the voltage and current waveforms for =300 and = 1200. Derive the expression for average output voltage and RMS output voltage. What is the effect of free wheeling diode on the output voltage? (JNTU Aug 00)

46. A three phase, half wave rectifier is operated by a three phase star connected 220 volts, 50 Hz supply. The load resistance is 12ohms. Load inductance is negligible. If it is required to obtain 75% of the maximum possible output voltage, calculate the i. firing angle ii. average and RMS load currents iii. average and RMS thyristor currents iv. rectification efficiency and v. transformer derating factor.

47. A three phase, half wave rectifier supplies a load with R1=5ohms and Ld=20mh. If the firing angle alpha=70 degree and the ac input voltages 160 volts (RMS), determine V and I.

48. .A three phase half wave rectifier is supplied by the transformer with a secondary voltage of 180volts (RMS) at 50 Hz. Other data are Rb=10 ohms, Ld=10mh, and back emf Eb=153volts. Determine V and I for firing angle of 60 degrees. Also sketch the wave forms.

49. A three phase half wave rectifier is supplied by a 220 volts 3 phase supply and feeds an Rb+Eb load with R1=15ohms and Eb=120volts. Determine the ranges of firing for which conduction is i. continuous and ii. discontinuous.

UNIT – VI

1. Explain the operation of a basic dc chopper and obtain the following as a function of E dc, R and duty cycle δ.

a. average output voltage and current b. rms value of the output voltagec. RMS and average load currents (JNTU May 09)

2. An ideal chopper operating at a chopping period of 2ms supplies a load of 4 ohms having an inductance of 8 mH from a 80V battery. Assuming the load is shunted by a perfect commutating diode, and battery to be loss less, compute load current waveforms for Ton / Toff values of 1/1, 4/1.

(JNTU May 09)

3. For the ideal type A-chopper circuit, following conditions are given, Edc = 220V, chopping frequency, = 500 Hz, duty cycle δ=0.3 and R = 1 ohm, L = 3mH and Eb = 23V. Compute the following quantities.

a. Check whether the load current is continuous or not.b. Average output currentc. maximum and minimum values of steady state output current (JNTU May 09)

4. a. Describe the principle of operation of a step down chopper. Derive an expression for the average output voltage in terms of input dc voltage and duty cycle.

b. A chopper circuit is operating on TRC principle at a frequency 1 KHz on a 220V dc supply. If the load voltage is 180V, calculate the conducting and blocking period of thyristor in each cycle.

(JNTU May 09)

5. Explain the operation of step-up chopper with neat circuit diagram and necessary output waveforms and also derive expression for output voltage. (JNTU May 09)

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6. For a current commutated chopper, peak commutating current is thrice the max. possible load current. The source voltage is 220V dc and main SCR turn-off time is 20 µs. For a max. load current of 180A. Compute

a. the value of commutating components L and Cb. Max. capacitor voltage andc. the peak commutating current. (JNTU May 09)

7. Explain the operation of a basic dc chopper and obtain the following as a function of Edc, R and duty cycle δ.

a. average output voltage and currentb. rms value of the output voltagec. RMS and average load currents (JNTU May 09)

8. Explain the operation of class -C commutation circuit and also give its application with neat circuit.(JNTU May 09)

9. Explain the time ratio control and current limit control strategies used for choppers, with necessary waveforms and circuit. (JNTU Nov, Feb 08)

10. Explain the operation of a basic dc chopper and obtain the following as a function of E dc, R and duty cycle δ.

a. average output voltage and currentb. rms value of the output voltagec. RMS and average load currents (JNTU Nov 08)

11. a load commutated chopper, fed from a 230V dc source has a constant load current of 50A. For a duty cycle of 0.4 and a chopping frequency of 2 KHz. Calculate

a. The value of commutating capacitanceb. Average output voltagec. Circuit turn-off time for one SCR paird. Total commutation interval (JNTU Nov 08)

12. Derive the expression for minimum and maximum values of load current for a type A chopper and also derive the current ripple. (JNTU Nov 08)

13. For the ideal type A-Chopper circuit, following conditions are given, Edc = 220V,chopping frequency, = 500 Hz, duty cycle δ=0.3 and R = 1 ohm, L = 3mH and Eb= 23V. Compute the following quantities.

a. Check whether the load current is continuous or not.b. Average output currentc. maximum and minimum values of steady state output current (JNTU Nov 08, 07)

14. A current commutated chopper controls a battery powered electric car. The battery voltage is 100V, starting current is 100A, thyristor turn-off time is 20 µs, chopping frequency is 400Hz. Compute the values of commutating capacitor and commutating inductor. Assume Icm / Iom = 3.

(JNTU Feb 08)

15. An ideal chopper operating at a chopping period of 2ms supplies a load of 4 ohms having an induction of 8 mH from a 80V battery. Assuming the load is shunted by a perfect commutating diode, and battery to be loss less, compute load current waveforms for Ton / Toff values of 1/1, 4/1. (JNTU Feb 08)

16. Explain the operation of step-up chopper with neat circuit diagram and necessary output waveforms and also derive expression for output voltage. (JNTU Feb 08)

17. Explain the operation of a basic dc chopper and obtain the following as a function of Edc, R and duty cycle δ.

a. average output voltage and currentb. rms value of the output voltagec. RMS and average load currents (JNTU Feb 08, Nov 07)

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18. Explain the operation of DC Jones chopper for RL loads with neat circuit diagram and output voltage and current waveforms. Also sketch firing signals (JNTU Feb 08)

19. An ideal chopper operating at a chopping period of 2ms supplies a load of 4 ohms having an inductance of 8 mH from a 80V battery. Assuming the load is shunted by a perfect commutating diode, and battery to be loss less, compute load current waveforms for Ton / Toff values of 1/1, 4/1 . (JNTU Feb 08)

20. Explain the working of Class-D commutation circuit and also mention its application with neat circuit(JNTU Nov 07)

21. Derive the output rms voltage, output rms current and source power factor for a single phase ac voltage controller fed to R-L load. (JNTU Feb 07)

22. Explain the operation of single phase midpoint cyclo converter with R-L load s for continuous conduction with relevant circuit diagram nd necessary output waveforms for f0 = 1/3 fs.


23. The ac voltage controller uses on-off control for heating a resistive load of R = 4 ohms and the input voltage is Vs = 208V, 60Hz. If the desired output power is Po = 3KW, determine the

i. duty cycle aii. input power factoriii. sketch waveforms for the duty cycle obtained in (i.) (JNTU Feb 07, Mar 06)

24. Discuss the working of a single phase bridge type cyclo converter with RL loads and for discontinuous operations with relevant output waveforms and circuit diagram for f0 = 1/2 fs


25. Explain the operation of a single phase ac voltage controller with neat circuit diagram and output waveforms with respect to source voltage waveforms at a= 600 for Resistive load.


26. For a single phase mid-point cyclo-converter, explain the operation of the circuit when fed to R-load with the help of neat circuit diagram and relevant output waveforms for a = 300 and a = 1200 for f0 = 1/4 fs. (JNTU Nov 06, May 05)

27. Two SCRs are connected back-to-back have a load resistance of 400 ohms and a supply of 110V ac. If firing angle is 600, find i. the rms output voltage ii. average power. (JNTU Nov 06)

28. A single phase full wave ac voltage controller has a resistance load of i. 10 ohms and ii. 5 ohms.The input ac voltage is 230V, 50Hz. For a delay angle of 900, determine the rms load voltage, rms load current, rms thyristor current and input power factor for above two loads.(JNTU Nov 06, 05, May 05)

29. Discuss the operation of a single phase ac voltage controller with RL load when a is less than, or equal to load phase angle. Hence show that for a less than load angle, the output voltage of the ac voltage controller can not be regulated. (JNTU Mar 06)

30. i. Explain the principle of ON-OFF control used in a.c. voltage controller.ii. Derive the expression for the input power factor in an a.c. voltage controller using ON-OFF control.iii. Explain its application with the help of a circuit and waveforms. (JNTU Mar 06)

31. An a.c. voltage controller supplies power to a resistive load of 20 ohms. The rms of input voltage is 220V at 50Hz. The thyristors are switched ON for 30 cycles and OFF for 70 cycles. Calculate the values of

i. the rms output voltageii. input power factoriii. the average and rms values of thyristor currents (JNTU Nov 05)

32. i. What is a cyclo converter?

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ii. What are the varieties of single phase cyclo converters.iii. What are the salient features of cyclo converters.iv. What are the major limitations of cyclo converters. (JNTU Nov 05)

33. Discuss the working of a single phase mid point cyclo converter with R-L loads and for discontinuous operation with neat circuit diagram and output rms voltage and current waveforms for f0=1/3 fs.

(JNTU Nov 05)

34. Explain 1Ø phase step down cycloconverter with output frequency of ¼ of input frequency with the help of bridge type for RL load continuous conduction with neat waveform. (JNTU May 05, 04)

35. Compare the operational features of 1Ø midpoint and bridge type of cyclo converters for R-L loads, with neat circuit diagram and waveforms. (JNTU May 05, 02)

36. A 1Ø 230V, 50 Hz source connected to an anti parallel connected thyristor circuit controlling power to

the following loads, when á = 300. Calculate output voltages, output current and load power factor i. R=10 ohms, L=0H ii. R=10 Ohms, L=20 MH. (JNTU May 05, 03)

37. Derive the expressions for the power dissipated in the load, rms load voltage and current for a single phase AC voltage controller feeding Resistive-inductive load for discontinuous operation of current. Explain the operation of the above circuit for continuous current condition. (JNTU May 05, 02)

38. Explain the operation of single phase A.C. voltage controller with Resistive and Resistive- sketch the transfer characteristics. (JNTU Nov 04)

39. Explain the working of single phase bridge type cyclo converter with RL load for i. Continuous conduction and for ii. discontinuous conduction with the help of neat circuit diagram and relevant output waveforms.

(JNTU Nov 04, May 04)40. Explain the operation of single phase A.C. Triac based circuit when controlling Power to RL loads.

Give the output voltage, current waveforms with neat circuit diagram. Suggest the firing circuit for Triac. (JNTU Nov 04)

41. i. What is cyclo converter? What are its limitations?ii. Compare the operational features of single phase midpoint and bridge type cyclo converter for R-L

loads, with neat circuit diagrams and waveforms. (JNTU Nov 04)

42. i. Derive the expressions for the output r.m.s voltage, output r.m.s current and output power for a single phase A.C voltage controller when feeding power to R-load.

ii. For a single phase AC voltage controller with R-load, obtain Vo r.m.s, Io r.m.s when supplied from 230V, 50Hz single phase source and fired at 65o. (JNTU Nov 04)

43. A 1-phase 230V, 50HZ source connected to as anti parallel connected thyrister circuit controlling power to the following loads, when =90o.Calculate output voltage and output current and load power factor for i. R=10 OHMS; L=0 H ii. R=10 OHMS; L=60mH. (JNTU Nov 04)

44. Discuss the working of single phase midpoint cycloconverter when feeding R and RL loads with neat circuit diagram and relavent output waveforms. (JNTU Nov 04)

45. For a given 1Ø AC Voltage controller obtain the transfer characteristics for i. Resistive load of 100¿ (JNTU May 04)ii. Resistive-inductive load of R=100, L=90 MH where fed from 230V, 50Hz, 1Ø Phase AC source.

46. Derive the expression for the output rms voltage, output rms current and output power for a 1Ø phase AC voltage controller when feeding power to R load. (JNTU May 03)

47. Enumerate the basic differences between a triac and a thyristor. Draw and explain V-I Characteristics of a Triac. Draw and explain a full wave triac phase control circuit. (GATE 95)

48. A single-phase ac regulator has a resistive load of R=20 ohms and input voltage (rms) 230 V, 50 Hz. The firing angles of both the thyristors are same and equal to 90 degree. Determine

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i. rms output voltage ii. Power dissipated in resistor iii. Supply PFiv. Average current of the thyristor v. rms current of thyristor (GATE 96)

49. Describe the operation of single phase half-wave a.c. voltage regulator withy the help of voltage and current waveforms. Also, derive the expression for average value of output voltage.

50. List the advantages and disadvantages of single-phase half-wave (unidirectional) a.c. regulator.

51. For a single-phase a.c. voltage regulator feeding a resistive load, draw the waveforms of source voltage, gating signals, output voltage, source and output currents and voltage across SCRs. Describe its working with reference to the waveforms drawn

UNIT – VII

1. Explain the auxiliary impulse commutation techniques used in the bridge type single phase inverter with neat circuit diagram. (JNTU May 09)

2. Draw and explain the simple SCR series inverter circuit employing class A type commutation. With the help of important waveforms. State the limitations of this inverter. (JNTU May 09)

3. a. A single-phase bridge Inverter feeds an R-L-C series load with R=3Ω, L=6mH & C=15µF. The output frequency is 120Hz, supply voltage being 180V. Express the output voltage in terms of Fourier series & determine, i. RMS values of thyristor current load current.ii. Current at the instant of commutation considering up to 7th harmonics only.

b. What is meant by load commutation in an Inverter? Under what condition commutation can be achieved by load. (JNTU May 09)

4. Draw and explain the simple SCR series inverter circuit employing class A type commutation. With the help of important waveforms. State the limitations of this inverter. (JNTU May 09)

5. Single phase half bridge inverter has a resistive load of R = 3 ohms and dc input voltage Edc = 50V. Calculate

a. rms output voltage at fundamental frequency E1

b. the output powerc. average and peak current of each thyristor (JNTU May 09)

6. Explain the auxiliary impulse commutation techniques used in the bridge type single phase inverter with neat circuit diagram. (JNTU Nov 08)



b. the output powerc. erage and peak current of each thyristor (JNTU Nov 08)

8. Draw and explain the simple SCR series inverter circuit employing class A type commutation. With the help of important waveforms. State the limitations of this inverter. (JNTU Nov 08)



b. the output powerc. average and peak current of each thyristor (JNTU Feb 08, Nov 07)

10. Draw and explain the simple SCR series inverter circuit employing class A type commutation With the help of important waveforms. State the limitations of this inverter. (JNTU Feb 08, Nov 07)

11. Single phase half bridge inverter has a resistive load of R = 3 ohms and dc input voltage E dc = 50V. Calculate


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b. the output powerc. average and peak current of each thyristor (JNTU Feb 08, Nov 07)

12. Explain the auxiliary impulse commutation techniques used in the bridge type single phase inverter with neat circuit diagram (JNTU Feb 08)

13. Explain the operation of a basic dc chopper and obtain the following as a function of Edc, R and duty cycle

i. average output voltage and currentii. rms value of the output voltageiii. RMS and average load currents (JNTU Feb 07, Mar 06, 05)

14. An ideal chopper operating at a chopping period of 2ms supplies a load of 4 ohms having an induction of 8 mH from a 80V battery. Assuming the load is shunted by a perfect commutating diode, and battery to be loss less, compute load current waveforms for Ton / Toff values of 1/1, 4/1.

(JNTU Nov 06)

15. A load commutated chopper, fed from a 230V dc source has a constant load current of 50A. For a duty cycle of 0.4 and a chopping frequency of 2 KHz, Calculate

i. the value of commutating capacitanceii. average output voltageiii. circuit turn-off-time for one SCR pairiv. total commutation interval (JNTU Nov 06)

16. Explain the operation of DC Morgan’s Chopper for resistive load with neat circuit diagram and output voltage and current waveforms. (JNTU Nov 06)

17. i. A step-up chopper with a pulse width of 150 µs operating on 220V, dc supply. Compute the load voltage if the blocking period of the device is 40 µs.

ii. What is the necessity of step-up chopper where do you use. (JNTU Nov 06)

18. A current commutated chopper controls a battery powered electric car. The battery voltage is 100V, starting current is 100A, thyristor turn-off time is 20 µs, chopping frequency is 400Hz. Compute the values of commutating capacitor and commutating inductor. Assume Icm / Iom = 3.

(JNTU Mar 06, Nov 05)

19. Explain the time ratio control and current limit control strategies used for choppers, with necessary waveforms and circuit. (JNTU Mar 06)

20. A dc on-off chopper operating at 1 KHz and duty cycle of 10% is supplied from a 200V source. If the load inductance is 10mH and resistance 10 ohms. Compute the max. and min. circuit in the load.

(JNTU Mar 06)21. i. A step-up chopper with a pulse width of 150 µs operating on 220V, dc supply. Compute the load

voltage if the blocking period of the device is 40 µs.ii. What is the necessity of step-up chopper where do you use. (JNTU Nov 05)

22. i. Explain the operation of Jones chopper with neat waveforms.ii. Mention the advantages of Jones chopper circuit over other chopper circuits. Give the applications of

this chopper. (JNTU May 04)

23. i. Describe the operation of a Morgan chopper with neat circuit diagram and associated waveforms. ii. Enumerate the demerits of Morgan chopper over Jones chopper and also give few applications.

(JNTU May 04)

24. i. Explain the principle of operation of an oscillation chopper with neat sketches. ii. Explain in brief how average voltage across the load is made more than DC supply voltage using

chopper .Derive the expression for average voltage. (JNTU May 04)

25. i. Explain the operation of single phase AC chopper.

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ii. With the help of voltage and current waveforms, explain the working of type D chopper.(JNTU May 04)

26. With the help of voltage and current waveforms explain the working of type D Chopper.(JNTU May 04)

27. i. Derive the expressions for the Power dissipated in the load, for a single phase AC voltage controller feeding Resistive-inductive load for discontinuous operation of current.

ii. Explain the operation of the above circuit for continuous current conditions. (JNTU Nov 03)

28. i. What is current limit control of chopper? Explain the operation.ii. The speed of a separately excited dc motor is controlled by a chopper. The dc supply voltage is 120V,

armature circuit resistance is Ra=0.5, armature circuit inductance is La=20mH, and motor back emf constant is Kb=0.05 v/rpm. The motor drives a constant torque load requiring an average armature current of 20A.Assume that motor current is continuous.Determine i. the range of speed control ii. the range of the duty cycle. (JNTU Jun 03)

29. i. Describe the operation of voltage commuted chopper with relevant circuit and voltage waveforms. ii. A load commutated chopper fed from a 230V, DC source, has a constant load current of 50A. For a

duty cycle of 0.4 and a chopping frequency of 2KHz compute i. the average output voltage ii. the value of commutating capacitance. (JNTU Jun 03)

30. i. Draw the power circuit diagram of a current commuted chopper. Explain the working of a chopper by dividing its commutation process interval into well defined modes.

ii. A step up chopper has input voltage of 220V and output voltage of 660V, if the non-conducting time of the thyristor chopper is 100 µsec, compute the pulse width of output voltage. In case pulse width is halved for constant frequency operation, find the new output voltage. (JNTU Jun 03)

31. Describe the principle of DC Chopper operation. Derive an expression for its average DC output voltage. (JNTU May 03)

32. A step up chopper has input voltage of 220 V and output voltage of 660V. The non-conducting time of the SCR chopper is 100 microsecs. Compute the pulse width of output voltage. In case pulse width is halved for constant frequency operation, find the new output voltage. (JNTU May 03)

33. A battery is charged from a constant dc source of 220 V through a chopper. The dc battery is to be charged from its internal emf of 90 V to 122 V.The battery has internal resistance of 1 ohm. For a constant charging current of 10 A. compute the range of duty cycle. (JNTU May 02)

34. A chopper circuit is operating on TRC principle at frequency 1KHZ on a 220 V dc supply .if the load voltage is 180, calculate the conducting and blocking period of thyristor in each cycle.

(JNTU May 02)

35. Describe the principle of operation of a step down chopper. Derive an expression for the average output voltage in terms of input dc voltage and duty cycle. (JNTU May 02)

36. In the chopper circuit shown, the main thyristor (TM) is operated at a duty ratio of 0.8 which is much larger the commutation interval. If the maximum allowable reapplied dvldt on TM is 50 VIP, what should be the theoretical minimum value of CI ? Assume current ripple through L0 to be negligible.

a. 0.2 μF b. 0.02 pF c. 2 μF d. 20μF (GATE 09)

37. A single phase voltage source inverter is feeding a purely indctive load as shown in the figure. The invertr is operated at 50Hz in 1800 square wave mode. Assume that the load current does not have any dc component. The peak value of the inductor current i0 will be (GATE 08)

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a. 6.37 A b. 10A c. 20A d. 40A

38. A load commutated chopper fed from a 230V, DC source has a constant load current of 50A. For a duty cycle of 0.4 and a chopping frequency of 2KHZ Compute. i. The average output voltage ii. The value of commutating capacitance (GATE 03)

39. A load commutated thyristor chopper circuit is operated at 500 Hz with 50% duty cycle. The load takes a constant current of 20A.

i. Evaluate the circuit turnoff time for the main thyristorii. Calculate the value of inductance L, if the peak current trough the main thyristor is limited to 180 % of

the load current.iii. Calculate the maximum instantaneous output voltage of the chopper. (GATE 01)

40. A voltage commutated thyristor chopper circuit is shown in figure. The chopper is operated at 500 Hz with 50% duty ratio. The load takes a constant current of 20A

i. Explain the circuit turn off times for the main thyristor Th1.ii. Calculate the value of the peak current through the main thyristor Th1.iii. Calculate the maximum instantaneous output voltage of the chopper. (GATE 01)

41. A separately excited DC motor is fed from a chopper operating at 500 Hz with a duty cycle of 50% and

is drawing an average current of 10A from a 200 V DC source. A freewheeling diode is connected across it. The motor has negligible armature resistance, a field inductance of 50 mh and a torque constant of 0.5 N-m/A. Determine the minimum and maximum motor current, motor back e.m.f. and the mechanical torque developed. (GATE 97)

42. The chopper circuit, shown in figure below, is operating at duty ratio of 0.5 at 100 Hz. The load current is continuous at steady state but varies between 10A and 3A Draw the following wave shapes of currents through,i. Load (iL) ii. Free wheeling diode (if) iii. Commutation capacitor (ic). (GATE 94)

43. An ideal chopper operating at a frequency of 500Hz feeds a RL load R=30 and L=9mH from a 48 V

battery. The load is shunted by a freewheeling diode. Battery is lossless. Assuming the duty cycle of chopper to be 50%, computei. Peak load current ii. Minimum load current iii. Average load currentiv. Average load voltage v. Current exertions in load current (GATE 96)

44. The circuit of a chopper driven separately excited dc motor. The single-pole double throw switch operates with a switching period (Ton/Ts) is 0.2.The motor may be assumed to be loss less, with an armature inductance of 10 mH. The motor draws an average current of 20 A at a constant back emf of 80 V steady state.

i. Sketch and label the label the voltage waveform.ii. Sketch and label the motor current for one switching period iii. Evaluate the peak-to-peak current ripples of the motor. (GATE 91)

45. A boost regulator has an input voltage of 5 V and the average output voltage of 15V. The duty cycle isi. 3/2 ii. 2/3 iii. 5/2 iv. 15/2 (IES 03)

46. Explain in brief how average voltage across the load is made more than DC supply voltage using chopper. Derive the expression for average voltage. (IES 03)

47. What is DC chopper? Discuss with necessary circuit diagram the principle of operation of ai. Step down chopper ii. Step up chopper,Give comments on chopping frequency. (IES 03)

243


48. Enumerate the basic difference between a Triac and a thyristor. Draw and explain V-I characteristic of a Triac. Draw and explain a full wave Triac phase control circuit. (IES 00)

49. What is a resonant pulse converter? List different types of converters. Discuss the advantages and disadvantages of parallel resonant inverters. (IES 97)

50. Draw the schematics of step-down and step-up choppers and derive an expression for output voltage in terms of duty-cycle for a step-up and step-down chopper.

UNIT – VIII

1. A single phase full bridge inverter uses a uniform PWM with two pulses per half cycle for voltage control. Plot the distortion factor, fundamental component, and lower order harmonics against modulation index. (JNTU May 09)

2. The single phase full bridge auxiliary commutated inverter has a load of R = 5 ohms, L = 10mH and C = 25µF. The input dc voltage is Vs = 220V and inverter frequency is f0 = 60Hz, tq = 18µs. Determine the optimum values of commutation components Cm and Lm. (JNTU May 09)

3. A single PWM full bridge inverter with a source voltage, 240V has to feed a purely resistive load of 10 ohms. The pulse width is so selected that the third harmonic current is eliminated.

a. Find out the output power and the average source currentb. What should be the pulse width and the output power, if the 5 th harmonic component is to be

eliminated. (JNTU May 09)

4. A single phase full bridge inverter uses a uniform PWM with two pulses per half cycle for voltage control. Plot the distortion factor, fundamental component, and lower order harmonics against modulation index. (JNTU May 09)

5. A single-phase full wave A.C voltage controller controls power to an R-L load. The source being 230V, angle of retard is 300. Obtain SPICE model statement for the same to compute o/p voltage, current and power . (JNTU May 09)

6. Explain the voltage control in case of single phase bridge inverter circuit, in order to get variable voltage and variable frequency output. (JNTU May 09)

7. The single phase modified Me Murray full-bridge inverter is fed by dc source of 300V. The d.c. source voltage may fluctuate by ±15% . The current during commutation may vary form 20 to 100A. Obtain the value of commutating components, if the thyristor turn-off time is 20 µs. Also compute the value of R.

8. A single phase full bridge inverter uses a uniform PWM with seven pulses per half cycle for voltage control. Plot distortion factor, fundamental component and lower order harmonics against the Modulation index. (JNTU May 09)

9. Calculate the output frequency of a series inverter circuit with following parameters, L = 10mH, C = 0.1 µF, R = 400 ohms, toff = 0.2 msec. Also determine the attenuation factor. (JNTU May 09)

10. Explain the forced commutation techniques used for single phase bridge inverter with neat circuits and waveforms. (JNTU Nov 08)

11. A single PWM full bridge inverter with a source voltage, 240V has to feed a purely resistive load of 10 ohms. The pulse width is so selected that the third harmonic current is eliminated.

a. Find out the output power and the average source currentb. What should be the pulse width and the output power, if the 5 th harmonic component is to be

eliminated. (JNTU Nov 08)

244


12. The single phase modified Me Murray full-bridge inverter is fed by dc source of 300V. The d.c. source voltage may fluctuate by ±15% . The current during commutation may vary form 20 to 100A. Obtain the value of commutating components, if the thyristor turn-off time is 20 µs. Also compute the value of R. (JNTU Nov 08)

13. Calculate the output frequency of a series inverter circuit with following parameters, L = 10mH, C = 0.1 µF, R = 400 ohms, toff = 0.2 msec. Also determine the attenuation factor. (JNTU Nov 08)

14. Explain the voltage control in case of single phase bridge inverter circuit, in order to get variable voltage and variable frequency output. (JNTU Feb 08)

15. A single PWM inverter feeds an RL load with R = 10 ohms, and L = 20mH. If the Vs = 120 V, find out the total harmonic distortion in the load current. The width of each pulse is 1200 and the output frequency is 50Hz. (JNTU Feb 08)

16. The single phase full bridge auxiliary commutated inverter has a load of R = 5ohms,L = 10mH and C = 25µF. The input dc voltage is Vs = 220V and inverter frequency is f0 = 60Hz, tq = 18µs. Determine the optimum values of commutation components Cm and Lm. (JNTU Feb 08)

17. a. What are the different pulse width modulation techniques used for inverters.b. Which of the schemes gives better quality of voltage and current (JNTU Feb 08, Nov 08, 07)

18. A single phase full bridge inverter uses a uniform PWM with two pulses per half cycle for voltage control. Plot the distortion factor, fundamental component, and lower order harmonics against modulation index (JNTU Feb 08, Nov 08, 07)

19. Explain the forced commutation techniques used for single phase bridge inverter with neat circuits and waveforms. (JNTU Feb 07, Mar 06)

20. Draw and explain the simple SCR series inverter circuit employing class A type commutation. With the help of important waveforms. State the limitations of this inverter.

(JNTU Feb 07, Mar 06, Nov 06, 05)


i. rms output voltage at fundamental frequency E1ii. the output poweriii. average and peak current of each thyristor. (JNTU Feb 07, Mar 06, Nov 05)

22. Calculate the output frequency of a series inverter circuit with following parameters, L = 10mH, C = 0.1 µF, R = 400 ohms, toff = 0.2 msec. Also determine the attenuation factor. (JNTU Feb 07)

23. The single phase full bridge auxiliary commutated inverter has a load of R = 5 ohms, L = 10mH and C = 25µF. The input dc voltage is Vs = 220V and inverter frequency is f0 = 60Hz, tq = 18µs. Determine the optimum values of commutation components Cm and Lm. (JNTU Nov 06)

24. i. What are the different pulse width modulation techniques used for inverters.ii. Which of the schemes gives better quality of voltage and current. (JNTU Nov 06, Mar 06)

25. A single PWM inverter feeds an RL load with R = 10 ohms, and L = 20mH. If the Vs = 120 V, find out the total harmonic distortion in the load current. The width of each pulse is 1200 and the output frequency is 50Hz. (JNTU Nov 06)

26. The single phase modified Me Murray full-bridge inverter is fed by dc source of 300V. The d.c. source voltage may fluctuate by ±15% . The current during commutation may vary form 20 to 100A. Obtain the value of commutating components, if the thyristor turn-o time is 20 µs. Also compute the value of R. (JNTU Nov 06)

27. What are the methods for voltage control within the inverters. Explain in detail with waveforms(JNTU Nov 08, Mar 06)

245


28. Explain the voltage control in case of single phase bridge inverter circuit, in order to get variable voltage and variable frequency output. (JNTU Mar 06, Nov 05)

29. A single phase full bridge inverter uses a uniform PWM with two pulses per half cycle for voltage control. Plot the distortion factor, fundamental component, and lower order harmonics against modulation index. (JNTU Nov 05)

30. Explain the auxiliary impulse commutation techniques used in the bridge type single phase inverter with neat circuit diagram. (JNTU Nov 05)

31. A single phase bridge Inverter feeds an RLC series load with R-3 ohms, L=6mH and C= 15mF. The output frequency is 120 Hz, supply voltage in 180V. Express the output voltage in terms of Fourier series and determine.i. RMS values of thryistor current load current.ii. Current at the instant of commutation consider up to 7th harmonics only. (JNTU Nov 05)

32. i. A single-phase bridge Inverter feeds an R-L-C series load with R=3, L=6mH & C=15µF. The output frequency is 120Hz, supply voltage being 180V. Ex-press the output voltage in terms of Fourier series & determine,i. RMS values of thyristor current load current.ii. Current at the instant of commutation considering up to 7th harmonics only.

ii. What is meant by load commutation in an Inverter? Under what condition commutation can be achieved by load. (JNTU May 05)

33. A single PWM full bridge inverter feeds an RL load with R = 10 ohms and L = 10 mH. If the source voltage is 120V, find out the total harmonic distortion in the output voltage and in load current. The width of each pulse is 1200 and output frequency is 50Hz. (JNTU May 05)

34. i. Compare Sinusoidal pulse width modulation over multiple pulse width modulation.ii. Explain Single pulse width modulation technique in a single phase bridge Inverter and mention its

salient points. (JNTU Nov, May 04)

35. A three phase fully controlled converter has R-L load of 1.5W and 4.5mH respectively and back Emf of 12V, the input voltage is 150V (rms)at 60Hz. Give the SPICE representation of the model circuit to calculate average and rms thyristor current and instantaneous o/p current at wt == 300.

(JNTU Nov 04)

36. i. Briefly discuss the different methods by which voltage control can be done externally in an inverter. ii. State why the output voltage in a parallel Inverter is not a pure sine wave.

(JNTU Nov, May 04, Jun 03)37. i. Explain the necessity of Inverters and list out the different applications of the same.

ii. Briefly explain the different types of Inverters with working principle. (JNTU Nov, May 04)

38. i. How it is possible to achieve voltage control within the Inverter. Briefly explain them.ii. Compare Single pulse width modulation over Multiple pulse width modulation technique.

(JNTU May 04)

39. i. Explain briefly the commutation process in an auxiliary commutated inverter with waveforms. ii. State the factors, which are going to affect the commutation interval in a McMurray-Bedford Inverter.40. State why the output voltage in a parallel Inverter is not a pure sine wave. (JNTU May 04)

41. Compare single pulse width modulation with multiple pulse width modulation technique.(JNTU May 04)

42. i. Give the difference between principle of operation of series and parallel Inverter circuits.ii. Distinguish between different methods commonly used for forced commutation in Inverters

(JNTU Nov, Jun 03)

43. i. Explain the operation of a parallel inverter and mention its merits.

246


ii. Mention the purpose of feedback diodes in Inverter and condition under which those are not required.(JNTU Nov, Jun 03)

44. i. Explain why output voltage control is required in Inverters.ii. Briefly list out the merits and demerits of any three types of voltage control technique used at the input

of Inverter. (JNTU Nov 03)

45. i. Discuss the main classification of dc to ac thyristor converters. Which of these is most commonly employed why? (JNTU Jun 03)

ii. Describe the principle DC chopper operation. Derive an expression for its average dc output voltage.

46. Give two differences between principle of operation of series and parallel inverter circuits.(JNTU May 03)

47. Distinguish between different methods commonly used for forced commutation in inverters.(JNTU May 03)

48. Mention the purpose of feedback diodes in inverter and condition under which those are not required.(JNTU May 03)

49. i. For a single-phase bridge inverter the source voltage is 60V, load is a resistance of 1.2ohm. Determine the RMS value of 1st , 3rd & 5th harmonic o/p current, load power, average and peak current in each thyristor, PIV across thyristor and total harmonic distortion and distortion factor.

ii. What are the factors to be considered while selecting commutating elements in Inverters?(JNTU May 02)

50. Briefly list out the merits and demerits of any three types of voltage control technique used at the input of inverter. (JNTU May 02)

51. Draw the possible output current and voltage waveforms possible in a 1Ø bridge inverter connected with R, R-L, R-C, R-L-C under C under/over damped circuits. Mention whether forced commutation is required or not in each case. Explain the significance of dead zone in series Inverters

(JNTU Nov 02)

52. Explain briefly the commutation process in an auxiliary commutated inverter with waveforms. State the factors, which are going to affect the commutation interval in a McMurray-Bedford Inverter.

(JNTU Nov 02)

53. The Current Source Inverter shown in figure is operated by alternately turning on thynstor pairs (TI, T2) and (T3, T4). If the load is purely resistive, the theoretical maximum output frequency obtainable will be

a. 125 kHz b. 250 kHz c. 500 kHz d. 50 kHz (GATE 09)

54. An HVDC lonk consists of rectifier, inverter transmission line and other equipments. Which one of the following is true for this link?

a. The transmission line produces/ supplies reactive powerb. The rectifier consumes reactive power and the inverter supplies reactive power from / to the respective

connected AC systemsc. Rectifier supplies reactive power and the inverted consumes reactive power to / from the respective

connected AC systems

247


d. Both the converters (rectifier and inverter) consume reactive power from the respective connected AC systems. (GATE 06)

55. For perfectly balanced operation of a certain 3-phase ac power electronic circuit generates odd harmonics currents of order of five and seven in the three phases of the ac mains. Identify which of these harmonics form a positive sequence system and which forms a negative sequence system.

(GATE 00)

248


5 SUBJECT WISE DETAILS

5.5 ELECTRICAL MACHINES-III

5.5.1. Objectives and Relevance

5.5.2. Scope

5.5.3. Prerequisites

5.5.4. Syllabus

i. JNTU

ii. GATE

iii. IES

5.5.5. Suggested Books

5.5.6. Websites

5.5.7. Expert Details

5.5.8. Journals

5.5.9. Recent Findings and Developments

5.5.10. Session Plan


5.5.12. Question Bank

i. JNTU

ii. GATE

iii. IES

249



The objective and relevance of this subject is to provide the student a comprehensive treatment of synchronous machines viz. synchronous generator which is universally employed for the generation of 3-phase power at all generation stations, synchronous motors and single-phase induction motors which are used in daily life like washing machines, fans, etc. The philosophy of the subject is to emphasize the physical understanding of basic principles underlying the operation of electrical machines. The physical concepts regarding the internal behaviour of electrical machines are important because these concepts only lead to creative engineering and motivation.

5.5.2 SCOPE

Most of the advances in the applications and control of electric machines have taken place owing to the break through in power electronics and microprocessor based control systems. As a result, a much broader spectrum of electric machine types are now available. Particularly permanent magnet and variable reluctance machines are now finding many applications that are bound to increase in future. AC drives are becoming more and more attractive in many applications, such as those requiring variable speed and flexible control while earlier DC machines were the only choice.

5.5.3 PREREQUISITES

The knowledge of various networks theorems, theory and operation of DC and AC electrical machines are required. Some of the basic principles from electromagnetic field and its applications are also essential to study this subject. The subjects to be referred are network theory, electro mechanics-I and electro mechanics-II.

5.5.4.i SYLLABUS – JNTU


The objective of this unit is to give detailed concepts on the working principle of various types of synchronous generators with their constructional details.

SYLLABUS

Synchronous Generator: Constructional features of round rotor and salient pole machines, armature winding, integral slot and fractional slot windings, distributed and concentrated windings, distribution pitch and winding factors, e.m.f. equation


The objective of this unit is to give detailed concepts on the various hormonics in generated e.m.f. and various methods to supress them and the study of various performance characteristics.

SYLLABUS

Harmonics in generated e.m.f., suppression of harmonics, armature reaction-leakage reactance, synchronous reactance and impedance, experimental determination, phasor diagram, load characteristics.


The objective of this unit is to deal with the rigorious details of most useful methods to find the regulation of cyllindrical and salient pole alternators with phasor diagrams.

250


SYLLABUS

Regulation by synchronous impedance method, M.M.F. method, Z.P.F. method and A.S.A. methods, salient pole alternators, two reaction analysis, experimental determinations of Xd and Xq (Slip test), phasor diagrams, regulation of salient pole alternators.


