Question Bank BE EE6402- TRANSMISSION AND DISTRIBUTION …library.bec.ac.in/kbc/FAQ BEC/EEE/4 SEM/EE6402... · Subject : EE6402- TRANSMISSION AND DISTRIBUTION Semester / Branch :

Question Bank

Programme : BE

Subject : EE6402- TRANSMISSION AND DISTRIBUTION

Semester / Branch : IV/EEE

Unit- 1

STRUCTURE OF POWERSYSTEM Structure of electric power system: generation, transmission and distribution; Types of AC

and DC distributors – distributed and concentrated loads – interconnection – EHVAC and HVDC

transmission - Introduction to FACTS.

Part-A 1. Classify overhead transmission lines. 2. Define transmission efficiency.MAY10,DEC15 3. Define Voltage regulation of a transmission line?. MAY 13,14 4. List out the common methods of representation of medium transmission lines MAY2015 5. State the condition for max power delivered and draw the power angle diagram DEC16 6. Define regulation of power transmission line 7. Explain tuned power line? 8. What is meant by surge impedance loading or natural loading?

DEC10,14MAY2010,14,15,DEC15 9. Point out the voltages regulating equipments used in transmission systems? 10. Mention various methods of voltage control in transmission line DEC 16 11. Define attenuation in a power transmission line? 12. Describe the units of generalized constants of a transmission line? 13 Define surge impedance loading? What is the range of surge impedance for an overhead transmission line? MAY13,DEC12 14. Explain power circle diagram? 15. Explain the receiving end power circle diagram

16 Explain Ferranti effect? What is the cause of Ferranti effect?.MAY 12,13,14,DEC11,13

17. Illustrate the Difference between voltage stability and rotor angle stability. 18. What is the importance of voltage control? MAY2015 16.Discuss What is the use of power circle diagram? 19 Show the causes of voltage drop and line loss in a transmission line?.. 20 .Describe the advantages of using series compensation?. 21 Discuss stringing chart? What are the uses of stringing chart?

22. Classify the factors which govern the performance of a transmission line

(8)

PART B

1.. (i) Describe and draw the structure of modern power systems with typical voltagelevels.

NOV 2007.MAY2008,NOV2009MAY2011,14 (16)

ii)What is the highest VDH level available in India?(3)

2.(i) Show its essential constituent sections and Draw the model power system with single line

representation(ii) Explain the AC transmission and distribution level voltages we have in India?

NOV11,12,MAY08

3.Explain radial distribution system in detail MAY 07,DEC10

4. Explain ring distribution system in detail state its advantages DEC10,12,13,MAY12

5.(i)Define a short note on distributed and concentrated loads

(ii) Define distributors? Explain its types in detail

6.Discuss the design of primary distribution systemwith respect toi)selection of voltage

ii)Choice of schemeiii)size of feeders

7.Explain i)sub mainsii)Stepped and tapered mains MAY15

8 .(i) Describe various types of HVDC links. Draw relevant diagrams

ii)Mention any one HVDClink available in Indiawith rating NOV11,12,MAY08NOV 07 (16)

9.(i) List out the main components of a HVDC system.MAY08 (8)

(ii) Discuss the highest voltage level available in India? MAY2008 (3)

. 10.(i) Describe the effect of high voltage on volume of copper and on efficiency. (8)M12

lines are 3 phase 4-wire circuits (8)

11.Demonstrate the different kinds of DC links? NOV 07,11,MAY08 (8)

Discuss various types of HVDC links 12.(i) Describe why EHV transmission is preferred? What are the problems involved i

EHV AC transmission?

ii)Advantages of EHVAC andHVDC transmission system NOV13..

13. Explain and Compare EHVAC and HVDC transmission on

i) economics of transmission ii) Reliabilityiii)Technical performanceMAY2009 MAY2012NOV 2013 (16)

14.i)Describe the principle with neat schematic of HVDC system operation. .. (16)

ii)What are the advantages and disadvantages of HVDC transmissionNOV 14

iii)State the advantages of HVDC over AC transmission MAY10,13,NOV 12

. 15.Explain about types of FACTS controllers with neat diagram JUN 2007MAY 2010NOV 2014, (16)

9

16 i)Write short notes on SVC NOV 09,MAY12

ii)Explain the principle of operation of compensators used for voltage controlNOV 11 (16)

.

