Electrical Machines 1 Lab Manual May 2015

ELECTRICAL MACHINES LAB ECB 3173 ELECTRICAL & ELECTRONICS ENG. PROG.

LABORATORY MANUAL ELECTRICAL MACHINES

ECB 3173

Electrical & Electronics Engineering Department Universiti Teknologi PETRONAS

Bandar Seri Iskandar 31750 TRONOH, Perak Darul Ridzuan

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Written, compiled and edited by : AP Ir Dr Nursyarizal Bin Mohd Nor AP Ir Dr Zuhairi Bin Baharudin

Dr. Mohd Fakhizan Bin Romlie

Revision : MAY 2015

CONTENTS LAB INFORMATIONS 3

LAB SAFETY AND PROCEDURE 4

EQUIPMENT INTRODUCTION 6

EXPERIMENT 1: SINGLE PHASE CAGE MOTOR

EXPERIMENT 2: DIRECT CURRENT MOTOR

18

26

EXPERIMENT 3: TRANSFORMERS 36

EXPERIMENT 4: ASYNCHROUNOUS MACHINES 63

EXPERIMENT 5: SYNCHROUNOUS MACHINES 87

EXPERIMENT 6: DC MACHINES 110

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LAB INFORMATIONS A total of six (6) lab sessions will be given throughout the semester. Students are expected to attempt the lab by grouping. Each groups need to submit the short report (hand written) at the end of the lab session. Viva is conducted for the first 15 minutes of the lab session. Mark for viva is given in individually basis. One long report (hand written) will be assigned to each group which needs to submit one week after the respective lab is conducted. Late submission will be penalized by deducting the mark. Punctuality is very important. The mark will be deducted to those are not punctual. Please follow all the lab safety and procedures. The formats of the short and long report are as follows:

1. Short Report: Results and Brief Discussion and Conclusion

2. Long Report: Title, Objective, Background/Introduction, Lab Procedures, Results, Discussion, Conclusion and References.

Rubric Assessments:

A. Viva Grading B. Laboratory Grading C. Short Report D. Long Report

NOTE: Attendance: Attendance is compulsory. A student, who is unable to attend the lab session due to some unforeseen circumstances, can replace the lab in another lab session within the same week as long as permission is obtained from the lecturer/technician.

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LAB SAFETY AND PROCEDURES

All students must read and understand the information in this document with regard to laboratory safety and emergency procedures prior to the first laboratory session. The first step is always to become familiar with the Lab itself. You should know where the fire extinguishers and the emergency exits are located. Each group is responsible for their Lab bench. After the Lab exercise is over, all equipment should be powered down and all probes, cords, etc. returned to their proper position. Do not cut and drop wires on the Lab bench. Lose cut wires have caused many short circuits. Your Lab grade will be affected if your bench is not tidy when you leave the Lab.

Common Sense

Good common sense is needed for safety in a laboratory. It is expected that each student will work in a responsible manner and exercise good judgment and common sense. If at any time you are not sure how to handle a particular situation, ask your lab assistant or tutor for advice. DO NOT TOUCH ANYTHING WITH WHICH YOU ARE NOT COMPLETELY FAMILIAR!!! It is always better to ask questions than to risk harm to yourself or damage to the equipment.

Personal and General laboratory safety

1. Never eat, drink, or smoke while working in the laboratory. 2. Open-toed shoes are not allowed in the laboratory. 3. Horseplay will not be tolerated. 4. Read labels carefully. 5. Do not use any equipment unless you are trained and approved as a user by your lab

assistant or tutor. 6. Equipment Failure - If a piece of equipment fails while being used, report it immediately to

your lab assistant or tutor. Never try to fix the problem yourself because you could harm yourself and others.

7. Double check circuits for proper connections and polarity prior to applying the power. 8. Never, ever modify, attach or otherwise change any high voltage equipment. 9. After wiring the bench equipment, the tutor must check the circuit before the supply is

switched on. 10. No leads are to be removed until the supply has been disconnected and any associated

machinery has stopped rotating. 11. Be aware of the location of the emergency stop and trip buttons. 12. Clean up your work area before leaving 13. Failure to comply with the above guidelines can result in you be ejected from the laboratory.