The objective of this unit is to acquire the detail knowledge on parallel operation and load sharing of synchronous generators and the effect of change of excitation and mechanical power input in synchronous generators.

SYLLABUS

Synchronizing alternators with infinite bus bars, synchronizing power torque, parallel operation and load sharing, effect of change of excitation and mechanical power input, analysis of short circuit current wave form, determination of sub-transient, transient and steady state reactances.


The objective of this unit is to give knowledge on the basic principle of operation of synchronous motor and the effect of excitation on armature current and power factor.

SYLLABUS

Synchronous Motor: Theory of operation, phasor diagram, variation of current and power factor with excitation, synchronous condenser, mathematical analysis for power developed


The objective of this unit is to describe the various methods of starting of synchronous motors, hunting and its supression in synchronous motors. This unit also gives knowledge on principle of operation of induction generator.

SYLLABUS

Excitation and power circles, hunting and its suppression, methods of starting, synchronous induction motor.


The objective of this unit is to give fair knowledge on single phase induction motors with construction details and analysis which are extensively used in general appliances in and around us.

SYLLABUS

Single phase motors: single phase induction motor, constructional features, double revolving field theory, elementary idea of cross field theory, split-phase motors, shaded pole motor.


The objective of this unit is to give fair knowledge on A.C series motor, basic principles on permanent magnet and reluctance motors and their applications.

251


SYLLABUS

Principle and performance of AC series motor, universal motor, principle of permanent magnet and reluctance motors.


UNIT – I Synchronous generator construction features and EMF equation.

UNIT – IINot covered.

UNIT – IIIRegulation of an alternator.

UNIT – IVParallel operation of synchrnous generator.

UNIT – VPrinciple and operation of synchrnous motor, synchrnous condensers.

UNIT – VIStarting methods of synchrnous motor.

UNIT – VIISingle phase induction motor, shadded pole motor.

UNIT – VIIIStepper motor.


UNIT – I Synchronous machine construction features, synchrnous reactance, EMF equation.

UNIT – II covered.

UNIT – III Regulation of an alternator.

UNIT – IV Parallel operation of synchrnous generator, short circuit - transient conditions.

UNIT – VSynchrnous motor principle and operation.

UNIT – VI Hunting.

UNIT – VII Single phase induction motor.

UNIT – VIII Stepper motor.

252



TEXT BOOKS

T1 Electric Machines, I.J. Nagrath and D.P. Kothari, 7th Edn.,Tata Mc Graw-Hill Publishshers, 2005.T2 Electrical Machines, P.S. Bimbra, Khanna Publishers.

REFERENCE BOOKS

R1 The Performance and Design of A.C.Machines, M.G. Say, ELBS and Pitman Sons.R2 Electric Machinery, A.E.Fitzgerald, C.Kingsley and S.Umans, 5th Edn., Mc Graw-Hill Companies,

1990.R3 Electrical Machines, Mukerjee and Chjakravarthy, Khanna Publishers.R4 Theory of Alternating Current Machinery, Langsdorf, 2nd Edn., Tata Mc Graw-Hill.R5 Electromachines-III (Synchronous and single-phase machines), S.Kamakashiah, Right Publishers.R6 Electrical Machines, S.K. Battacharya, Tata Mc Graw-Hill Publishers.R7 Alternating Current Machines, E.R. RK Rajput, Laxmi Publications.

5.5.6 WEBSITES

1. www.mit.edu (massachusetts institute of technology)2. www.soe.stanford.edu (stanford university)3. www.grad.gatech.edu (georgia institute of technology)4. www.gsas.harward.edu (harward university)5. www.eng.ufl.edu (university of florida)6. www.iitk.ac.in 7. www.iitd.ernet.in8. www.iitb.ac.in9. www.iitm.ac.in10. www.iitr.ac.in11. www.iitg.ernet.in12. www.bits-pilani.ac.in13. www.bitmesra.ac.in14. www.psgtech.edu15. www.iisc.ernet.in16. www.ieee.org17. www.school - for - champions.com / science / actransformers.html18. www.onesmartclick.com / engineering / electrical - machines.html


REGIONAL

1. Name : Dr. DhanvanthriDesignation : Head of EEE DepartmentDepartment : EEE DepartmentOffice Address : Bharat Engg. College, HyderabadPhone No. : 9849052608Email :



253






NATIONAL



2. Name : Dr. Sivaji ChakravortiDesignation : ProfessorDepartment : EEE DepartmentOffice Address : Jadavpur University, Kolkatta - 700032, IndiaPhone No. :Email : [email protected] / [email protected].

INTERNATIONAL






254


5.5.8 JOURNALS



3. Name of the Journal : IEEE Transactions on power electronicsPublisher : IEEE Publications










5.5.9 FINDINGS AND DEVELOPMENTS

1. Title : “Electrical motor insulation conditions ac testing

Author : Ban, D.; Cettolo, M.; Miletic, B

Journal : IEEE Transactions

Year, Vol. & Page No. : Dec 1998 , Volume 5, Issue 6, Page(s):917 - 921.

2. Title : Torque-maximizing field-weakening control: Design, analysis and

parameter “selection

Author : L. Harnefers, K.pietilainen and L.Gertmar

Journal : IEEE Transaction Ind. electron

Year, Vol. & Page No. : Feb, 2001, Vol.48.no.1, pp 161-168,.

3. Title : “Hysteresis modelling in an electromagnetic transient program

Author : J.G.Frame, N.Mohan and T.Lil.

Journal : IEEE Transaction Power App Syst

Year, Vol. & Page No. : Vol. PAS 101 no9 pp3404-3412,sep 1982

255


4. Title : “Electrical motor insulation conditions ac testing

Author : Ban, D.; Cettolo, M.; Miletic, B

Journal : IEEE Transactions

Year, Vol. & Page No. : Dec 1998 , Volume 5, Issue 6, Page(s):917 - 921.

5. Title : Torque-maximizing field-weakening control: Design, analysis and

parameter “selection

Author : L. Harnefers, K.pietilainen and L.Gertmar

Journal : IEEE Transaction Ind. electron

Year, Vol. & Page No. : Feb, 2001, Vol.48.no.1, pp 161-168,.

6. Title : “Hysteresis modelling in an electromagnetic transient program

Author : J.G.Frame, N.Mohan and T.Lil.

Journal : IEEE Transaction Power App Syst

Year, Vol. & Page No. : Vol. PAS 101 no9 pp3404-3412,sep 1982.

7. Title : An Axial-Flux Permanent Magnet Synchronous Generator for a Direct-Coupled Wind-Turbine System,

Author : T.F. Chan and L.L. Lai, Journal : IEEE Transactions on Energy ConversionVol. Year & Page No. : Vol 22, No. 1, Mar. 2007.

256


5.5.10 SESSION PLAN

Sl. No.

JNTU Syllabus Topics Modules and Sub ModulesLecture


Page Nos.Remarks

UNIT – I – CONSTRUCTION AND PRINCIPLE OF OPERATION (No. of Lectures – 08)

1 Synchronous Generator

Introduction and operating principle of synchronous generatorRevolving armature and revolving field type alternators

L1

T1-Ch8 (P: 397-398)T2-Ch3 (P: 236-243)R2-Ch10 (P:388-391)R3-Ch1(P: 1.2-1.4)R4-Ch5 (P: 411)

GATE IES

2Constructional features of round rotor and salient pole machines

StatorRotorSalient pole and cylindrical rotorsBearings

L2

T1-Ch8 (P:397-398)T2-Ch3 (P:236-238)R1-Ch10 (P:388-391)R3-Ch1 (P:1.4-1.8)R4-Ch5 (P:415-418)

3 Armature windings

NomenclaturePhase groupingSingle layer windingsConcentric windings

L3T1-Ch6 (P:273-280 )T2-Ch7 (P:874-877 )R3-Ch1 (P:1.9-1.15 )

4Integral slot windings, fractional slot windings

Double layer windings L4 T1-Ch6 (P:276-280)T2-Ch7 (P:856-857)R3-Ch1 (P:419-421)Example L5

5

Distributed windings and concentrated windingsPitch factor Distribution factor Winding factor

Tooth rippleHarmonic content in distributed winding

L6

T1-Ch6 (281, 208)T2-Ch3 (272-282)R4-Ch5(P:419-421)R3-Ch1(P:1.21-1.24)

Problems on pitch factor and distribution factor

L7

T1-Ch6 (P:297)T2-Ch3 (P:268-285)R4-Ch5 (P:419-421)R3-Ch1 (P:1.40-1.47)

6 EMF EquationDerivation of EMF equationProblems on EMF equation

L8

T1-Ch5 (P:215-217)T2-Ch3 (P:250-253)R4-Ch5 (P:422-435)R3-Ch1 (P:1.25-1.27)

UNIT – II – SYNCHORONOUS GENERATOR CHARACTERISTICS (No. of Lectures – 06)

7Harmonics in generated EMF Suppression of harmonics

Problems on EMF equation L9T1-Ch5 (P:215-217)T2-Ch3 (P:260-263)R4-Ch5 (P:431-435)

GATE IES

Problems on EMF equation L10T1-Ch5 (P:215-217)T2-Ch3 (P:260-263)

8

Armature reaction Leakage reactance Synchronous reactance and impedance

Nature of armature reaction L11T1-Ch8 (P:426)R3-Ch1(P:1.32-1.34)

9Experimental determination

OCC, SCC and short circuit ratio L12T1-Ch8 (P:408-412)R3-Ch2 (P:2.4-2.8)

Problems on short circuit ratio, XS and ZS

L13T1-Ch8 (P:498)R3-Ch2 (P:2.9-2.11)

10Phasor diagramsLoad characteristics

UPF, lagging and leading power factors

L14T1-Ch8 (P:401-403)T2-Ch5 (P:551-552)R4-Ch5 (P:440-442)

UNIT – III – REGULATION OF SYNCHRONOUS GENERATORS (No. of Lectures – 15)11 Regulation by

synchronous impedance method

Voltage regulation Vector diagramsProblems

L15 T1-Ch8 (P:405)T2-Ch5 (P:567)R1-Ch10 (P:400-402)R4-Ch5 (P:440-444)R3-Ch2 (P:2.2-2.4)

GATE IES

257


Problems on regulation by synchronous impedance method

L16

T1-Ch8 (P:408)T2-Ch5 (568-569)R1-Ch10 (P:409-412)R4-Ch5 (P:446-450)R3-Ch2 (P:2.34-2.50)

12Regulation by MMF method

Relevant vector diagramsProblems

L17

T1-Ch8 (P:408)T2-Ch5 (P:563-564)R1-Ch10 (P:414-416)R3-Ch2 (P:2.11-2.15)

Problems on MMF method L18


13Regulation by ZPF method

Relevant vector diagramsProblems

L19

T1-Ch8 (P:418-426)T2-Ch5 (P:565)R1-Ch10 (P:404-406)R3-Ch2 (P:2.16-2.19)

Problems on ZPF method L20


14Regulation by ASA method

Relevant vector diagramsComparison between various methods

L21

T1-Ch8 (P:418-426)T2-Ch5 (P:565)R1-Ch10 (P:417-419)R3-Ch2 (P:2.24)

Problems on various methods L22


15Salient pole alternatorsTwo reaction analysis

EMF equation L23T1-Ch8 (P:452-454)T2-Ch5 (P:617-623)R3-Ch2 (P:2.25-2.28)

Analysis of phasor diagramProblems

L24


Power angle characteristicsIntroductionPower angle characteristics of cylindrical machines with and without resistance

L25


Power angle characteristics of salient pole machines

L26T1-Ch8 (P:459-461)T2-Ch5 (P:628-629)R3-Ch3 (P:3.3-3.4)

Problems L27T1-Ch8 (P:498-501)T2-Ch5 (P:631-636)R3-Ch3 (P:3.33-3.60)

16Experimental determination of Xd and Xq (Slip test)

Phasor diagrams L28T1-Ch8 (P:462-463)T2-Ch5 (P:650-655)R1-Ch10 (P:428)

17Regulation of Salient pole alternator

Regulation of salient pole alternator L29T2-Ch5 (P:557)R3-Ch2 (P:2.25-2.26)

UNIT – IV – PARALLEL OPERATION OF SYNCHORONOUS GENERATOR (No. of Lectures – 09)18 Synchronizing

alternators with infinite bus bars Synchronizing power and torque

Synchronizing alternators with infinite bus bars Synchronizing power and torque

L30T1-Ch8 (P:427-428)T2-Ch5 (P:639-642)R3-Ch3 (P:3.2)

GATE IES

Problems on synchronizing power and torque

L31 T2-Ch5 (P:639-642)R3-Ch3 (P:3.33-3.60)

258


19Parallel operation and load sharing

Parallel operation requirements Synchronizing procedure Synchronoscope

L32

T1-Ch8 (P:464-465)T2 -Ch5 (P:511)R1-Ch12 (P:450-457)R4-Ch5 (P:3.10-3.13)

Load sharing and problems on parallel operation

L33T1-Ch8 (P:464-465)R4-Ch5 (P:458-459)R3-Ch3 (P:3.33-3.60)

Problems on parallel operation L34T1-Ch8 (P:498-501)R3-Ch3 (P:3.33-3.60)

20Effect of change of excitation

Operation at constant load with variable excitationMinimum excitationEffect of unequal excitations on alternators in parallel

L35

T1-Ch8 (P:432-433)T2-Ch5 (P:540-542)R4-Ch5 (P:460-462)R3-Ch3 (P:3.12)

21 Mechanical power input Power flow equationsDerivation

L36T1-Ch8 (P:442-447)T2-Ch5 (P:580-584)R3-Ch3 (P:3.15-3.19)

22

Analysis of short-circuit current waveform Determination of sub-transient, transient and steady state reactances

Analysis of short-circuit current waveform, determination of sub-transient, transient and steady state reactances

L37T1-Ch8 (P:470-476)R1-Ch10 (P:453)R3-Ch3 (P:321-3.24)

Short circuit transient in synchronous machine

L38T1-Ch8 (P:470-477)R1-Ch11 (P:450)R3-Ch4 (P:3.23-3.24)

UNIT – V – SYNCHRONOUS MOTORS, PRINCIPLE OF OPERATION (No. of Lectures – 05)

23Synchronous motor theory of operation Phasor diagram

CharacteristicsApplications

L39T1-Ch8 (P:470-477)R1-Ch11 (P:491)R3-Ch4 (P:4.2-4.6)

GATE IES

24

Variation of power factor and current with excitationSynchronous Condenser

V curves and curvesAs a capacitor As a inductor

L40T2-Ch5 (P:613-616)R1-Ch11(P:498-475)R3-Ch4 (P:4.17-4.21)

Problems on synchronous motor L41T1-Ch8 (P:498-501)T2– Ch5 (P:624-626)R3-Ch4 (P:4.46-4.80)

25Mathematical Analysis for power developed

Maximum power developed L42R1-Ch11 (P:477)R3-Ch4 (P:4.19)

Problems on power developed L43R1-Ch11 (P:477)R3-Ch4 (P:4.26-4.80)

UNIT – VI – POWER CIRCLES (No. of Lectures – 05)

26Excitation and Power circles

Excitation and Power circles L44T2-Ch5 (P;604-609)R3-Ch4 (P:4.11-4.13)

GATE IES

Maximum power condition Problems L45T2-Ch5 (P:583-604)R3-Ch4 (P:4.26-4.80)

27Hunting andsuppressionMethods of starting

Auxiliary motor starting Induction motor starting

L46

T1-Ch8 (P:466-468)T2-Ch5 (P:647-651)R1-Ch11 (P:484-486)R4-Ch5 (P:460-464)R3-Ch4 (P:4.24-4.25)

28Synchronous induction motor

Determination of equivalent secondary currentCurrent diagram

L47 R3-Ch4 (P;4.21-4.24)

Problems on synchronous motors L48T1-Ch8 (P:498-501)T2-Ch5 (P:680-702)R3-Ch4 (P:4.26-4.80)

259


UNIT – VII – SINGLE PHASE MOTORS (No. of Lectures – 10)

29Single phase induction motor Constructional features

Introduction to single phase induction motors Types

L49T1-Ch10 (P:591)R4-Ch6 (P:494-500)R3-Ch5 (P:5.2-5.7)

GATE IES

30Double revolving field theory

Double revolving field theory L50

T1-Ch10 (P:591-592)R1-Ch9 (P:380-381)R4-Ch6 (P:498-500)R3-Ch5 (P:5.3)

Torque speed characteristics (qualitative treatment and semi quantitative treatment)

L51

T1-Ch10 (P:593)R1-Ch9 (P:380-381)R4-Ch6 (P:501)R3-Ch5 (P:5.4)

Problems on Equivalent Circuit L52T1-Ch10 (P:625-628)R1-Ch9 (P:371)R3-Ch5 (P:5.10-5.12)

31Elementary idea of cross field theory

Elementary idea of cross field theory L53R1-Ch9 (P:364)R4-Ch6 (P:497-498)R3-Ch5 (P:5.30)

32 Split phase motors

Starting torqueResistance split phase motor Capacitance split phase motorsProblems on split phase motors

L54T1-Ch10 (P:614-615) R4-Ch6 (P:501-507)R3-Ch5 (P:5.16-5.21)

Problems on single phase motors L55T1-Ch10 (P:614-615)R4-Ch6 (P:511-514)R3-Ch5 (P:5.85-5.90)

33 Shaded pole motor Problems on single phase motors

L56T1-Ch10 (P:649-650)R4-Ch6 (P:508-510)R3-Ch5 (P:5.22)

L57

T1-Ch10 (P:646-648)R2-Ch11 (P:613-615)R4-Ch6 (P:521-522)R3-Ch5 (P:5.43-5.47)

L58

T1-Ch10 (P:638-640)R2-Ch11 (P:613-615)R4-Ch6 (P:514-516)R3-Ch5 (P:5.68)

UNIT – VIII – SPECIAL MOTORS (No. of Lectures – 02)

34

Principle and performance of AC series motorUniversal motor

Circuit model Phasor diagram Torque developedPerformance characteristics

L57

T2-Ch2 (P:161-213)R2-Ch5 (P:5.43-5.45 & 5.73)

GATE IES

35Principle of permanent magnet motor and reluctance motors

Working and speed torque characteristicsComparison between single phase and three phase induction motors

L58 R2-Ch7 (P:7.6)

260



1. Title : Starting the Single Phase Switched Reluctance Motor using Rotor Shorting Rings

Author : J.E. Fletcher, A. Helal and B.W. WilliamsJournal : IEEE Transactions on Energy ConversionVol. Year & Page No. : Vol 21, No. 4, Dec 2006.

2. Title : Closed Loop Estimation of Permanent Magnet Synchronous Motor Parameters by PI Controller Gain Tuning

Author : S.B. LeeJournal : IEEE Transactions on Energy ConversionVol. Year & Page No. : Vol 21, No. 4, , Dec 2006

3. Name : High H2 gas Consumption in Turbo GeneratorsAuthor : Udai Raj Meena, Journal : Eletrical IndiaYear, Vol. & Page No. : Vol 47, No. 1, January 2007.

4. Name : Ventilation Systems of Fanless HV MotorsAuthor : J.K. Patel, M.B. Kanitkar, H.V. K.ShettyJournal : Eletrical IndiaYear, Vol. & Page No. : Vol 47, No.1, January 2007.

5. Name : Insulation Resistance and Polarization Index Test for Generator and Motor

Author : Mayadhar SwainJournal : Electrical IndiaYear, Vol. & Page No. : Vol 47, No. 1, January 2007.

6. Name : Electric Motor : Major Causes of Failure and DetectionAuthor : Prof. V.N. Ghate and Dr. S.V. DudulJournal : Electrical IndiaYear, Vol. & Page No. : Vol 47, No. 2, Feb 07.

261



UNIT – I

1. a. What are the causes of harmonics in the voltage and current waveforms of electrical machinery and what means are taken in design to reduce them?

b. Find the value of Kd for an alternator with 9 slots per pole for the following cases.i. one winding in all the slotsii. one winding using only the first 2/3 of the slots/poleiii. three equal windings placed sequentially in 600 group. (JNTU May 09, Nov 08)

2. a. By means of a neat diagram, describe the main parts of an alternator with their functions.b. For a 3-phase winding with 4 slots/pole/phase and with the coil span of 10 slots pitch, calculate the

values of the pitch factor and distribution factor. (JNTU May 09)

3. a. Describe the main constructional features of cylindrical rotor and salient pole alternators.b. Derive the expressions for distribution and pitch factors. (JNTU May 09, Nov 08)

4. a. Why stationary armature is preferred over rotating armature? Give the classification of alternators based on rotor used.

b. A 3-Φ, 4 pole, star connected alternator has 72 slots with two conductors per slot. The pitch of the coil has 4 slots less than the pole pitch. The flux per pole is 0.163 wb. Calculate the no-load terminal voltage, if the speed of the alternator is 1500 rpm. (JNTU May 09)

5. a. Explain the construction of stator of a 3-Φ alternator? Why stationary armature is preferred over rotating armature? (JNTU May 09)

b. A 16 pole 3-Φ, alternator has a star connected winding with 144 slots & 10 conductors per slot. The flux per pole is 0.03 wb distributed sinusoidaly and the speed is 375 RPM. Find the line voltage.

6. a. Explain the various winding factors? Explain the effects of each of them. (JNTU May 09)b. Determine the slot distribution and the pole phase group sequence for a 45 slot, 6 pole, 3-Φ winding.

7. The flux distribution in a salient pole machine is rectangular, the base being two thirds of pole - pitch. The peak value of flux density is 1WB/m2 . Draw one complete cycle of the e.m.f induces in a single - turn coil which has the pitch of five - sixthe of full pitch and moves with a uniform velocity of 30m per sec. The armature conductor length is 2m. Calculate the r.m.s. value of the voltage.

(JNTU May 09)

8. a. Explain the classification of alternators based on rotor used with the help of neat diagrams.b. A 16 pole, 3-Φ, alternator is coupled to a engine running at 375 rpm. It supplies an IM that has a full

load speed of 1450 rpm. Find the slip & number of poles of the motor. (JNTU Nov 08)

9. a. Explain the differences between stationary armature and rotating armature. What are the advantages of rotating armature over stationary armature?

b. A 4 pole alternator has an armature with 25 slots and 8 conductors per slot and rotates at 1500 rpm and the flux per pole is 0.05 wb. Calculate the EMF generated, if winding factor is 0.96 and all the conductors in a phase are in series. (JNTU Nov 08)

10. a. Derive the expression for the EMF induced in a 3-Φ alternator?b. Calculate the no load terminal voltage of a 3-Φ, 8 pole, star connected alternator running at 750 rpm

having the following data:Sinusoidaly distributed flux per pole = 55 mwb, total number of slots on the armature = 72, conductors per slot = 10, distribution factor = 0.96. Assume full pitch coils. (JNTU Nov 08)

11. a. Obtain the expression for the short pitch factor & distributed winding factor?b. A 3-Φ, 4 pole, star connected alternator has 60 slots with 2 conductors per slot. The pitch of the coil is

3 slots less than pole pitch. The flux per pole is 0.125 wb. Calculate the no load terminal voltage if the speed of alternator is 1500 rpm. (JNTU Nov 08)

262


12. a. What is a fractional pitch winding (JNTU Nov 08)b. Calculate the distribution factor for a single ?phase alternator having 6 slots/pole,

i. when all the slots are wound andii. When only four adjacent slots/pole are wound and the remaining being not wound.

13. i. Explain the following terms related to armature winding:a. Double layer b. Single Layer c. Short pitch d. Distributed.

ii. Give the winding calculation for a 3-phase armature winding with following details: Pole = 8, Number of slots = 54, Double layer winding. (JNTU Feb 08)

14. i. Explain the differences between stationary armature and rotating armature. What are the advantages of rotating armature over stationary armature?

ii. A 4 pole alternator has an armature with 25 slots and 8 conductors per slot and rotates at 1500 rpm and the flux per pole is 0.05 wb. Calculate the EMF generated, if winding factor is 0.96 and all the conductors in a phase are in series. (JNTU Feb 08)

15. i. What are the various terms related with windings? Explain each of them with their importance.ii. A star connected 3-phase, 6 pole synchronous generator has a stator with 90 slots & 8 conductors per

slot. The rotor revolves at 1000 rpm. The flux per pole is 40 mWb. Calculate the EMF generated, if all the conductors in each phase are in series. Assume sinusoidal flux distribution & full pitched coil.

(JNTU Feb 08)

16. Explain the construction and working principle of alternators with a neat diagram.(JNTU Feb 08)

17. A 4-pole, 3-phase, 50Hz, star-connected alternator has 60 slots, with 4 conductors per slot. Coils are short-pitched by 3 slots. If the phase spread is 600 find the line voltage induced for a flux per pole of 0.943Wb distributed sinusoidally in space. All the turns per phase are in series. (JNTU Feb 08, 07)

18. i. What is short pitch winding & distributed winding? Why the armature winding is distributed & short pitch type?

ii. Calculate the EMF of a 4 pole, 3-phase, star connected alternator running at 1500 r.p.m from the following data: Flux per pole = 0.1 wb, Total number of slots = 48, Conductors per slot (in two layers) = 4, coil span = 1500. (JNTU Nov 07)

19. i. Explain the various winding factors? Explain the effects of each of them. ii. Determine the slot distribution and the pole phase group sequence for a 45 slot, 6 pole, 3-phase

winding. (JNTU Nov 07)

20. i. Obtain the expression for the RMS value of EMF induced in an alternator.ii. An alternator is operating at no load has an induced EMF of 346.4 V/ph and a frequency of 60 Hz. If

the pole flux is deceased by 15 % & the speed is increased by 6.8 %; determine a. The induced EMF b. Frequency (JNTU Nov 07)

21. i. By means of a neat diagram, describe the main parts of an alternator with their functions.ii. For a 3-phase winding with 4 slots/pole/phase and with the coil span of 10 slots pitch, calculate the

values of the pitch factor and distribution factor (JNTU Feb 07)

22. i. Derive emf equation for an alternator from fundamentals.ii. A 50 Hz alternator has a flux of 0.1 wb/pole, sinusoidally distributed. Calculate the rms value of the

emf generated in one turn of the winding, which spans 3/4 of a pole pitch.(JNTU Feb 07, Nov 06, 05)

23. A 3-phase, 50 Hz, 8-pole alternator has a start connected winding with 120 slots and 8 conductors per slot. The flux per pole is 0.05 wb sinusoidally distributed. Determine the phase and line voltages.

(JNTU Feb 07, May 05, Nov 03)24. i. What is a fractional pitch winding

ii. Calculate the distribution factor for a single phase alternator having 6 slots/pole,a. When all the slots are wound andb. When only four adjacent slots/pole are wound and the remaining being not wound.

(JNTU Feb 07, May 05)

263


25. i. Derive the expressions for distribution and pitch factors ii. Calculate the distribution factor of a 3-phase winding with 1200 phase spread when the winding is

a. Uniformly distributed b. occupies 6 slots per pole. (JNTU Feb 07, May 05)

26. i. Describe the main constructional features of cylindrical rotor and salient pole alternators.ii. Derive the expressions for distribution and pitch factors. (JNTU Feb 07, Nov 06, 05, Mar 06)

27. Derive an expression for an induced e.m.f. in an synchronous generator. Also explain how the e.m.f. is having sinusoidal wave form. (JNTU Feb 07, Nov 06, 04, 03, 02)

28. i. Draw and explain the phasor diagram of an alternator at lagging power factor ii. A 6-pole alternator rotating at 1000 r.p.m has a single-phase winding housed in 3 slots per pole, the

slots in groups of three being 200 apart. If each slot contains 10 conductors, and the flux per pole is 2x10"2Wb,Calculate the voltage generated, assuming the flux distribution to be sinusoidal.

(JNTU Nov 06)29. A 3-phase, 16-pole alternator has a star-connected winding with 144 slots and10 conductors per slot.

The flux per pole is 0.03 Wb, Sinusoidally distributedand the speed is 375 r.p.m .Find the frequency in rpm and the phase and linee.m.f. assume full ?pitched coi (JNTU Nov 06)

30. i. Describe the different types of prime movers employed in case of alternators.ii. Calculate the pitch factor of an alternator having 24 stator slots with 4 poles when the coil span is 1 to 6

slots. (JNTU Nov 06)

31. A 6-pole alternator rotating at 1000 r.p.m has a single-phase winding housed in 3 slots per pole, the slots in groups of three being 200 apart. If each slot contains 10 conductors, and the flux per pole is 2x10-2 wb, Calculate the voltage generated, assuming the flux distribution to be sinusoidal.

(JNTU Nov 06, Mar 06, 05)

32. A 4-pole, 3-phase, 50 Hz, star-connected alternator has 15 slots, with 10 conductors per slot. All the conductors are connected in series, the winding factor is 0.95. When running on no loads for a certain flux per pole, the terminal voltage was 1825V. If the windings were lap connected as in a dc machine, what would be the emf between the brushes for the same speed and same flux per pole. Assume sinusoidal distribution of flux. (JNTU Mar 06)

33. i. Derive from fundamentals the emf equation of an alternator.ii. One phase of a 3-phase alternator consists of 12 coils in series. Each coil has an rms voltage of 10 V

induced in it and the coils are arranged in slots so that there is successive phase displacement of 10 electrical degrees between the emf in each coil and the next. Find the rms value of total phase voltage developed by the winding. If the alternator has six poles and is driven at 100 rpm. Calculate the frequency of the emf generated. (JNTU Mar 06)

34. i. What is a distribution factor? What is its effect? Derive an expression for distribution factor of a winding having Q slots per pole per phase and a slot angle of βΩ

ii. A certain alternator has 6 slots per pole and the coils are short pitched by 1 slot. The coil span is 5 slot pitches. Calculate the pitch factor. (JNTU Mar 06, Nov 04)

35. i. Explain the constructional differences between round rotor and salient pole synchronous machines.ii. Find the value of Kd for an alternator with 9 slots per pole for the following cases.

a. one winding in all the slotsb. one winding using only the first 2/3 of the slots/polec. three equal windings placed sequentially in 600 group. (JNTU Nov 05)

36. i. Explain the essential between cylindrical and salient pole rotors used in large alternators.ii. A certain alternator has 6 slots per pole and the coils are short pitched by 1 slot. The coil span is 5 slot

pitches. Calculate the pitch factor. (JNTU Nov 05)

37. A 4-pole, 3-phase, 50 Hz, star-connected alternator has 60 slots, with 2 conductors per slot and having armature winding of the two-layer type. Coils are short-pitched in such a way that if one coil side lies in slot number 1, the other lies in slot number 13. Determine the useful flux per pole required to generate a line voltage of 6000V. (JNTU Nov 05)

264


38. Calculate the speed and open circuit line and phase voltages of a 4-pole, 3-phase, 50 Hz, star connected alternator with 6 slots and 30 conductors per slot. The flux per pole is 0.0496 wb and is sinusoidally distributed. (JNTU Nov 05)

39. The armature of a single-phase alternator is wound completely with T single turn coils, which are uniformly distributed. The induced e.m.f. in each turn is 2V(rms). Calculate the e.m.f of the whole winding with T number of coils connected in series. (JNTU Nov 05, 04)

40. i. Describe the constructional features of cylindrical rotor synchronous generators and the function of each part.

ii. Distinguish between integral slot and fractional slot winding and their merits and demerits.(JNTU Nov 05, 04, 03)

41. An alternator has 18 slots/pole and the first coil lies in slots 1 and 16. Calculate the pitch factor fori. Fundamental ii. 3rd harmonicsiii. 5th harmonics and iv. 7th harmonics. (JNTU May 05)

42. Calculate the speed and open –circuit line and phase voltages of a 4-pole, 3-phase, 50HZ, star-connected alternator with 36 slots and 30 conductors per slot. The flux per pole is 0.0496 Wb and is sinusoidally distributed. (Nov 04)

43. What factors affect the size of alternator? (JNTU Nov 04)

44. i. Explain briefly about the different types of armature windings?ii. Find the value of Kd for an alternator with 9 slots per pole for the following cases:

a. One winding in all the slotsb. One winding using only the first 2/3 of the slots/polec. Equal windings placed sequentially in 600 groups. (JNTU Nov 04)

45. Draw a fractional pitch lap winding for 3-phases 4-pole, 2 layer with 2 slots per pole per phase. Discuss the merits and demerits between full pitch and fractional pitch windings.(JNTU May 04)

46. i. Write the effect of short pitch on the induced emf of synchronous generator.ii. Calculate the distribution factor of a 3-phase winding with 120° phase spread when the winding is i.

uniformly distributed, ii. occupies 6 slots per pole. (JNTU May 04)

47. Discuss the factors affecting the terminal voltage of an alternator. (JNTU Nov 03)

48. Describe how the armature windings are arranged in synchronous generators. What is the effect of distribution factor on the performance of the generator? (JNTU Nov 03, 02)

49. Define “Distribution factor” and find its value for a 3 phase winding with 60° phase spread when the winding is uniformly distributed over 9 slots per pole. (JNTU Nov 02)

50. Explain why alternators are rated in KVA and what is the necessity to mention pf on the name plates.(JNTU Nov 02)

51. A 3 phase 50 Hz, 10 pole alternator has 90 slots with a star connected winding to give a no load emf of 11 KV. The coils are chorded by 1 slot. If the flux per pole is 0.11 wb calculate the number of series turns required in each phase. (JNTU Nov 02)

52. A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A isa. 1 V b. 10 V c. 100 V d. 1000 V (GATE 09)

53. Distributed winding an dshort chording employed in AC machines will result in (GATE 08)a. increase in emf and reduction in hrmonics. b. reduction in emf an dincrease in harmonicsc. increase in othy emf and harmonics d. reduction in both emf and harmonics.

265


54. In a stepper motor, the detent torque meansa. minimum of the static torque with the phase winding excitedb. maximum of the static torque with the phase winding excitedc. minimum of the static torwue with the phase winding unexcitedd. maximum of the static torque with the phase winding unexcited (GATE 08)

55. A synchronous motor is connected to an infinite bus at 1.0 pu voltage and draws 0.6 pu current at unity power factor. Its synchronous reactance is 1.0 pu and resistance is negligible. (GATE 08)a. 0.8 pu and 36.860 lag b. 0.8 pu and 36.860 leadc. 1.17 pu and 30.960 lead d. 1.17 pu and 30.960 lag

56. A synchronous motor is connected to an infinite bus at 1.0 pu voltage and draws 0.6 pu current at unity power factor. Its synchronous reactance is 1.0 pu and resistance is negligible. (GATE 08)a. 0.995 lagging b. 0.995 leading c. 0.791 lagging d. 0.848 leading

57. A 4 pole, 50Hz, synchronous generator has 48 slots in which a double layer winding is housed. Each coil has 10 turns and is short pitched by an angle to 360 electrical. The fundamental flux per pole is 0.025Wb. (GATE 06)

58. Calculate the rms value of the induced emf per phase of a 10 pole, three phase, 50 Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. The coil span is 1500. The flux per pole is 0.12 wb. (IES 08)

UNIT – II

1. a. Derive emf equation for an alternator from fundamentals.b. A 50Hz alternator has a flux of 0.1 wb/pole, sinusoid ally distributed. Calculate the rms value of the

emf generated in one turn of the winding, which spans 3/4 of a pole pitch. (JNTU May 09)

2. a. What are slot harmonics and how they are suppressed.b. The armature of a single-phase alternator is wound completely with T single turn coils, which are

uniformly distributed. The induced e.m.f. in each turn is 2V(rms). Calculate the e.m.f of the whole winding with T number of coils connected in series. (JNTU May 09)

3. a. Explain de-magnetising, cross magnetising & magnetising nature of armature reaction.b. Calculate the RMS value of the induced EMF per phase of a 4 pole, 3-Φ, 50 Hz, alternator with 3 slots

per pole per phase and 6 conductors per slot in two layers. The coil span is 150o. The flux per pole has a fundamental component of 0.2 wb & a 16 % third harmonic component. (JNTU May 09)

4. a. Explain with neat diagram, the various tests to be conducted on an alternator to obtain its synchronous reactance.

b. Find the synchronous impedance and reactance in an alternator in which a given field current produces an armature current of 250 A on short circuit nad generates an open circuit voltage of 1500 volts. The effective armature resistance is 0.5Ω /ph. Hence calculate the terminal PD when a load of 250 A 6600 V at a power factor of 0.8 lagging is switched off potential difference. (JNTU May 09)

5. a. Explain the operation and effect of load power factor on the performance of alternator.b. The effective resistance of a 2200 V, 50 Hz, 440 kVA, single phase alternator is 0.5Ω . On short

circuit, a field current of 4 A gives the full load current. The EMF on open circuit for the same field current is 1160 V. Find Synchronous impedance, Synchronous reactance and % regulation of 0.6p.f lagging. (JNTU May 09)

6. Explain the effect of armature reaction on terminal voltage of an alternator at a. u.p.f. b. zero p.f. load.Draw the relevant phasor diagrams. What is leakage reactance? (JNTU May 09)

266


7. a. Explain the sources of harmonics. What are the various effects of harmonics on generated emf in an alternator?

b. Find the RMS value of fundamental & third harmonic EMF per phase for an alternator having following data: 50 Hz, 3-Φ, 20 poles, 4 slots/pole/phase, double layer winding with 6 conductors/slot, coil span of 150o, flux per pole: fundamental is 0.1 wb, third harmonic 17 % of fundamental. All coils of a phase are connected in series. (JNTU Nov 08)

8. a. Explain the effects of harmonics on electrical power system & utility. b. Calculate the RMS value of EMF induced per phase of a 10 pole, 3-Φ, 50 Hz, alternator with 2 slots

per pole per phase and 4 conductors per slot in two layers. The coil span is 150o electrical. The flux per pole has a fundamental component of 0.12 wb & a 20% of third harmonic component. (JNTU Nov 08)

9. a. Explain the causes of harmonics? Explain the concept of fictitious poles.b. A 10 pole, 3-Φ, 50 Hz, alternator has 8 slots per pole & 6 conductors per slot. The winding is 7/8

pitch. There are 0.03 wb entering the armature from each north pole & this flux is sinusoidaly distributed along the air gap. The star armature coils are connected in series. Determine the open circuit EMF of the alternator. Find the breadth factor for 3rd & 5th harmonics. (JNTU Nov 08)

10. a. What is armature reaction? Explain armature reaction for different power factors of load?b. Data from tests performed to determine the parameters of a 200 kVA, 480 V, 60 Hz, 3-Φ, stat

connected alternator are Voc=480 V, Isc=209.9A for constant If & for DC test VDC = 91.9 V, IDC=72.8 A (stator). Determine synchronous impedance & the SCR of the alternator. (JNTU Nov 08)

11. a. What do you mean by synchronous reactance? Explain the term synchronous impedance of an alternator.

b. Calculate the speed and open - circuit line and phase voltages of a 4-pole, 3-phase, 50HZ,star-connected alternator with 36 slots and 30 conductors per slot. The flux per pole is 0.0496 Wb and is sinusoidally distributed. (JNTU Nov 08)

12. a. Derive from fundamentals the emf equation of an alternatorb. One phase of a 3-phase alternator consists of 12 coils in series. Each coil has an rms voltage of 10V

induced in it and the coils are arranged in slots so that there is successive phase displacement of 10 electrical degrees between the emf in each coil and the next. Find the rms value of total phase voltage developed by the winding. If the alternator has six poles and is driven at 100rpm Calculate the frequency of the emf generated. (JNTU Nov 08)

13. i. Explain the effects of harmonics present in generated emf of alternator. ii. The flux distribution curve of a smooth core 50 Hz generator is B = sin 0 + 0.2 sin 30 + 0.2 sin 50 + 0.2

sin 70 wb/m2 where 0 is the angle measured from neutral axis. The pole pitch is 35 cm the core length is 32 cm and stator coil span is four-fifth pole pitch. Find equation for EMF induced in one turn its RMS value. (JNTU Feb 08)

14. i. Explain the factors affecting synchronous reactance of alternator.ii. The SC, OC & DC test data for a star connected 25 kVA, 240 V, 60 Hz, alternator are (between two

terminals):VOC = 240 V, ISC = 60.2 A - - - - For same field currentVDC = 120.6 V, IDC = 50.4 ADetermine: Synchronous reactance. (JNTU Feb 08)

15. i. What is armature reaction? Explain armature reaction for different power factors of load?ii. Data from tests performed to determine the parameters of a 200 kVA, 480 V, 60 Hz, 3-phase, stat

connected alternator are VOC=480 V, ISC=209.9A for constant If & for DC test VDC = 91.9 V, IDC=72.8 A (stator). Determine synchronous impedance & the SCR of the alternator.