17.Illustrate with neat diagram about UPFC NOV07 , 09 , 10

18.Explain the working of STATCOM with a neat circuit diagramNOV10,MAY14 (8)

19.Discuss in detail the problems associated with EHVAC transmission .Also state how these problems

are being solved NOV 13

Unit- 2

TRANSMISSION LINE PARAMETERS

Parameters of single and three phase transmission lines with single and double

circuits - Resistance, inductance and capacitance of solid, stranded and bundled conductors, Symmetrical and unsymmetrical spacing and transposition - application of self and mutual GMD; skin and proximity effects - interference with neighboring communication circuits - Typical configurations, conductor types and electrical parameters of EHV lines, corona discharges.

Part- A

1. Define feeder and Distributor

2. Define Skin effect DEC 16 3. Explain proximity effect? MAY 11,13,14,15,NOV 07 4. State the applications of HVDC transmission DEC 16 5. Differentiate the stranded conductor and bundled conductor.

6. What is bundling of conductors,list the advantages MAY 06,08,09,12,14,NOV 09,10,14 DEC 16

7. What if double circuit is added in transmission line?. 8. Define - Self and mutual –G.M.D. DEC07MAY08 9. Explain inductive interference? 10. Explain transposition of conductors 11. Illustrate ACSR conductor? 12. Define Visual critical voltage JUN 2013 13. Define unsymmetrical and symmetrical spacing 14. Explain corona discharge? list thefactors which affect corona MAY2012 15. Show why skin effect is absent in dc system? MAY2010 16. Illustrate On what factors skin effect depends? 17. Discuss what is a bundle conductor? What are its advantages? 18. Discuss what are composite conductors? What are the main disadvantages of corona?. 19. Compose local corona? What are the methods adopted to reduce corona? 20. Define inductance of a line. Mention the factors governing inductance of a line. 21. Discuss what is the necessity of a double circuit line? 22. Compose an expression for inductance of a single phase transmission system 23. Define corona and critical disruptive voltage NOV 2011,13,14

Part-B 1. (i)Compose the fundamentals derive an expression for inductance of a single phase

Transmission line

2. Discuss and derive an expression for capacitances of a single phase transmission system

and discuss the effect of earth on capacitance with suitable equation. MAY2008 (16)

3. Discuss and Derive an expression for inductance

i) A conductor is composed of seven identical copper strands each having a radius r.

Find the self-GMD of the conductor. (8)

4.i) Define and derive an expression for the capacitance between conductors of a Single

phase overhead line. DEEC09 MAY 2013 (8)

ii) Identify the capacitance between the conductors of a single-phase 10 km long line. The

diameter of each conductor is 1.213cm. The spacing between conductors is 1.25m. Also

find the capacitance of each conductor neutral.

5.Derive the expression for the flux linkage of one conductor in a group of n

conductor carrying currents whose sum is zero. Hence derive an expression for

inductance of composite conductors of a single phase line consisting of mstrands in

one conductors and n-strands in other conductor DEC 14

6.Explain why and how transposition of 3phase transmission line are done DEC 09 (8)

7. i) Derive the expression for inductance of a two wire 1Φ transmission line .. (8)

ii) Derive the expression for capacitance of a 1Φ transmission line .. (8)

8. i) Explain what are the advantages of bundled conductors? (4)

(ii) Explain and derive the expression for capacitance of double circuit line for hexagonal

spacing. (8)

9. Explain the concept of self GMD and mutual GMD for evaluating inductance of

transmission line MAY 12,DEC 14 (6

10. i) Explain clearly the skin effect and the proximity effects when referred to overhead

lines.MAY05, 12 ,DEC 13 (8)

11. Explain the inductive interference between power and communication lines

DEC 04,05,13 MAY 15 (8)

12. i) Describe the expression for the capacitance per phase of the 3

Φ double circuit line flatvertical spacing with transposition. . (8)

ii) Identify a 3 Φ overhead transmission line has its conductors arranged at the corners of

an equilateral triangle of 2m side. Calculate the capacitance of each line conductor per

km. Given the diameter of each conductor is 1.25cm. (8)