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Incident/ Accident Reporting

Everyone including employees, contractors and students shall report to UTP HSE Unit immediately of the occurrence of any incident or accident including near misses according to UTP accident reporting format. They shall also alert fire brigade, police and /or other authorities relevant to the incidents or accidents. The Contractor shall be responsible for reporting accidents and incidents to DOSH. UTP HSE Unit shall report to DOSH for any works incident involves staff or student.

All incidents or accidents that result in or have the potential to cause serious injury or property damage must be suitably investigated by the Contractor or UTP.

Emergency Evacuation Plan In the event of evacuation, the alarm will ring continuously. Please follow the evacuation procedure; as follows: 1. Leave by the nearest safe exit. Proceed in calm. 2. Proceed to your assigned Emergency Assembly Area (EAA). 3. Please leave all personal belonging. 4. Choose another exit route if you detect or sense a hazard. 5. Be ready to provide management or emergency response personnel with information they need

for documentation. Security Officers are located at every building to control the situation. 6. Return to the building only after you are told it is safe to do so

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EQUIPMENT INTRODUCTION This manual describes the typical experiments that are conducted in University Laboratories as practical hands-on training of a course on Electrical Machines. They are treated in detail by explaining the objectives, discussing electrical diagrams, by showing a brief overview of the theory and associated formulae for a thorough understanding and summarization of the results for subsequent analysis and discussion. The list of experiments proposed is not exhaustive: more experiments, to be implemented with the same equipment, can be designed by teachers and students to satisfy additional training requirements. The components suggested, machines and accessories, are chosen from our own catalogue as they are all designed under the same standards with the specific purpose of being easily integrated and capable of ensuring consistent results. For the same reason the suggested Power Supply is the ELECTRON Model A0240 of which a picture of the front panel and a brief description are given at page 7. The power of the electrical machines may be of three different ranges (to be specified with the order, see ELECTRON Model Codes in our Catalogue): 200-300W, 1KW and 3KW. The following Electrical Machines are covered: 1. Transformers (single phase) 2. AC Asynchronous Machines (three phase) 3. AC Synchronous Machines (three phase) 4. DC Machines The collection and analysis of data can be performed in two ways: - By reading the instruments and manually recording the data in the tables provided and drawing

diagrams where applicable. This manual describes these procedures.

Note: The necessary instruments are identified with each experiment. They should be procured locally and should be of adequate rating and precision. On request, we can provide them together with the equipment.

- By collecting and analyzing data by means of an optional Personal Computer and specifically

designed Software that are provided with a comprehensive user manual.

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EQUIPMENT INTRODUCTION (continued) The manual is divided into four sections, one for each family of electrical machine, and each section contains the related experiments that are all described with the following approach. 1. Objectives of the experiment: what it is about and what method will be used for its execution 2. Theoretical review: a brief discussion of the theory behind the subject being investigated 3. Formulae: a reminder of the main formulae involved 4. Components required: a list of the equipment required; ELECTRON equipment is suggested for

ensuring ease of integration and consistency of results 5. Circuit Diagrams: how the components are logically and practically connected 6. Execution of the experiment: the steps to be taken to achieve its objectives 7. Worksheets for manually collecting, recording results and their analysis 8. Graphs of the experiments results (where applicable) NOTES:

The suggested components sections contain a list of the ELECTRON machines that can be experimented. Their theoretical connection diagrams are also shown while the execution diagrams are only shown for one machine of each group. The others can be easily developed from that. When exercising a DC generator with shunt excitation it is possible that no output is obtained because the excitation current at starting is not sufficient to overcome an opposite residual magnetism. In such a case it is sufficient to reverse the generator's rotation or to feed the excitation independently (ex. from Section PS4 of the A0240 Power Supply). The exercises for determining the working characteristics of motors are based on the use of a braking DC generator Model A4430 for providing the load. The exercises can be performed in exactly the same way, with the same setup and procedure if a different type of brake is used, such as a powder brake Model A4410, Eddy current brake Model A4420 or hysteresis brake Model A4440. INDEX Brief description of the Optional PC Assisted Measurement System. User instructions for the ELECTRON Power Supply Model A0240 used in the tests. User Instructions for the ELECTRON Torque Meter A4730 and Load Cell A4731. User Instructions for the ELECTRON Digital Measuring Set Model A4750D.