(JNTU Feb 08)

16. i. Explain the characteristics and nature of harmonics present in generated emf of alternator?ii. The flux density distribution in the air gap of an alternator is B = B1sin 0 + B3 sin 30 + B5 sin 50

wb/m2, where B3 = 0.3B1 & B5 = 0.2B1. The total flux per pole is 0.08 wb. The coil span is 80% of pole pitch. Find the RMS value of EMF induced in single turn machine. (JNTU Feb 08)

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17. i. Explain the load characteristics of an alternator.ii. The phase EMF of a 3-phase alternator consist of fundamental, 20 % 3rd harmonic & 10 % fifth

harmonic. The amplitude of fundamental is 1000 V. Calculate the RMS value of line & phase voltage, when the alternator is connected in a. Star b. Delta (JNTU Nov 07)

18. i. Explain the effect of armature reaction on the EMF induced. Is it possible to obtain load voltage more than EMF induced? if yes, how?

ii. A 200 kVA, 480 V, 50 Hz, star connected synchronous generator with a rated field current of 5A was tested and the following data were obtained: OC test: 540 V between lines on open circuit.SC test: 300 A.When a DC voltage of 10 V was applied to two of its terminals, a current of 25 A was measured, find the value of synchronous impedance, synchronous reactance voltage regulation of 0.6 p.f leading.

(JNTU Nov 07)

19. i. A 16 pole, 3-phase star connected alternator has 144 slots. The coils are short pitched by one slot. The flux per pole is phase = 100 sin 0 + 30 sin 30 + 20 sin 50. Find the harmonics as percentage of phase voltage & line voltage.

ii. Definea. synchronous reactance b. synchronous impedance and c. leakage reactance in an alternator.

20. Justify the statement ‘The terminal voltage of an alternator is not only depends on the load current, but also on the nature of load’. (JNTU Nov 07)

21. What is armature reaction? How it is accounted as a reactance drop? (JNTU Feb 07)

22. What is armature reaction? Explain the effect of armature reaction on the terminal voltage of an alternator at (JNTU Feb 07, May 05, Nov 03)i. Unity power factor load ii. Zero lagging power factor loadiii. Zero leading power factor load. Draw the relevant phasor diagram.

23. What is synchronous reactance? How do you calculate synchronous impedance experimentally?(JNTU Feb 07, Nov 03)

24. Draw and explain the phasor diagram of an alternator at lagging power factor (JNTU Nov 06)

25. With neat circuit diagrams, explain the various tests conducted on an alternator to determine its synchronous reactance. (JNTU Mar 06)

26. Describe armature reaction and explain its effect on terminal voltage. (JNTU Nov 05)

27. What are slot harmonics and how they are suppressed. (JNTU Nov 05, 04)

28. Discuss how synchrnous impedance of alternator can be determined. (JNTU Nov 05)

29. Explain the effect of harmonics on pitch and distribution factors. (JNTU May 05)

30. What are the causes of harmonics in the voltage and current waveforms of electrical machinery and what means are taken in design to reduce them? (JNTU May 05)

31. A 3-phase, 50 hz cylindrical rotor synchronous machine has the following parameters.Self inductance per phase = 3.15 mHArmature leakage inductance = 0.35 mH for this machine, calculate the mutual inductance between armature phases and its synchronous reactance. (JNTU Nov 06, May 04)

32. A 3.3 KV, 3-phase, star connected alternator has full-load current of 100A. Under short circuit condition it takes 5A filed current to produce full-load short circuit current. The emf on open circuit for the same excitation is 900V (line to line). The armature resistance is 0.9 Ohm per phase. Determine synchronous reactance per phase. (JNTU Nov 04)

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33. The following data is obtained for 100KVA, 1100V, 3-phase alternator (JNTU Nov 04)D.C. resistance test between lines = 10VCurrent in line = 10 A.Line circuit test; field current If = 12 A.Line voltage = 420V;Short circuit test; If = 12 A.Line current Lsc = rated valueCalculate synchronous impedance

34. Determine their values for a 3-phase winding with 4 slots per pole per phase, the coil span being 10 slot pitches. Calculate the percentage increase in R.M.S. Value of the phase voltage due to a 25% third harmonic. (JNTU Nov 04)

35. Discuss the effect of armature reaction in an alternator. (JNTU Nov 04)

36. Describe the method of finding synchronous impedance of a given alternator. (JNTU Nov 04)

37. Explain about harmonics generated in e.m.f. of a synchronous machine. How do you suppress them? What are the problems due to harmonics. (JNTU Nov 04)

38. Explain the effect of armature reaction on terminal voltage of an alternator at i. u.p.f. ii. zero p.f. load. Draw the relevant phasor diagrams. What is leakage reactance? (JNTU Nov 04, 03)

39. i. Explain how open circuit and short circuit tests are conducted on a synchronous machine.ii. What is an air-gap line? In an alternator, explain why short circuit characteristic is a straight line where

as open circuit characteristic is a curve. (JNTU May 04)

40. A 3-Phase star connected, 4-pole, 50 Hz., alternator develops an open circuit voltage of 12.5 KV for an applied field voltage of 400 V. For a field circuit resistance of 10 Ohms, Calculate the amplitude of armature to field mutal inductance. (JNTU May 04)

41. Draw and explain the phasor diagram of alternator under loaded conditions. (JNTU Nov 03)

42. Draw and explain the phasor diagram of alternator under loaded conditions. (JNTU Nov 03)

43. Each winding of a 3 phase, 50 Hz alternator has an e.m.f. wave consisting of a fundamental with a maximum value of 1200 volts, a 20% third harmonic and a 10% fifth harmonic. Calculate the R.M.S. value of the line voltage for the cases, when the windings are connected in star and in delta.

(JNTU Nov 02)

44. A 3 phase, 12 pole, 500 r.p.m. star connected alternator has 144 slots with 10 conductors per slot. The coils are full pitch and the flux per pole is 0.094 wb. Determine the phase and line emf. What harmonics do you expect due to slots and why? What will be the phase voltage if the coils are the connected to form a balanced two phase winding? (JNTU Nov 02)

45. Draw load characteristics of an alternator and explain how it is derived from phasor diagrams. (JNTU Nov 02)

46. Each winding of a 3 phase, 50 Hz alternator has an e.m.f. wave consisting of a fundamental with a maximum value of 1200 volts, a 20% third harmonic and a 10% fifth harmonic. Calculate the R.M.S. value of the line voltage for the cases, when the windings are connected in star and in delta.

(JNTU Nov 02)

47. A 3 phase, 12 pole, 500 r.p.m. star connected altrnator has 144 slots with 10 conducters per slot. The coils are full pitch and the flux per pole is 0.094 wb. Determine the phase and line emf. What harmonics do you expect due to slots and why? What will be the phase voltage if the coils are the connected to form a balanced two phase winding? (JNTU Nov 02)

48. Draw load characteristics of an alternator and explain how it is derived from phasor diagrams. (JNTU Nov 02)

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49. Discuss open circuit and short circuit characteristics of a synchronous generator.Draw the phasor diagram under short circuit condition. What do you understand by the term “short circuit ration”? Discuss how short circuit ratio can be calculated from the two characteristic curves?

(JNTU Nov 02, IES 00)

50. A synchronous generator is feeding a zero power factor (lagging) load at rated current. The armature reaction is i. magnetizing ii. demagnetizing iii. cross-magnetizing iv. ineffective (GATE 08)

51. A synchronous generator is feeding a zero power factor (lagging) load at rated current. The armature reaction is a. magnetizing b. demagnetizingc. cross-magnetizing d. ineffective (GATE 06)

52. The resultant flux density in the air gap of a synchronous generator is the lowest during.i. open circuit ii. solid short circuit iii. full load iv. half load (IES 08)

53. Sketch and explain the open circuit and short circuit characteristics of a synchronous machine(IES 06)

UNIT – III

1. a. What is voltage regulation? Discuss the synchronous impedance method of calculating voltage regulation.

b. A 500V, 50KVA, 1-phase alternator has an e_ective resistance of 0.2.A field current of 10A produces an armature current of 200A on short circuit and an emf of 450V on open circuit. Calculatei. Synchronous impedance and reactanceii. Full-load regulation with 0.8p.f. lagging. (JNTU May 09)

2. a. Explain the AT method of finding voltage regulation.b. A 1 MVA, 6.6 kV, 3-_ star connected synchronous generator has a synchronous reactance of 25 per

phase. It supplies full load current at 0.8 lagging pf and a rated terminal voltage. Compute the terminal voltage for the same excitation when the generator supplies full load current at 0.8 leading pf.

(JNTU May 09)

3. A 3-Φ, 200 kVA, 1.1 kV, 50 Hz star connected alternator having an effective per phase resistance of 0.62 gave the following results: Field Current (A) 20 35 50 80 100 120OC Voltage VL 692.82 1120 1450 1750 1953 2180SC Current (A) 0 22 44 66 88 110Using MMF method, find the voltage regulation at 100 A

a. 0.8 pf lagging b. 0.8 pf leading. (JNTU May 09)

4. a. Explain the various tests to be conducted on an alternator to find the voltage regulation of an alternator.b. Explain the effect of ‘Saturation’ on the performance of an alternator. How the effect of saturation can

be overcome in calculation. (JNTU May 09)

5. Explain the merits and demerits of EMF and MMF methods. Explain what are the assumptions made in each case. (JNTU May 09)

6. a. What is the synchronous impedance method? Why the method is called so? What are the limitations of this theory?

b. The following table gives the OCC & SCC of a 2 pole, 11kV, 50 Hz, 3-Φ star connected alternator. The stator resistance between two terminals is 0.2. Calculate the regulation at full load current of 125 A at 0.8 pf lagging (by synchronous impedance method)If 16 20 25 32 45 (JNTU Nov 08)EOL-kV 4.4 5.5 6.6 7.7 8.8 (where EoL is line voltage at no load)

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7. a. Explain the AT method of finding voltage regulation. (JNTU Nov 08)b. A 1 MVA, 6.6 kV, 3-Φ star connected synchronous generator has a synchronous reactance of 25Ω per

phase. It supplies full load current at 0.8 lagging pf and a rated terminal voltage. Compute the terminal voltage for the same excitation when the generator supplies full load current at 0.8 leading pf.

8. a. Explain the various tests conducted on an alternator to find the voltage regulation of an alternator by Potier triangle method.

b. The no load excitation of an alternator required to give rated voltage is 1 pu. In a short circuit test with full current flowing in the armature, the field excitation was 0.85 pu. Determine the approximate excitation that will be required to give full load current at 0.78 PF leading at the rated terminal voltage.

(JNTU Nov 08) 9. a. Explain the ‘Zero power factor’ method of finding voltage regulation of an alternator.

b. The no load excitation of an alternator required to give rated voltage is 1 pu. In a short circuit test with full current flowing in the armature, the field excitation was 0.75 pu. Determine the approximate excitation that will be required to give full load current at 0.866 PF lagging at the rated terminal voltage. (JNTU Nov 08)

10. a. Compare synchronous impedance method and ampere -turn method of predetermining regulation of

alternators.b. A 6600-V star -connected, 3-phase non -salient pole synchronous generator has the following open -

circuit characteristicPhase voltage (V)2600 3500 4130 4600 5000 5500Field current(A) 100 150 200 250 300 400Full load current on short circuit is obtained with an excitation of 175A. Using the ampere-turn method; determine the full-load regulation when the pf is 0.9 lagging. The resistance drop is negligible and the reactive drop is 10% on full load. (JNTU Nov 08)

11. a. Develop the expression for finding voltage regulation of salient-pole alternator. b. The no-load and full-load zero factor characteristics for a 23.5MVA, 13.8KV, 3-phase, star-connected

turbo-generator are given below in per unit values: No-load characteristic:If 0.10 0.20 0.40 0.60 0.80 1.0 1.2 1.4 1.6 2.0 2.5V 0.13 0.23 0.45 0.69 0.87 1.0 1.09 1.15 1.21 1.28 1.36Zero p.f. Characteristic:If 1.2 1.3 1.4 1.6 1.8 2.0 2.2 2.4 2.6V 0.015 0.13 0.25 0.49 0.69 0.83 0.92 0.99 1.04Determine the regulation at full-load, 0.8p.f.lag by the zero p.f.method. Neglect armature resistance.

(JNTU Nov 08)

12. a. Discuss the m.m.f method of calculating voltage regulation?b. A 3-phase star connected, 1000KVA, 2000V, 50Hz,alternator gave the following. open circuit and

short circuit test readings.Field current A 10 20 25 30 40 50Open circuit voltage V 800 1500 1760 2000 2350 2600Short circuit armature current A - 200 250 300 - -Draw the characteristic curves and estimate the full load percentage regulation at

i. 0.8pf lagging and ii. 0.8pf leading The armature effective resistance/phase may be taken as 0.2Ω(JNTU Nov 08)

13. i. Explain the Roher’s AT method of finding voltage regulation. ii. A 1 MVA, 6.6 kV, 3-phase star connected synchronous generator has a synchronous reactance of 25

ohms per phase. It supplies full load current at 0.8 lagging pf and a rated terminal voltage. Compute the terminal voltage for the same excitation when the generator supplies full load current at 0.8 leading pf.

(JNTU Feb 08)

14. i. How the MMF method is different from EMF method in finding voltage regulation of an alternator? Explain the drawbacks of each method.

ii. A 1 MVA, 11 kV, 3-phase, star connected synchronous machine has following OCC test data:(where EOL is the line voltage at no load)

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The short circuit test yielded full load current at a field current of 60 A. The ZPF yielded a full load current at terminal voltage for a field current of 150 A. The armature resistance is negligible. Calculate the voltage regulation at full load 0.866 pf lagging by Potier triangle method. (JNTU Feb 08)

15. i. What is the synchronous impedance method? Why the method is called so? What are the limitations of this theory?

ii. The following table gives the OCC & SCC of a 2 pole, 11kV, 50 Hz, 3-phase star connected alternator. The stator resistance between two terminals is 0.2ohms. Calculate the regulation at full load current of 125 A at 0.8 pf lagging (by synchronous impedance method)(where EoL is line voltage at no load) (JNTU Feb 08)

16. A 3-phase, 440 V, 50 Hz, delta connected alternator has direct axis & quadrature axis reactance of 0.12 ohms and 0.09 ohms respectively. If the alternator supplies 900 A at 0.8pf lagging, calculate the following:

i. the excitation EMF, neglecting saliency (Xd = Xq)ii. the excitation EMF, taking into account the saliency.

Neglect armature resistance. (JNTU Feb 08)

17. i. Explain the voltage regulation method of an alternator by which the armature reaction & leakage reactance can be separated.

ii. A 3-phase, star connected salient pole synchronous generator is driven at a speed near synchronous with the field circuit open and the stator is supplied from a balanced 3-phase supply. Voltmeter connected across the line gave minimum and maximum readings of 1196 V & 1217 Volts. The line current fluctuated between 120 & 225 Amp. Find the direct and quadrature axis reactances per phase. Neglect armature resistances. (JNTU Nov 07)

18. A 3-phase, 200 kVA, 1.1 kV, 50 Hz star connected alternator having an effective per phase resistance of 0.62 ohms gave the following results: Using MMF method, find the voltage regulation at 100 Ai. 0.8 pf lagging ii. 0.8 pf leading. (JNTU Nov 07)

19. i. With proper explanation & diagram, Justify the statement ‘MMF method for finding voltage regulation is optimistic and EMF method for finding voltage regulation is pessimistic’.

ii. The no load excitation of an alternator required to give rated voltage is 160 A. In a short circuit test with full current flowing in the armature, the field excitation was 135 A. Determine the approximate excitation that will be required to give full load current at 0.8 PF lagging at the rated terminal voltage.

(JNTU Nov 07)

20. i. Derive an expression for finding regulation of salient - pole alternator using two reaction theory . Draw its Phasor diagram. (JNTU Feb 07, Nov 06)

ii. A generator rated at 25 MVA, 0.8 pf lag, 13.8 kV, 3- phase is operating at normal terminal voltage and rated load . The direct axis synchronous reactance is 7.62, Quadrature axis synchronous reactance is 4.57 and the armature resistance is 0.15/ph. Determine the direct axis and quadrature axis components of armature current and internal induced voltage. Also find the regulation. (JNTU Feb 07)

21. i. Explain why synchronous-impedance method of computing the voltage regulation leads to a pessimistic value at lagging power factor loads.

ii. The open and short - circuit test readings forField Amps: 10 20 25 30 40 50O.C.Terminal V 800 1500 1760 2000 2350 2600S.C.armature current in A: - 200 250 300 - -The armature effective resistance is 0.2 per phase. Draw the characteristic curves and estimate the full-load percentage regulation ata. 0.8 p.f.lagging b. 0.8 p.f. leading. (JNTU Feb 07, Nov 06)

22. i. Explain the two reaction theory applicable to salient pole synchronous Machine. (JNTU Feb 07) ii. A 4500 KVA,50 Hz,3-phase,synchronous generator having a synchronous reactance of 0.3 p.u. is

running at 1500 r.p.m and is excited to give 11000 V.If the rotor deviates slightly from its equilibrium position, what is the synchronizing torque in N-m per degree mechanical displacement.

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23. i. Explain the terms direct axis synchrnous reactance and quadrature axis synchronous reactance of a salient pole alternator. On what factors do these values depend?

ii. A 3 MVA, 6 ple alternator runs at 1000 rpm in parallel with other machines on 3.3 KV bus bars. The synchronous reactance is 20%. Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchrononizing torque when the alternator as supplying full load at 0.8 lag p.f. (JNTU Feb 07, Mar 06, 05)

24. i. What is voltage regulation? Discuss the synchronous impedance method of calculating voltage regulation.

ii. A 500V, 50KVA, 1-phase alternator has an effective resistance of 0.2Ω, field current of 10A produces an armature current of 200A on short circuit and an emf of 450V on open circuit. Calculate i. Synchronous impedance and reactance ii. Full-load regulation with 0.8p.f. lagging.

(JNTU Feb 07, Nov 06, 05, May 05)

25. i. Explain the potier - triangle method of determining the voltage regulation of an alternator.ii. A 3-phase star-connected alternator is rated at 1600KVA and 13,5000V. The armature effect

resistance and synchronous reactance per phase are 1.5 and 30 respectively. Calculate the percentage regulation for a load of 1280KW at p.f ofi. 0.8 lagging ii. unity iii. 0.8 lead (JNTU Feb, Nov 07, 05)

26. i. What happens to the value of synchronous reactance if air gap is increased.ii. A 30KVA, 440V, 50Hz, 3-Phase, Star-connected alternator gave the following test data:

Field Current (A) 2 4 6 7 8 10 12 14Terminal Voltage (V) 155 287 395 440 475 530 570 592S.C. Current (A) 11 22 34 40 46 57 69 80Resistance between any two terminals is 0.3 Ohms. Find the regulation at full load, 0.8 p.f. lagging, by MMF method (JNTU Feb 07, Nov 03)

27. Explain how the Potier triangle can be drawn with the help of O.C.C and any two points on the Z.P.f curve and also explain the Potier reactance method of determining regulation of an alternator.

(JNTU Nov 06)

28. A 2000 KVA, 11KV, 3-phase, star connected alternator has a resistance of 0.3 ohm and reactance of 5 ohm per phase It delivers full-load current at 0.8 lagging p.f at rated voltage. Compute the terminal voltage for the same excitation and load current at 0.8 p.f leading. (JNTU Nov 06)

29. i. What is an infinite bus? State the characteristics of an infinite bus. What are the operating characteristics of an alternator connected to an infinite bus?

ii. A 3 MVA,6-pole alternator runs at 1000 r.p.m in parallel with other machines on 3.3 KV bus-bars. The synchronous reactance is 20%.Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchronizing torque. (JNTU Nov 06)

30. i. Describe the slip test method for the measurement of Xd to Xq of synchronous machines.ii. A 3.5 MVA, slow-speed, 3-phase synchronous generator rated at 6.6 KV has 32 poles its direct and

quadrature axis synchronous reactances as measured by the slip test atre 9.6 ohm and 6 ohm respectively. Neglecting armature, determine the regulation and the excitation emf needed to maintain 6.6 KV at the terminals when supplying a load of 2.5 MW at 0.8 pf lagging. What maximum power can the generator supply at the rated terminal voltage, if the field becomes open-circuited?

(JNTU Nov 06, 05, Mar 06, May 05)

31. i. Develop the expression for finding regulation of salient pole alternator using two-reaction theory. Draw its phasor diagram. (JNTU Nov 06)

ii. A 3-phase, star-connected, 50 Hz synchronous generator has direct-axis synchronous reactance of 0.6 pu. and quadrature axis synchronous reactance of 0.45 p.u. The generation delivers rated KVA at rated voltage. Drw the phasor diagram at full-load 0.8 p.f. Lagging and hence calculate the open circuit volage and voltage regulation. Resistive drop at full-load is 0.015 p.u. (JNTU Mar 06)

32. Explain the factors responsible for making terminal voltage of an alternator less than the induced voltage. (JNTU Mar 06)

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33. i. Explain the MMF method of determining the voltage regulation of alternator.ii. A 1000KVA, 11000V 3-phase, 50 Hz, star-connected turbo-generator has an effective resistance of

2ohm/phase. The O.C.C. and zero p.f. full load data is as follows:O.C. Voltage (V) 5805 7000 12550 13755 15000Field current (A) 40 50 110 140 180T V at F.L. Zero p.f 0 1500 8500 10500 12400Estimate the % regulation for F.L. at 0.8 p.f lagging. (JNTU Mar 06)

34. i. Sketch and explain the open-circuit and short circuit characteristics of a synchronous machine. How voltage regulation can be calculated by the use of their results.

ii. A 3-phase star connected alternator is rated at 1600KVA, 13,500 V. The armature effective resistance and synchronous reactance are 1.5 ohm and 30 ohm respectively per phase. Calculate the percentage regulation for a load of 1280 KW at power factors of a. 0.8 leading and b. 0.8 lagging. (JNTU Mar 06)

35. Draw the phasor diagram of an alternator corresponding to zero full load regulation.(JNTU Mar 06, Nov 03)

36. i. Discuss about two reaction theory with relevant phasor diagram.ii. A 4 pole, 50 Hz, 22 KV, 500 MVa synchronous generator having a synchronous reactance of 1.57 pu is

feeding into a power system, which can be represented by a 22 KV infinite bus in series with a reactance of 0.4. The generator excitation is continually adjusted (by means of an automatic voltage regulator) so as to maintain a terminal voltage of 22 KV independent of the load on the generator.i. Draw the phasor diagram, when the generator is feeding 250 MVA into the power system. Calculate the generator current, its power factor and real power fed by it. What is the excitation emf of the generator. (JNTU Nov 05)

37. i. Explain how regulation is determined from slip test.ii. A 3-phase salient pole synchronous generator has Xd=0.8 p.u; Xq = 0.5 p.u and Ra=0 generator

supplies full-load at 0.8 p.f. Lagging at rated terminal voltage. Computeri. Power angle and ii. No-load voltage if excitation remains constant. (JNTU Nov 05)

38. i. Define and explain the terms synchronous impedance and voltage regulation of an alternator. State the assumptions made in the synchronous impedance method.

ii. A 3-phase, 50 Hz, star-connected, 2000KVA, 23000V alternator gives a short circuit current of 600A for a certain field excitation. With the same excitation, the O.C. Voltage was 900 V. The resistance between a pair of terminal was 0.12. Find full-load regulation at a. u.p.f b. 0.8 p.f lagging c. 0.8 p.f leading. (JNTU Nov 05)

39. i. Develop the expression for finding voltage regulation of salient-pole alternator.ii. The no-load and full-load zero power factor characteristics for a 23.5MVA, 13.8 KV, 3-phase, star-

connected turbo-generator are given below in per unit values: No-load charactersticsNo-load characterstics If 0.10 0.20 0.40 0.60 0.80 1.0 1.2 1.4 1.6 2.0 2.5V 0.13 0.23 0.45 0.69 0.87 1.0 1.09 1.15 1.21 1.28 1.36Zero power factor characterstics If 1.2 1.3 1.4 1.6 1.8 2.0 2.2 2.4 2.6V 0.015 0.13 0.25 0.49 0.69 0.83 0.92 0.99 1.04Determine the regulation at full-load, 0.8 p.f lag by the zero p.f method. Neglect armature resistance.

(JNTU Nov 05)

40. i. Define voltage regulation of an alternator. Explain the various factors, which may affect the regulation of an alternator.

ii. A 100-KVA, 3000V, 50Hz, 3-phase, star –connected alternator has effective armature resistance of 0.2. The field current of 40A produces short-circuit current of 200A and an open-circuit emf of 1040V(line value). Calculate the full-load voltage regulation at 0.8 p.f.lagging and 0.8 p.f.leading. Draw phasor diagrams. (JNTU Nov 04, 03, 02)

41. i. Sketch and explain the open –circuit and short circuit characteristics of a synchronous machine. How voltage regulation can be calculated by the use of their results.

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ii. A 3-phase, 50Hz, star-connected, 2000KVA, 2300-V alternator gives a short –circuit current of 600A for a certain field excitation. With the same excitation, the O.C. Voltage was 900V.The resistance between a pair of terminal was 0.12W.Find full –load regulation at i. u.p.f. ii. 0.8 p.f. lagging iii. 0.8 p.f. leading. (JNTU Nov 04, 02)

42. i. Explain the method of determining the voltage regulation of an alternator by ASA method.ii. An alternator has a synchronous reactance of 20% and negligible resistance calculate its voltage

regulation when working at full load.i. 0.8 P.f Lag ii. Unity P.f and iii. 0.8 P.f. Lead (JNTU Nov 04, 03)

43. i. Explain the two reaction theory applicable to salient pole synchronous Machine.ii. A 6.6 kV, 1MVA, 3ø alternator is delivering full load at 0.8 p.f. lagging. Its reactance is 20% and

resistance is negligible. By changing the excitation, the e.m.f. is increased by 25% at this load. Calculate the new current and the power factor. The machine is connected to infinite bus-bars.

(JNTU Nov 04)

44. i. Describe synchronous impedance method to determine regulation of an alternator for Lagging power factor.

ii. A 600V, 60KVA, Single-phase alternator has an effective resistance of 0.2 Ohms. A field current of 10A produces an armature current of 210A on short circuit and an e.m.f. of 480V on open circuit calcute.i. Synchronous impedance and reactance.ii. Regulation with 0.8 P.f Lagging and unity P.f. leading (JNTU Nov 04, 03, 02)

45. How do you find Xd and Xq of a given salient - pole alternator experimentally. (JNTU May 04)

46. What are the precautions to be taken while conducting Slip test? Draw the Phasor diagram when the load connected is of Leading p.f. (JNTU May 04)

47. The following data was obtained for the OCC of a 10MVA, 13KV, 3 Phase, 50 hz, Star connected synchronous generator.IF (A) 50 75 100 125 10 162.5 200 250 300VOC (Line)(KV) 6.2 8.7 10.5 11.8 12.8 13.2 14.2 15.2 15.9An excitation of 100A causes the full load current to flow during the short circuit test. The excitation required giving the rated current at zero p.f. and rated voltage is 290A.

i. Calculate the synchronous reactance of the machine.ii. Calculate the leakage reactance of the machine assuming the resistance to be negligible.iii. Determine the excitation required when the machine supplies full load at 0.8 P.f Lagging by using the

leakage reactance and drawing the MMF Phasor diagram. What is the voltage regulation of the machine? (JNTU Nov 03)

48. Explain the Phasor diagram of salient pole synchronous machinei.At Lagging P.f. ii. At Leading P.f. (JNTU Nov 03)

49. A 1000 KVA, 11000V, 3 Phase star connected alternator has an effective resistance of 2 Ohms/Phase. The characteristics on Open – circuits and with full load current at zero P.f. and the open circuit core losses are:Field Current (A) 40 50 110 140 180OC teminal Voltage (V) — 7000 12500 13750 15000Core loss (KW) — 7.5 16.6 22.4 33.5Saturation curve zero P.f (V) 0 — 8500 10500 12400Deduce by the Z.P.f method.

i. The percentage regulation for full load at a Lagging 0.8 P.f. Find also.ii. The efficiency at this load, given that the field current has resistance of 0.5 Ohms and that the

mechanical and additional losses amount to 10 KW. (JNTU Nov 03, 02)

50. A 600KVA, 3300V, 8 pole, 3 Phase, 50 Hz alternator has the following characteristics.Amp-turns/pole 4000 5000 7000 10000Terminal EMF 2850 3400 3850 4000

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There are 200 conductors in series per phase. Find the SC characteristics, the field ampere-turns for full load 0.8 P.f (lagging) and the voltage regulation, having given that the inductive drop at full load is 7% and that the equivalent armature reaction in amp-turns per pole= 1.06 X ampere conductor per phase per pole. (JNTU Nov 03)

51. i. Explain the A.S.A. method of predetermining the regulation of an alternator.Note: You need not explain how to conduct the tests necessary for this method but take the test results.

ii. The open and short circuit test date on a 3 phase, 1 MVA, 3.6 KV, star connected synchronous generator is given below:Field Current (Amps) 60 70 80 90 100 110Voc (line) volts 2560 3000 3360 3600 3800 3960S.C. Test (Amp.) 180 - - - - -Find the unsaturated synchronous reactance, the adjusted synchronous reactance and the short circuit ratio. (JNTU Nov 03)

52. Explain Potier triangle method of finding regulation of an alternator. (JNTU Nov 02)

53. Develop phasor diagram for a salient pole alternator supplying a leading pf load and explain 2 reaction theory. (JNTU Nov 02)

54. A 10 KVA, 380 V, 4 pole, 50 HZ star connected salient pole alternator has direct axis and quadrature axis reactances of 12W and 8W respectively. The armature has a resistance of 1W per phase. The generator delivers rated load at 0.8 Pf lagging with terminated voltage being maintained at rated value. If the load angle is 16.15 degrees determine

i. Direct and quadrature axis components of armature currentii. Excitation voltage of generator. (GATE 08)

55. A 100 kVA, 415V (line), star-connected synchronous machine generates rated open circuit voltage of 415 V at a field current of 15A. The short circuit armature current at a ield current of 10A is equal to the rated armature current. The per unit saturated sunchronous reactance is (GATE 07)a. 1.731 b. 1.5 c. 0.666 d. 0.577

56. A 10 KVA, 380 V, 4 pole, 50 HZ star connected cylindrical rotor alternator has a stator resistance and synchronous reactance of 1W and 15W respectively. It supplies a load of 8 KW at rated voltage and 0.8 power factor lagging.

i. Draw a Phasor diagramii. Express resistance and synchronous reactance in per unit values with the machine rating as base.iii. Calculate percentage regulationiv. What is terminal voltage if the load is suddenly removed. (GATE 06)

57. In which one of the following is reluctance power developed ?i. Salient pole alternator ii. Non-salient pole alternatoriii. Squirrel cage induction motor iv. Transformer (IES 06)

58. Find the synchronous impedance and reactance of a single phase alternator in which a given field current produces an armature current of 250A, on short circuit and a generated emf of 1500V on open circuit. The armature resistance is 2 ohms. Calculate potential difference when the load of 250A at 6.6 Kv at a lagging p.f of 0.8 is switched off. (IES 03)

59. A 2000 KVA, 11 KV, 3 phase, Y connected alternator has a resistance of 0.3 and reactance of 5per phase. It delivers full load current at a p.f of 0.8 lagging and normal rated voltage. Compute the terminal voltage for the same excitation and load current at a 0.8 pf leading. (IES 08)

60. i. A 10KVA, 440 V, 50 Hz three phase alternator has the following occ: (IES 99)Field current Terminal voltage1 1003 3005 4408 55011 600

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15 635With full load zero power factor load applied an excitation of 14A produced a critical voltage of 500V. On short circuit, 4 A excitation was required to circulate the full load current. Using MMF method determine the full load percentage regulation for p.f. lagging and 0.6 pf leading

ii. Explain how to determine the direct and quadrature axis reactances of a salient pole synchronous machine

61. A 3.5 MVA, slow speed, 3 phase synchronous generator rated at 6.6 KV has 32 poles. Its direct and quadrature axis synchronous reactances as measured by the slip test are 9.6 and 6.2 respectively. Neglecting regulation and the excitation emf needed to maintain power. Can the generator supply at the rated terminal voltage, if the field becomes open-circuited (IES 94)

62. i. A 10 KVA, 440 V, 50 Hz, 3 phase alternator has the following O.C.CField current (amp) 1.5 3.0 5.0 8.0 11.0 15.0Terminal voltage (volts) 150 300 440 550 600 635With full load zero p.f load applied; an excitation of 14A produced a terminal voltage of 500V on the short circuit, 4A excitation was required to circulate full load current. Using MMF method determine the full load percentage regulation for 0.8 pf lagging and 0.8 pf leading

ii. When three phase supply is given to a three phase winding, a rotating magnetic field of constant amplitude will be produced. Justify the above statement. (IES 93)

63. A 3 ph star connected synchronous generator is rated at 1.5 MVA, 11 KV. The armature effective resistance and synchronous reactance are 1.2 and 25 respectively per phase. Calculate the percentage voltage regulation for a load of 1.4375 MVA.i. 0.8 pf lagging ii. 0.8 pf leading. Also find out the pf at which the regulation becomes zero (IES 92)

64. In an alternator, a lagging current weakens the main field but in a synchronous motor it strengthens the main field. Explain why? (IES 92)

UNIT – IV

1. a. A 2 MVA, 8 pole, 3-_, alternator is connected to 6000 V, 50 Hz bus bars & has a synchronous reactance of 4 /ph. Calculate the synchronizing power & synchronizing torque per mechanical degree of rotor displacement at no load. Assume normal excitation.

b. Explain the e_ect of damper winding & field winding on the transient behavior of an alternator. How the effect of these two can be minimised? (JNTU May 09)

2. a. Explain the various methods of synchronization of alternators.b. Two similar 4 MVA alternators operate in parallel. The governor of first machine is such that

frequency drops from 50 Hz at no load to 47.5 Hz at full load. The corresponding drop for second machine is 50 Hz to 48 Hz. i. How will they share a load of 6 MW? (JNTU May 09)ii. What is the maximum load they can share at UPF without over loading any generator?

3. a. Why parallel operation of alternators is necessary? What are the advantages of connecting alternators in parallel?b. A 5 MVA, 10kV, 1500 RPM, 3-_, 50 Hz alternator is opening on infinite bus bar. Find synchronizing

power per mechanical degree of angular displacement at: i. No loadii. Full load at rated voltage & 0.8 power factor lagging. Also find synchronizing torque for a 0.5o mechanical displacement in each case. xs=20% (JNTU May 09)

4. a. Explain all the necessary conditions for successful parallel operation of alternators.b. A 2 MVA, 3-Φ, star connected, 4 pole, 750 RPM alternator is operating on 6000 V bus bars, xs is 6/ph.