13 i) Solve the capacitance per km per phase of a 3Φ line arrangement in a horizontal plane

spaced 8 meters apart. The height of all conductors above the earth is 13 meters. The

diameter of each conductor is 2.6 cm. the line is completely transposed and takes the

effect of ground into account. (8)

14.. Discuss the concept of GMR and GMD in the calculation of transmission line

inductance

15. Estimate the corona for a 3 phase,110kv,50 hz150 km long tr,lineconsisting of 3

conductorseach 10mm diaand spaced 2.5m apart in equilateral triangle formatiomThe temp

of air is 30o Cand the atm.pressure is 750mm of mercury.Assume the irregularity factoras

0.85.Ionisataion of air may be assumedto take place at a max voltage gradient at 30kv/Cm

JUN 14 (16) 16.Explain the following with respect to CORONA DEC12,MAY 15 (16)

i)corona ii)effects of corona iii)disruptive critical voltage iv)visual critical voltage v)

corona power loss (8)

Unit- 3

MODELLING AND PERFORMANCE OF TRANSMISSION LINES

Classification of lines - short line, medium line and long line - equivalent circuits, phasor diagram, attenuation constant, phase constant, surge impedance; transmission efficiency and voltage regulation, real and reactive power flow in lines, Power - circle diagrams, surge impedance loading, methods of voltage control; Ferranti effect.

Part-A 1 Classify overhead transmission lines. 2 Define transmission efficiency.MAY10,DEC15 3 Define Voltage regulation of a transmission line?. MAY 13,14 4 List out the common methods of representation of medium transmission lines MAY2015 5 State the condition for max power delivered and draw the power angle diagram DEC16 6 Define regulation of power transmission line 7 Explain tuned power line? 8 What is meant by surge impedance loading or natural loading? DEC10,14MAY2010,14,15,DEC15 9 Point out the voltages regulating equipments used in transmission systems? 10 Mention various methods of voltage control in transmission line DEC 16 11 Define attenuation in a power transmission line? 12. Describe the units of generalized constants of a transmission line?

13. Define surge impedance loading? What is the range of surge impedance for an overhead transmission line? MAY13,DEC12

14 .Explain power circle diagram?

15. Explain the receiving end power circle diagram

16. Explain Ferranti effect? What is the cause of Ferranti effect?.MAY 12,13,14,DEC11,13

17 .Illustrate the Difference between voltage stability and rotor angle stability.

18. What is the importance of voltage control? MAY2015 16.Discuss What is the use of power circle diagram?

19. Show the causes of voltage drop and line loss in a transmission line?..

20. Describe the advantages of using series compensation?.

21.Discuss stringing chart? What are the uses of stringing chart?

22.Classify the factors which govern the performance of a transmission line?

Part- B 1 .Give the classification of transmission lines and their characteristics MAY 07,14 (8)

2 .Derive the expression for regulation and efficiency of a short transmission line.Draw

required circuit and phasor diagram MAY 06 (8)

3 .Draw phasor representation of a short transmission line MAY 07 (8)

4.Explain the following methods of medium transmission line MAY 09,13 (10)

i)End condenser method

ii) Nominal T method (middle condenser method)

5. Derive the expression for the real and reactive power flow through transmission lines(16)

DEC 16

6. Identify the efficiency and regulation of a 3phase, 100Km, 50 Hz transmission line delivering 20 MW at a power factor of 0.8 lagging and 66 kV to a balanced load. The

conductors are of copper, each having resistance 0.1 Ω / Km, 1.5 cm outside dia, spaced

equilaterally 2 meters between centres.Use nominal T methods. . (16) 7. What if a three phase 5 km long transmission line, having resistance of 0.5 Ω / km and

inductance of 1.76mH/km is delivering power at 0.8 pf lagging. The receiving end voltage is

32kV. If the supply end voltage is 33 kV, 50 Hz, find line current, regulation and

8. i) Define regulation of a transmission line and derive the approximate expression for the

regulation of a short transmission line. (8)

9. What if a 220kV, 3Φ transmission line has an impedance of (40+j200)Ω and Shunt admittance of (0+j0.0015) mho. Determine the sending end voltage and sending end

current when the receiving end current is 200 A at 0.95 pf lagging. Use nominal method.