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EXPERIMENTS: 1. SINGLE PHASE CAGE ROTOR (Capacitor start & run)

1.1 Objectives 1.2 Equipment required 1.3 Conducting of experiment 1.4 Question & result 2. DIRECT CURRENT MOTOR (Shunt wound)

2.1 Objectives 2.2 Equipment required 2.3 Conducting of experiment 2.4 Question & result

3. TRANSFORMERS LABORATORY (Single phase) 3.1 Measurement of the winding resistance 3.2 Measurement of the transformation ratio 3.3 No load test 3.4 Short circuit test 4. AC ASYNCHRONOUS MACHINES LABORATORY (three phase) 4.1 No load test 4.2 Short circuit test 4.3 Determination of working characteristics 5. AC SYNCHRONOUS MACHINES LABORATORY (three phase) 5.1 No load test 5.2 Short circuit test 5.3 Determination of the external characteristics 6. DC MACHINES LABORATORY 6.1 Measurement of the winding resistance 6.2 Magnetic characteristics 6.3 No load test

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POWER SUPPLY ELECTRON MODEL A0240

Section PS1 Sections PS2 + 3 Section PS4 A Ammeters mA Milli-Ammeter AC Exits L1, L2, L3, N, Ground (Section PS1) AC + DC Exits AC L1, N (Section PS2) / Ground / DC +, - (Section PS3) DC Exits +, -, Ground (Section PS4) Key Key-Lock P Protections POI Power On Indicator AC Power Outlets 1 x Three Phase, 2 x Single Phase Ext. Contact (Optional) A normally closed external contact may be used to control the unit,

otherwise connect a jumper SES Start, Emergency, Stop Pushbuttons V Voltmeters VAK Voltage Adjust Knobs VS Voltage to Voltmeter Selector User Instructions Section PS1 delivers a Three Phase plus Neutral supply voltage that can be varied with the Voltage Adjust Knob (VAK). With Voltage Selector VS, Voltmeter V can be connected to monitor any phase-to-phase or phase-to-neutral voltage. It is used to power single and three phase electrical machines. Section PS2 delivers a single phase-to-neutral voltage that is adjusted with the VAK of Section 1. Used to power single phase machines and for tests that require AC single phase supply. Section PS3 delivers a DC voltage that is also adjusted with the VAK of Section V1: this output is normally used to feed DC machines armatures or for tests that require a DC source. Section PS4 delivers a low power DC voltage, normally used to feed DC and synchronous machines excitations. Can be varied with its dedicated VAK.

AC Power Outlets SES VS AC Exits AC+DC Exits DC Exits

Key POI VAK

VAK

P A A A A mA

V V V

P P

P Ext. Contact

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TORQUE METER AND LOAD CELL MODELS A4730-A4731 The A4730 is a torque measuring instrument housed in a desk-top metallic enclosure that matches the design philosophy and appearance of the other ELECTRON equipment for the Electrical Machine Laboratory. It operates by processing the input signal of the A4731 Load Cell that consists of a strain sensing arm with force transducers in a bridge configuration. The Load Cell can be easily mounted on the Electrical Machines Coupling Base A4840 by means of the accessories provided (example setting in Fig.1) and is connected to a brake such as magnetic brake or braking generator. The A4730 (see Fig. 2) can provide torque indications in 2 ranges (preset at the factory), respectively up to 2 Nm (1.99) and 20 Nm (19.99). The A4730 + A4731 system can be easily checked and calibrated by using the procedure indicated below.

Fig.1 - Set-up of the load cell on a Magnetic brake

Fig. 2 - Load Cell and Torque Meter Each A4730 is pre-calibrated at the factory to work with its load cell and both are labeled with the same identification number to prevent exchanging of units. Before making calibrations or taking any measurement, always allow a 15 minute warm-up period in order to reach thermal equilibrium in the gauge amplifier.

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When the meter has reach the operating temperature, adjust the Zero indication and Gain by means of the FINE ADJUSTMENTS potentiometers accessible on the front panel of the unit. The Zero adjustment is performed with the cell unloaded while for Gain adjustment follow the procedure explained below. In the rare case that the Fine Zero or Gain adjustment controls of the front panel do not allow the correct indications, it may be necessary to re-calibrate the internal Coarse adjustment trimmers located on the amplifier board (refer to Fig.3). The procedure is described in the following section.

Fig.3 - Location of the coarse adjustment trimmers.