Find synchronizing power and torque for full load 0.8 power factor lagging. (JNTU May 09)

5. a. What conditions must be fulfilled before an alternator can be connected to an infinite bus?b. Calculate the synchronizing torque for unit mechanical angle of phase displacement for a 5000KVA, 3-

phase alternator running at 1500 rpm when connected to 6600 volt. 50 Hz , bus-bars. The armature has a short circuit reactance of 15%. (JNTU May 09)

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6. a. What is an infinite bus? State the characteristics of an infinite bus. What are the operating characteristics of an alternator connected to an infinite bus?

b. A 3 MVA,6-pole alternator runs at 1000 r.p.m in parallel with other machines on 3.3 KV bus-bars. The synchronous reactance is 20%.Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchronizing torque. (JNTU May 09)

7. a. Explain different synchronization methods used for synchronizing alternators.b. A 3 MVA,6-pole alternator runs at 1000 r.p.m in parallel with other machines on 3.3 KV bus-bars. The

synchronous reactance is 20%.Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchronizing torque when the alternator is supplying full load at 0.8 p.f lag. (JNTU May 09)

8. a. Develop the expression for finding regulation of salient pole alternator using two-reaction theory. Draw its phasor diagram.

b. A 3-phase, star -connected,50-Hz synchronous generator has direct-axis synchronous reactance of 0.6 p.u. and quadrature-axis synchronous reactance of 0.45 p.u.The generator delivers rated KVA at rated voltage. Draw the phasor diagram at full -load 0.8 p.f. Lagging and hence calculate the open –circuit voltage and voltage regulation. Resistive drop at full-load is 0.015 p.u (JNTU May 09)

9. a. Define the significance of transient and sub-transient reactances in an alternator.b. Two 15KVA, 400V, 3-phase alternators in parallel supply a total load of 25 KVA at 0.8 p.f. lagging. If

one alternator shares half the power at unity power factor, determine the power factor and KVA shared by the other alternator. (JNTU May 09)

10. a. Explain the various methods of synchronization of alternators.b. Two similar 4 MVA alternators operate in parallel. The governor of first machine is such that

frequency drops from 50 Hz at no load to 47.5 Hz at full load. The corresponding drop for second machine is 50 Hz to 48 Hz. i. How will they share a load of 6 MW? (JNTU May 09)ii. What is the maximum load they can share at UPF without over loading any generator?

11. a. Explain the operational differences in parallel operation of two alternators & synchroning an alternator to infinite bus bars.

b. Two star connected alternators supply a load of 3 MW at 0.8 pf lagging and share the load equally. The excitation of second machine is adjusted so that it is supplying 150 A at a lagging pf. The synchronous impedances are 0.4 + j12 Ω /ph& 0.5 + j10Ω /ph. Find current, power factor, induced EMF and load angle of each machine. Terminal voltage is 6.6 kV. (JNTU Nov 08)

12. a. Explain the term synchronization, and hence explain, synchronizing power.b. Two identical 3 MVA alternators are running in parallel. The frequency drops from no load to full load

for the two alternators are 50 Hz to 47 Hz and 50 Hz to 48 Hz respectively. i. How they will share a load of 4000 kW?ii. What is maximum unity factor load which they can supply jointly supply without any one of them over loaded? (JNTU Nov 08)

13. a. Explain the effect of change in excitation on the parallel operation of two alternators.b. Two similar stat connected alternators 3-Φ alternators share a load of 7500 kW equally at 6000 V and

0.8 pf lagging. The synchronous impedance of 2.5 + j50Ω /ph. The excitation of second machine is changed, so that it delivers 40 A at a lagging pf. Find: i. Armature current of first machine ii. EMF of each machineiii. Power factor of each machine. (JNTU Nov 08)

14. a. What conditions must be fulfilled before an alternator can be connected to an infinite bus?b. Calculate the synchronizing torque for unit mechanical angle of phase displacement for a 5000KVA, 3-

phase alternator running at 1500 rpm when connected to 6600 volt. 50 Hz , bus-bars. The armature has a short circuit reactance of 15%. (JNTU Nov 08)

15. a. Describe the slip test method for the measurement of Xd to Xq of synchronous Machines.b. A 3.5 MVA, slow-speed, 3-phase synchronous generator rated at 6.6KV has 32 poles its direct - and

quadrature - axis synchronous reactances as measured by the slip test are 9.6 and 6 respectively.

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Neglecting armature, determine the regulation and the excitation emf needed to maintain 6.6KV at the terminals when supplying a load of 2.5MW at 0.8pf lagging. What maximum power can the generator supply at the rated terminal voltage, if the field becomes open-circuited? (JNTU Nov 08)

16. a. What are the conditions that must be fulfilled before synchronizing an alternator? Describe any one

method of synchronizing an alternator.b. A 3-phase, star -connected,50-Hz synchronous generator has direct-axis synchronous reactance of 0.6

p.u. and quadrature-axis synchronous reactance of 0.45 p.u.The generator delivers rated KVA at rated voltage. Draw the phasor diagram at full -load 0.8 p.f. Lagging and hence calculate the open –circuit voltage and voltage regulation. Resistive drop at full-load is 0.015 p.u. (JNTU Nov 08)

17. A 5 MVA, 10 kV, 1500 RPM, 3-phase, 50 Hz alternator is running in parallel with other machines. Its synchronous reactance is 20 %.Find synchronizing power & synchronizing torque per degree mechanical displacement, for no load & full load, 0.8 pf lagging. (JNTU Feb 08)

18. i. Explain the ‘two bright one dark’ & ‘all dark’ method of synchronization of alternators.ii. The EMFs of two alternators are 3000200 & 290000 V. Their synchronous impedances are 2 + j20 /ph

& 2.5 + j30 /ph. The load impedance is 10 +j4 /ph. Find the circulating current.(JNTU Feb 08, Nov 07)

19. i. Explain, why synchronous motor is not self starting?ii. A 3-, 600 V, star connected SM has effective per phase armature resistance & synchronous reactance

of 0.4 & 3.6 respectively. Calculate the induced EMF per phase if the motor works on full load delivering 326 kW. The full load efficiency is 87 % having power factor of 0.8 leading. Also calculate the load angle. (JNTU Feb 08, Nov 07)

20. i. Explain all the necessary conditions for successful parallel operation of alternators.ii. A 2 MVA, 3-, star connected, 4 pole, 750 RPM alternator is operating on 6000 V bus bars, ×s is 6 /ph.

Find synchronizing power and torque for full load 0.8 power factor lagging. (JNTU Nov 07)

21. i. State and explain the different conditions for operating alternators in parallel.ii. Two three - phase alternators operate in parallel. The rating of one machine is 200 MW and that of the

other is 400 MW. The droop characteristics of their governors are 4% and 5% respectively from no - load to full load of 600 MW be shared between them? What will be the system frequency at this load? Repeat the problem if both governors have a drop of 4%. (JNTU Feb 07)

22. i. Explain the necessity of parallel operation of alternators.ii. Two 50MVA, 3-phase alternators operate in parallel. The settings of the governors are such that the

rise in speed from full-load to no-load in 2% in one machine and 3% in the other, the characteristics being straight lines in both cases. If each machine is fully loaded when the total load is 100MW,what will be the load on each machine when the total load reduced 60MW?

(JNTU Feb 07, Mar 06, 05, Nov 05)

23. A 3 MVA, 6- Pole alternator runs at 1000 rpm in parallel with other machines on 3.3KV bus bars .The synchronous reactance is 20%. Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchronizing torque when the alternator as supplying full load at 0.8 lag p.f. (JNTU Feb 07, May 05)

24. i. Discuss load sharing between two alternators.ii. Two 750 KW alternators operate in parallel. The speed regulation of one set is 100% to 102% from

full load to no load and that of the other is 100% to 104%. How will the two alternators share a load of 1000KW and at what load will one machine cease to supply any portion of the load.


25. A 6000 KVA, 5000V, 50 Hz, 3 phase alternator with 4 poles and a synchronous reactance of 25% operates an constant voltage and constant frequency bus bars. The moment of inertia of the whole rotating system is 16800 kg-m2. Calculate the time of one complete oscillation for full load and unity power (JNTU Feb 07, May 04)

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26. What conditions must be fulfilled before an alternator can be connected to an infinite bus?(JNTU Nov 06)

27. i. Explain the procedure how to bring the incoming machine to operate in parallel with running machines.ii. Two alternators working in parallel supply a lighting load of 300kw and a motor load aggregating to

5000kw at a p.f. of 0.71. One machine is loaded to 5000kw at 0.8 p.f. Lagging. What is the load and power factor of the other machine. (JNTU Nov 06)

28. Describe the effect of sudden short circuit on the performance of synchronous generator.(JNTU Nov 06)

29. Show that in order to obtain a constant - voltage constant frequency of practical bus bar systems the number of alternators connected in parallel should be as large as possible. (JNTU Nov 06)

30. i. Prove that sharing of common load by the alternators in parallel depends upon input to the prime movers.

ii. Two identical 2000 KVA alternators operate in parallel. The governor of first machine is such that the frequency drops uniformly from 50 HZ on no load to 48 Hz on full load. The corresponding uniform speed drop of the second machine is 50 Hz to 47.5 Hz.i. how will the two machines share a load of 3000 Kw?ii. What is the maximum load at unity power factor that can be delivered without over loading either machine? (JNTU Nov 06, Mar 06)

31. i. What is an infinite bus? State the characteristics of an infinite bus. What are the operating characteristics of an alternator connected to an infinite bus?

ii. A 3 MVA, 6-pole alternator runs at 1000 rpm in parallel with other machines on 3.3 KV bus-bars. The synchronous reacftance is 20%. Calculate the synchronizing power per one mechanical degree of displacement and the corresponding synchronizing torque. (JNTU Nov 06, 05, 04)

32. i. Derive the expression for load sharing between the dissimilar alternators.ii. Two identical 2000 KVA alternators operate in parallel. The governor of first machine is such that the

frequency drops uniformly from 50 HZ on no load to 48 Hz on full load. The corresponding uniform speed drop of the second machine is 50 Hz to 47.5 Hz.a. how will the two machines share a load of 3000 Kw?b. What is the maximum load at unity power factor that can be delivered without over loading either machine? (JNTU Nov 06, May 05)

33. i. Derive the expressions for load sharing between the dissimilar alternators.ii. Calculate the synchronizing torque for unit mechanical angle of phase displacement for a 5000KVA, 3-

phase alternator running at 1500 rpm when connected to 6600 volt. 50 Hz, bus-bars. The armature has a short circuit reactance of 15%. (JNTU Nov 06, 05)

34. Two similar 6000V, 3-Phase generators are running in parallel at constant voltage and frequency bus bars. Each has an equivalent resistance and reactance of 0.05 Ohms and 0.5 Ohms respectively and supplies one half of a total load of 10000KW at a lagging power factor of 0.8, the two machines being similarly excited, If the excitation of one machine is adjusted until the armature current is 438 A and the steam supply to the turbine remains unchanged, find the armature current, the emf and the power factor of the other alternator. (JNTU Nov 06, May 04)

35. Two single phase alternators are connected in parallel and the excitation of each machine is such as to generate an open circuit emf of 3500V. The stator winding of each machine has a synchronous reactance of 30 Ohms and negligible resistance. If there is a phase displacement of 40 electrical degrees between the emf’s. Calculate.

i. The current circulating between the two machines.ii. The terminal voltage andiii. The power supplied from one machine to the other. (JNTU Nov 06, 03)

36. i. Describe any two methods for synchronizing alternators?

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ii. A 3-hase, Y-Connected synchronous generator supplies current of 10A having phase angle of 200 lagging at 400V. Find the load angle and the components of armature current Id and Iq if Xd=10 ohm and Xq=6.5 ohm. Assume armature resistance to be negligible. (JNTU Mar 06)

37. i. Explain the procedure to determine the followingi. Sub transient reactance ii. Transient reactance iii. Steady state reactance

ii. The speed regulation of two 500 KW alternators A and B running in parallel are 100% to 104% and 100% to 105% from full load to no load respectively. How will the two alternators share a load of 800KW and also find the load at which one machine ceases to supply any portion of the load?

(JNTU Mar 06, May 05, Nov 05)

38. i. Show that for alternators running in parallel, the division of load between them is governed mainly by the speed load characteristics of their prime movers.

ii. Two 15 KVA, 400V, 3-phase alternators in parallel supply a total load of 25 KVA at 0.8 power factor lagging. If one alternator shares half the power at unity power factor, determine the power factor and KVA shared by the other alternator. (JNTU Nov 05, 04)

39. i. Derive the expression for load sharing between the dissimilar alternators.ii. Two similar 13,000 V, 3-phase alternators are operated in parallel on infinite bus-bars. Each machine

has an effective resistance and reactance of 0.05 ohm and 0.5 ohm respectively. When equally excited, they share equally a total load of 18 MW at 0.8 power factor lagging. If the excitation of one generator is adjusted until the armature current is 400A. And the steam supply to its turbine remains unaltered, find the armature current, the emf and the power factor of the other generator. (JNTU May 05)

40. Two similar 13,000V, 3- phase alternators are operated in parallel on infinite bus-bars. Each machine has an effective resistance and reactance of 0.05 ohm and 0.5 ohm respectively. When equally excited, they share equally a total load of 18MW at 0.8 power factor lagging .If the excitation of one generator is adjusted until the armature current is 400A. and the steam supply to its turbine remains unaltered, find the armature current, the e.m.f and the power factor of the other generator. (JNTU May 05)

41. A 5000KVA, 10 KV, 1500 rpm, 50 Hz alternator runs in parallel with other machines. Its synchronous reactance is 20%. Find the synchronizing power per unit mechanical angle of the phase displacement for (JNTU May 05, Nov 04, 03)a. No load and b. Full load at 0.8 p.f (lag)Also calculate the synchronizing orque if the mechanical displacement is 0.50.

42. i. Show that the behavior of a synchronous machine of infinite bus is quite different from its isolated operation.

ii. Two single phase alternators operate in parallel and supply a load impedance of (3+j4). If the impedance of the machine is (0.2+j2) and emfs are (220+j0) and (220+j0) volts respectively, determine for each machine. i.Terminal voltage ii. power factor and iii. output. (JNTU Nov 04)

43. A 3-phase, star –connected,50-Hz synchronous generator has direct-axis synchronous reactance of 0.6 p.u. and quadrature-axis synchronous reactance of 0.45 p.u. The generator delivers rated KVA at rated voltage. Draw the phasor diagram at full –load 0.8 p.f. Lagging and hence calculate the open –circuit voltage and voltage regulation. Resistive drop at full-load is 0.015 p.u. (JNTU Nov 04)

44. Two Exactly similar turbo – alternators are rated 20 MW each. They are running in parallel. The speed – load characteristics of the driving turbines are such that the frequency of alternator 1 drop uniformly from 50 Hz on no-load to 48 Hz on full – load, and that of alternator 2 from 50 Hz to 48.5Hz. How will the two machines share a load of 30MW? (JNTU Nov 04)

45. Explain different synchronization methods used for synchronizing alternators. (JNTU Nov 04)

46. Define the significance of transient and sub transient reactances in an alternator. (JNTU Nov 04)

47. i. How do you calculate the time constant in case of an alternator.ii. Show that an alternator running in parallel at constant voltage and frequency bus bars has a natural time

period of oscillation. Deduce of formulae for the time of one complete oscillation and calculate the value for a 500KVA, 3 phase, 10000V machine running at 1500 rpm and constant 50Hz bus bars. The

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moment of Inertia of the whole moving system is 14112 Kg-m2 and the steady short – circuit current is five times the normal full load values. (JNTU May 04)

48. Two identical 2 MVA alternators operate in Parallel. The governor of the first machine is such that frequency drops uniformly from 50 Hz on no load to 48 Hz on full load. The corresponding uniform speed drop of the second machine is 50 Hz to 47.5 Hz.

i. How will the two machines share a load ot 3 MWii. What is the maximum load at UPF that can be delivered without overloading either machine.

(JNTU Nov 03)

49. In brief explain the operation of a 3 phase cylindrical rotor alternator under constant load with variable excitation. Draw the phastor diagram. (JNTU Nov 02)

50. i. What are the conditions for parallel operation of alternators?ii. A 3 MVA 6 pole alternator runs at 1000 rpm in parallel with other machines on 3300V bus bars. The

synchronous reactance is 25%. Calculate the synchronizing power per one mechanical degree displacement and the corresponding synchronous torque. (JNTU Nov 02)

51. Derive the power angle characteristic of synchronous generator when it is connected to infinite bus bars. (JNTU Nov 02)

52. Define synchronizing power coefficient and synchronizing power. When does it come into action? How is it related to the stability limit of a synchronous machine? (JNTU Nov 02)

53. i. From the equivalent circuit of an alternator determine the expression for input power and output power.ii. A 3 phase Y connected alternator is operated at a constant voltage of 6.63 KV and its excitation voltage

is adjusted to 6.4 KV. Find the maximum output power and pf at this power assuming Zs = 1 + 10j ohm per phase. (JNTU Nov 02)

54. A star connected alternator is synchronized with an infinite bus of 11 KV, its steam input is then increased till its output power is 15 MW. Now when its excitation emf is increased to 130%. The synchronous machine starts operating at a pf of 0.8 lagging. Compute synchronous reactance of the machine. Neglect armature resistance. Determine the power factor, load angle and armature current of the machine before the excitation emf increased. (JNTU Nov 02)

55. Explain how an alternator is synchronized to the bus bars. (JNTU Nov 02)

56. Two identical synchronous generators, each of 100 MVA, are working in parallel supplying 100 MVA at 0.8 p.f at rated voltage. Initially the machines are sharing load equally. If the field current of first generator is reduced by 5% and of the second generator increased by 5%, find the sharing of load (MW and MVAR) between the generators. Assume Xd=Xq=0.8 p.u., no field saturation and rated voltage across load. Reasonable approximations may be made. (GATE 01, 08)

57. A 5 MVA, 11 kV, 3-phase star connected alternator is synchrnonized to the bus bars and is operating with an nduced EMF of 125% of the rated voltage. If the load current is 500 A, what is the power factor of operation? The machine has a synchronous reactance of 5Ω and negligible resistance per pahse. (GATE 99)

58. A 10,000 KVA, 3 phase, star connected 11,000 V, 2 pole turbo-generator has a synchrnous impedance of (0.0145+j0.5) ohms per phase, the various losses in this generator are as follows:Open circuit core loss at 11000 V is 90 kWWindage and friction loss is 50 kWShort circuit load loss at 525 A is 220 kWField windings resistance is 3 ohms, Field current is 175 ampsIgnoring the change in field current, compute the efficiency at i. rated load 0.8 power factor leading.

ii. half rated load, 0.9 power factor lagging. (GATE 96)59. A 10 kVA, 380V, 4-pole, 50 Hz, star connected cylindrical rotor alternator has a stator resistance and

synchronous reactance of 1 ohm and 15 ohms respectively. It supplies a load of 8 kW at rated voltage and 0.8 power factor lagging.

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i. Draw a phasor diagram of operationii. Express the resistance and synchrnous reactance in per unit values with the machine rating as the base.iii. Calculate the percentage regulation. (GATE 91)

60. What is the value of the load angle when the power output of a salient oike synchronous generator is maximum ?i. 00 ii. 450 iii. 900 iv. None of the above (IES 06)

61. A star-connected 3-phase alternator delivers a 3-phase star-connected load at power factor of 0.8 lagging. A wire connects the load and the alternator. The terminal voltage at no-load is 2500 V and at full-load of 1460 kW it is 2200 V. Determine the terminal voltage when it delivers a 3 phase star-connected load having a resistance of 6 ohms and reactance 8 ohms per phase respectively. Assume constant current and field excitation. (IES 08)

62. Two identical 60 MVA alternators operate in parallel. The governor of the first m/c is such that the rise in speed from full load to no load is 3% and second is 4% in the other. The characteristics being straight lines in both cases. If each machine is fully loaded when the total load is 160 MW, what will be the load on each machine when total load is reduced to 100 MW. (IES 03)

63. A cylindrical rotor hydro generator is feeding an active power of 0.25 pu into a large network bus which is held at 1.0 pu voltage. The generator is overexcited with an induced voltage of 1.5 p.u. The synchronous impedance of the generator and connecting link are j0.725 pu/ phase and j0.11 p.u/ phase respectively. Calculate the percentage in the reactive power output measured at the network bus in each of the following cases

i. i. If the turbine torque is increased by 100% keeping the excitation of generator constantii. If the turbine torque is held constant at initial value, but the excitation is increased by 20%.

ii. Using double revolving field theory explain the working of a single phase induction motor(IES 02)

64. Two alternators working in parallel supply a lighting load of 300 KW and motor load aggregating to 5000 KW at a pf of 0.71 one machine is loaded upto 5000 KW at 0.8 pf lagging. What is the load and power factor of the other machine. (IES 02)

65. A 5 MVA, 10 KV, 1500 rpm, 50 Hz alternator runs in parallel with other machines. The synchrnous reactance is 90% find for i. no load, ii. full load power factor 0.8 lagging, synchronizing power per unit mechanial angle of phase displacement, and calculate the synchronizing torque if the mechanical displacement is 0.5. (IES 01)

66. Using synchronous-impedance method, determine the voltage regulation of a 2000 volt single-phase alternator supplying a load current of 100A at rated voltage and a power factor of i. unity ii. 0.8 leading, and iii. 0.707 lagging. The test results available are as follows: The full load current of 1000A is produced on short-circuit by a field excitation of 2.5 A, an emf of 500 V is produced on open circuit by the same excitation, and the armature resistance is 0.8 ohm. (IES 98)

67. What is meant by infinite bus bars? State i. The conditions required to be satisfied for connecting a synchronous generator to a infinite bus bar.

Explain how the instant for synchronizing can be determined.ii. A generator has synchronous reactance of 1.7241 p.u and is connected to a very large system. The

terminal voltage of the generator is 1.0 p.u. and generator is supplying to the system a current of 0.8 p.u at 0.9 pf lagging. Neglecting resistance calculate i. Internal voltage.ii. Active and reactive power output of the generatoriii. The power angle and reactive power output of the generator if the excitation of the generator is increased by 20% keeping active power constant. (IES 98)

UNIT – V

1. a. Explain, why synchronous motor is not self starting?

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b. A 3-Φ, 600 V, star connected SM has effective per phase armature resistance & synchronous reactance of 0.4 & 3.6 respectively. Calculate the induced EMF per phase if the motor works on full load delivering 326 kW. The full load efficiency is 87 % having power factor of 0.8 leading. Also calculate the load angle. (JNTU May 09)

2. A 500 V, 3-Φ, star connected synchronous motor has resistance & Synchronous reactance of 0.4/ph & 3.6/ph respectively. The OC voltage is 600V. If friction and core losses are 1 kW, calculate the line current & power factor when the motor output is 62 kW. (JNTU May 09)

3. A 3-Φ, 400 V, 40 kVA, star connected synchronous motor is supplying 15 kW load with 0.8 pf lagging. The windage & friction losses are 1.5 kW & core losses are 1.0 kW. Calculate the following:

a. Armature current & Excitation voltageb. Armature current & power factor if the excitation is increased by 40% and power supplied to the load

remains constant. (JNTU May 09)

4. A 3-Φ, 30 kW, 400V, star connected synchronous motor operates on full load at 0.8 pf lagging. The machine has synchronous reactance of 4Ω & negligible armature resistance. Calculate the new value of current & power factor if the excitation is increased by 50%. (JNTU May 09)

5. a. Derive the expressions for load sharing between the dissimilar alternators.b. Two identical 2000KVA alternators operate in parallel. The governor of first machine is such that the

frequency drops uniformly from 50HZ on no load to 48Hz on full load. The corresponding uniform speed drop of the second machine is 50 Hz to 47.5 Hz.i. How will the two machines share a load of 3000 Kw?ii. What is the maximum load at unity power factor that can be delivered without over loading either machine? (JNTU May 09, Nov 08)

6. a. Explain the procedure how to bring the incoming machine to operate in parallel with running machines.b. Two alternators working in parallel supply a lighting load of 300kw and a motor load aggregating to

5000kw at a p.f. of 0.71. One machine is loaded to 5000kw at 0.8 p.f. Lagging. What is the load and Power factor of the other Machine. (JNTU May 09)

7. a. Explain about parallel operation of alternators.b. Two Exactly similar turbo - alternators are rated 20 MW each. They are running in parallel . The speed

-load characteristics of the driving turbines are such that the frequency of alternator1 drop uniformly from 50 Hz on no-load to 48 Hz on full - load, and that of alternator 2 from 50 Hz to 48.5Hz. How will the two machines share a load of 30MW? (JNTU May 09)

8. a. What are the advantages of smaller units in parallel than single larger units (JNTU May 09)b. Two station generators A and B operate in parallel. Station capacity of A is 50 MW and that of B is 25

MW. Full-load speed regulation of station A is 3% and full-load speed regulation of B is 3.5%. Calculate the load sharing if the connected load is 50 MW, no-load frequency is 50 HZ.

9. a. Derive an expression for power developed in a synchronous motor? b. A factory has an average load of 300KW at a p.f. of 0.6 lagging. A synchronous motor with an

efficiency of 88% is used to raise the combined p.f. to 0.90 lagging and at the same time supply a mechanical load of 60KW. Calculatei. Total load KVA ii. KVA capacity of the synchronous motor andiii. synchronous motor operating power factor. (JNTU May 09)

10. a. A sub-station operating at full load of 1200 kVA supplies a load at 0.7 power factor lagging. Calculate the permissible additional load at this power factor and the rating of synchronous condenser to raise the substation power to 0.9 lagging. (JNTU Nov 08)

b. Derive the expression for the maximum power developed by a synchronous motor

11. a. An industrial plant has a load of 800 kW at power factor of 0.8 lagging. It is desired to purchase a synchronous motor of sufficient capacity to deliver a load of 200 kW and also serve to correct the over all plant power factor to 0.92. Assuming that the synchronous motor has an efficiency of 92%, determine its kVA input rating and power factor at which it will operate.

b. Explain the load angle characteristics of a synchronous motor. (JNTU Nov 08)

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12. a. A 3-Φ, synchronous motor observing 60 kW is connected in parallel with a factory load of 240 kW

having lagging pf of 0.8. If the combined load has a pf of 0.9 lagging, what is the value of leading kVAR supplied by the motor & at what power factor it is working?

b. Explain the ‘power factor v/s field current’ & ‘armature current v/s field current’ characteristics of synchronous motor. (JNTU Nov 08)

13. a. An industrial load of 4 MW is supplied at 11 kV, the power factor being 0.8 lagging. A synchronous motor is required to meet an additional load of 1103.25 kW and at the same time to raise the resultant power factor to 0.95 lagging. Determine the kVA capacity of the motor and the power factor at which it must operate. The efficiency of motor is 80 %.

b. Explain the various power stages of synchronous motor. What are the various losses taking place in synchronous motor. (JNTU Nov 08)

14. a. What are the effects of change of excitation and mechanical power input on alternators operated in parallel.

b. Two three - phase alternators operate in parallel. The rating of one machine is 50 MW and that of the other is 100 MW.both alternators are fitted with governors having a droop of 4 percent. How will the machines share a common load of 100 MW? (JNTU Nov 08)

15. a. State and explain the different conditions for operating alternators in parallel.b. Two three - phase alternators operate in parallel. The rating of one machine is 200 MW and that of the

other is 400 MW.The droop characteristics of their governors are 4% and 5% respectively from no - load to full load of 600 MW be shared between them? What will be the system frequency at this load ?Repeat the problem if both governors have a drop of 4%. (JNTU Nov 08)

16. A 3-, 6600 V, star connected synchronous motor has effective per phase synchronous reactance / phase

of 15 & negligible armature resistance. For a certain load, the input is 900 kW at normal voltage and the induced line EMF is 8900 V. Determinea. Line current b. Power factor. (JNTU Feb 08)

17. i. Compare (all 3-) synchronous motor, Induction motor & transformer.ii. A synchronous motor absorbing 50 kW is connected in parallel with a factory load of 200 kW at 0.8

lagging pf. If the resultant power factor after connecting SM is 0.9 lagging, how much leading kVAR are supplied by synchronous motor. At what power factor is it working? (JNTU Feb 08)

18. i. An industrial load of 4 MW is supplied at 11 kV, the power factor being 0.8 lagging. A synchronous motor is required to meet an additional load of 1103.25 kW and at the same time to raise the resultant power factor to 0.95 lagging. Determine the kVA capacity of the motor and the power factor at which it must operate. The efficiency of motor is 80 %.

ii. Explain the various power stages of synchronous motor. What are the various losses taking place in synchronous motor. (JNTU Feb 08)

19. i. Explain the construction & working principle of Synchronous motor. ii. A 3-, 400 V star connected SM has effective per phase armature resistance & synchronous reactance of

0.2 & 2 respectively. It takes 20 A to deliver a certain load. Calculate the excitation EMF induced in the motor if it works with a. 0.8 pf lagging b. 0.8 pf leading (JNTU Nov 07)

20. A 20 pole, 30 kW, 660 V, 50 Hz, star connected synchronous motor is operating with it’s per phase generated voltage exactly equal to the phase voltage applied to armature. At loaded condition the motor is retarded by 5o mechanical from its synchronous position. Per phase synchronous reactance & the effective armature resistance are 10 & 1 respectively. Calculate:

i. Armature currentii. The total power drawn by the motor from bus.iii. The developed power. (JNTU Nov 07)

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21. Derive the expression for the maximum power developed by a synchronous motor. (JNTU Nov 07)

22. A substation operating at full load of 1200KVA supplies a load at 0.7 pf lagging. Calculate the permissible additional load at this power factor and the rating of synchronous condenser to the raise of the substation power factor to 0.9 pf lagging. (JNTU Nov 07, 04)

23. i. What happens when the excitation of the D.C machine is changed? Is the eect is same in a synchronous motor?

ii. A 220V, 3-phase, star connected synchronous motor has a resistance of 0.22 per phase and a synchronous reactance of 2.4 per phase. The motor is operating at 0.6 power factor leading with a line current of 180A. Determine the value of generated emf. (JNTU Feb 07)

24. i. What is the effect on synchronous motor when the excitation is varied.ii. A 3000KVA, 15KV, 1500 rpm, 50HZ alternator runs in parallel with other machines. Its synchronous

reactance is 30%. Find the synchronizing power per unit mechanical angle of the phase displacement fori. No load andii. Full load at 0.7pf (lag)Also calculate the synchronizing torque if the mechanical displacement is 0.60. (JNTU Feb 07)

25. A synchronous motor has an equivalent armature reactance of 3.3. The exciting current is adjusted to such a value that the open circuit emf is 950V. Find the pf at which the motor would operate when it takes 80kW from 800V supply line. (JNTU Feb 07)

26. i. What are the advantages of synchronous motor over induction motors?ii. Why at any load, the power factor decreases and the armature current increases if the field current is

varied above and below the normal excitation. (JNTU Feb 07, Nov 06)

27. i. Explain about different torques of a synchronous motor? (JNTU Feb 07, Nov 06, 05)ii. A 400V, 3-phase synchronous motor takes 52.5A at a power factor of 0.8 leading. Calculate the power

supplied and induced emf. The motor impedance per phase is (0.25+j3.2) ohm.

28. Why it is necessary to increase the excitation to obtain minimum current with the application of load.(JNTU Feb 07, Mar 06, Nov 05, May 05)

29. The synchronous reactance per phase of a 3-phase star connected 6600V synchronous motor is 10. For a certain load, the input is 900KWand the induced line emf is 8900V(line value). Evaluate the line current. Neglect resistance. (JNTU Feb 07, Nov 06, 05, May 05)

30. i. Describe briefly the effect of varying excitation upon the armature current and p.f. of a synchronous motor when input power to a motor is maintained constant.

ii. A 400V, 50Hz, 3-Ø, 37.3KW, star connected synchronous motor has a full load efficiency of 88%. The synchronous impedance of the motor is (0.2 + j1.6) Ohms/Phase. If the excitation of the motor is adjusted to give a leading p.f. of 0.9, calculate for full-load i. the induce emf ii. the total mechanical power developed. (JNTU Feb 07, Nov 05)

31. i. What are the causes of faulty starting of synchronous motor?ii. The input to a 11kV, 3-phase star connected synchronous motor is 60A. The eective resistance and

synchronous reactance per phase are 1 and 30. Find the power supplied to the motor and the induced emf for power factor of 0.8 leading. (JNTU Nov 06)

32. i. What are the advantages and disadvantages of the synchronous motor?ii. A Synchronous motor takes 25kWfrom 400V supply mains. The synchronous reactance of the motor is

4. Find the power factor at which the motor would operate when the exciting current is so adjusted that the generated emf is 500V. (JNTU Nov 06, 05, Mar 06, May 05)

33. A synchronous motor has an equivalent armature reactance of 3.3 Ohms The exciting current in adjusted to such a value that the open circuit emf is 950V. Find the pf at which the motor operate when it takes 80kW from 800V supply line. (JNTU Nov 06, 03)

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34. i. Write short notes on the power factor improvement with synchronous motor?ii. A 2300V, 3-phase, star connected synchronous motor has a resistance of 0.2 per phase and a

synchronous reactance of 2.2 per phase. The motor is operating at 0.6 power factor leading with a line current of 200A. Determine the value of generated emf per phase. (JNTU Nov 06)

35. Write short notes on the following.i. V and inverted V curves of synchronous motor.ii. Synchronous condensor for power factor improvement. (JNTU Mar 06)

36. i. Explain why a synchronous motor will only develop a continuous torque at synchronous speed. How does it reach synchronous speed?

ii. A three phase synchronous motor has 12 poles and operates from 440V, 50 Hz supply calculate its speed. If it takes a line current of 100A at 0.8 pf leading what torque will be the machine developing. Neglect the losses. (JNTU Mar 06)

37. i. What is the effect of load on a synchronous motor?ii. A 400V, 8KW, 3-phase synchronous motor has a negligible resistance and a synchronous reactance of

8 ohm per phase. Determine the minimum current and the corresponding induced emf for full load condition. Assume an efficiency of 88%? (JNTU Nov 05)

38. i. What is the effect on synchronous motor when the load is changed.ii. A 3300V, star connected synchronous motor is operating at constant terminal voltage and constant

excitation. Its synchronous impedance is (0.8+j5) ohm. It operates at a p.f of 0.8 leading when drawing 800KW from the mains. Find its power factor when the input is increased to 1200KW, excitation remaining constant. (JNTU Nov 05)

39. i. Explain synchronous motor ratings?ii. A 3-phase, star connected synchronous motor has a synchronous reactance of 4 ohm per phase and is

working on 1100V. Calculate the power factor of the machine when taking 90KW from the mains. The excitation being adjusted to a value corresponding to an induced emf of 1200V. Neglect armature resistance? (JNTU May 05)

40. A 400V, 3 phase, Y connected synchronous motor takes 3.73KW at normal voltage and has an impedance of (1+j8) per phase. Calculate the current and pf if the induced emf is 460V.

(JNTU May 05)

41. A 3-phase, star connected synchronous motor has a synchronous reactance of 4 per phase and is working on 1100V. Calculate the power factor of the machine when taking 90KW from the mains. The excitation being adjusted to a value corresponding to an induced emf of 1200V. Neglect armature resistance? (JNTU May 05)

42. i. What is synchronous condenser? What is the use of synchronous condenser?ii. A 500V, 50 Hz, 3- circuit takes 20A at a lagging power factor of 0.8 A synchronous motor is used to

raise the power factor to unity. Calculate the KVA input to the motor and its power factor when driving a mechanical load of 7.5 KW. The motor has an efficiency of 85% (JNTU Nov 04)

43. A synchronous motor runs at a load angle of 20° at rated voltage and at rated frequency. Armature circuit resistance is neglected. For constant field current, compute the value of load angle with the following changes in its operating conditions:

i. Frequency increased by 10%, load power and applied voltage constant.ii. Frequency reduced by 10%, load torque and applied voltage constant.iii. Both applied voltage and frequency reduced by 10%, load power constant.iv. Both applied voltage and frequency reduced by 10%, load torque constant. (JNTU Nov 04)

44. i. Define back – emf. Draw the equivalent circuit diagram of synchronous motor. Also deduce the expression for i. excitation voltage, ii. Synchronous impedance and iii. armature current.

ii. A 3-Ø, Y-connected Synchronous motor take 48KW at 693V (line), the p.f. being 0.8 lag. The induced emf is now increased by 30%, the power input being the same. Find the new current and power factor. Synchronous impedance equals to (0+2j) Ohms/Phase. (JNTU Nov 04)

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45. i. Explain the characteristics features of a synchronous motorii. The excitation of a 400V, 3-phase mesh connected synchronous motor is such that the induced emf is

510V. The impedance per phase is (0.6+j4.5) . If the friction and iron losses are constant at 800W, Calculate power output, line current and power factor. (JNTU Nov 04)

46. i. Draw the phasor diagram of a salient pole synchronous motor working at leading p.f. and obtain there from an expression for power in terms of load angle d Neglect armature resistance.

ii. A salient pole synchronous motor has the following per unit constants:Xd = 1.25; Xq = 1.00 Find the excitation voltage when the motor takes rated current (leading) at rated voltage, delivering 0.5 p.u. mechanical power. Ignore all losses. (JNTU Nov 04, May 04)

47. A salient pole synchronous motor with ra = 0, Xd = 0.5 p.u. is operated on infinite bus-bar of 1.0 p.u. voltage. Show that for 1.00 synchronous power, the excitation voltage is Er = Cosec – Cos0. Also derive the condition for load angle when synchronous power is maximum. (JNTU Nov 04)

48. The input to a 1100V, 3-phase, star connected synchronous motor is 60A. The effective resistance and synchronous reactance are 1 ohm and 30 ohm respectively. Find the power supplied to the motor and the induced emf for power factor 0.8 leading. (JNTU Nov 04)

49. i. Explain the principle of operation of a synchronous motor.ii. A 3-Ø, star connected synchronous motor has a synchronous reactance of 4 Ohms/phase and is

working on 1,100V bus-bar. Calculate the power factor of this machine when taking 90KW from the mains, the excitation being adjusted to a value corresponding to an induced emf of 1,200 V. Neglect armature resistance. (JNTU Nov 04)

50. i. What are the salient features of a synchronous motor.ii. The input to a 11 KV, 3Ø, Y connected synchronous motor is 60 A. The effective resistance and

synchronous reactance per phase are 1 Ohm and 30 Ohms respectively. Find i. Power supplied to the motor and ii. the induced emf for a power factor of 0.8 leading. (JNTU Nov 04)

51. i. Explain the construction and principle of operation of synchronous motor?ii. Explain the characteristics features of a synchronous motor (JNTU Nov 04, 03)

52. i. For a salient pole synchronous motor, working at lagging p.f., Show that ii. Find an expression for power in terms of load angle 0, for a salient pole synchronous motor working at

a lagging p.f. Armature resistance may be neglected. (JNTU Nov 03)

53. A 750 KW, 11KV, 2 Phase star connected synchronous motor has a synchronous reactance of 35 Ohms / Phase and negligible resistance. Determine the excitation emf per phase when the motor is operating on full load at 0.8 pf leading. Its efficiency under this condition is 93%.