.. 8. Identify the efficiency and regulation of a three phase 200 km, 50Hz transmission line

delivering 100MW at a pf of 0.8 lagging and 33kV to a balanced load. The conductors are of copper, each having resistance 0.1 Ω/km, and 1.5cm outside dia, spaced equilaterally 2m

between centers. Neglect leakage reactance and use nominal T and π methods. (16)

9. Explain the Ferranti effect with a phasor diagram and its causes.DEC08 (8) 10. Solve a 50Hz transmission line 300 km long total series impedance of 40+j25 Ω and total

shunt admittance of 10-3 mho. The 220 KV with 0.8 lagging power factor. Find the sending

end voltage, current, power and power factor using nominal pi method. 11.i) Explain the classification of lines based on their length of transmission. .. MAY04 (6)

ii) Explain ABCD constants. Derive the values of generalised network constants ABC

and D using nominal pi equivalent circuit for medium transmission line DEC 12 (12)

12. Perform the analysis of long transmission lines using RIGOUROUS method DEC12

(12)

13.Explain the procedure for determining the transmission efficiency and voltage

regulationof a long transmission line MAY 05,DEC 05 (8)

14.Define the following

i)Surge impadence

ii)Attenuation constant

iii)voltage regulation

iv)Transmission efficiency DEC 14 (8)

15.Explain the concept of surge impedance loading MAY 09,DEC12,13(6)

16.Explain the method of drawing receiving end power circle diagram MAY 14 (16)

Unit-4

INSULATORS AND CABLES

Insulators - Types, voltage distribution in insulator string, improvement of string efficiency, testing of insulators. Underground cables - Types of cables, Capacitance of Single-core cable, Grading of cables, Power factor and heating of cables, Capacitance of 3- core belted cable, D.C cables

Part-A 1. Why are insulator used with overhead lines and give its types MAY10,15,NOV14

List out various types of insulators used for overhead transmission lines List out various types of insulators used for overhead transmission lines 2. List out various materials used in insulators used for overhead transmission

lines.,MAY2012,13 List out various types of insulators used for overhead transmission lines 3. What are the properties of insulators Discuss the main causes for failure of insulators?

DEC 06MAY10 DEC10 MAY11 4. List out various types of insulators used for overhead transmission linesJUN2012 5. Define string efficiency List the methods for improving string

efficiency?MAY04,10,JUN06,09,13,14,DEC04DEC 16 6. Define puncture test. 7. Explain impulse ratio. 8. Label the 3 parts of cable 9. Discuss the necessity of armour in a cable..MAY2015 NOV2010 10. Explain the properties of insulating materials. 11. Mention any 4 insulating materials used for underground cables DEC 16 12. Define grading of cables. DEC04,12 13. List the advantages of PVC over paper insulated cables. 14. Explain In what way AI sheaths are superior to lead sheaths? 15. Assess Why protective covering is done in cables?. 16. Explain serving of a cable 17. Where CSA sheath is used in cables? Why is it used? 18. List the advantages of polythene insulators

19. How are cables classified based on operating voltage JUN12,14

20. What are the factors to be considered while selecting a service for aparticular service NOV2014..

21. Mention any 4 insulating materials used in cables JUN 09,13

Part-B

.

1.Discuss any two methods to increase the value of string efficiency, with suitable

sketches Discuss the different methods to improve string efficiency of an

insulator?.DEC07,09,12,MAY08,10,11,

2.Why are insulaters usedwith overhead lines?Discuss the desirable properties of

insulators MAY 05 DEC 13 MAY05 DEC 13

3. Discuss about sting efficiencylist the methods to improve it MAY 07 (6)

Elaborate the various methods to improve string efficiencywith suitable sketches (16)

DEC 07,09,12MAY 08,10,11

4.Explain the general construction of a 3 conductor underground cablewith a neat sketch