(JNTU Nov 03)

54. i. What are the advantages of synchronous motor over induction motors?ii. Why at any load, the power factor decreases and the armature current increases if the field current is

varied above and below the normal excitation. (JNTU Nov 03)

55. A 500V, 3 Phase, mesh connected motor has an excitation emf of 600V. The motor synchronous impedance is (0.4 + j5) Ohms while the windage, friction and iron losses are 1200 W. What maximum power output can it deliver? What is the corresponding line current, pf and motor efficiency.

(JNTU Nov 03)

56. Why it is necessary to increase the excitation to obtain minimum current with application of load?(JNTU Nov 03)

57. A 3 Phase synchronous motor is designed for a terminal voltage of 3300V and its synchronous impedance is 0.25 + j2.00 Ohms/Phase. The excitation is adjustable to a value which corresponds to an open circuit terminal voltage of 3500 V Determine the current and p.f. from an output of 750 kW.

(JNTU Nov 03)

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58. Explain V curves and inverted V curves. (JNTU Nov 03)59. i. Mention the essential parts of a synchronous motor. Explain neatly with diagrams each one of them.

ii. A 3Ø, 220V, 50Hz, 1500 rpm, mesh connected synchronous motor has a synchronous impedance of 4 Ohms/Phase. It receives an input line current of 30 Amps. at a leading p.f. of 0.8 Find the line value of the induced emf and the load angle in mechanical degrees. If the mechanical of current under the new conditions. Neglect losses. (JNTU Nov 03)

60. i. Explain the operation of a synchronous motor with variable load at constant excitation.ii. Derive the torque developed in a synchronous motor. (JNTU Nov 03)

61. A 1000 KVA, 11 KV, 3-phase star connected synchronous motor has an armature resistance and reactance are perphase are 3.5 ohm and 40 ohm respectively. Determine the induced emf and angular retardation of the rotor when fully loaded at unity power factor (JNTU Nov 02)

62. A-3 phase, 400 V, 5 kW, star connected synchronous motor having an internal reactance of 10 ohms is operating at 50% load, unity pf. Now, the excitation is increased by 1%. What will be the new load in percent, if the power factor is to be kept same ? Neglect all losses and consider linear magnetic circuit.i. 67.9% ii. 56.9% iii. 51% iv. 50% (GATE 06)

63. A 415V, 2 pole, 3 phase, 50 Hz, star connected, non-salient pole synchronous motor has synchronous reactance of 2 per phase and negligible stator resistance. At a particular field excitation, it draws 20 A at unity power factor from a 415V, 3 phase, 50 Hz supply. The mechanical load on the motor is now increased till the stator current is equal to 50A. The field excitation remains unchanged. Determine:i. The per phase open circuit voltage E0.ii. The developed power for new operating condition and corresponding power factor. (GATE 08)

64. A three-phase synchronous motro connected to ac mains is running at full load and unity power factor. If its shaft load is reduced by half, with field current held constant, its new power factor will be a. unity b. leading c. lagging d. dependent on machine parameters

(GATE 07)

65. A 3 phase, 400V, 5kW, star connected synchronous motor having an internal reactance of 10Ω is operting at 50% load, unity p.f. Now, th excitation is increased by 1%. What will be the new load in percent, if the powe factor is to be kept same? Neglect all losses and consider linear magnetic circuit. a. 67.9% b. 56.9% c. 51% d. 50% (GATE 06)

66. A 415V, 2 pole, 50Hz supply, the mechanical load on motor is now increased till the stator current is equal to 50A. The field excitation remains unchanged. Determine per phase open circuit voltage Eo developed power for the new operating condition and corresponding power factor. (GATE 02)

67. Driving it by another motor tests a 50 KW synchronous motor. When the excitation is not switched on, the driving motor takes 800W. When the armature is short circuited and rated armature current of 10A is passed through it, the driving motor requires 2500W on open circuiting the armature with rated excitation, the driving motor takes 1800W. Calculate the efficiency of synchronous motor at 50% load. Neglect looses in driving motor. (GATE 01)

68. Two alternators working in parallel supply a lighting load of 3000 kW and a motor load aggregating to 5000 kW at a.p.f. of 0.72. One machine is loaded upto 5000 kW at 0.8 p.f. lagging. What is the load and power factor of the other machine ? (IES 06)

69. Why synchronous motors have no starting torque of their own? (IES 03)

70. A 500V, 50 Hz, 3-Ø circuit takes 20A at a lagging power factor of 0.8 A synchronous motor is used to raise the power factor to unity. Calculate the KVA input to the motor, and its power factor when driving a mechanical load of 7.5KW. The motor has an efficiency of 85% (IES 08)

UNIT – VI

1. a. Explain the circumstances leading a synchronous motor to work as an ideal synchronous condenser? A 400V synchronous motor gives a net output mechanical power of 7.35KW and operates at 0.92

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power factor lagging. Its effective resistance is 0.7. If the iron and mechanical losses are 550W and excitation losses are 750W, Calculate armature current and commercial efficiency?

(JNTU May 09)

2. a. What are the advantages and disadvantages of the synchronous motor?b. A Synchronous motor takes 25KW from 400V supply mains. The synchronous reactance of the motor

is 4. Find the power factor at which the motor would operate when the exciting current is so adjusted that the generated emf is 500V. (JNTU May 09)

3. a. Explain the construction and principle of operation of synchronous motor.b. Explain the characteristics features of a synchronous motor. (JNTU May 09)

4. a. Explain about different torques of a synchronous motor?b. A 400V, 3-phase synchronous motor takes 52.5A at a power factor of 0.8 leading. Calculate the power

supplied and induced emf. The motor impedance per phase is (0.25+j3.2)Ω. (JNTU May 09)

5. a. Explain the procedure to plot ‘V curves’ & ‘inverted V’ curves for a given synchronous machine with help of its circles diagrams.

b. A 2 pole, 50 Hz, 3-Φ turbo alternator is excited to generate a bus-bar voltage of 11 kV on no load. The machine is star connected and the short circuit current for this excitation is 1000 A. Calculate the synchronizing power per degree of mechanical displacement of the rotor and the corresponding synchronizing torque. (JNTU May 09, Nov 08)

6. a. What is hunting? Why it is essential to suppress the hunting?b. Explain the various staring methods of synchronous motor. (JNTU May 09)

7. a. Explain the ‘powercircle’ for a given synchronous motor.

b. A 4.5 MVA, 50 Hz, 3-Φ, synchronous generator having a synchronous reactance of 0.3 pu is running at 1500 RPM and excited to give 11 kV. If the rotor deviates slightly from its equilibrium position, what is the synchronizing torque in Nm per degree mechanical displacement? (JNTU May 09)

8. The data for no load saturation curve of a 6.6 kV, 1.8 MVA. 3-Φ, 50 Hz, star connected synchronous motor is given below:V (k V) 3.6 5.9 7.4 7.9 8.4If Amp 45 91 130 160 210The effective resistance & synchronous reactance per phase of the motor are 0.35 & 7 respectively. Plot the V curves for this machine when the input is maintained constant at 450 kW.

(JNTU May 09)

9. a. Assuming two axis model, draw the phasor diagram of a synchronous motor drawing leading current.b. Explain V and inverted V curves. (JNTU May 09)

10. A 1000 HP, 6.0 kV, 3-Φ, star connected synchronous motor has a synchronous impedance of 1.5+j16/ph. It is excited to develop an open circuit EMF of 5 kV. Draw the locus diagram of current for loads up to 1250 HP, with constant excitation. Determine the maximum value of power factor.

(JNTU Nov 08)

11. a. Explain the procedure to plot ‘V curves’ with the help of ‘power circle’ & ‘excitation circle’.b. Explain the effect of damper winding on the performance of a synchronous machine.

(JNTU Nov 08)

12. The effective resistance & synchronous reactance per phase of a 50 Hz, 6.6 kV, 1 MVA, 3-_, star connected synchronous motor are 0.5 & 12 respectively. Plot the V curves for this machine when the input is maintained constant at 250 kW. No load saturation curve:If 50 100 150 175 200V 3400 5700 7200 7900 8400 (JNTU Nov 08)

13. a. What are the advantages and disadvantages of the synchronous motor?

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b. A Synchronous motor takes 25KW from 400V supply mains. The synchronous reactance of the motor is 4. Find the power factor at which the motor would operate when the exciting current is so adjusted that the generated emf is 500V. (JNTU Nov 08)

14. a. Explain about different torques of a synchronous motor?b. A 400V, 3-phase synchronous motor takes 52.5A at a power factor of 0.8 leading. Calculate the power

supplied and induced emf. The motor impedance per phase is (0.25+j3.2)Ω. (JNTU Nov 08)

15. Explain the characteristics of synchronous induction motor. (JNTU Nov 07)

16. i. What are the different methods of starting a synchronous motor? (IES 06)ii. What are the uses of damper winding in a synchronous motor? (JNTU Feb 08, Nov 07, 03)

18. i. Explain the procedure for starting of synchronous motor.ii. A 500V, 3-phase mesh connected motor has an excitation emf of 600V. The motor synchronous

impedance is (0.4+j5) while the windage, friction and iron losses are 1200W. What maximum power output can it deliver? (JNTU Feb 07)

19. What are the uses of damper windings in a synchronous motor?(JNTU Feb 07, Mar 06, Nov 05, May 05)

18. What could be the reasons if a synchronous motor fails to start?(JNTU Feb 07, Nov 06, 05, May 05)

19. What is meant by hunting in a synchronous motor? (JNTU Nov 06, 03)

20. Show that the current locus of a synchronous motor developing constant power is a circle. Determine its center and radius. (JNTU Mar 06, Nov 04)

21. Explain the excitation circles of synchronous motor. (JNTU May 05)

22. Explain the power circle diagrams of the synchronous motor. (JNTU May 05, Nov 03, 02)

23. Show that the current locus of a synchronous motor developing constant power is a circle. Determine its radius and centre. (JNTU Nov 04)

24. Describe the methods of starting of synchronous motor. (JNTU Nov 02)

25. In relation to the synchronous machines, which one of the following statements is false ?i. In salient pole machines, the direct-axic synchronous reactance is greater than the quadrature-axis

synchronous reactance.ii. The damper bars help the synchronous motor self startiii. Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to

the rated armature current.iv. The V-curve of a synchronous motor represents the variation in the armature current with field

excitation, at a given output power. (IES 06, GATE 05)

26. A-3 phase, 400 V, 5 kW, star connected synchronous motor having an internal reactance of 10 ohms is operating at 50% load, unity pf. Now, the excitation is increased by 1%. What will be the new load in percent, if the power factor is to be kept same ? Neglect all losses and consider linear magnetic circuit.i. 67.9% ii. 56.9% iii. 51% iv. 50% (GATE 06)

27. A 415V, 2 pole, 3 phase, 50 Hz, star connected, non-salient pole synchronous motor has synchronous reactance of 2 per phase and negligible stator resistance. At a particular field excitation, it draws 20 A at unity power factor from a 415V, 3 phase, 50 Hz supply. The mechanical load on the motor is now increased till the stator current is equal to 50A. The field excitation remains unchanged. Determine:i. The per phase open circuit voltage E0.ii. The developed power for new operating condition and corresponding power factor. (GATE 02)

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28. A 415V, 2 pole, 50Hz supply, the mechanical load on motor is now increased till the stator current is equal to 50A. The field excitation remains unchanged. Determine per phase open circuit voltage Eo developed power for the new operating condition and corresponding power factor. (GATE 02)

29. Driving it by another motor tests a 50 KW synchronous motor. When the excitation is not switched on, the driving motor takes 800W. When the armature is short circuited and rated armature current of 10A is passed through it, the driving motor requires 2500W on open circuiting the armature with rated excitation, the driving motor takes 1800W. Calculate the efficiency of synchronous motor at 50% load. Neglect looses in driving motor. (GATE 01)

30. Two alternators working in parallel supply a lighting load of 3000 kW and a motor load aggregating to 5000 kW at a.p.f. of 0.72. One machine is loaded upto 5000 kW at 0.8 p.f. lagging. What is the load and power factor of the other machine ? (IES 06)

31. Which one of the following is the type of single phase induction motor having the highest power factor at full load ? (IES 06)i. Shaded pole type ii. Split-phase type iii. Capacitor-start type iv. Capacitor-run type

32. A single phase induction motor is running at N r.p.m. Its synchronous speed is Ns. If its slip with respect to forward field is s, what is the slip with respect to the backward field ?i. s ii. – s iii. (1 – s) iv. (2 – s) (IES 06)

33. Why synchronous motors have no starting torque of their own? (IES 03)

34. A 500V, 50 Hz, 3-Ø circuit takes 20A at a lagging power factor of 0.8 A synchronous motor is used to raise the power factor to unity. Calculate the KVA input to the motor, and its power factor when driving a mechanical load of 7.5KW. The motor has an efficiency of 85% (IES 98)

35. Two alternators working in parallel supply a lighting load of 300 KW and motor load aggregating to 5000 KW at a pf of 0.71 one machine is loaded upto 5000 KW at 0.8 pf lagging. What is the load and power factor of the other machine. (IES 02)

36. A 5 MVA, 10 KV, 1500 rpm, 50 Hz alternator runs in parallel with other machines. The synchronous reactance is 90% find for i. no load, ii. full load power factor 0.8 lagging, synchronizing power per unit mechanical angle of phase displacement, and calculate the synchronizing torque if the mechanical displacement is 0.5. (IES 01)

37. Using synchronous-impedance method, determine the voltage regulation of a 2000 volt single-phase alternator supplying a load current of 100A at rated voltage and a power factor of i. unity ii. 0.8 leading, and iii. 0.707 lagging. The test results available are as follows: The full load current of 1000A is produced on short-circuit by a field excitation of 2.5 A, an emf of 500 V is produced on open circuit by the same excitation, and the armature resistance is 0.8 ohm. (IES 98)

38. What is meant by infinite bus bars? State i. The conditions required to be satisfied for connecting a synchronous generator to a infinite bus bar.

Explain how the instant for synchronizing can be determined.ii. A generator has synchronous reactance of 1.7241 p.u and is connected to a very large system. The

terminal voltage of the generator is 1.0 p.u. and generator is supplying to the system a current of 0.8 p.u at 0.9 pf lagging. Neglecting resistance calculate i. Internal voltage.ii. Active and reactive power output of the generatoriii. The power angle and reactive power output of the generator if the excitation of the generator is increased by 20% keeping active power constant. (IES 98)

39. Briefly explain the phenomenon of ‘hunting’ of a synchronous machine. How is it remedied.(IES 96)

40. Show that as the power developed goes on increasing, the radius of power circle goes on decreasing.

41. Derive the condition for maximum power with respect to radius using power.circle diagram.

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42. Briefly explain the bad effects of hunting.

43. Why hunting is called as phase swinging, explain ?

44. Explain about the incomplete type and complete type damper windings.

46. A 1100-V, 50 Hz, 3-phase star-connected cylindrical-rotor synchronous motor has its synchronous impedance of 0.7 + j3.2 ohm per phase. It is working at rated voltage, rated frequency with an input of 350 kW. The field current is adjusted to give and electromative force of 1650 V. Calculate the armature current, power factor and load angle.

47. Develop the excitation circles for a cylindrical rotor synchronous motor. How are these circles helpful in studying the steady state behaviour of synchronous motors?

48. Explain the development of power circles for a cylindrical rotor synchronous motor.Show that :

i. Zero-power circle passes through origin.ii. Pmax = andiii. Efficiency at maximum power output = 50%

49. Explain how the excitation and power circles can be superimposed to obtain V-curves of a cylindrical rotor synchronous motor.Hence show that :

i. Minimum and maximum currents for any power occur at u.p.f.ii. Minimum p.f. for any load power occurs when the current line is tangent to the power circle for that

load.

50. A salient-pole synchronous motor with damper bars is connected to an infinite bus system. Its field current is reduced to zero and the load on the synchronous motor is gradually increased. It has been found in practice that after the motor has fallen out of step, it continues running at sub-synchronous speed. Explain how it happens. What will happen to the magnitude of armature current and its p.f. ?

51. i. Describe, with physical concepts, the hunting phenomenon in synchronous machines. Explain why hunting is objectionable. What are the various causes of hunting ? How can it be reduced ?

ii. Explain the action of damper bars in damping out the rotor-oscillations.iii. What is the effect of damper bars, under steady-state operating conditions?

52. State and explain the difference between the damper windings of an alternator and induction-start synchronous motor.

53. i. Show that a synchronous motor has no net starting torque.ii. Describe the methods of starting the synchronous motors against light-load torque.iii. Explain the methods of starting synchronous motors against high-torque loads.

54. During induction-motor starting of a synchronous motor, explain why it is necessary i. to start the motor at reduced voltage andii. to short-circuit the field winding at the time of starting

55. A 1000 KVA, 11 KV, 3-phase star connected synchronous motor has an armature resistance and reactance are perphase are 3.5 ohm and 40 ohm respectively. Determine the induced emf and angular retardation of the rotor when fully loaded at unity power factor

UNIT – VII

1. a. Explain the procedure for starting of synchronous motor.b. A 500V, 3-phase mesh connected motor has an excitation emf of 600V. The motor synchronous

impedance is (0.4+j5)Ω while the windage, friction and iron losses are 1200W. What maximum power output can it deliver? (JNTU May 09)

2. a. What is the effect on synchronous motor when the load is changed.

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b. A 3300V, star connected synchronous motor is operating at constant terminal voltage and constant excitation. Its synchronous impedance is (0.8+j5) Ω. It operates at a p.f of 0.8 leading when drawing 800KW from the mains. Find its power factor when the input is increased to 1200KW, excitation remaining constant. (JNTU May 09)

3. a. Explain the differences between a synchronous motor and an induction motor? b. A 20 pole, 693V, 50Hz, 3-phase star connected synchronous motor is operating at no load with normal

excitation. It has negligible armature resistance and synchronous reactance of 10Ω. If rotor is retarded by 0.50 (mechanical) from its synchronous position, computei. rotor displacement in electrical degreesii. armature emf per phaseiii. armature current per phase (JNTU May 09)

4. a. Show that the current locus of a synchronous motor developing constant power is a circle. Determine

its center and radius.b. The input to a 11,000V, 3-phase star connected synchronous motor is 60A. The effective resistance

and synchronous reactance per phase are 1 and 30. Find the power supplied to the motor and the induced emf for power factor of 0.8 leading. (JNTU May 09)

5. Explain the equivalent circuit of single phase Induction motor & give all necessary equations.(JNTU May 09)

6. a. Explain the various types of single phase Induction motor. (JNTU May 09, Nov 08)b. What is splitting of phases? Why splitting of phase is necessary in single phase Induction motor.

7. a. The following data pertains to a single phase Induction motor:No. of poles = 4, Supply voltage = 110, Rated output = 125 W, Slip = 6%, total full load copper losses = 25 W, Rotational losses = 25W. Calculate the full load efficiency & the rotor copper loss caused by the backward field. Neglect stator resistance.

b. Give the comparison between ‘capacitor start-capacitor run’ single phase Induction motor & ‘capacitor start-run motor’ single phase Induction motor. (JNTU May 09)

8. a. Explain, the speed of single phase Induction motor can be controlled by supply voltage where as them is not possible with 3 -Φ IM, why?

b. The name plate of single phase IM, 4 pole Induction motor gives the following data:Output = 410 W, Supply voltage = 230 V, Frequency = 50 Hz, Input current = 3.2 A, Power factor = 0.7, speed = 1410 RPM. Calculate:i. The efficiency of the motorii. The slip of the motor when delivering rated output. (JNTU May 09)

9. a. Prove that a single phase motor winding when excited by a single phase supply produces two equal and

opposite revolving fields.b. “The centrifugal switch of a single phase motor failed to open”. Explain the after effects in the

performance. (JNTU May 09)

10. a. Why single phase motors are not self starting?b. Explain the necessary arrangements made to make single phase Induction motor self starting & with

neat diagram explain the operations of same. (JNTU Nov 08)

11. a. Explain the ‘doubly revolving field theory’ related to single phase Induction motor.b. Explain the construction & give the applications of single phase Induction motor.

(JNTU Nov 08)

12. a. Explain the construction & operation of ‘capacitor start and run’ single phase Induction motor.b. Explain ‘double revolving field theory’ of single phase Induction motor. (JNTU Nov 08)

13. a. Describe the methods of starting of synchronous motor

b. A 1000KVA, 11KV, 3-phase star connected synchronous motor has an armature resistance and synchronous reactance per phase are 3.5 and 40 respectively. Determine the induced emf and angular retardation of the rotor when fully loaded at unity power factor. (JNTU Nov 08)

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14. a. Explain the power circle diagrams of the synchronous motor. (JNTU Nov 08)b. A 400V, 3 phase, Y connected synchronous motor takes 3.73Kw at normal voltage and has an

impedance of (1+j8) per phase. Calculate the current and pf if the induced emf is 460V.

15. a. Explain why a synchronous motor will only develop a continuous torque at synchronous speed. How does it reach synchronous speed?

b. A three phase synchronous motor has 12 poles and operates from 440V, 50Hz supply calculate its speed. If it takes a line current of 100A at 0.8 pf leading what torque will be the machine developing. Neglect the losses. (JNTU Nov 08)

16. a. What are the uses of damper windings in a synchronous motor? (JNTU Nov 08)b. Why it is necessary to increase the excitation to obtain minimum current with the application of load.

17. a. Explain the ‘doubly revolving field theory’ related to single phase Induction motor.

b. Explain the construction & give the applications of single phase Induction motor. (JNTU Feb 08)

18. The constants of a quarter HP, 230 V, 50 Hz, 4 pole single phase IM are as follows:Stator resistance = 10.0 ; Stator reactance = 12.8 , Magnetising reactance = 258 , Rotor resistance referred to stator =11.65 , Rotor reactance referred to stator =12.8 The total load is such that the machine runs at 3% slip, when the voltage is at 210V. The iron losses are 35.5 W at 210 V. If mechanical losses are 7 W; Calculate:

a. Input currentb. Power developedc. Shaft powerd. Efficiency. (JNTU Feb 08)

19. The following test results were obtained in case of a 220 V single phase induction motor: Free running test: 220V, 5.8 A, 310 WBlocked rotor test: 120 V, 13.8 A, 530 WStator winding resistance = 1.4 Determine the approximate equivalent circuit of motor. (JNTU Feb 08)

20. a. Explain the equivalent circuit of single phase Induction motor & give all necessary equations.(JNTU Feb 08)

b. Explain how the direction of a single phase Induction motor cab be reversed. (JNTU Nov 08)

21. a. Why single phase motors are not self starting?b. Explain the necessary arrangements made to make single phase Induction motor self starting & with

neat diagram explain the operations of same.

22. a. Explain, the speed of single phase Induction motor can be controlled by supply voltage where as them is not possible with 3 - IM, why?

b. The name plate of single phase IM, 4 pole Induction motor gives the following data:Output = 410 W, Supply voltage = 230 V, Frequency = 50 Hz,Input current = 3.2 A, Power factor = 0.7, speed = 1410 RPM.Calculate:i. The efficiency of the motorii. The slip of the motor when delivering rated output.

23. i. Using double revolving field theory explain the torque-slip characteristic of a single phase induction motor and prove that it cannot produce starting torque.

ii. Explain the constructional details and principle of operation of a split phase induction motor. List out its industrial applications. (JNTU Nov 07, May 04)

24. “A single phase motor is not a self starting motor” justify the statement. (JNTU Nov 07, Jun 03)

25. Explain what is meant by the split-phase method of motor starting (JNTU Feb 07, Nov 06, 04, Mar 06)

26. i. Explain the cross field theory of a single phase induction motor.

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ii. A 230V, 6 pole, 50Hz, single phase induction motor has the following impedance at standstill.Auxiliary winding ra= 5 xa= 5Main winding rm=1.5 xm= 4.0.The resistance of the rotor winding when referred to the main stator winding is 0.5. Assuming the number of turns of the main winding and Auxiliary winding are equal, estimate the resistance to be added to the auxiliary winding to obtain maximum starting torque and also estimate the value of the maximum starting torque. (JNTU Feb 07)

27. The full load slip of a single phase induction motor is higher than of corresponding 3phase induction motor. Why? (JNTU Feb 07)

28. A 220V, 500W, 50Hz series motor has a total resistance of 2 ohm and total reactance of 20 ohm. The full load stray losses and speed are 40W and 500rpm. Determine the current taken by the motor and power factor at rated load. (JNTU Feb 07, May 05)

29. Draw the slip-torque characteristics of all types of single phase induction motors and compare their merits and demerits. (JNTU Feb 07, Nov 04)

30. Why cannot a shaded pole motor be made to rotate in the reverse direction? (JNTU Feb 07, Nov 03)

31. i. Explain capacitor split phase motor.ii. A 220V, 4 pole, 50Hz, capacitor split phase motor has the following impedance at standstill.

Auxiliary winding ra= 3, xa= 6Main winding rm = 2, xm = 5.The resistance of the rotor winding when referred to the main stator winding is 0.5. Assuming the number of turns of the main winding and Auxiliary winding are equal, estimate the starting torque, maximum starting torque and the capacitance to be inserted to get maximum starting torque.

(JNTU Nov 06)32. Write short notes on following:

i. Double revolving field theory.ii. Capacitor Start single phase induction motor. (JNTU Nov 06)

33. i. Compare the performance characteristics of a.c. series motor when it is connected acrossi. a.c. supply andii. D.C. supply.

ii. Describe the construction and principle of operation of a single phase shaded pole motor with a neat diagram. Give its industrial applications. (JNTU Nov 06)

34. Compare operating characteristics of a resistance-start induction –run-motor with those of a capacitor start induction–run motor. (JNTU Nov 06, 04)

35. i. Draw the equivalent circuit of a single phase induction motor and discuss the experimental procedure to determine the parameters.

ii. Find the mechanical power out put of a 185Watts, 4 pole 110 volts, 50 Hz single phase induction motor whose constants are given below at a slip of 0.05R1 = 1.86 Ohms X1 = 2.56 OhmsXm = 53.5 Ohms R2 = 3.56 OhmsX2 = 2.56 Ohms Core loss = 4.0 WattsFriction and windage losses = 13.0 Watts. (JNTU Nov 06, May 04)

36. Explain double field revolving theory. (JNTU Nov 06, 02)

37. A 110V, 6 pole, 50Hz, single winding single phase induction motor has the following equivalent circuit parameters as referred to the stator r1= 1.5W x1= 2.5W r2=0.75W x2= 1.0W.Neglecting the magnetizing current, estimate the following when the motor is running at a slip of 3%.i. the ratio (Esf/Esb) ii. the ratio (Vf/Vb)iii. the ratio (Tf/Tb) and iv. the gross total torque. (JNTU Nov 05)

38. A laboratory test on a single-phase induction motor has given the following data with rotational losses being equal to 17W.Block rotor test: Vsc= 110V, Isc=14.8A and Psc=1130W

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No load test: Vo=110V, Io= 2.8A and Po=60WDetermine the parameters of the equivalent circuit and the core loss. (JNTU May 05)

39. Describe the construction and operation of a shaded pole motor. (JNTU Nov 04)

40. Show that in a shaded pole motor, the flux in the shaded part of pole segment lags behind the flux of the shaded pole segment both in space and time, resulting a rotational torque in the motor.

(JNTU Nov 04)

41. i. Explain how the performance of a single phase induction motor is estimated from the equivalent circuit?

ii. A 2 pole, 50Hz single phase induction motor has an effective rotor resistance and stand still leakage reactance of 0.5 ohm and 5.0 ohms respectively. If the motor is running at 2600 rpm, determine the frequencies of the motor current components and the relative magnitude of the forward and backward fluxes. Neglect magnetization and stator impedance drop. (JNTU Nov 04)

42. i. A capacitor connected in series with the starting winding of a resistance start split phase induction motor. Explain the changes in the performance characteristics.

ii. A 220V, 50 Hz 4 pole single phase induction motor has the following equivalent circuit parametersRlm = 3.6 Ohms (X1m + X2) = 15.6 OhmsR2 = 6.8 Ohms X = 96 OhmsThe rotational losses of the motor are estimated to be 80 watts. Calculate the current, power factor and efficiency when the motor is running 1410 rpm. (JNTU May 04)

43. i. Compare various types of single phase induction motors in terms of construction and performance.ii. The resistance and inductive reactance of each winding of a 50 Hz single phase capacitor induction

motor are 80 Ohms and 237.5 Ohms respectively. Additional resistance “R” and a capacitor “C” are in series with one winding inorder to achieve a phase difference of 90 degrees while both winding carry equal current. Calculate the values of R C (JNTU May 04)

44. i. Prove that a single phase motor winding when excited by a single phase supply produces two equal and opposite revolving fields.

ii. “The centrifugal switch of a single phase motor failed to open”. Explain the factory effects in the performance. (JNTU Nov 03)

45. i. Explain the constructional features and principle of operation of a capacitor start induction run motor. Draw the slip-torque characteristic and list out its merits over split phase motor.

ii. In a direct load test on a single phase motor the following readings were obtained Supply voltage : 230VLine Current : 12.0 A Watt meter reading 1.96KWSpeed : 1410 rpmTorque : 1.01 kg-m, Determine i. Slip ii. efficiency iii. Power factor. (JNTU Nov 03)

46. i. Describe cross field theory as applied to single phase induction motor.ii. The following data pertains to a 50Hz single phase motor.

Supply Voltage : 110VRated Output : 125WRated speed : 1410 rpmTotal copper loss at full load : 25 wRotational losses : 25WCalculate the full load efficiency and the rotor copper loss caused by the backward field. Neglect stator losses. (JNTU Nov 03)

47. In a direct load test on a single phase motor the following readings were obtained supply voltage is 230V, line current 12.0A. Wattmeter reading 1.96KW, speed 1410 rpm, torque 1.01 Kg-m. Determine i. slip ii. efficiency iii. power factor. (JNTU Nov 03)

48. The following test results were obtained in case of a 230V single phase induction motor no load test – 230V, 4.8A, 350W; Locked rotor test – 125V, 15.6 A, 550W; Stator winding resistance = 1.8 Ohms. Determine the approximate equivalent circuit of motor. (JNTU Nov 03)

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49. A capacitor connected in series with the starting winding of a resistance start split phase induction motor. Explain the changes in the performance characteristics. (JNTU Nov 03, 02)

50. Classify single phase induction motor and explain? (JNTU Nov 03)

51. “The centrifugal switch of a single phase motor failed to open” explain the after effects in the performance. (JNTU Jun 03)

52. Describe the construction and principle of operation of a single phase shaded pole motor with a neat diagram. Give its industrial applications. (JNTU Jun 03)

53. i. Discuss the different between capacitor start induction run motor and capacitor start and run induction motor. Draw the performance characteristics.

ii. The following tests results were obtained in respect of 230 Volts single phase induction motor.No load tests 230V, 6.25A 360 WattsLocked rotor test 126v, 15.0A, 577 WattsStator winding resistance = 1.5 OhmsDraw the equivalent circuit diagram with parameters (JNTU Jun 03)

54. Explain the constructional details and principle of operation of split phase induction motor. List out its industrial applications. (JNTU Jun 03)

55. Explain single phase induction motors fail to start but continues to run once started by double revolving field theory. (JNTU Nov 02)

56. Explain cross field theory. (JNTU Nov 02)

57. A 220V, 50 Hz, single-phase induction motor has the following connection diagram and winding orientations shown. MM ' is the axis of the main stator winding and AA' is that of the auxiliary winding (A1A2). Directions of the winding axes indicate direction of flux when currents in the windings are in the directions shown. Parameters of each winding are indicated. When switch S is closed, the motor (GATE 09)

a. rotates clockwise b. rotates anticlockwisec. does not rotate d. rotates momentarily and comes to a halt

58. A three-phase, three-stack, vaiable reluctance step motro has 20 poles on each rotor and stator stack. The step angle of this step motor is a. 30 b. 60 c. 90 d. 180 (GATE 07)

59. For a single phase capacitor start induction motor which of the following statements is valid?a. The capacitor is used for power factor improvement b. The direction of rotation can be changed by reversing the main winding terminalsc. The direction of rotation cannot be changedd. The direction of rotation can be changed by interchanging the supply terminals. (GATE 06)

60. The main and auxiliary winding impedances of a 50hz capacitor start single phase induction motor are Main winding Zim = 5 + j3.6, Auxiliary Winding Zia = 8 + j4. Determine the value of capacitor to be

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connected in series with the auxiliary winding to achieve a phase difference of 60° between the currents of two windings at start. (IES 08)

61. Why is it advantageous to use double revolving field theory for determining the running performance of a single phase induction motor. Draw torque speed characteristics of 1-phase induction motor based on double revolving field theory and discuss about the magnitude of torque at zero speed and synchronous speed. (IES 01)

62. The following data permits a single phase motor Number of Poles = 4; Supply of voltage= 110V; Rated output = 125 W; Slip at rated output = 6%; Total copper loss at full load rotational losses= 25W. Calculate full load efficiency and rotor copper loss caused by the background field. Neglect stator loss.

(IES 98)

63. For a 220V, 1-Ø induction motor with 220V, 6.15A, 348W no load test results and 126V, 15A, 577W locked rotor test results with stator winding resistance = 15 Ohms. Determine R1, R2, X1 and Xm.

(IES 98)UNIT – VIII

1. a. Draw and explain the torque speed characteristics of single-phase induction motor based on the concept of double field revolving theory.

b. Describe the construction and principle of operation of a split phase motor. (JNTU May 09)

2. a. Describe the constructional feature and principle of operation of a shaded pole motor.b. Explain what is meant by the split-phase method of motor starting. (JNTU May 09)

3. Write short notes on following: (JNTU May 09, Nov 08)a. Double revolving field theory. B. Capacitor Start single phase induction motor.

4. a. Explain capacitor split phase motor. (JNTU May 09, Nov 08)b. A 220V, 4 pole, 50Hz, capacitor split phase motor has the following impedance at standstill.

Auxiliary winding ra= 3Ω xa= 6 ΩMain winding rm = 2 Ω xm = 5 Ω.The resistance of the rotor winding when referred to the main stator winding is 0.5 Ω. Assuming the number of turns of the main winding and Auxiliary winding are equal, estimate the starting torque, maximum starting torque and the capacitance to be inserted to get maximum starting torque.

5. Write short notes on following:a. AC series motor b. Universal motor (JNTU May 09, Nov 08)c. Variable reluctance stepper motor d. Permanent magnet stepper motor.

6. a. Explain the construction of variable reluctance stepper motor.b. Explain the torque-speed characteristics of AC series motor. (JNTU May 09)

7. a. Discuss the difference between capacitor start induction run motor and capacitor start and run induction motor. Draw the performance characteristics.

b. The following tests results were obtained in respect of 230Volts single phase induction motorNo load tests 230V, 6.25A 360Wattslocked rotor test 126v, 15.0A. 577WattsStator winding resistance = 1.5 ohmsDraw the equivalent circuit diagram with parameters (JNTU May 09)

8. a. Explain the working principle of reluctance motor.b. Compare working of AC series motor & Universal motor. (JNTU Nov 08, Feb 08)

9. With neat diagram explain the construction & working of variable reluctance stepper motor. Also explain its static & dynamic characteristics. (JNTU Nov 08)

10. a. Explain what is meant by the split-phase method of motor startingb. Why are small fractional horse power ac series motors called universal motor? (JNTU Nov 08)

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11. With neat diagram explain the construction & working Universal motor. Explain its operation with the help of vector diagram. (JNTU Feb 08)

12. i. Neatly draw & explain the vector diagram of Universal motor. Give your observations.ii. How step angle for a given stepper motor is decided? Obtain the relation between step angle & rotor

teeth. (JNTU Feb 08)

13. i. Explain the construction of variable reluctance stepper motor.ii. Explain the torque-speed characteristics of AC series motor. (JNTU Feb 08)

14. i. Compare AC series motor & Universal motor.ii. Compare variable reluctance stepper motor & permanent magnet stepper motor. (JNTU Nov 07)

15. i. Give the applications of various types of permanent magnet motors.ii. Explain the working principle of permanent magnet motors. (JNTU Nov 07)

16. i. Explain the static characteristics of stepper motor.ii. Explain the role of compound winding in the operation of AC series motor. (JNTU Nov 07)

17. Why are small fractional horse power ac series motors called universal motors?(JNTU Feb 07, Nov 06, Mar 06, Nov 04)

18. Explain the operating characteristics of AC series motor. (JNTU Feb 07, May 05)

19. Compare the constructional features of AC series motor with DC series motor.(JNTU Feb 07, Nov 03)

20. What are the differences between AC and DC series motors? (JNTU Nov 04)

21. Explain the construction and operation of Universal motor. List out its merits and demerits.(JNTU Nov 04, May 04)

22. Explain the function of compensation winding in a.c. series motors. (JNTU May 04)

23. The resistance and total inductance of a single phase a.c. series motor are 36 ohms and 0.58H respectively. It draws 0.92 A current and runs at 2000 rpm when connected across 230 Volts D.C. supply. Calculate the speed and power factor when connected to 230V, 50 Hz a.c. supply, drawing the same current. (JNTU May 04)

24. What is the difference between conductively compensated series motor and an inductively compensated series motor. (JNTU Jun 03)

25. Compare the performance characteristics of AC series motor when it is connected across a. AC supply and b. DC Supply. (JNTU Jun 03)

26. Explain the design modifications necessary for satisfactory operation of a DC series motor from and AC supply. (JNTU Nov 02)

27. Write short notes on repulsion motor. (JNTU Nov 02)

28. Draw and explain vector diagram of a compensated single phase series motor. (JNTU Nov 02)

29. A 250V, 50 C/s universal motor has a total resistance of 30 ohms and total reactance of 160 ohms. Estimate the power factor when running at a speed of 1500 rpm and taking a current of 0.8 A. Find the speed when motor is connected to a 250V D.C. supply and loaded to a current of 0.8 A.