DEC 12 MAY 15 (8)

i) Explain different types of insulators (8) DEC16

II) A string of five insulator units has mutual capacitance equal to 10 times the pin to

earth capacitance find voltage distribution across various units as per the percent of the

total voltage across various units as the percent of the total voltage across the string and

string efficiency DEC 16

5.i) List out the properties of insulatingmaterials used for cables MAY 12 (8)

ii)Advantages of underground cable over overhead lines MAY12 (8)

6.Draw with neat sketches and explain about pin and suspension type insulator

Compare their merits and demerits DEC10,14,MAY06 MAY 14 (16)

7. What is grading of cables? Explain any two methods of grading of cables with

necessary diagrams. MAY08,09,10,11,13DEC 07,10 (16)

8.Discuss the capacitance grading of underground cables MAY 14 (16)

9 Describe an experiment to determine the capacitance of a belted cable DEC 13 10 A 33kv single core cable has a conductor diameter of 1cm and a sheath of inside

diameter 4cm. Find the maximum and minimum stress in the insulators NOV 13 (6)

11 In a 33 kV line there are 3 units in the string insulators.If the capacitance between each

insulator pin and earth is 11% of self capacitance of self efficiency JUN 07 (16)

12 An insulator string for 66kV line has 4 discs. The shunt capacitance between each joint

and metal work is 10% of the capacitance of each dis c Find the voltage across the different

discs and string efficiency DEC 08 ,13 (16)

ii) Explain in a 3-unit insulator, the joint to tower capacitance is 20% of the capacitance of

each unit. By how much should the capacitance of the lowest unit be increased to get a string efficiency of 90%. The remaining two units are left unchanged. (8)

13. i) Describe and derive the expression for insulator resistance, capacitance and electric stress in a single core cable. Where is the stress maximum and minimum? ..DEC10,14 (8)

ii) solve A single core 66kv cable working on 3-phase system has a conductor diameter of 2cm and sheath of inside diameter 5.3cm. If two inner sheaths are introduced in such a way that the stress varies between the same maximum and minimum in the three layers find:

a) position of inner sheaths b) voltage on the linear sheaths

c) Maximum and minimum stress

14. An insulator string consists of 3 units insulator nearest to the line having a safe working

voltage of 20kv The ratio of self to shunt capacitance is 6:1Determine the maximum

safe working voltage of the string and string efficiency MAY 05,12 NOV 11 (16)

15. Identify a 3 phase overhead transmission line is being supported by three disc insulators. The potential across top unit (i.e. near the tower) and the middle unit are 8kV and

11kV respectively. Calculate,

a) The ratio of capacitance between pin and earth to the self capacitance of each

unit (4)

b) Line Voltage c)String Efficiency (2)

(2)

16. i) Derive the expression for insulation resistance, capacitance, electric stress and

dielectric loss of a single core cable DEC10,14(8)

17.A 2km long 3 core 3 phase cable has capacitance 0.5 micro F/km between two

conductors bunched with sheath and the third conductor The capacitance between the

conductors is also measured when bunched together and the sheath and found to be 0.75

microF/km Determine i)capacitance between phasesii) capacitance betweenconductor and

the sheathiii)effective per phase capacitanceiv)capacitance between 2 conductors connecting

a third conductor to the sheath v)charging current if the supply voltage is 11kv/50 hz

DEC 16

18. i) Describe the various properties of insulators? Also briefly explain about suspension type insulators. (8)

ii) Calculate the most economical diameter of a single core cable to be used on 132kV, 3

phase system. Find also the overall diameter of the insulation; if the peak permissible stress does not exceed 60kV/cm. also derive the formula used here. (8)

19 A cable is graded with three dielectrics of permittivity 4, 3 and 2. The maximum permissible potential gradient for all dielectrics is same and equal to 30 kV/cm. The core diameter is 1.5cm and sheath diameter is 5.5cm. (16)

20. i) Explain the constructional features of one LT and HT cable (8) ii) Contrast and Compare over head lines and underground cablesMAY12 (8)