(JNTU Nov 02)

30. Which one among the following the highest numerical value in a stepper motor ?i. Detent torque ii. Holding torque iii. Dynamic torque iv. Ripple torque (IES 06)

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31. Why are the compensating winding and interpole used in universal motor for a.c operation. Draw schematic connection diagram of all the stator windings and the armature for an a.c operated series motor. (IES 96)

32. Describe a series (universal) motor. Give its cross-sectional view when connected to AC supply. Describe its performance characteristics? (IES 95)

33. A universal motor (ac operated) has a two pole armature with 960 conductors. At a certain load the motor speed is 5000rpm and the armature current is 4.6A. The armature terminal voltage and input are respectively 100V and 300 W. Compute the following, assuming an armature resistance of 3.5 ohms.

i. Effective armature resistanceii. Maximum value of useful flux / pole.

34. Which one among the following the highest numerical value in a stepper motor ?i. Detent torque ii. Holding torque iii. Dynamic torque iv. Ripple torque (IES 06)

35. Why are the compensating winding and interpole used in universal motor for a.c operation. Draw schematic connection diagram of all the stator windings and the armature for an a.c operated series motor.

36. Describe a series (universal) motor. Give its cross-sectional view when connected to AC supply. Describe its performance characteristics? (IES 95)

37. Obtain the circuit model and draw the phasor diagram for a.c. series motor.

38. What are the different types of emfs induced in a.c. series motors? Derive the necessary equations.

39. Explain the torque-speed characteristics of reluctance motor.

40. The resistance and total inductance of a single phase fractional horse power series motor are 30 ohms and 0.5 H respectively. It draws 0.8A current and runs at 2000 rpm, when connected to 250V D.C. supply. Calculate the speed and power factor when connected to 250V, 50Hz supply and loaded to take the same current.

41. Draw and explain the torque-speed characteristics of universal motor.


43. A universal motor (ac operated) has a two pole armature with 960 conductors. At a certain load the motor speed is 5000rpm and the armature current is 4.6A. The armature terminal voltage and input are respectively 100V and 300 W. Compute the following, assuming an armature resistance of 3.5 ohms.

i. Effective armature resistanceii. Maximum value of useful flux / pole.

44. Obtain the circuit model and draw the phasor diagram for a.c. series motor.

45. What are the different types of emfs induced in a.c. series motors? Derive the necessary equations.

46. Explain the torque-speed characteristics of reluctance motor.


48. Draw and explain the torque-speed characteristics of universal motor.

301



302


5. SUBJECT DETAILS

5.6 LINEAR AND DISCRETE SYSTEMS ANALYSIS

5.6.1 Objective and Relevance

5.6.2 Scope

5.6.3 Prerequisites

5.6.4 Syllabus

i. JNTU

ii. GATE

iii. IES


5.6.6 Websites


5.6.8 Journals


5.6.10 Session Plan



i. JNTU

ii. GATE

iii. IES

303



The objective of this course is to analyze any Linear and Discrete Systems through the Electrical networks by incorporating Laplace transform, Fourier transform and Z-transforms. The response of various networks topology's is analysed with case studies. The analysis and synthesis of single port networks using different testing methods also is covered.

5.6.2 SCOPE

The student will have in depth knowledge of powerful tools though Laplace Transforms Z-transforms and Fourier Transforms to analyze and synthesize any type of Linear and discrete systems immaterial whether the system is Electrical or Non Electrical. The student would be able to design and analyze even a Non-Electrical Linear System through the Analagous system methodology.

5.6.3 PREREQUISITES

Knowledge of Laplace transform, Fourier transform Z-transforms and electrical network theory

5.6.4.i SYLLABUS – JNTU

UNIT-IOBJECTIVE

It is an introduction to state space representation of differential equations. Modeling of electrical networks in state space model is explained. Different methods for state space modeling is dealt-with. Solution to state space model equations by different methods is studied.

SYLLABUS

Choice of state variables in electrical networks. Formulation of state equations for electrical networks-equivalent source methods and network topological method. Solution of state equations-analysis of simple networks with state variable approach.

UNIT - II & IIIOBJECTIVE

Introduction to Fourier series and transforms. Theorems, and limitation of Fourier transforms. Mathematical Representation of non periodic functions-Examples. Fourier transform of Non periodic functions.

SYLLABUS

RMS, average value of a non sinusoidal periodic wave from. Expression for power with non sinusoidal voltage and current, power factor. Effect of harmonics. Analysis of simple circuits with non sinusoidal inputs. Representation of non periodic function, Fourier integral, Fourier transform, Graphical representation, properties of Fourier transform, Persaval’s theorem, Fourier transform of constant, unit step, unit impulse, unit ramp signals and exponential functions, relationship with Laplace transform.

UNIT-IVOBJECTIVE

Introduction to Laplace Transfors. Theorems, limitation of Laplace transforms. Application of Laplace Transformation to linear system analysis for different electrical networks.

SYLLABUS

Response of RL, RC and RLC networks to step, ramp, pulse and impulse function, shifting and scaling theorem, Laplace transform of periodic functions, convolution theorem, convolution integral, applications.

304


UNIT-V & VIOBJECTIVE

It gives an insight to network synthesis. Analysis of two port network model. Different theorems to analyze the stability of the linear systems. Synthesis of electrical networks in forster and Cauer forms

SYLLABUS

Elements of realizability, Hurwitz polynomials, positive real functions, properties, testing, Sturm’s test, synthesis one port LC networks, Foster and Cauer method, synthesis of RL and RC one port network, Foster and Cauer methods.

UNIT-VIIOBJECTIVE

In this unit we study a very important theorem called sampling theorem and the sampling process and continuous-time signal reconstruction from samples are studied latter and the effect of undersampling is also discussed.

SYLLABUS

Sampling theorem, graphical and analytical proof for band limited signal impulse sampling, natural and flat top sampling, reconstruction of signal from its samples, effect of under sampling, aliasing, introduction to band pass sampling, cross correlation and auto correlation of functions, properties of correlation function, energy density spectrum, power density spectrum, relation between auto correlation function and energy / power spectral density function.


In this unit we understand the fundamental difference between continuous and discrete time signals and latter we discuss Z-Transforms and the distinction between laplace, Fourier and Z-Transforms.

SYLLABUS

Fundamental difference between continuous and discrete time signals, discrete time complex exponential and sinusoidal signals, periodicity of discrete time complex exponential signal, concept of z-transform of a discrete sequence, Distinction between Laplace, Fourier and Z-transforms, Region of convergence in Z-transforms, constraints on ROC for various classes of signals, inverse Z-transforms, properties of Z-transforms


UNIT-IState space analysis.

UNIT-IIFourier series and applications.

UNIT-IIIFourier transforms and its applications.

UNIT-IVLaplace transform and its applications.

UNIT-VNot applicable.

UNIT-VINetwork analysis

305


UNIT-VIINot applicable.

UNIT-VIIINot applicable.


UNIT-IState space analysis.

UNIT-IINot applicable.

UNIT-IIINot applicable.

UNIT-IVLaplace transform and applications,

UNIT-VNot applicable.

UNIT-VINot applicable.

UNIT-VIINot applicable.

UNIT-VIIINot applicable


TEXT BOOKS

T1 Signals, Systems M.J. Roberts, TMH Edition.T2 Linear system analysis A.N. Tripathi, New Age Publications.T3 Network Analysis and synthesis, F.F. Kuo, John Wiley 2nd Edition.

REFERENCE BOOKS

R1 Analysis of linear systems, David K. Cheng (NPH)R2 Signals and systems 4th Edition, Rodger E. Ziemer

5.6.6 WEBSITES

1. www.ntu.ac.sg2. www.utoronto.ca3. www.ee.washington.edu4. www.esca.com5. www.ne.ac.sg6. www.iitm.ac.in7. www.annauniv.edu8. www.irfca.com9. www.ieindia.org10. www.eere.energy.gov11. www.stanford.edu12. www.seas.upenn.edu

306



REGIONAL






NATIONAL

1. Name : Dr. Jagadeesh Kumar, V.,Designation : Professor,Department : Department of Electrical Engineering,Address : IIT Madras, Chennai - 600 036,Phone No. :Email : [email protected].

2. Name : Dr. Janakiraman, P. A.,Designation : Professor, Department of Electrical Engineering,Department : Department of Electrical Engineering,Address : IIT Madras, Chennai - 600 036,Phone No. :Email : [email protected].

3. Name : Dr. S.Ponnu SwamyArea : Complex AnalysisDepartment : Dept. of Mathematics, Office Address : IIT, MadrasPhone no. : +91-44-22574615Email : [email protected]

INTERNATIONAL

1. Name : Chirka Evgenii MikhailovichArea : Complex AnalysisDepartment : Department of MathematicsOffice Address : Steklov mathematic InstitutePhone no. : +7(495) 938-39-76Email : [email protected]

307


2. Name : Stephen P. Boyd,Designation : Professor, Information Systems Laboratory,Department : Department of Electrical Engineering,Address : Stanford University, Packard 264, Stanford, CA 94305,Phone No. :Email : [email protected].

3. Name : Prof. Paul R. GarabedianArea : Complex AnalysisDepartment : School of MathematicsOffice Address : Courant Institute of Mathematical Sciences, New York UniversityPhone no. : 212-998-3237Email : [email protected]

4. Name : Ali Jadbabaie,Designation : Asst. Prof., Department : Dept. of Electrical and Systems Engineering,Address : University of Pennsylvania, 365 GRW Moore Bldg,

200 South 33rd Street, Philadelphia, PA 19104,Phone No. :Email : [email protected].

5.6.8 JOURNALS

1. Name of the Journal : Control System Publisher : IEEE Publications

2. Name of the Journal : Circuits and System Publisher : IEEE Publications

3. Name of the Journal : Complex Variables and Elliptic EquationsPublisher : Taylor & Francis

4. Name of the Journal : Elsevier Journal of Signal and SystemsPublisher : IEEE Publishers

5. Name of the Journal : IEEE Signals and Systems Publisher : IEEE Publishers

6. Name of the Journal : Journal of Institution of Engineers (Electrical Engineering).Publisher : Chary Publications Pvt Ltd.

7. Name of the Journal : Journal of System Society of India.Publisher : Century Publications Pvt Ltd

8. Name of the Journal : Journal of Instrumentation and Control Society of India.Publisher : Chary Publications Pvt Ltd.


1. Title : Optimal Periodic Trajectories for Band-Limited SystemsAuthor : Fleming, A. J.; Wills, A. G.Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 3, Page(s): 552-562

2. Title : Control in Computationally Constrained EnvironmentsAuthor : Bhattacharya, R.; Balas, G. J.Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 3, Page(s): 589-599

308


3. Title : Coordinated and Reconfigurable Vehicle Dynamics ControlAuthor : Wang, J.; Longoria, R. G.Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 3, Page(s): 723-732

4. Title : Optimal Real-Time Scheduling of Control Tasks With State Feedback Resource Allocation

Author : Ben gaid, M.E.-M.: Cela, A.S.; Hamam,Y.Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 2, Page(s): 309-326

5. Title : A Dynamical State Space Representation and Performance Analysis of a Feedback-Controlled Rotary Left Ventricular Assist Device

Author : Simaan, M.A.; Ferreira, A.; Shaohi Chen; Antaki, J.F.; Galati, D.G.

Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 1, Page(s): 15-28

6. Title : Design of a Data-Driven PID ControllerAuthor : Yamamoto, T.; Takao, K.; Yamada, T.Journal : IEEE Transaction Control Systems TechnologyVol., Year & Page No. : May 2009, Volume: 17, Issue 3, Page(s): 29-39

309


5.6.10 SESSION PLAN

Sl. No.

JNTU Syllabus Topics

Modules and Sub modulesLecture


Page Nos.Remarks

UNIT – I – STATE VARIABLE ANALYSIS (No. of Lectures – 08)

1Choice of State variables in Electrical networks

Introduction to state space analysis, basic definitions Assumptions, limitations of State space analysis

L1T1-Ch8 (P:237-240)R2-Ch14 (P:624-657)

Simple problems for state space modeling

L2

2Formulation of state equations for Electrical Networks

Modeling of Electrical network components.

L3T1-Ch8 (P:231-239)R2-Ch14 (P:624-657)Interconnection of components

for state space matricesL4

3Equivalent source method

Equivalent source method with example

L5 R2-Ch14 (P: 624-657)

4Network Topological method

Network Topological method with Example

L6R2-Ch14 (P:624-657)

Network Topological method with Example

L7

5Solution of state equations and problems

Solving state variable equations by different methods.

L8T2-Ch8 (P:241-243)R2-Ch14 (P:624-657)

UNIT-II – APPLICATION OF FOURIER SERIES (No. of Lectures – 06)

6RMS, Average values of non sinusoidal and periodic wave forms

Introduction to RMS and Average value Definition and derivations.

L9T2-Ch4 (P:91-93)R3-Ch16 (P:768-769)

Determination of RMS and Average value for non sinusoidal and periodic wave forms

L10T2-Ch4 (P:91-93)R3-Ch16 (P:768-770)R2-Ch4 (P:187-244)

7Expression for power with non sinusoidal voltage and current.

Expression for power with non sinusoidal voltage and current.Problems

L11T2-Ch4 (P:91-93)R3-Ch16 (P: 769-790)R2-Ch4 (P:187-244)

8

Expression for power factor with non sinusoidal voltage and current.

Expression for power factor with non sinusoidal voltage and current,Examples

L12

R2-Ch4 (P:187-244)

9 Effect of Harmonics

Introduction to harmonicsThe effect of harmonics on electrical networksModeling of harmonics

L13

10Analysis of simple circuits with non sinusoidal inputs

Analysis of simple circuits with non sinusoidal inputsDetermination of Average value RMS value Power and power factor

L14T1-Ch4 (P: 93-99) R2-Ch4 (P:187-244)

UNIT-III – FOURIER TRANSFORM APPLICATIONS (No. of Lectures – 08)

11 Fourier transformIntroduction to fourier transform

L15 T1-Ch5 (P: 113-354)R3-Ch8 (P: 105-152)R1-Ch4 (P:181-244)Introduction to fourier series L16

12Properties of Fourier transforms

Properties of Fourier transforms

L17T1-Ch5 (P: 117-121 R2-Ch4 (P:187-244)

13 Fourier integral-Graphical representation

Comparison of laplace and fourier transform Graphical representation

L18 T1-Ch5 (P:142)R3-Ch8 (P: 369-370)R1-Ch4 (P:105-152

310


14 Parsenval’s theoremParsenval’s theorem with examples

L19

15Representation of non periodic functions

Mathematical Representation of non periodic functions with examples

L20 T1-Ch5 (P:117-121)R2-Ch4 (P:187-244)R1-Ch4 (P:105-152)Fourier transform of Non

periodic functionsL21

16

Fourier Transform of periodic functions constant, step, impulse and ramp

Fourier Transform of constant step, impulse, ramp and exponential functions.

L22T1-Ch5 (P:120-125)R2-Ch4 (P: 187-244)R1-Ch4 (P: 105-152)

UNIT – IV – LAPLACE TRANSFORM APPLICATIONS (No. of Lectures – 09)

17Laplace transforms of periodic functions

Introduction to laplace transform Necessity andadvantages Assumptions and limitations.Laplace transform of periodic functions sine and non sinusoidal functions

L23

T1-Ch6 (P: 234)R3-Ch4 (P:152-154)R2-Ch5 (P:230-234)R1-Ch5 (P:245-263) (P:160-199)

18Shifting and Scaling theorems

Shifting and Scaling Theorems with examples

L24R3-Ch7 (P:301-304)

19Response of RL circuit for different inputs

Linear Analysis of RL circuit for step, ramp, pulse and impulse inputs

L25

R2-Ch16 (P:699-727)Linear Analysis of RL circuit for step, ramp, pulse and impulse inputs

L26

20Response of RC circuit for different inputs

Linear Analysis of RC circuit for Step input and ramp input

L27R2-Ch16 (P:699-727)

Pulse input and impulse input L28

21Response of RLC circuit for different inputs

Linear Analysis of RLC circuit Step input and ramp input

L29R2-Ch16 (699-727)

Pulse input and impulse input L30

22Convolution theorem and convolution integral applications

Introduction to convolution theorem determination of convolution integral and applications

L31

R1-Ch5 (P:126-134)R3-Ch7 (P:305-307)R1-Ch13 (P:592-601)R1-Ch10 (P:593-428)

UNIT-V – TESTING OF POLYNOMIALS (No. of Lectures – 06)

23 Network synthesisIntroduction to two port networks from the point of synthesis

L32T2-Ch10 (P:290-294)R3-Ch17 (P:792-795)

24Elements of realizability

The objective and definition of network

L33 T2-Ch10 (P: 290-294)R3-Ch17 (P:790-837)R2-Ch17 (P:744-767)Elements L34

25Hurwitz polynomials-positive real functions

The definition of. Hurwitz polynomials-positive real functions and Examples.

L35T2-Ch10 (P:294-298)R3-Ch17 (P:792-795)R2-Ch16 (P:699-727)

26Properties of Hurwitz polynomials

Properties of Hurwitz polynomials: The necessary and sufficient properties for realizability

L36T2-Ch10 (P:294-298)R3-Ch17 (P:790-837)R2-Ch17 (P:699-727)

27Testing of Hurwitz polynomials

Testing of Hurwitz polynomials by Sturn’s test

L37T3-Ch10 (P: 294-298)R3-Ch17 (P:790-837)R2-Ch17 (P:699-727)

311


UNIT-VI – NETWORK SYNTHESIS (No. of Lectures – 06)

28Synthesis of one port LC networks

Synthesis of one port LC networks-Assumptions and applications.

L38T2-Ch11 (P:315-333R3-Ch18 (P:838-882)

29Foster and Cauer Methods

Foster and Cauer Method for LC network synthesis

L39T3-Ch11 (P:315-324)R3-Ch19 (P: 883-917)

Foster and Cauer Method for RL network synthesis

L40T2-Ch11 (P:331-332)R3-Ch19 (P:883-917)

Foster and Cauer Method for RC network synthesis

L41T2-Ch11 (P:331-332)R3-Ch19 (P: 883-917)

Examples on Network synthesis

L42L43

R3-Ch19 (P:336-340) (P: 883-917)

UNIT-VII – SAMPLING (No. of Lectures – 09)

30

Sampling Theorem, Graphical and analytical proof for band limited signals

Sampling Theorem, Graphical and analytical proof for band limited signalsIntroduction for samplingSampling Theorem

L44L45

T1-Ch7 (P: 515-535)

GATE31

Impulse sampling, Nature and Flat top sampling

Impulse sampling, Nature and Flat top samplingIntroduction for samplingSampling TheoremNature and flat top sampling

L46L47

R1-Ch12 (P: 515-535)

32Reconstruction of signal from its samples

Reconstruction of signal from its samples with examples

L48 R1-Ch12 (P:515-535)

33Effect of under sampling aliasing

Effect of under sampling-Aliasing

L49R1-Ch12 (P:515-535)

34Introduction to Band Pass sampling

Introduction to Band loss sampling

L50

35Cross correlation and auto correlation of functions

Properties of correlation and auto correlation Energy and power density spectrums Relation between auto correlation function and Energy and power spectrums density functions Problems

L51L52

R1-Ch12 (P:515-535)

UNIT – VIII – Z - TRANSFORMS (No. of Lectures – 06)

36Continuous and discrete time signals

Continuous and discrete time signalsFundamental difference between Continuous and discrete time signalsDiscrete time signal representation using complex exponential and sinusoidal components.

L53L54

T1-Ch8 (P:231-239)

GATE

37Periodicity of discrete time using complex exponential signal

Periodicity of discrete time using complex exponential signal

L55 T1-Ch8 (P:231-239)

38 Z-transform Z-transformConcept of Z-transform of a discrete sequence.Distinction between Laplace, Fourier and Z transforms.Problems

L56 T1-Ch11 (P:624-657)

312


39

Region of convergence in Z-transform,Constrains on ROC for various classes of signals

Region of convergence in Z-transformProblems L57 T1-Ch8 (P:231-239)Constrains on ROC for various classes of signals

40Inverse Z-transform,Properties of Z-transform

Inverse Z-transform Problems

L58 T1-Ch8 (P:231-239)Properties of Z-transformProblems


1. Title : Linear SISO systems with Extremely Sensitive Zero Structures Author : Jordan Berg and Harry G.KwantyJournal : IEEE Tractions on Automatic Control SystemsVol. Year & Page No. : vol 41, no 7, July 2001, pp1037-1040

2. Title : The Generalized Lagrange Formulation for Nonlinear RLC Networks

Author : Harry G. Kwatny, Francis MJournal : IEEE transactions on circuits and systemsVol. Year & Page No. : vol. cas-29, no. 4, April 2004

3. Title : Adaptive wave LMS Network for adequacy analysis in power systems

Author : R.M.Saloman DanarajJournal : 25th National system conferenceVol. Year & Page No. : Dec2005, IIT Kharakhpur

4. Title : Adaptive wave LMS Network for Thermocouple modeling Author : R.M.Saloman DanarajJournal : 24th National system conferenceVol. Year & Page No. : Dec2006, PSG tech Coimbatore. IIT Kharakhpur

5. Title : Blind Extraction of chastic signal from an Instantaneous linear mixes

Author : B.V. Wang & W X ZhengJournal : IEEE transaction on circuit and systemsVol. Year & Page No. : Feb. 2008

313



UNIT-I

1. a. Obtain the state variable model for the circuit as shown in figure 1a.

b. Obtain the transfer function representation for a system represented by matrixes.

, , (JNTU May 09)

2. a. Write the state variable formulation of the network as shown in figure 1a.R1 = R2 = 1Ω, L = 1H,C1 = C2 = 1F

b. Obtain the time response of the following system and y = [1 0] x where

u(t) is unit step input and the initial condition x1(0) = 0, x2(0) = 0. (JNTU May 09)

3. a. Derive the state space representation for the network given as shown in figure 1a.

b. Consider the vector matrix differential equation given as

, with

Find the state transition matrix and x(t). (JNTU May 09)

4. a. Obtain the state variable model for the circuit as shown in figure.

314


b. Obtain the transfer function representation for a system represented by matrixes.

(JNTU May 09, Feb 08)

5. a. Obtain the state variable model for a system described by the following differential equation.

b. Determine the state transition matrix for the state matrix

(JNTU Nov 08)

6. a. Devleop the state variable model equation for the circuit as shown in figure.

b. A system matrix is given by obtain the state transition matrix. (JNTU Nov 08)

7. a. Show that the inductor current iL(t) in the circuit as shown in figure is given by

b. A dynamical system is described by the differential equation . Show that the stte

variable formulation is

(JNTU Nov 08)

8. a. Write the state equation for the circui as shown in figure.

315


b. Find the state response of the system shown in figure

9. a. Write the state equations for the network given as shown in figure.

b. Use the eigen method, find the state transition matrix for the system with the following parameter matrices.

A = B =

C = D = (JNTU Feb 08)

10. a. An engineer has designed the electrical circuit as shown in figure to supply power from the voltage source to the three resistive loads.

11. a. Define state variables and find the corresponding state and output equations in matrix form for this electric circuit.

316


b. Determine transfer function for the system described by the following differential equation

(JNTU Nov 07)

317


12. a. The natural response of a certain system is described by the homogeneous state equation.

b. Show that the state variable formulation for the Circuit as shown in figure 1b can be written as

13. Show that the state variable formulation for the Circuit as shown in figure 1b can be written as

14. a. Write the state equations for the circuit as shown in figure.

b. Solve the state equations with initial conditions

(JNTU Nov 07)

15. Obtain the state variable model for the circuit shown in figure. (JNTU Apr/May 07)

318


16. The system characteristic equation is and . Find the response of the

system. (JNTU Apr/May 07)

17. The transfer function of a system is obtain the state variable representation of the

systems. (JNTU Apr/May 07)

18. Determine the state transition matrix f or the system represented by the characteristic matrix

(JNTU Apr/May 07)

19. Evaluate the complete state response of the system characterized by A = with initial

state vector (JNTU Apr/May 06)

20. a. Write matrix state equation for the circuit shown in figure. (JNTU Feb 08, Nov 07, Apr/May 06)

b. Find the response of the circuit as shown in figure. (JNTU Feb 08, Nov 07)

21. Find the complete state response of the system.

(JNTU Apr/May 06)

22. Evaluate the state transition matrix for the system characterized by.

(JNTU Apr/May 06)

319


23. Develop the state equations of the following network: figure.

(JNTU Apr/May 06)

24. Derive the expression to find the solution of the state equations X(t) = A x(t)+ B u(t) with x (0) = x0 using state Transition Matrix approach. (JNTU Apr/May 06)

25. i. The transfer function of a system is

Obtain the state variable Representation of the systems. ii. Determine the state transition matrix for the system represented by the characteristic matrix.

(JNTU Nov 05)

26. i. Obtain the state equations for the network shown in figure. Where i1(t) and i2(t) are loop currents. ii. Evaluate the complete state response of the system characterized by A = With initial state vector

(JNTU Nov 05)

27. Construct a state variable model of a system characterized by the different equation.


28. Obtain the state equation and output equation of the electric network as shown. In Fig.

(JNTU Nov 04)

29. Obtain the solution of a system whose state model is given by X = A X(t) + B U(t) ; X(0) =X0 and hence define state Transition matrix. (JNTU Nov 04)

30. Obtain the transfer function of a control system whose state model is (JNTU Nov 04)

31. Write the state equations for the block diagram given. (JNTU Nov 04)

320


32. Obtain state space mode for given mechanical system. (JNTU Nov 04)

33. Obtain the state equations in canonical form for transfer function given

(JNTU Nov 04)

34. The state equations of a Linear system are as follows.

(JNTU Nov 04)

y = [2 1 -1] x. Determine the transfer function y(s)/u(s).

35. Explain various methods of evaluation of state transition matrix. (JNTU Nov 04)

36. Derive the expression for the transfer function from the state model. (JNTU Nov 04)x = Ax + Buy = Cx + Du

37. Obtain state variable representation of an armature controlled D.C. motor. (JNTU Nov 04)

38. Obtain state variable representation of a field controlled D. C. motor.

39. Find the state transition matrix for a given system. (JNTU Nov 04)

40. A system described by

Find the transfer function . (JNTU Nov 04)

41. For the given system X = Ax + Bu where

Find the characteristic equation of the system and its roots. (JNTU Nov 04)

42. Given Find the unit step response when,

(JNTU Nov 04)

321


43. a. Given the state equation

b. Find the State Transmission Matrix and zero input response for (JNTU Feb 08, Nov 04)

44. The closed loop transfer function is given by Obtain the state variable

model. (JNTU Nov 04)

45. For the given system X = AX + BU, Y + CX

Obtain Jordan form representation of state equation of A. Also find the transfer function.(JNTU Nov 04)

46. Derive the expression for the transfer function G(s) = Y(s)/U(s). Given the state modelX = A X + B UY = C X + D U (JNTU Nov 04)

47. Obtain the time response of the following system and output

where u(t) is the unit step input and the intitial condition x1(0), x2(0) = 0. (JNTU Nov 04)

48. Derive the expression for the transfer function from the state model.

(JNTU Nov 04)

(JNTU Apr 04)

49. Find the solution of the following state model

Obtain the state model of the system whose transfer function is given on

(JNTU Apr 04)

50. Reduce the matrix A to diagonal matrix. (JNTU Apr 04)

51. Obtain the state transition matrix f (t) given the system matrix (JNTU Apr 04)

52. Obtain the time response of the system given by (JNTU Apr 04)

where u(t) is a unit step occurring at t = 0 and xT (0) = (1 0).

53. Reduce the matrix A to diagonal matrix. (JNTU Apr 04)

322


54. Obtain the state transition matrix f (t) given the system matrix (JNTU Apr 04)

55. Obtain the time response of the system given by (JNTU Apr 04)

where u(t) is a unit step occurring at t = 0 and xT (0) = (1 0).

56. A system is characterized by the following state space equations.

i. Find the Transfer Function ii. Compute the state transition matrixiii. Solve the state equation for a unit step input under zero initial condition. (JNTU Apr 04)

57. Write a short on the following:i. State vectorii. State transition matrix (JNTU Apr 04)

58. Given the Matrix . Write down the characteristic equation and obtain the

eigen values. Also obtain the diagonal matrix. (JNTU Apr 04)59. For the following system determine :

i. State transition matrix;ii. State vector x(t).

Assume (JNTU Apr 04)

60. Find the response of the system (GATE 92)

where u(t) is unit step function.x1(0) = 1, x2(0) = 0.

323


61. From the following state variable representation, determine the transfer function of the system.

(IES 02)

UNIT – II

1. a. Determine the output voltage response ν(t) across the capacitor to a current source excitation i(t) = e-tu(t) as shown in figure 2a.

b. Calculate the impedance, resistance, power and power factor of a Circuit whose expression for voltage and current are given byV = 100 sin (ωt + 600) - 50 sin (3ωt - 300) Volti = 10 sin (ωt + 600) + 5 cos (3ωt + 600)amp (JNTU May 09)

2. Find the complex Fourier series expansion of the following waveform shown in figure 2.

If this voltage is applied to a series RL series circuit with R =1Ω, L = 2H. Find the expression for current I(t). (JNTU May 09)

3. a. Derive the expression for average power of complex wave which is expressed in terms of Fourier series.

b. The current waveform shown in figure 2b is applied to a circuit containing 0.01 micro farad in parallel with 1 kilo ohm with a range of frequency 13 to 14 KHz. Find the average power delivered to the resistor. (JNTU May 09)

4. a. Derive an expression for the effective value of non-sinusoidal periodic waveform.b. A periodic current source given by i(t) = 5+3 cos (100t + 450)+2 cos (200t - 100) is applied to a parallel

RL circuit as shown in figure 2b. Calculate the response V(t) and average power. (JNTU May 09)

5. The input to the circuit of figure 2(a) is a rectified sine wave as shown in figure 2(b).

324


Determine the current following through 1 ohm resistor. ω = 1 rad/sec. Draw the magnitude spectrum and find out the nth harmonic of i(θ). (JNTU Nov 08)

6. A rectangular waveform of magnitude 10V,duty ratio 75% and frequency 50Hz is applied across a resistance of 1ohm in series with an inductance of 100mH. Determine the steady state current in the circuit. Also find the power and P.F of the load current. (JNTU Nov 08)

7. Find the trigonometric form of the following voltage waveform shown figure 2 and hence compute average power and power factor of the load if voltage is applied to series RL circuit with R = 1, L = 1H. (JNTU Nov 08)

8. a. Determine and plot the voltage across the resistor in the circuit shown in figure 2a, using circuit analysis techniques if the input is a square wave with T =1 and T0 = 1/4 as shown in figure.

(JNTU Feb 08)

b. Determine the power represented by following and also determine the voltampere and power factor V = 100 sin (ƒ t + 300).50 sin (3ƒ t + 600)+25 sin 5ƒ t volts. i = 20 sin (ƒ t - 300) + 15 sin (3ƒ t + 300) + 10 cos (5ƒ t - 600)amperes. (JNTU Nov 08)

10. a. Find the Fourier series of the waveform shown in figure using exponential form. Plot the amplitude and phase spectrum. (JNTU Nov 08)

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b. Determine the effective voltage, effective current and average power supplied to a passive network of the applied voltage is v(t) = 100 + 50 cos (10t + 30) + 25 cos (30t + 60) volts and the resulting current is i(t) = 2 cos (10t + 750) + 3 cos (30t + 780)amp. (JNTU Feb 08)

11. a. Find the trigonometric Fourier series of the triangular waveform shown in figure.

b. A periodic function f( )with period 2 is expressed in Fourier Series as

Prove that


12. A 2 ohm resistive load is supplied from a full wave rectifier connected to 230V, 50Hz single phase supply. Determine the average and rms values of load current. Also find out the proportion of DC power and AC power to the total power in the load. Investigate the effect of adding an inductance in series with the load. (JNTU Feb 08, Nov 07)

13. a. A series RLC circuit with R=25ohms, L = 1H and C = 10mF is energized with a source v(t) = 15 sin 100t + 20 sin 200t + 5 sin 200t. Determine the effective value of current and average power consumed by the circuit.

b. What is meant by Fourier series of a non-sinusoidal periodic waveform? Explain the significance of the term “Half wave symmetry” used in determining the Fourier series of a given waveform.

(JNTU Nov 07)

14. The Fourier series expansion for a non-sinusoidal periodic waveform is found to contain only even harmonic cosine terms. Explain the time domain symmetry properties for this waveform.

(JNTU Nov 05)

15. i. The Fourier series of a voltage wave form is given by v(t) = 10 sin 100t+sin300t + sin500t . find power consumed in the circuit if it contains few resistor of 1 ohm.

ii. What would be the power factor when v(t) applied across RLC circuit R = 100 ohms, L = 1H and C = 10 micro farads. (JNTU Apr 02)

16. i. Find the exponential form of fourier series for a square wave having with T/2.ii. Find the fourier series coefficients of full wave rectified sign wave in real form. (JNTU Apr 02)

326


17. Find the fourier transform of a square wave form of duration two seconds and an amplitude of 10 volts given to a RC circuit where R=2 Ohms, C = 10 micro farads, frequency = 50 Hz, derive the expression for 5th harmonic current, average power, power factor. (JNTU Apr 02)

18. What are the assumptions made in fourier analysis. (JNTU Apr 02)

19. Explain the importance and advantages of fourier series for electrical engineering.(JNTU Apr 02)

20. Find fourin series for the waveform f(t) shown in figure (GATE 02)

21. Derive the equations for RMS and average value of a non sinusoidal periodic wave forms.

22. Expand the square wave voltage signal as shown in fig. into a fourier series.

23. Find the fourier series expansion of the periodic rectangular waveform shown in fig.(JNTU Nov 07)

24. Explain indetail the effects of harmonics in electrical systems.

25. A feedback system is characterized by the closed loop transfer function. Construct state model for this system and give block diagram representation of state model.

(JNTU Apr 04)

26. What are the properties of state transition matrix ? (JNTU Apr 04)

27. Write short notes on the solution of state equations: (JNTU Apr 04)

28. Obtain the solution of a system whose state model is given by X = A X(t) + B U(t) ; X(O) =X0 and hence define state Transition matrix. (JNTU Apr 04)

29. Obtain the transfer function of a control system whose state model is :X (t) = A X(t) + B U(t),Y(t) = CX(t) Where

(JNTU Apr

04)

327


30. For system shown below obtain state variable model : (JNTU Apr 04)

31. Consider the transfer function Y(s)/U(s) = (2s2 + s + 5) / (s3 + 6s2 + 11s + 4). Obtain the state equation by direct decomposition method and also find state transition matrix. (JNTU Apr 04)

32. Explain the advantages of state space model over input-output model. (JNTU Apr 04)

33. Consider the state-space model X = AX+BõY = CX+DõShow that the above state-space model is not unique. (JNTU Apr 04)

34. Determine the state transition matrix for the following system

(JNTU Apr

04)

35. What are the advantages of state space representation ? (JNTU Apr 04)

36. A control system is described by the differential equation where y(t) is the observed

output and u(t) is the input.i. Describe the system in the state variable formii. Calculate the state transition matrixiii. Is the system controllable (GATE 92)

37. For the system shown below, obtain state variable model:

(GATE 92)38. For the circuit choose a set of state variables and derive the voltage/current equation necessary for

solving the circuit interms of the choosen state variables. (IES 99)

39. Show that the system designated by is completely state controllable (IES 96)

40. Find the unit step, response of the following system.

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XT(0) = [1, 0] (JNTU Nov 04)41. Construct the state variable model for the system characterized by the differential equation.

y + 6y + 11y + 2y = 41 + 1 Also give the block diagram of the model. (JNTU Nov 04)

42. A linear time invariant system is denoted by the differential equationD3y + 3D2y + 3Dy + y = U where D = d y/dti. Write the state equationsii. Find the state Transition matrixiii. Find the characteristic equation and eigen values of A. (JNTU Nov 04)

43. Obtain state space model for the following system Figure. (JNTU Nov 04)

44. Derive the expression for rms value of complex (of voltage) wave which is expressed in terms of fourier series.

45. find the effective value of the function, i=100+50 sin . Also find power and power factor.