Unit-5 MECHANICAL DESIGN OF LINES AND GROUNDING

Mechanical design of transmission line – sag and tension calculations for different weather

conditions, Tower spotting, Types of towers, Substation Layout (AIS, GIS), Methods of

grounding

Part – A 1. What is meant by SAG ?. NOV2013

2. What is deviation tower? MAY 13

3. Give factors that affect sag in an overhead line? NOV 10,12DEC16

4. What is stinging chart and what is its use?MAY 04,06,11NOV11

5. What is sag template DEC 15,MAY14

6. What is the economic value of span for 400kv transmission line 7. Define earth resistance?Need and objectives of earthingMAY2011DEC13 8. Methods of neutral groundingDEC11,JUN14

9. List the types of transformer substations? What are the equipments used in a transformer substation? 10. What are major equipment of a substation DEC10 NOV 14

11. Design factors to be considered for bus bar?.

12. Discuss methods,advantages,significance of neutral grounding or neutral

earthing?DEC11,JUN14,12MAY10 Illustrate about GIS? 13. Explain the different types of bus bar arrangements in substations? 14. Explain bus bar?

15. What is the function of isolators.MAY10,DEC13

16. Discuss the reason for sag in transmission line?

17. Name the types of towers.

18. Enumerate various methods of neutral grounding or Earthing DEC 11 JUN14

19. What is the need for earthing ? DEC16

20. Discuss the two disadvantages of ungrounded neutralDEC2009

21. Name the various types of grounding.

22. Show the capacitance effect is taken into account in a long line?

23. .Define substation?List the types of substation NOV2009

24. Describe what is meant by towerspotting?.DEC15

Part-B 1. Explain Factors affecting SAG DEC 13 (6)

2.Derive an approximate expression for SAG in querhead line when supports are at equalDEC 12,13(16)

3.Derive an expression for the SAG in a transmission line

i) when the supports at equal heights

ii)when the supports at unequal heights MAY 11 (8)

4.With a neat layout and schematic connection explain the pole mounted sub station MAY 14 DEC 08 (16)

5Explain different types of substations

6 What is SAG template Explain howthis is useful for location of power

7.With a new layout and schematic connectionexplain the pole mounted substionMAY14 DEC 08 (16)

8. Explain the following:MAY 10,13

i) Neutral Grounding

ii.Resonant grounding.

iii) Resistance grounding.

iv Reactance grounding. (16)

9. Describe with short notes on AIS. .. (16)

11.Explain resonant grounding.,Need for neutral earthing DEC06 (16) 12. Solve an overhead line has a span of 336 m. The line is supported, at water crossing from two towers

whose heights are 33.6 m and 29 m above water level. The weight of conductor is 19990.33 N/m and tension

in the conductor is not to exceed 3.34 × 104 N. Find (i) Clearance between the lowest point on the conductor

and water (ii) horizontal distance of this point from the lower support. (16) 13 a)Discuss and Derive expressions for sag and tension in a power conductor strung between to supports

at equal heights taking into account the wind and ice loading also. . (8)

14. Solve a transmission line conductor at a river crossing is supported from two towers at a height of 50 and

80 m above water level. The horizontal distance between the towers is 300 m. if the tension in the conductor

is 2000 kg find the clearance between the conductor and water at a point midway between the towers. Weight

of conductor/m = 0.844 kg. Derive the formula used.

. Solve a transmission line conductor at a river crossing is supported from two towers at a height of 30 m and 80 m above water level and span of 300m. if the tension in the

conductor is 2000 kg find the clearance between the conductor and water at a point midway

between the towers. Weight of conductor/m = 1 kg/m. Derive the Formula used.

(

1

6

)

15. Write short notes on (MAY 10,13)

i. Explain the design principles of substation grounding system

ii. Indoor and outdoor substations

16.Compose With the neat layout and schematic connection explain the pole mounted substation

MAY 14,DEC08

17.Assuming that the shape of an overhead

line can be approximated by the parabola, deduce expressions for calculating sag and conductor length

How can the effect of wind and ice loadings be taken into account DEC13,12NOV 15 (16)

18.what are different types of busbar arrangement used in substations? Illustrate your answer with suitable

diagrams NOV 15

19. A 230KV 3 PHASE 50Hz,200km transmission line has a capacitance to the earth of 0.02uF/km/phase.

Calculate the inductance and KVA rating of the Peterson coilused for earthing the above system

(16)