46. determine the rms value of the voltage defined by

47. A series RLC circuit has an applied voltage of V= 10 sint + 5 sin 3ti = 5 sin 2t + 2 sin 5t. Determine the effective current and average power?

48. In an electric circuit voltage and current are given by:V= 10 sint + 5 sin 3ti = 5 sin 2t + 2 sin 5t. Determine the average power in the circuit?

49. A Complex voltage V(t) = 100 sin ωt + 30sin 3ωt + 20 sin 5ωt, where ω= 10 rad/sec. If this voltage is applied to a load of 10Ω in series with 0.01H. Determine the current, average power and power factor of the current.

UNIT – III

1. a. Evaluate the following integrals and functions.

i.

ii.

b. Find the FT for the following functions.i. Unit step function ii. Dirac Delta function. (JNTU May 09)

2. a. Find the fourier transform of the following functions.i. Impulse function δ(t) ii. DC signal

b. State and prove time differentiation property of the fourier transform. (JNTU May 09)

3. a. Determine the spectrum for the following waveforms shown in figure 3(a)i, figure 3(a)ii.i. figure 3(a)i

329


ii. figure 3(a)ii

b. Determine Sketch the relative frequency distribution. (JNTU May 09)

4. a. Show that a periodic signal can be expressed as continuous sum of everlasting exponentials.b. Find the F.T. of

i. δ(t - t0) ii. rect (t/T) (JNTU May 09)

5. a. Use the duality property of F.T, find the transform of

b. Using the superposition and time shifting properties, Find the F.T. of the signals shown in figure 3b. Sketch the amplitude spectrum assuming τ<< To. (JNTU Nov 08)

6. a. Determine the F.T. of a trapzoidal function and triangular RF pulse f(t) shown in figure 3(a)i and figure 3(a)ii. Draw its spectrum.i. Figure 3(a)i

b. Show that a normalized Gaussian pulse is its own fourier transform. (JNTU Nov, Feb 08)

7. a. State and prove the time scaling property of F.T.b. Find the fourier transform of the pulse functions shown in figure 3b. (JNTU Nov 08)

330


8. a. Verify the parsevals theorem for the signal g(t) = eatu(t)b. If show that (JNTU Feb 08)

10. a. Let x(t) be a real, odd signal. Show that is pure imaginary and odd.

b. Prove the modulation property (JNTU Feb 08)

11. a. Use properties of FT, show that the FT of >

b. Explain the FT of the real and imaginary parts of the complex valued function g(t) in terms of G(t) and its complex conjugates. (JNTU Feb 08)

12. a. Explain the concept of continuous spectrum.b. Find the Fourier Transform for the following functions as shown in Figure (i)

13. a. Does the FT of external signal cosùot exist? If no, give reasons. Derive FT of cosùot. Draw the spectral density function.

b. Find the fourier transform for the doublet pulse and normalized ganssion pulse as shown in figure a, figure b.

figure (a) figure (b) (JNTU Nov 07)

14. a. Evaluate the following integrals and functions.

i.

ii.

15. Find the FT for the following functions.i. Unit step function ii. Dirac Delta function. (JNTU Nov 07)

16. A complex voltage e(t) = 100 sin w t + 30 sin 3wt + 20 sin 5 wt where w = 100t. If this voltage is applied to a load of 10 ohms in series with 0.01H, find the current, average power and power factor of the circuit. (JNTU Apr/May 07)

17. Find the Fourier transform of the waveform shown in figure6. (JNTU Apr/May 07)

18. Find the Fourier transform of double sided exponential for –a < a t < a

(JNTU Apr/May 07)19. State and explain the properties of Fourier Transform. (JNTU Apr/May 07)

331


20. Define Signum function and hence develop the expression for Fourier transform of it.(JNTU Apr/May 07)

21. ind the Fourier transform of the function F(t)= u(t+1) ? 2u(t) + u(t-1) (JNTU Apr/May 07)

22. Find the inverse Fourier transform of the following function. (JNTU Apr/May 07)

where and

23. Find the Fourier transform of a gate function (JNTU Apr/May 07)

= 0 otherwise 24. Find the Fourier transform of the constant signal (JNTU Apr/May 07)

25. i. Find the Fourier transform of a gate function

= 0 otherwise

ii. Find the Fourier transform of the constant signal f(t) = A (-a <t <a) (JNTU Apr/May 06)

26. i. State and explain Parseval’s theorem.ii. Derive the expression for Fourier transform of unit step function. (JNTU Apr/May 06)

27. i. State and explain the properties of Fourier Transform.ii. Define Signum function and hence develop the expression for Fourier transform of it.

(JNTU Apr/May 06)

28. Find the fourier Transform of

(JNTU Apr 05)

29. Find the fourier transform of (JNTU Apr 05)

30. Find the fourier transform of for (JNTU Apr 05)= 0 elsewhere

31. State and explain the properties of Fourier Transform. (JNTU Nov 05)

32. i. State and Explain Parsenval’s Theorem with an exampleii. Derive the expression for Fourier transform of Unit step function (JNTU Nov 05)

33. Find the function f(t) whose fourier transform are as follows : (JNTU Apr 04)i. F(w) = A exp (-J w to)ii. F(w) = A exp (J p/2) ; -wo < w < 0

34. Derive the relation of laplace with fourier transform. (JNTU Apr 04)

35. Find the fourier transform of a square wave form of duration two seconds and an amplitude of 10 volts given to a RC circuit where R = 2 Ohms, C = 10 micro farads, frequency = 50 Hz, derive the expression for 5th harmonic current, average power, power factor. (JNTU Apr 02)

36. State the applications of fourier transform and series in electrical engineering. (JNTU Apr 02)37. Write the properties of fourier transforms.

38. Explain how can you represent non periodic functions using fourier transform.

332


39. Compare Fourier Transform with laplace Transform

40. Find a state model for the system with transfer function.

(JNTU Apr 04)

41. Obtain the state space representation of the electrical network shown. (JNTU Apr 04)

42. A feedback system is characterized by the closed loop transfer function.

Construct state model for this system and give block diagram representation of state model.(JNTU Apr 04)

UNIT – IV

1. a. State and prove second shifting theorem.

b. Find the Inverse Laplace Transform of (JNTU May 09)

2. a. State and prove the convolution theorem. (JNTU May 09)b. Determine the LT for the following functions.

i. Unit step ii. Impulse function. iii. Ramp functions.

3. a. Determine the current in a series RL circuit shown in below driven by a Square wave voltage source of amplitude 1 and half period T/2 = 1.

b. Find v(t) for a system whose using of Heaviside theorem. (JNTU May

09)

4. a. Explain time and frequency convolutionb. Find Laplace Transform for the following functions

i. Sin2ω(t – t0) ii. t cos(ωt + θ) (JNTU May 09)

333


5. a. Explain the graphical interpretation of convolution with the following functions. As shown in figure 4a.

b. A voltage e u(t) is applied to a series RC network as shown in figure 4b.

Find the voltage V0(t) using frequency domain analysis. (JNTU Nov 08)

6. a. Find the LT of the following functions.i. f(t) = Kt K is a real constant >1 ii. f(t) = tδ′(t)

b. The impulse response of a certain linear system is given byh(t) = e-2tu(t) t ≥ 0

= 0 t < 0Using the convolution integral, determining the response y(t) due to the ramp inputx(t) = 0 t < 0

= t t ≥ 0. (JNTU Nov 08)

7. a. Find the convolution for the signals.i.

ii. b. Given LT, how do you obtain its F.T. (JNTU Nov 08)

8. a. Evaluate the following convolution integrals.i. u(t) * e-t u(t)ii. u(t) * tu (t)

b. Find the Inverse LT of the following function

(JNTU Nov 08)

9. a. Determine the LT, ROC and location of poles and zeros of x(s) for the following signals.

i.

ii.

b. Determine the initial and final values of a signal x(t) whose unilateral LT is

i.

ii. (JNTU Feb 08)

10. a. Find the LT of

i.

334


ii.

b. Find the LT of x(t) = e-5t [u(t) - u(t-5)] and its ROC. (JNTU Feb 08)

11. a It is given that

find a,b and c such that f (0+) = f1 (0+) = fn (0+) = 1b. Find the LT’s for the waveforms shown in figure (a), figure (b). (JNTU Feb 08)

figure (a)

Figure (b)

12. a. Find the convolution integral when and

b. A rectangular voltage pulse of unit height and duration T seconds is applied to a series RC circuit at t = 0 as shown in figure. Determine the voltage across the capacitor as a function of time. Assume the condenser to be initially uncharged. (JNTU Feb 08)

13. a. Determine the current in a series RL circuit shown in below driven by a Square wave voltage source of amplitude 1 and half period T/2 = 1.

b. Find v(t) for a system whose using of Heaviside theorem. (JNTU Nov 07)

14. a. Find the Inverse LT of

335


b. Use the LT, find the voltage across the capacitors, y(t) for the RC circuit shown in figure, in response

to the applied voltage and initial condition y(0-) = -2 (JNTU Nov 07)

15. a. In the RC circuit shown in figure, switch is closed at time t = 0. Determine the current i(t) after the switch is closed. Assume that there is no change in the capacitor before switching.

b. Find the Inverse LT of the following function. (JNTU Nov 07)

16. a. A step DC current of 5 ampers is applied at time t = 0 to a parallel RLC circuit shown in figure, consisting of resistor R = 1/7 ohms, induction L = 0.1 Henry and Capacitor C =1 Farad. Determine the voltage V(t) across the circuit. Assume zero change across the capacitor C.

b. Current I(s) in a network is given by . Find i(t), the current at any time.

(JNTU Nov 07)

17. Define the following functions and obtain the Laplace transform of these: (JNTU Apr/May 07)i. Shifted step functionii. Pulseiii. Shifted ramp functioniv. Impulse function

18. Distinguish between unit impulse function and unit doublet function and hence develop the Laplace transform of these functions. (JNTU Apr/May 07)

19. Find the expressions for the current i(t) in a series R-L-C circuit, with when it is fed by a ramp voltage of 12 r(t-2). (JNTU Apr/May 07)

20. Find the current i(t) is a series circuit comprising when it is fed by a ramp voltage of 3r(t-1).(JNTU Apr/May 07)

21. i. Distinguish between unit impulse function and unit doublet function and hence develop the Laplace transform of these functions.

336


ii. Find the expressions for the current i(t) in a series R-L-C circuit, with R=5W, L=1H, C=1/4 F, when it is fed by a ramp voltage of 12 r(t-2). (JNTU Apr/May 06)

22. i. Assuming stair case function shown in figure,4 is not repeated, and is applied to an R-L series circuit with R=1W, L=1H, find the current i(t).

ii. Find inverse Laplace transform of using convolution theorem.

(JNTU Apr/May 06)

23. A series R-C ckt. With R = 1 W, F is fed by a voltage of non-periodic waveform shown in figure 3. Find the response i(t) using Laplace transform approach. (JNTU Apr/May 06)

24. i. Determine the current in a series R-L circuit driven by a square wave, periodic function shown in figure 4 With R=1W, L=1H.

ii. Find the convolution of h(t)=t, and f(t)=e-µ t for t>0, using the inverse Laplace transform of H(s) F(s).

(JNTU Apr/May 06)

25. i. A pulse voltage of 3V between 1 to 2 sec. is applied to a series R-L circuit with R=3 W , L=1H, Find the current i(t).

ii. Find the current is i(t) in a series R-L-C circuit with R=3W, L=1H, C=1/2F when it is driven by an impulse voltage of ä (t-2).

(JNTU Apr/May 06)

26. i. Find the inverse Laplace transform of the periodic signal shown in figure. ii. When an unit impulse voltage is applied to a certain network, the output voltage is Vo (t) = 4 u(t)-4u(t-

2) Volts. Find and sketch Vo (t) if the input voltage is 2u(t-1) Volts. (JNTU Apr/May 06)

27. i. Distinguish between unit impulse function and unit doublet function and hence develop the Laplace transform of these functions.

ii. Find the expressions for the current i(t) in a series R-L-C circuit, with R=5, L=1H, C=1/4F, when it is fed by a ramp voltage of 12 r(t-2). (JNTU Nov 05)

28. i. Find the Laplace transforms function of the periodic waveform shown in figure

337


ii. State and prove convolution theorem (JNTU Nov 05)iii. Show that convolution of any function with unit impulse function is the Functions itself

29. i. Show that Laplace transform of a full-wave rectified sine wave with amplitude of 1 is:

ii. Using the convolution integral find f(t)

iii. Obtain Laplace transform of a train of unit impulses with a period of 1 sec (JNTU Nov 05)

30. Consider the circuit shown in fig. The switch is thrown from position 1 to 2 at time t = 0. Just before the switch is thrown, the initial conditions are iL(0+) = 2A, VC (0+) = 2V. Find the current i(t) after the switch thrown. Assume L = 1H R = 3C = 0.5F V1 = 5 V

31. Assume zero initial conditions find i1 and i2 is the network shown by using laplace transform method.

(JNTU Nov 05)32. Draw the network in laplace domain and then i1(t) and i2(t).

(JNTU Nov 05)33. Consider the voltage wave form shown in fig. find

i. D.C. component of Vii. The amplitude of the fundamental component of Viii. The rms value of the at V.

(JNTU Nov 05)34. Consider the circuit shown in fig. determine V0(t) informs of i(t). Evaluate

S, is closed when t = 0 (JNTU Nov 05)

35. Write the Laplace transformed equation for the mechanical system of Fig.5 using force voltage analogy

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(JNTU Apr 02)36. Derive an expression for i(t) in the circuit shown in fig. by laplace transform. (JNTU Apr 02)37. Derive an expression for i(t) in the circuit shown in fig. by laplace transform. (JNTU Apr 02)

38. Apply the laplace transform method to determine the mesh currents in the circuit shown in fig. Assume switch is closed at t = 0. (JNTU Apr 02)

39. Find the laplace transform of the single half-sine cycle shown in figure. (JNTU Apr 02)

40. Derive from the first principle the laplace transform on a unit step function. Hence or other wise determine the laplace transform of unit ramp function and unit impulse function. (GATE 00)

41. Derive an expression for i(t) in the circuit shown in fig. by laplace transform. (NITC Apr 02)42. Derive from the first principle the laplace transform on a unit step function. Hence or other wise

determine the laplace transform of unit ramp function and unit impulse function. (GATE 00)

43. Derive from the first principle the laplace transform on a unit step function. Hence or other wise determine the laplace transform of unit ramp function and unit impulse function. (GATE 00)

44. Find the laplace transform of the periodic, rectified half-since wave shown in figure. (GATE 00)

45. Find the laplace transform of the periodic saw tooth wave shown in fig. (GATE 00)

38. Find the laplace transform of the trapezoidal function in figure. (GATE 00)

39. Use convolution to prove the trigonometric identity

Cos at cos bt =

40. An impulse voltage source Vi=10δ(t) is connected in series with a resistance of 2 ohms an capacitance of ½ farad. Determine the time constant, the current at t = 0 and sketch the current waveform and write an analytic expression for it.

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UNIT – V

1. a. Explain Sturm’s theorem.b. Test whether the following function is a positive real function and the polynomials are Hurwitz or not

using Sturm’s test.

(JNTU May

09)

2. a. Prove that an LC impedance function is ratio between either even and odd or odd and even polynomials.

b. Test the polynomial F(s) = s7 + 2s6 + 2s5 + s4 + 4s3 + 8s2 + 8s + 4 for being Hurwitz.(JNTU May 09)

3. a. State necessary and sufficient conditions for positive real function. (JNTU May 09)

b. Test whether the given polynomial be a positive real function.

4. a. What are the properties of LC driving point immitance function?b. Find the range of ‘a’ so that H(s) = 2s4 + s3 + as2 + s + 2 is Hurwitz. (JNTU May 09)

5. a. State and explain the properties of positive real function. (JNTU Nov 08)b. Check whether given polynomial H(s) = 2s4 +5s3 +6s2 +2s +1 is Hurwitz or not.

6. a. List the properties of positive real function. (JNTU Nov 08)

b. A function is given by . Determine the positive realness of the function.

7. Given

a. What are the conditions on ‘X’ for Z(s) to be a positive real function?b. Find ‘X’ for Re (Z (jω)) to have a second order zero at ω = 0. (JNTU Nov 08)

8. a. Explain Sturm’s theorem.b. Test whether the following function is a positive real function and the polynomials are Hurwitz or not

using Sturm’s test.

(JNTU Nov

08)

9. a. State and explain the properties of positive real function.b. Check whether given polynomial H(s) = 2s4 +5s3 +6s2 +2s +1 is Hurwitz or not.


10. a. What is Hurwitz polynomial? State the properties of Hurwitz polynomial.b. Test whether the polynomial P(s) = s4 + s3 + 2s2 + 3s + 4 is Hurwitz or not. (JNTU Feb 08)

11. a. Find the range of value of ‘a’ so that H(s) = s4 + s3 + as2 + s + 3 is Hurwitz.

b. Find the even and odd parts of impedance function and hence find out Re Z(s) and

Im Z(s) is positive real as well as realizable. (JNTU Feb 08, Nov 07)

12. a. Explain the properties of positive real function.b. Test whether the following functions are positive real functions or not (JNTU Feb 08)

340


i.

ii.

13. a. Check if the polynomial H(s) = 2s4 + 5s3 + 6s2 + 2s + 1 is Hurwitz or not.b. Check whether the function is a positive real function. (JNTU Nov 07)

a. Show that the function is positive real.

14. Check if the polynomial H(s) = s4 + s3 + 2s2 + 2s + 24 is Hurwitz or not.(JNTU Nov 07)

15. State and explain the properties of positive real functions. (JNTU Apr/May 07)

16. Test whether the following function is positive real function or not?

(JNTU Apr/May 07)

17. State and explain the properties of Hurwitz polynomial. (JNTU Apr/May 07)

18. Check whether the following polynomial is Hurwitz or not? (JNTU Apr/May 07)

19. Check whether the following polynomial is Hurwitz or not?(JNTU Apr/May 07)

20. Find the range of values of ‘a’ so that is Hurtwitz (JNTU Apr/May 07)

21. Explain how the removal of pole at infinity of an impedance Z(s) can realize an element in the network.(JNTU Apr/May 07)

22. Realize the network with the following driving point impedance function using first Foster form. Z(s) = (s+2) / s(2s+5) (JNTU Apr/May 07)

23. i. Check whether the following polynomial is Hurwitz or not? H(s) = s4 + 2s2 + 3s + 6ii. Find the range of values of ‘a’ so that H(s) = s4 +s3 +as2 +s+3 is Hurwitz. (JNTU Apr/May 06)

24. i. Explain how the removal of pole at infinity of an impedance Z(s) can realize an element in the network.

ii. Realize the network with the following driving point impedance function using first Foster form.Z(s) = (s+2) / s(2s+5) (JNTU Apr/May 07)

25. i. Check whether the following polynomial is Hurwitz or not? P(s) = 2s4 + 5s3 + 6s2 + 2s + 1ii. All driving point immittances of passive networks are positive real functions. Substantiate the

statement.iii. State the analytical tests to be considered for a polynomial to check whether it is a positive real

function or not? (JNTU Apr/May 07)


ii. Realize the network with the following driving point impedance function using first Foster form.Z(s) = (s+2) / s(2s+5) (JNTU Apr/May 07)

341


27. i. Check whether the following polynomial is Hurwitz or not? H(s) = s4 + 2s2 + 3s + 6ii. Find the range of values of ‘a’ so that H(s) = s4 +s3 +as2 +s+3 is Hurwitz. (JNTU Apr/May 07)

28. i. State and explain the properties of Hurvitz Polynomial. (JNTU Apr 05)i. Check whether the following polynomial Hurvitz or not.

H(s) = s4 + s3 + 5s2 + 3s + 4

29. Check the polynomial is Hurvitz or not. S7 + 2s6 + 2s5 + s4 + 4s3 + 8a2 + 8s + 5 (JNTU Apr 05)

30. Test Whether the following function is postive real or not.N(s) = (s3 + s2 + 3s + 5) / (s2 + 6s + 8) (JNTU Apr 05)

31. The driving point immittance of a L-C network is given by Z(s) = (10s4 + 12s2 + 1) / 2s(s2 + 1) for this function determine the first Cauer configuration find the values of each element in the network.

(JNTU Apr 05)

32. i. All driving point admittances of passive networks are positive real functions”. Substantiate the statement.

ii. State the analytical tests to be considered for a polynomial to check whether it is a positive real function or not? (NITC Apr 04)

33. Test weather the following polynomilals are Hurwitz.i. S3 + 4S2 + 5S + 2 ii. S7 + 2S6 + 2S5 + + S4 + 4S3 + 8S2 + 8S + 4 (NITC Nov 04)

34. Test for Hurwitz.i. S4 + 7S3 + 6S2 + 21S + 8 ii. S3 + 4S2 + 5S + 2 (Anna Nov 04)

35. Check the positive realness of the following functions. (Anna Nov 03)

36. Find the unit step, response of the following system.

XT(0) = [1, 0] (JNTU Nov 04)

37. Construct the state variable model for the system characterized by the differential equation.y + 6y + 11y + 2y = 41 + 1 Also give the block diagram of the model. (JNTU Nov 04)

38. A linear time invariant system is denoted by the differential equationD3y + 3D2y + 3Dy + y = U where D = d y/dti. Write the state equationsii. Find the state Transition matrixiii. Find the characteristic equation and eigen values of A. (JNTU Nov 04)

342


39. Obtain state space model for the following system Figure. (JNTU Nov 04)

40. Find the solution of the following state model (JNTU Nov 04)

with

Obtain the state model of the system whose transfer function is given o16. Explain in detail the effects of harmonics in electrical systems.

41. A feedback system is characterized by the closed loop transfer function (JNTU Apr 04)Construct state model for this system and give block diagram representation of state model.

(JNTU Apr 04)


43. Write short notes on the solution of state equations: (JNTU Apr 04)


45. Obtain the transfer function of a control system whose state model is :X (t) = A X(t) + B U(t),Y(t) = CX(t)

Where (JNTU Apr 04)


47. For the following system determine :i. State transition matrix;ii. State vector x(t).

Assume and v (t) = (t) (JNTU Apr 04)

48. Consider the transfer functionY(s)/U(s) = (2s2 + s + 5) / (s3 + 6s2 + 11s + 4)Obtain the state equation by direct decomposition method and also find state transition matrix.

(JNTU Apr 04)

49. Given the Matrix . Write down the characteritistic equation and obtain the

eigen values. Also obtain the diagonal matrix. (JNTU Apr 04)

UNIT – VI

343


1. a. Synthesize the first and second foster forms of networks for the impedance

b. Realize the second foster form of the driving point impedance function is given by

(JNTU May 09)

2. Synthesize the functions in two Foster forms (JNTU May 09)

3. Realize in all four forms.

4. a. Given the driving-point impedance function Synthesize a ladder network of the

first Cauer form for this impedance function.b. A network is made up of a series connection of an RL network and RC network. Assuming that neither

of the networks is a short circuit find the location of poles and also the location of zeros. What is the behavior at the origin and at infinity? (JNTU May 09, Nov 08)

5. Find the networks for the following functions in one Foster and one Cauer form

a. b. (JNTU Nov 08)

6. a. Given the driving point admittance function . Synthesize ladder network of

the first Cauer form.b. State and explain Foster’s reactance theorem for LC networks. (JNTU Nov 08)

7. Indicate which of the following functions are either RC, RL, or LC impedance functions. Give reasons.

a. b.

c. d. (JNTU Nov 08)

8. An impedance function has all the poles and zeros located on imaginary (jw) axis with poles at w=2, 0, -2 and zeros at w=3, 1, -1, -3. If Z(-2) = -130/16, synthesize the impedance in Foster-I and II forms

(JNTU Feb 08)

9. Synthesize the following functions in Cauer form.

a. b. (JNTU Feb 08, Nov 07)

10. Synthesize following F(s) in two Foster forms (JNTU Feb 08)

11. a. Given the driving-point impedance function Synthesize a ladder network of

the first Cauer form for this impedance function.b. A network is made up of a series connection of an RL network and RC network. Assuming that neither

of the networks is a short circuit find the location of poles and also the location of zeros. What is the behavior at the origin and at i2.* If Z(-2) = -130/16, synthesize the impedance infinity? (JNTU Feb 08)Cauer-I and II forms

344


12. Indicate which of the following functions are either RC, RL, or LC impedance functions. Give reasons.

a. b.

c. d. (JNTU Nov 07)

13. An impedance function is given by

Find the R-L representation ofa. Foster-I and II forms. b. Cauer-I and II forms. (JNTU Nov 07)

14. The driving point impedance of an L- C network is given by Z(s) = (12s 4 + 10s2 + 1)/(4s2 + 2s) Determine the first Cauer configuration and find the values of the elements in the network.

(JNTU Apr/May 07)

15. The impedance functions of an L-C network is given by Z(s) = (3s + 8s2)/(3 + 10s2 + 2s4) Find the second Cauer network and find the values of the elements. (JNTU Apr/May 07)

16. The driving point impedance of a one port L- C network is given by Z(s) = 4(s 2 + 1)(s2 + 16)/s(s2 + 4) Write partial fractions expansion for Z(s) and for Y(s). Synthesize the first and second Foster form of equivalent circuits. (JNTU Apr/May 07)

17. The driving point impedance of a one port L- C network is given by Z(s) = 5s(s 2 + 4)/(s2 + 1)(s2 + 9) Obtain the first and second Foster form of equivalent networks. (JNTU Apr/May 06)

18. State and explain the properties of L-C immittance function deriving necessary conditions.(JNTU Apr 05)

19. Explain the procedure to test a function can be represented has L-C immittance form and explain how synthesizing is carried out in second fostal form. (JNTU Apr 05)

20. State and explain various tests to be conducted whether a polynomial can be has Hurvitz.(JNTU Apr 05)

21. The driving point immittance of a single port L-C network is given by Z(s) = 4(s2+1)(s2+9)(s2+25)/s(s2+4)s2+16) obtain the first and second foster form of equivalent networks. (JNTU Apr 05)

22. Synthesize the L-C Admittance function into First and second Cauer form networkZ(s) = (2s4 + 20s2 + 18)/s(s2+4) (JNTU Apr 05)

23. i. Test whether the following polynomial is Hurwitz or not?H(s) = S4 + 2S3 + 2S2 + 6S + 10

ii. Test whether the following function is positive real or not?F(s) = (S3 + 2S2 + 1) / (S4 + S3 + 3S2 + S + 1) (JNTU Apr 04)

24. The driving point impedance of a one port L- C network is given byZ(S) = 4 (S2 + 1) (S2 + 9) (S2 + 25) / S(S2 + 4) (S2 + 16) (NITC Apr 04)

25. The driving point impedance of a one port L- C network is given by Z(s) = 4(s2 + 1)(s2 + 9)(s2 + 25)/s(s2 + 4) (s2 + 16) Obtain the first and second Foster form of equivalent networks (JNTU Apr 04)


ii. Realize the network with the following driving point impedance function using first Foster form. Z(s) = (s+2) / s(2s+5) (JNTU Nov 04)

345


27. Determine the foster and cauer form of realization of the given driving-point impedance function.

(JNTU Nov 04)

28. Synthesize in cauer forms.

(JNTU Nov 04)

29. Synthesize first and second foster and cauer forms of the LC driving point impedance function.

(JNTU Nov 04)

30. Synthesize first and second foster and cauer forms of the RL driving point impedance function.

(JNTU Nov 04)

31. Given the driving point impedance function of an RC network

(JNTU Nov 04)

Determine the foster first and second forms of realization and the caver first and second forms of realization.

32. Synthesize in foster II form: (JNTU Nov 02)

33. What are the advantages of foster and caver methods in Electrical networks. A feedback system is characterized by the closed loop transfer function. (JNTU Nov 02)

Construct state model for this system and give block diagram representation of state model.

(JNTU Apr 04)


35. Write short notes on thesolution of state equations: (JNTU Apr 04)


37. Obtain the transfer function of a control system whose state model is :X (t) = A X(t) + B U(t),Y(t) = CX(t) Where

(JNTU Apr 04)


346


347


39. For the following system determine :i. State transition matrix;ii. State vector x(t).

(JNTU Nov 01)

40. Consider the transfer functionY(s)/U(s) = (2s2 + s + 5) / (s3 + 6s2 + 11s + 4)Obtain the state equation by direct decomposition method and also find state transition matrix.

(NITC Apr 04)

41. Given the Matrix . Write down the characteritistic equation and obtain the

eigen values. Also obtain the diagonal matrix. (NITC Apr 04)

42. Explain the advantages of state space model over input-output model. (NITC Apr 04)

43. Consider the state-space model X = AX+BuY = CX+DuShow that the above state-space model is not unique.

44. A 2 ohm resistive load is supplied from a full wave rectifier connected to 230V, 50Hz single phase supply. Determine the average and rms values of load current. Also find out the proportion of DC power and AC power to the total power in the load. Investigate the effect of adding an inductance in series with the load. (JNTU Feb 08, Nov 07)

45. A series RLC circuit with R=25ohms, L = 1H and C = 10mF is energized with a source v(t) = 15 sin 100t + 20 sin 200t + 5 sin 200t. Determine the effective value of current and average power consumed by the circuit.

46. What is meant by Fourier series of a non-sinusoidal periodic waveform? Explain the significance of the term “Half wave symmetry” used in determining the Fourier series of a given waveform.

(JNTU Nov 07)

47. The Fourier series expansion for a non-sinusoidal periodic waveform is found to contain only even harmonic cosine terms. Explain the time domain symmetry properties for this waveform.

(JNTU Nov 05)

48. The Fourier series of a voltage wave form is given by (JNTU Apr 02)v(t) = 10 sin 100t+sin300t + sin500t . find power consumed in the circuit if it contains few resistor of 1 ohm.

49. What would be the power factor when v(t) applied across RLC circuit R = 100 ohms, L = 1H and C = 10 micro farads.

50. i. Find the exponential form of fourier series for a square wave having with T/2.ii. Find the fourier series coefficients of full wave rectified sign wave in real form. (JNTU Apr 02)

51. Find the fourier transform of a square wave form of duration two seconds and an amplitude of 10 volts given to a RC circuit where R=2 Ohms, C = 10 micro farads, frequency = 50 Hz, derive the expression for 5th harmonic current, average power, power factor. (JNTU Apr 02)

52. What are the assumptions made in fourier analysis. (JNTU Apr 02)

53. Explain the importance and advantages of fourier series for electrical engineering.(JNTU Apr 04)

54. Find fourin series for the waveform f(t) shown in figure (GATE 02)

348


55. Derive the equations for RMS and average value of a non sinusoidal periodic wave forms.

56. Expand the square wave voltage signal as shown in fig. into a fourier

UNIT – VII

1. a. A power signal f(t) has a power Sf(w). Find the power density spectrum of the signal df/dt.b. Give physical interpretation of power density spectrum.c. Derive the relation between power spectral densities of the input and the response of a linear system

with transfer H(f). (JNTU May 09)

2. Determine the minimum sampling rate and Nyquist interval for the following signals:a. Sa(100t) b. Sa2(50t)c. Sa(100t) + Sa(50t) d. Sa(100t) + Sa2(60t). (JNTU May 09)

3. a. Define Energy density spectrum. How is it useful in analyzing a spectrum? Or give the interpretation of Energy density.

b. Define Power density spectrum. Give the interpretation of power density. (JNTU May 09)

4. a. The signals m1(t) = 10cos100πt and m2(t) = 10cos50πt are both sampled with fs = 75 Hz. Show that the two sequences of samples so obtained are identical.

b. The signal g(t) = cos10 πt+0.5cos 20 πt is sampled with the interval between samples is Ts. Find the maximum allowable time for Ts.

c. Determine the sampling rate for the band pass signal whose centre frequency fc is 5 fm with a signal band width of 2fm. (JNTU May 09)

5. Find the mean square value of the output voltage vo(t) of an RC network shown in figure 7 if the input voltage has a power density spectrum Si(ω) given by (JNTU Nov 08)

a. Si (ω)= kb. Si (ω)= G2(ω) [gate function with cutoff at ω=1]c. Si (ω)= π [δ(ω + 1)+δ(ω - 1)]

In each case, also calculate the power of the input signal.

5. a. How does flat top sampling differ from impulse sampling? Discuss the merits and drawbacks of both types of sampling.

b. Show that the continuous time signal xa(t) = A cos (ωot+φ) can be uniquely recovered from its sampled version x[n]=xa(nT) if the sampling frequency is ωs = 2 π/T > 2wo. (JNTU Nov 08)

6. For a low pass signal with a bandwidth of 6000Hz, what is the minimum sampling frequency for perfect reconstruction of the signal? What is the minimum required sampling frequency if a guard band of 200Hz is required? What is the minimum required sampling frequency and the value of ‘K’ for perfect reconstruction if the reconstruction filter has the following frequency response

(JNTU Nov 08)7. For a low pass signal with a bandwidth of 6000Hz, what is the minimum sampling frequency for

perfect reconstruction of the signal? What is the minimum required sampling frequency if a guard band

349


of 200Hz is required? What is the minimum required sampling frequency and the value of ‘K’ for perfect reconstruction if the reconstruction filter has the following frequency response

(JNTU Feb 08)

8. Find the mean square value of the output voltage vo(t) of an RC network shown in figure 7 if the input voltage has a power density spectrum Si( ) given by

a. Si (ω)= k b. Si (ω)= G2(ω) [gate function with cutoff at =1]c. Si (ω)=π [δ( + 1)+ δ ( -1)]

In each case, also calculate the power of the input signal. (JNTU Feb 08)

9. A signal m(t) = cos 200 πt+2 cos 320 πt is ideally sampled at fs =300Hz. If the sampled signal is passed through an ideal LPF with a cutoff frequency of 250Hz, what frequency components will appear in the output?

10. Verify that ms(t) = m(t) (JNTU Feb 08)

11. Derive the relation between Auto-correlation function and Energy/Power spectral density function. (JNTU Feb 08)

12. Find out an expression for the correlation function of a square wave having the values 1 or 0 and a period T. (JNTU Feb 08)

13. The sampling theorem with Ts= that is m(t)= m(nTS) n(t) where

, Show that n(t) is orthogonal over the

interval - oo < t < 1 and1 (JNTU Nov

07)

14. Show that if the sampling rate is equal to or greater than twice the highest message frequency, the message m (t) can be recovered from the natural sampled signal xns(t) by low-pass filtering.

(JNTU Nov 07)

15. A periodic signal f(t) shown in the figure 7 is transmitted through a system with transfer function H(w). For these different values of T (T = 2 /3, /3 and /6), find the power density spectrum and the power of the output signal. Calculate the power of the input signal f(t). (JNTU Nov 07)

16. Explain how sampling is done in the case of band pass signals and how the message is reconstructed from its samples.

17. A band pass signal has a center frequency fo and extends from fo-5 KHz to fo+5 KHz. The signal is sampled at a rate fs = 25 KHz. As the center frequency of varies from fo = 5KHz to fo = 50KHz. Find the ranges of fo for which the sampling rate is adequate. (JNTU Nov 07)

350


18. State uniform sampling theorem. Prove graphically with neat diagrams in time and frequency domains and analytically by proving the results used.

19. Explain signal recovery from its sampled signal. (JNTU Nov 04)

20. State sampling theorem for Low pass signals. Prove analytically and mention various results used.

21. Define and draw aliasing phenomenon in frequency domain. (JNTU Nov 04)

22. State sampling theorem for Low pass signals. Prove analytically and mention various results used.

23. Define and draw aliasing phenomenon in frequency domain. (JNTU Nov 04)

24. State and explain sampling theorem.

25. The signal x(t)= cos (5π)t + 0.5 cos (10π)t is intastantaneously sampled. Determine the maximum interval of sampling. (JNTU May 02)

26. Use convolution integral to fid the response y(t) of an LTI system with impulse response h(t)=u(t - 1) to the input x(t) = e-2tu(t) (JNTU May 02)

27. Represent the function shown by a exponential Fourier series over the internal -π to π(JNTU Nov 02)

A

π

-π 28. State and prove the sampling theorem. Illustrate the effect of over sampling and under sampling.

29. Determine the Fourier transform of a two sided exponential pulse x(t)= e-|t| (JNTU Nov 02)

30. State and prove Modulation theorem

31. Using the modulation theorem find out the Fourier transform of RF pulse given as y(t) = A rect(t/t) Cos2 (JNTU Nov 02)

32. What is the effect of the undersamplig a signal? (JNTU May 99)

33. Write short notes on any three.i. Parseval’s relationii. Pole=zero plot and frequency responseiii. variation of Zo in constant K filtersiv Latticeequalizersv. Sampling theorem (JNTU Nov 99)

34. The signal x(t) 4+8 cos 8π is sampled at a rate of 16 samples per second. Plot the amplitude spectrum of the sampled signal, showing the weight and the frequency of each component for |f| < 40Hz. How can the signal be reconstructed from the samples. (JNTU May 98)

35. Write short notes on any three of the followingi. Sampling theoremii. Convolution integraliii. Dirichlet’s conditionsiv. Band elimination filters (JNTU Nov 98)

36. Write short notes on any three

351


i. Convergence of Fourier series ii. Modulation property of Fourier transformiii. Sampling theorem iv. Initial and final value theoremsv. Region of converence of Z-transform. (JNTU Nov 98)

37. A real-valued signal x(t) is known to be uniquely determined by its samples when the sampling frequency is ωs = 10000π. For what values of is X(jω) guaranteed to be zero?

38. A continuous time signal x(t) is obtained at the output of an ideal lowpass filter with cut-off frequency ωc = 1000π. If impulse -train sampling is performed on x(t), which of the following sampling period would guarantee that x(t) can be recovered from its sampled version suig an appropriate low pass filter?i. T = 0.5 x 10-3 ii. T = 2 x 10-3 iii. T = 10-4

39. The frequency which, under the sampling theorem, must be exceeded by the sampling frequency is called the Nyquist rate. Determine the Nyquist rate corresponding to the following signalx(t) = 1 + cos (2000πt) + sin (4000πt)(Signals and Systems - by Alan V. Oppendheim, Alan S. Willsky, Chapter 7.)

40. Let x(t) be a signal with Nyquist rate ω0. Dtermine the Nyquist rate for each of the following signals.

i. x(t)+ x(t-1) ii. iii. x2t iv. x(t)cosω0t

41. Consider a real, odd, and periodic signal x(t) whose Fourier series representation may be expressed as

)tksin(2

1)t(x

k5

0k

Let x(t) represent the signal obtained by performing impulse -trai samplig on x(t) using a sampling period of T=0.2

i. Does aliasiing occur when this impulse-train sampling is performed on x(t)?ii. If x(t) is passed through an ideal lowpass filter with cutoff frequency /T and passband gain T,

determine the Fourier series representation of the output signal g(t).

42. Consider the signal

Which we wish to sample with a sampling frequency of ωs = 150π to obtain a signal g(t) with Fourier transform G(jw). Determine the Maximum value of ω0 for which it is guaranteed that G(jω) = 75X(jω) for |ω| ≤ω0 Where X(jw) is the Fourier transform of x(t)

43. Determine whether each of the following statements is true of falsei. The signal x(t)=u(t+T0) - u(t-T0) can undergo impulse -trains sampling without aliasing, provided that

the samplig period T<2T0.ii. The signal x(t) with Fourier transform X(jω)=u(ω+ω0) - u(ω+ω0) can undergo impulse-train sampling

without aliasing, provided that the sampling period T<π/ω0.iii. The signal x(t) with Fourier transform X(jω)= u(ω) - u(ω-ω0) can undergo umpulse-train sampling

without aliasing, provided that the sampling period T<2p/ω0.44. Impulse-train sampling of x[n] is used to obtain.

If X(ejω) = 0 for 3π/7≤ |ω|≤π, determine the largest value for the sampling interval N which ensures that no aliasing takes place while sampling x[n]

352


45. The frequency which, under the sampling theorem, must be exceeded by the sampling frequency is called the Nyquist rate. Determine the Nyquist rate corresponding to the following signal

46. Suppose the impulse response of an ideal discrete-time lowpass filter with cut off frequency π/2 is interpolated (in accordance with Figure) to obtain an upsampling by a factor of 2. What is the frequency response corresponding to this upsampled impulse response?

UNIT – VIII

1. a. What is the condition on ROC for a system to be stable & causal and why?

b. Given Find h(n) if

i. System is causal ii. System is stablec. Given the differential equation y(n)-αy(n-1) = βx(n)+x(n-1). For what values of α, β the system is

stable? (JNTU May 09)

2. a. Distinguish between Laplace & Z-Transforms.b. The system function of a discrete-time linear shift invariant system is H (z). Assume that H(z) is a

rational function of z and that H(z) is causal and stable. Determine which of the following systems are stable and or causal:i. G(z) = H(z)H*(z*)ii. G(z) = H1(z), where H1(z) = d/dzH(z)iii. G(z) = H(z-1)iv. G(z) = H(-z). (JNTU May 09)

3. Find the Z-transform of the sequence y(n) where

and y(n) = 0; n < 0, Assume that |α| < 1. (JNTU May 09)

4. Using the relation . Find the Z-transform of the following:

a. x1(n) = nan-1u[n]b. x2(n) = n(n-1)an-2u[n]c. x3(n) = n(n - 1)......(n – k + 1)au[n]. (JNTU May 09, Nov 08)

5. How many different sequences have a Z-transform given by

(JNTU Nov 08)

6. For a causal discrete-time LTI system, if the input x(n) is .

Then the out put is

a. Determine the impulse response h(n) and the system function H(z)b. Find the difference equation that characterizes this system. (JNTU Nov 08)

7. The output y(n) of a discrete-time LTI system is found to be 2(1/3)nu(n) when the input x(n) is u(n)a. Find the impulse response h(n) of the system.

353


b. Find the output y(n) when the input x(n) is (JNTU Nov

08)

8. Use the derivative property, to find the Z-transform of the following sequences:i. x1(n) = n (½)n u(n-2)ii. x2(n) = n/2 (-2)-nu(-n-1) (JNTU Feb 08)

9. i. Deduce the relation between Z-plane and S-plane.ii. Using the relation in (i) if a pole is located at ‘-a’ in S-plane then where does this get located in Z-

plane?

10. The output y(n) of a discrete-time LTI system is found to be 2(1/3)nu(n) when the input x(n) is u(n)a. Find the impulse response h(n) of the system.b. Find the output y(n) when the input x(n) is (½)nu(n) (JNTU Feb 08)

11. Find the Z-transform of the sequences:

i.

=0, n < 0

ii. (JNTU Feb 08)

12. Show that if x(n) is a right-sided sequence and X(z) convergence for some value of z, then the ROC of X(z) is of the form |z| > rmax or oo > |z| > rmax where rmax is the maximum magnitude of any of the poles of X(z). (JNTU Nov 07)

13. a. How is the region of convergence defined for a finite duration signal?b. Derive the differentiation property in Z-domain.c. Explain the relationship between S-plane & Z-plane. (JNTU Nov 07)

14. The output y(n) of a discrete-time LTI system is found to be 2(1/3)nu(n) when the input x(n) is u(n) a. Find the impulse response h(n) of the system.b. Find the output y(n) when the input x(n) is (1/2)nu(n) (JNTU Nov 07)

15. a. Find the fundamental period of following signals if they are periodic?

i.

ii.

iii.

iv.b. Determine the energy, E for the following sequences: (JNTU Nov 07)

16. i. Given X (z) = z / [z-1]^3, find x (n) using contour integration method ii. Distinguish between one-sided and two sided z-transforms. What are this applications.

(JNTU May 05)

17. i. State and prove the scaling and time shifting properties of z transformii. Find the z transform of (a^n) cos (np/2) (JNTU May 05)

18. i. Explain in detail, the contour integration method of finding inverse z transform.ii. For the given signal as under,

a. Determine the parameter values for which z transform will existb. Find the z transform ( c ) Plot ROC

354


X(n) = - (b^n) u (-n-1) + (0.5^n) u (n) (JNTU May 05)

19. i. Find the inverse z transform of X (z) = (z)/[z+2][z-3] when ROC is i. ROC =|z| < 2 ii. ROC = 2 < |z|< 3

ii. Derive an expression for H(z) from the convolution sum. (JNTU Nov 04)

20. Prove that the sequences x1 (n) =an u (n) and x2 (n) = - an u (-n-1) have the same X (z) and differ only in ROC. Plot their ROCs. (JNTU Nov 04)

21. i. State and prove the convolution and scale change properties in z transform.ii. Prove that the final value of x (n) for X (z) = z2/[z-1][z-0.2] is 1.25 and its initial value is unity

(JNTU Nov 04)

22. i. Given X(s) = [s+3]/[s+1][s+2], obtain X(z)ii Find the inverse transform of X (z) = 1/[1-kz-1], |kz-1|< 1 (JNTU Nov 04)

23. i. Find the signal corresponding to the z transform X (z) = 1/1+ 0.2z-1(1- 0.2z-1.^2 ii. Explain the reason, why the complex exponentials are called eigen functions. (JNTU May 04)

24. i. Given H (z.=z+1/(3(z^2)-4z+1, find h (n) by partial fraction method. R.O.C. |z|> 1 ii. Prove the differentiation property of z-transaction. (JNTU May 04)

25. i. Find the inverse z transform of X (z) using power series method, given X (z)=1/(1-az-1.,|z|<|a|ii. Prove that for causal sequences the R.O.C in exterior of circle of some radius ‘r’ (JNTU May 04)

26. i. Find the inverse z transform of X (z) using contour integral method, given X (z)=1/(1-az-1), |z|>a ii. State and prove initial and final value theorems of z-transform. (JNTU May 04)

27. i. State and prove the convolution theorem of z transform. ii. Explain with a simple example how convolution of 2 sequences is performed. (JNTU Nov 03)

28. Find the first 4 terms of causal signal whose z transform is as under

(JNTU Nov 03)

29. Cash flow between 2 group concerns occurs once each day. For a 10 day period, with t = 0 as day one, cash flow in lakhs of rupees is represented by the discrete time signal XT(n) = (1.6, 2.3, -3.7, 0.5, -1.2, 5.2, 1.5, -2.3, -4.3, 1.0., 1day. Write the expression for the sequence x(n) corresponding to cash flow signal XT(n). (JNTU Nov 03)

30. What are the methods by which inverse Z-transformation can be found out? (JNTU May 03)

31. Given , |z|>|a|. Find x(n) using long division method.(JNTU May 03)

32. i. Explain the properties of the region of convergence of X(z).ii. Discuss in detail about the double sided and single sided Z-transform. Correlate Laplace transform and

Z-transform in their end use. (JNTU May 03)

33. For the sequence x(n) = 2n, n < 0 = (1/2)n, n = 0, 2, 4.......

= (1/3)n, n = 1, 3, 5.......Prove the the absolute convergence region is given by (1/2)< |Z| <2 (JNTU Nov 02)

34. Given . Find x(n) (JNTU Nov 02)

35. Given X(z) = z / [z-1]^3, find x(n) using contour integration method. (JNTU Nov 02)

355


36. i. Given the Z – transform find y (n) for n ≥ 0

ii. Prove the time shifting property of one sided z transformiii. Find the z transform of the sinusoidal signal XT (n) = Sin(bn) UT(n) (JNTU May 02)

37. i. Define Z - transform. Finc the Z transform and the region of convergence of the following function.

0nb

0nna)n(x

n

n

ii. The input x(n) and output y(n) of a discrete system is represented by the following difference equation:y(n)-7y(n-1)+10y(n-2) = x(n) - 2x(n-1) Determine its impulse response (JNTU May 02)

38. i. Derive the z-transform of x(n) = rnsin(n) u(n)

ii. Find the inverse z-transform of: (JNTU Nov 99)

39. i. Find the z-transform of n(n+3)u (n) where u(n) is unit step sequenceii. Find the inverse z-transform of X(z)=sin z (JNTU Nov 99)

40. i. State and prove the convolution property of Z-transformii. Determine the z-transform and region of convergence for the following sequence

00

032)(

nfor

nfornx

nn

iii. Determine the inverse z-transform for the following (JNTU May 99)

41. i. Find the Z-transform of x(n) = nCran-ru(n)ii. Find the inverse Z-transform of Exp (z) (JNTU May 98)

42. i. State the properties of the z-transform. Determine the z-transform for the following functional

i.

ii.

iii. δ(n-1)Indicate the region of convergence and sketch the pole zero plot

ii. Determine the sequence x[n] with z-transform if X(z) = (1+2z)(1 + 3z-1)(1-z-1) (JNTU May 98)43. A sequence x(n) with the Z-transform x(z) = z4 + z2 + -2z - 3z-4 is applied as an input to a linear,

Time-invariant system with the impulse response h(n) = 2(n-3) where Find the output at n=4 (JNTU May 98)

44. Find the z-transform of the following discrete-time signals.i. s(n) = sin ωn ii. s(n) = cos ωn

45. Find the z-transform of s(n) = n2 e-án

46. Find the z-transform of the discrete-time signal s(n) = -Anu(-n –1). Also sketch its ROC.

47. Find the z-transform and ROCs for the following discrete-time signalsi.

ii.

iii.

356


48. Find the z-transform of the following discrete-time sequences

i. ii. s(n) = ejnð/4 u(n)

iii. s(n) = δ(n – 5) iv.

49. Find the bilateral or two-sided z-transform of the sequence

50. Use convolution sum to determine discrete-time signal s(n) if S(z) is given by

51. Determine the output y(n) of a discrete-time LTI system using convolution property of z-transform when input s(n) = 1,2,3,1,-1,1 and impulse response h(n) = 1,1,1

52. Find the convolution sum of discrete-time signals s(n) and h(n) using z-transform method where

0nαn,

0n0,ns

and Specify the answers if, i. α not= β ii. α = β

53. Determine the cross-correlation sequence rs1s2(l) of the following discrete-time sequence.

54. Let x(n) be an absolutely summable signal with rational z -transform X(z). If X(z) is know to have a pole at z=1/2, could x(n) bei. a finite -duration signal? ii. a left-sided signal?iii. a right-sided signal? iv. a two-sided signal?

357


8 LABORATORY DETAILS

8.1 ELECTRICAL MACHINES – II LABORATORY

8.1.1 Objectives and relevance

8.1.2 Scope

8.1.3 Prerequisites

8.1.4 Syllabus

8.1.5 Lab schedule


8.1.7 Websites


358


359



The main objective of this lab is to gain practical hands on experience by exposing the students to various experiments on transformers, induction motors, Alternators and synchronous motor.This lab provides an opportunity to apply the theoritical knowledge which they acquired in previous semister.

8.1.2 PREREQUISITES

A basic knowledge about the following subjects is required.Network theory, Electro Mechanics-II, Electromagnetism, electrostatics and basic electrical laws.

8.1.3 SCOPE

Most of the advances in the applications and control of electric machines have taken place owing to the break through in power electronics and microprocessor based control systems. As a result, a much broader spectrum of electric machine types are now available. Particularly permanent magnet and variable reluctance machines are now finding many applications that are bound to increase in future. AC drives are becoming more and more attractive in many applications, such as those requiring variable speed and flexible control while earlier DC machines were the only choice.

PREAMBLE

This lab covers the experiments in Electro Mechanics-II and Electro Mechanics-III subjects. The JNTU has given 16 experiments in the syllabus out of 8 experiments are compulsory and from the remaining 8 experiments any two shall be conducted. The students are advised to go through the theory part in the mentioned suggested books.

EM – II 8.1.4 SYLLABUS - JNTU

UNIT-I

No experiments covered in this unit as per syllabus

UNIT -IINo experiments covered in this unit as per syllabus

UNIT -III

EXPERIMENT NO. 1OC and SC test on single phase Transformer

OBJECTIVEThe objective is experiment is toTo predetermine the efficiency, regulation at different operating conditions To determine the equivalent circuit parameters.To draw equivalent circuit of the transformer By conducting open circuit and short circuit tests on a single-phase transformer

PREREQUISITESKnowledge on construction and working principle of singel phase transformer, regulation and efficiency.

DESCRIPTIONi. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of efficiency and regualtioniv. Theoritaical calculations of equivalent cicuit parameters.

360


APPLICATIONSi. The efficiency and % regulation of Transformer at different power factors & different load currents can

be calculated very easily.ii. The efficiency of transformer can be calculated without direct loading of the transformer.iii. The equivalent circuit parameter’s can be calculated from O.C. & S.C. test.

REFERENCE

T2 Electric Machines by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II(A.C. Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S.Bimbra, Khanna Publishers.R3 Electrical Machines-S.K.Battacharya.

EXPERIMENT NO. 2

Sumpner’s test on a pair of single phase transformers

OBJECTIVE

To conduct Sumpner’s test on similar 1-phase transformers and to find the efficiency and regulation of each transformer at different load conditions

PREREQUISITES

Knowledge on losses of transformers and theoritical knowledge about sumpner’s test.

DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of losses and efficiency for the given Transformer pair.iv. Theoritical calculations of equivalent cicuit parameters.

APPLICATIONS

i. Transformers used at generating station for step-up the voltage.ii. Transformers used at receiving and for step-down the voltage.iii. Transformers used for minimizing the power losses in a transmission lines. REFERENCE

T2 Electric Machines by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II (A.C. Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S.Bimbra, Khanna Publishers.R3 Electrical Machines-S.K.Battacharya.

EXPERIMENT NO. 3

Separation of core losses of a single phase Transformer

OBJECTIVE

To separate the eddy current losses and Hysterisis loss from the iron loss of single phase transformer.

PREREQUISITES

Theoritical knowledge on losses of transformer.

361


DESCRIPTION

i. Introduction to Experiment-30 minii. circuit connections and its verificationiii. Experimental determination of core losses of Transformer.iv. Separating the losses using the Graphs plotted betwen w/f with respect to f.

APPLICATIONS

i. Transformer is used to step-up and step-down the voltage.ii. Separation of core losses is to be done in the design of Transformer. REFERENCET2 Electric Machines by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II (A.C. Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S.Bimbra,Khanna Publishers.R3 Electrical Machines-S.K.Battacharya.

UNIT – IV EXPERIMENT NO. 4

parallel operation of single phase transformers

OBJECTIVE

To conduct parallel operation on given single phase transformers and to find load shring of each Transformer.

PREREQUISITES

Knowledge about construction and principle of operation of Transformers, Necessary conditions for parallel operation of Transformers.

DESCRIPTION

i. Introduction to Experiment-30 minii. circuit connections and its verificationiii. Experimental determination of individual load currents.iv. Theoritical calculations load sharing by each transformer.

APPLICATIONS

i. More reliable supply to the customer is possible, even one transformer fails still we can supply from other sound transformer.

ii. We can reduce the burden on single transformer.iii. More economical to supply large load with two single phase transformers connected in parallel instead

of single large capacity transformer REFERENCE

T2 Electric Machines by I.J. Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II (A.C. Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S.Bimbra, Khanna Publishers.R3 Electrical Machines-S.K.Battacharya. EXPERIMENT NO.5

scott connection of transformers

362


OBJECTIVE

To conduct Scott Connections of Transformer test on 3-phase transformers and convert 3-Phase to 2-Phase supply.

PREREQUISITES

Knowledge on conversion from 3-Phase to 2-Phase Supply and knowledge about the scott connection

DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of losses and efficiency for the given Transformer pair.iv. Theoritical calculations of equivalent cicuit parameters.

APPLICATIONS

i. Transformers used at generating station for step-up the voltage.ii. Transformers used at receiving and for step-down the voltage.iii. Transformers used for minimizing the power losses in a transmission lines. REFERENCE

T2 Electric Machines by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II (A.C.Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S. Bimbra, Khanna Publishers.R3 Electrical Machines-S.K.Battacharya. UNIT – VNo experiments covered in this unit as per syllabus

UNIT –VINo experiments covered in this unit as per syllabus UNIT –VIIEXPERIMENT NO. 6

Break test on three phase induction motor

OBJECTIVE

To determine the performance characteristics of a 3-phase induction motor by performing a brake test on it

PREREQUISITES

Knowledge on balanced and unbalanced 3-phase systems and knowledge about the construction and working principle of 3 phase induction motor.

DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of efficiency, torque and slip.iv. Theoritical calculations of equivalent cicuit parameters.

APPLICATIONS

i. This motor is used for Industrial and agriculture purpose.ii. Constant speed drives like lathe machines, spinning mills, etc.

363


REFERENCE


EXPERIMENT NO. 7

No-load and blocked rotor test on three phase induction motor

OBJECTIVE

To conduct No-load test and Blocked Rotor Tests on a Three-phase Induction Motor and pre-determine its performance by drawing the circle diagram.

PREREQUISITES

Knowledge on construction and working principle of 3 phase induction motor.

DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of noload & blocked rotor test readings.iv. Calculation of equivalent circuit parametrs.

APPLICATIONS

Transfer function analysis is used to find the performance analysis of physical systems e.g., Generators, Motors, and many more which has been using in electrical and electronics applications.

REFERENCE

T2 Electric Machines by I.J. Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II (A.C. Machines) S.Kamakshaiah Right PublishersR2 Electrical Machines-P.S.Bimbra, Khanna Publishers.R3 Electrical Machines-S.K.Battacharya.

UNIT –VIIINo experiments covered in this unit as per syllabus

EM – III UNIT – I No experiments covered in this unit as per syllabus UNIT – II No experiments covered in this unit as per syllabus UNIT – III EXPERIMENT NO. 8

Regulation of a 3 phase alternator by synchronous impedence and MMF methods

OBJECTIVE

To obtain the % regulation of an alternator at full load by using i. Snychronous Impedence method andii. MMF method at different power factor values

364


PREREQUISITES

The knowledge about the construction and working principle of Alternator. Theoritical knowledge about the synchronous impedance and MMF method. Knowledge about regulation and its significance is also required.

DESCRIPTION

i. Introduction to Experiment-30 minii. circuit connections and its verificationiii. Experimental determination of open circuit voltage and short circuit current values corresponding to

different field currents.iv. Theoritical calculations of regulation at different power factor both by synchronous impedance method

and MMF method.

APPLICATIONS

i. It is used in power houses to generate the power.ii. This is used to improve the p.f.iii. It is used where the continuous operation & constant speed is available.

REFERENCE


EXPERIMENT NO. 9

Determination of Xd and Xq of a salinet pole synchronous system

OBJECTIVE

To conduct the slip test on three phase alternator and to predetermine the regulation through vecter diagram.

PREREQUISITES

Knowledge about the construction and working principle of the salient pole Alternator.

DESCRIPTION

a. Introduction to Experiment-30 minb. Circuit connections and its verificationc. Experimental determination of direct and quadrature axis reactance.d. Theoritical calculations regulation of alternator.

APPLICATIONS

1. In manufactures of alternator2. To find the synchronzing power of alternator.3. Used in turbo alternators. REFERENCE


365


EXPERIMENT NO.10

Regulation of Alternator by ZPF and ASA methods

OBJECTIVE

To determine the regulation of alternator by Z.P.F. and ASA method.

PREREQUISITES

Theoritical knowledge of assumptions we have to make for calculation of regulation of alternator in ASA and ZPF method and also he should be able to draw vector diagrams related to the methods. DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination of open circuit volatge and short circuit curent at different field currents. iv. Theoritical calculations of Regulation by ASA and ZPF method.

APPLICATIONS

i. Alternator is used in power houses to generate the power.ii. This is used to improve the p.f. by using it as a synchronous condenseriii. As a synchronous Motor, it is used where the continuous operation & constant speed is available.iv. ZPF method is used to predict the performance of the Alternator in the design REFERENCE


UNIT – IV No experiments covered in this unit as per syllabus UNIT – V EXPERIMENT NO.11

V and inverted V curves of three phase synchronous motor

OBJECTIVE

To draw ‘V’ curves and inverted ‘V’ curves of a 3-phase synchronous motor by loading at different loads.

PREREQUISITES

Knowledge about principle of synchronous genrator and synchronous motor ith different excitations.

DESCRIPTION

i. Introduction to Experiment-30 minii. Circuit connections and its verificationiii. Experimental determination power factors and load currents at different excitaions.iv. Plotting the power factor & load currents at different excitations.

366


APPLICATIONS

i. Used to pre-determine the performance characteristics of an Induction Motor.ii. Used in the design of 3 phase induction motoriii. Used in the design of 1 phase induction motor

REFERENCE


UNIT – VI No experiments covered in this unit as per syllabus

UNIT – VII EXPERIMENT NO. 12

Equivalent circuit of single phase indcution motor

OBJECTIVE

To obtain the equivalent circuit of Induction motor by conducting O.C. & Blocked Rotor test on it.

PREREQUISITES

knowledge about construction and working principle of three phase induction motor.

DESCRIPTION

i. Introduction to Experiment-30 minii. circuit connections and its verificationiii. Experimental determination of OC and blocked rotor test values.iv. Theorotical calculations of equivalent cicuit parameters.

APPLICATIONS

i. All home appliances, fan, mixer, washing machine, Hair dryer, Shaving machine etc. ii. Small fraction H.P. Pumps. iii. In the design of induction motors.

REFERENCE


UNIT – VIII No experiments covered in this unit as per syllabus

EXPERIMENT NO.13

Regulation of Alternator by ZPF and ASA methods

OBJECTIVE

To determine the regulation of alternator by Z.P.F. and ASA method.

367


PREREQUISITES

Theoritical knowledge of assumptions we have to make for calculation of regulation of alternator in ASA and ZPF method and also he should be able to draw vector diagrams related to the methods.

DESCRIPTION

i. Introduction to Experiment-30 min

ii. Circuit connections and its verification

iii. Experimental determination of open circuit volatge and short circuit curent at different field currents.

iv. Theoritical calculations of Regulation by ASA and ZPF method.

APPLICATIONS

i. Alternator is used in power houses to generate the power.

ii. This is used to improve the p.f. by using it as a synchronous condenser

iii. As a synchronous Motor, it is used where the continuous operation & constant speed is available.

iv. ZPF method is used to predict the performance of the Alternator in the design

REFERENCE

T2 Electric Machines by I.J. Nagrath & D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004

T3 Electromechanics-II (A.C. Machines) S.Kamakshaiah Right Publishers

R2 Electrical Machines-P.S.Bimbra, Khanna Publishers.

R3 Electrical Machines-S.K.Battacharya.

368


8.1.5 LAB SCHEDULE: (GROUP-I)

CYCLE 1 :

BATCHES 30-06-08 07-07-08 14-07-08 21-07-08 28-07-08 06-08-08 13-08-08B1 Demo Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5 RevisionB2 Demo Exp. 2 Exp. 3 Exp. 4 Exp. 5 Exp. 1 RevisionB3 Demo Exp. 3 Exp. 4 Exp. 5 Exp. 1 Exp. 2 RevisionB4 Demo Exp. 4 Exp. 5 Exp. 1 Exp. 2 Exp. 3 RevisionB5 Demo Exp. 5 Exp. 1 Exp. 2 Exp. 3 Exp. 4 Revision

CYCLE 2 :


LAB SCHEDULE (GROUP-II)

CYCLE 1 :


CYCLE 2 :


8.1.6 SUGGESTED TEXT BOOKS

TEXT BOOKS

T1 Performance and design of AC machines- M.G..Say BPB Publications. T2 Electic Machines by I.J.Nagrath& D.P.Kothari, Tata Mc Graw-HIll Publishers, 3rd edition2004T3 Electromechanics-II(A.C.Machines) S.Kamakshaiah Right Publishers.

369


REFERENCE BOOKS

R1 Electric Machinary-A.E. Fritzgerald, C.Kingsley& S.Umans Mc Graw Hill companies, 5th editionR2 Electrical Machines-P.S.Bimbra,Khanna Publishers.R3 Electrical Machines-S.K.Battacharya.R4 Theory of alternating current machinery -by Langsdroff,Tata mc Graw-Hill Companies, 2nd edition.R5 Electric Machines-M.V.Deshpande, Wheeler Publishing 1997.

8.1.6 WEBSITES

1 www.mit.edu(masachusetts instititute of technology )2. www.soe.stanford.edu(standford university) 3. www.grad.gatech.edu(Georgia instittute of technology)4 www.gsas.harward.edu(harward university)5. www.eng.ufl.edu(university of Florida)6. www.iitk.ac.in7. www.iitd.ernet.in8 www.iitb.ac.in9. www.iitr.ac.in.10. ww.iitg.ernet.in.11. www.iisc.ernet.in12. www.ieee.org13. www.school-for-Champions.com/science.14. www.onesmartclick.com/engineering /electrical-machines.html


REGIONAL








370


NATIONAL



2. Name : Dr. Sivaji ChakravortiDesignation : ProfessorDepartment : EEE DepartmentOffice Address : Jadavpur University, Kolkatta - 700032, IndiaPhone No. :Email : [email protected] / [email protected].

INTERNATIONAL






371


8. LABORATORY DETAILS

8.2 CONTROL SYSTEMS


8.2.2 Scope

8.2.3 Prerequisites

8.2.4 Syllabus - JNTU

8.2.5 Lab Schedule


8.2.7 Websites


372


373



The control systems laboratory provides an integrated treatment of all those aspects of control systems engineering that prepare the student for early productivity upon entering industrial practice.

This lab helps in gaining familiarity with available hardware so that commercially available Components to implement the design can be selected and the knowledge of the tools of ‘control system design tool box’ comprising time-tested design procedures helps in gaining competence in control concepts.

8.2.2 SCOPE

The lab is aimed to introduce the students to the principles and applications of control systems in every day life. It also enables the students to understand the process of simulation and modelling of control systems.

8.2.3 PREREQUISITES

A basic knowledge of following subjects is requiredNetwork TheoryControl systemsElectrical machines

8.2.4 JNTU SYLLABUS UNIT-I

No experiment from this unit as per syllabus.

UNIT-IIEXPERIMENT NO. 1

Transfer function of DC motor

OBJECTIVE

To find the transfer function of d.c. Motor.

PREREQUISITES

Mathematical modelling of physical systems, DC motor operation, Knowledge of Brake test, No Load test and retardation test

DESCRIPTION

i. Introduction to Experiment-30 minii Connectionsiii. Determination of motor parameters and then its transfer function

APPLICATIONS

The dynamic and steady state performance of the system can be analyzed through this experiment.

EXPERIMENT NO. 2

Effect of feedback on DC servomotor

OBJECTIVE

To study the effect of feedback on DC Servo motor.

374


PREREQUISITES

Feedback characteristics of control systems, DC servomotor operation, characteristics & transfer function. Time domain specifications.

DESCRIPTION

i. Introduction to Experiment-30 minii. Connectionsiii. Determination of motor transfer function, steady state performance with and without feedback and

there by studying the effect of feedback on a DC Servomotor.

APPLICATIONS

i. Machine tool position center.ii Constant tension control of sheet rolls in paper millsiii. Radar tracking system.iv. Roll stabilization of shipsv. Positioning of heavy gems on the tanks for defence application.

EXPERIMENT NO. 3

Characteristics of synchros

OBJECTIVE

i. Determination of Characteristics of synchro as a transmitter.ii. Determination of Characteristics of synchro transmitter and Synchro receiver pair.iii. Study of the operation of Synchro as a torque synchro.

PREREQUISITES

Operation of synchros as a transmitter & Receiver.

DESCRIPTION

i. Introduction to Experiment-30 minii. Connectionsiii. Determination of motor transfer function, steady state performance with and without feedback and

there by studying the effect of feedback on a DC Servomotor.

APPLICATIONS

Synchros is used as a error detector

EXPERIMENT NO. 4

Characteristics of magnetic amplifiers

OBJECTIVE

To study the characteristics of magnetic amplifiers.

PREREQUISITES

Operation of magnetic amplifier.

375


DESCRIPTION

i. Introduction to Experiment-30 minii. Connectionsiii. Determination of characteristics of magnetic amplifier.

APPLICATIONS

i. Measurement of large DC currentsii Alternator voltage regulationiii. Servo amplifier.

UNIT-IIIEXPERIMENT NO. 5

Time response of second order systems

OBJECTIVE

To determine the time response specifications of a second order system

PREREQUISITES

Knowledge of characteristic equation ,time domain specifications and error constants

DESCRIPTION

i. Introduction to experiment-30ii. Connectionsiii. Experimental verification of time domain specifications with that of theoretical values

APPLICATIONS

Determination of performance of control systems

EXPERIMENT NO. 6

Simulation of transfer function using op-amps

OBJECTIVE

To Simulate i. First order systemii. Second order system.Using Op-amps and R-C elements.

PREREQUISITES

Pin configuration of IC 741, op-amp as an integrator, inverter and summing amplifier, Definition of transfer function and Knowledge of time domain specifications

DESCRIPTION

i. Introduction to experiment-30ii. Connectionsiii. Realization of 1st order and 2nd order systems using op-amps.iv. Time response of 2nd order system and determination of time domain specifications

376


APPLICATIONS

i. Differentiator and integrators are used in PI, PD and PID controllersii. Integrators are used in delta modulation circuit in digital communications

UNIT-IV & VEXPERIMENT NO. 7

Root locus plot, Bode plot from MATLAB

OBJECTIVE

To determine the stability of a given system upto 5th order by plotting root locus, bode plot and nyquist plot using MATLAB.

PREREQUISITES

Knowledge of MATLAB software (control system toolbox) and construction of root locus and bode plot

DESCRIPTION

i. Introduction to experiment-30ii. Connectionsiii. Enter the program in M-file iv. Obtain the root locus plot for different values of gain and phase and gain margin for bode plot.

APPLICATIONS

i. Root locus technique is used to find the stability of system in time domain analysisii. .Bode and nyquist techniques are used to find stability of the system in frequency domain.

UNIT-VI

No experiments in this unit as per syllabus.

UNIT-VIIEXPERIMENT NO. 8

Lag and lead compensator-Magnitude and phase plot

OBJECTIVE

To design, implement and study the effects of different cascade compensation networks for a given system

PREREQUISITES

Lead and lag compensator-its transfer function, purpose, frequency response and realization using R-C elements.Compensator design methods

DESCRIPTION

i. Introduction to experiment-30ii. Connectionsiii. Determination of transfer function from bode plot and realization of appropriate compensator

based on design specifications.

APPLICATIONS

i. Lead compensator is used for sluggish systems

377


ii. Lag compensator is used for improving steady state performance

EXPERIMENT NO. 9

Temperature controller using PID

OBJECTIVE

To control the temperature using proportional integral & derivative controller.

PREREQUISITES

PID controller-its transfer function ,purpose and realization. Knowledge of TCT software

DESCRIPTION

i. Introduction to experiment-30ii. Connectionsiii. Operation of trainer kit both in real and simulation mode

APPLICATIONS

It eliminates offset problem .it can be used in large load changes.

UNIT-VIIIEXPERIMENT NO. 10

State space model for classical transfer function using MATLAB-verificationOBJECTIVE

Determination of state model from transfer function using MATLAB

PREREQUISITES

Knowledge of MATLAB software and determination of state model from transfer function

DESCRIPTION

i. Introduction to experiment-30ii. connectionsiii. Enter the program in M-file and run the program to convert transfer function into state model

APPLICATIONS

It eliminates offset problem .it can be used in large load changes

378


8.1.5 LAB SCHEDULE: (GROUP-I)

CYCLE 1 :


CYCLE 2 :


LAB SCHEDULE (GROUP-II)

CYCLE 1 :


CYCLE 2 :



1. Control systems engineering by I.J.Nagrath & M Gopal2. Modern control engineering by K Ogata3. Control systems engineering by NISE4. Control systems by N K Sinha5. Feedback & Control systems by J.Disetefano,A.Stubberud6. A text book of electrical technology by B L Theraja & A K Theraja

379


8.2.7 WEBSITES

1. www.ntu.ac.sg2. www.utoronto.ca3. www.ee.Washington.edu4. www.esca.com5. www.itm.ac.in6. www.bitmesra.ac.in7. www.iisc.ernet.in8. www.bits-pilani.ac.in9. www.vjit.ac.in10. www.ieeecss.org11. www.control.eng.com.ac.uk12. www.control.utortonto.ca


REGIONAL

1. Name : Dr. Bhagwan K.MurthyDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone number : +91-870-2431616(JNTU O)e-mail : [email protected] [email protected]

2. Name : V.T. SomashekharDesignation : Associate ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone number : +91-870-2453416 (JNTU O)

e-mail : [email protected], [email protected]


Osmania University, Hyderabad-500007Phone number : +91-040-27682382 (JNTU O)e-mail : [email protected]

4. Name : Prof. M SyduluDesignation : ProfessorDepartment : Electrical and Electronics EngineeringOffice Address : Department of Electrical and Electronics Engineering

NIT-Warangal – 506004.Phone number : +91-870-2431616(O)e-mail : [email protected]

380


NATIONAL


Dy. Director (Administration.), IIT - Delhi,Hauzkhas, New Delhi - 110016.

Phone number : +91-11-26591250 (JNTU O) , Fax : 91-11-26862037,e-mail : [email protected], [email protected]

2. Name : Dr. Jagadish Kumar,Designation : ProfessorDepartment : Department of EEE,Office Address : IIT, Madras, Chennai,Phone No. :email : [email protected].

3. Name : Dr. S.V. Kulkarni,Designation : Associate Professor,Department : Office address : IITBombay, Powai, Mumbai - 400076, India,Phone number : +91- 22-25671098,e-mail : [email protected]


Office Address : Room No. II/211, IIT Delhi Phone number : +91 11 2659 1094 ,91 11 2659 1886

email : [email protected]

INTERNATIONAL

1. Name : Gary S. MaryDesignation : ProfessorDepartment : School of Electrical EngineeringOffice address : Georgia Institute of Technology, USA.Phone Number :e-mail : [email protected]

2. Name : Dr. Clayton R Paul, Designation : ProfessorDepartment : Electrical and Computer Engineering,Office address : School of Engineering, Mercer University, Macom, Georgia-31207Phone Number : (JNTU 912) 301-2213,website : www.faculty.mercer.edu.paul_cr


Department : Dept. of Electrical EngineeringOffice address : Ira A.Fulton School of Engineering, Arizona State University. Tempe, AZPhone Number : 85287-7206e-mail : Jushan Zhang @ee.gatech.edu

4. Name : Mr.Sameer S. Saab,Designation : ProfessorDepartment : Department of Electrical and Computer Engineering,Office address : Lebanese American University, Byblous, Lebanan,email : [email protected].

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7.6.8 JOURNALS

1. Name of the Journal : IEEE Transaction on Automatic ControlPublisher : IEEE Publications

2. Name of the Journal : EEE Control Systems MagazinePublisher : IEEE Publications

3. Name of the Journal : Instrumentation & ControlPublisher : IEEE Publications

4. Name of the Journal : IEEE Transaction on Control System Technology Publisher : IEEE Publications

5. Name of the Journal : IEEE Transactions on Circuits and Systems.Publisher : IEEE Publications

6. Name of the Journal : IEEE Proceedings on Circuits, Devices and Systems.Publisher : IEEE Publications

7. Name of the Journal : International Journal of Circuit theory and Applications (Ireland)Publisher : Marco Publications









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3 EEE-09-10-1 seml

Documents

tightly coupled microprocessors

1s complement notation

modern power engineers

findthe sumand difference

error detection codes

2s complement notation

cse office address

iete technical review