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CALIBRATION OF THE A4730 AND A4731 UNITS Remove the upper cover of the cabinet. Connect the load cell on the unit. Allow a period of

time for warm-up of the unit.

Note: No load should be applied to the load cell at this stage. Place the Zero and Gain controls of the front panel to the mid-run position. Locate the Coarse Zero and Gain trimmers on the circuit board as shown in Fig.3. Adjust the Coarse Zero trimmer for an indication as close as possible to 0.00 Apply the calibration weight to the load cell and adjust the Coarse Gain control for an

indication as near as possible to the calibration value. Proceed as follows:

Hang a 5,000gr weight on the torque arm at a distance of exactly 250 mm from the brake shaft centre, i.e. exactly at the position where the brake unit support is normally located. In order to keep the arm in the horizontal position, it may be necessary to insert a wedge between the arm and the brake shaft holder. Refer to Figs.4 and 5 for the set-ups.

Fig.4 - Set-up for full scale adjustment using a magnetic brake Adjust the Full Scale trimmer for an indication calculated as follows: C = torque = 5 kg x 0.25 m = 1.25 kgm = 12.25 Nm Remove the 5 kg weight and avoid excessive stress of the load cell so that the calibration remains stable.

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Replace the outer cover of the cabinet.

Perform the final FINE ADJUSTMENTS of the Zero and Gain of the unit by operating the front panel

controls. The A4730 and A4731 units are now ready for operation. The calibration procedure is the same when a braking DC generator is used instead of a magnetic Brake (see Fig. 5)

Fig.5 - Set-up for the calibration using a braking DC generator.

250mm

5 Kg

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MEASURING THE TORQUE WITH ARM AND WEIGHT SYSTEM The torque can be measured with an arm and weight system. The brake dynamo has two pivots on its sides on which two arm tubes are inserted: one short and the other 1 meter long with graduations. Follow this procedure and refer to the drawing below:

1. Insert the arm tubes on the machine pivots 2. With the dynamo stopped, locate a 5 Newton weight on Position 0 (Zero) of the long,

graduated arm 3. Put a second 5 Newton weight on the short arm in a position such as to balance the

machine 4. Operate the machine, load it and shift the 5 Newton weight along the graduated arm until

the machine is balanced and record the distance in meters from the Zero Position 5. Repeat the readings at the different load conditions 6. The Torque values in Newtons /Meter are obtained by multiplying the load in Newtons (5) by

the distance in Meters. (see Fig. 6)

Figure 6 - Multiplying the load in Newtons (5) by the distance in Meters.

Driving Motor

Brake Dynamo

Balancing 5N Weight

Measuring 5N Weight

Graduated Arm

Zero Position

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DIGITAL ELECTRICAL POWER MEASURING SET MODEL A4750D

The Digital Electrical Power Measuring Set contains three instruments that make it suitable for most laboratory and education requirements. The instruments are: DC Ammeter with a range up to 10A DC Voltmeter with a range up to 800V Three Phase Power Analyzer for measuring several electrical parameters as explained below.

Front Panel + - + - Current Voltage In Out NOTE: The location of the instruments may be different from that illustrated above.

R U X S V Y T W Z N N

Ammeter Voltmeter Power Analyzer

RS485

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Three Phase Power Analyzer This Digital Power Analyzer measures various electrical parameters of three phase systems, with or without neutral, and displays the readings separately for each phase or cumulatively. Connection information is detailed in the manual provided with each instrument. Before connecting the instrument verify that the voltages to be measured are compatible with the instrument range. Set-Up The instrument parameters are set at the factory to default values. If so desired, they can be changed by means of front panel pushbuttons as explained in the instrument manual provided with it. Serial line connection (optional) On request, the instrument can be equipped with the connection to a serial line RS485. Voltage Inputs Nominal input voltage is 440V (max. phase-to-phase is 600V); for higher voltages use appropriate transformers and respect their input and output phase sequence. Current Inputs Maximum current input from current transformers is 5A. Power Supply Power requirement is max 5VA at 115/220V (+15 -20%), 50/60Hz Front Panel 1 - 2 Keys for entering the configuration menu and changing the set-ups. Factory settings do not normally require modifications.

3 - 4 Keys for scrolling up and down the displayed readings. 12 sets of readings are available as illustrated below.

SETUP

ENTER

1 2

3 4

DIGITAL DISPLAY

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Display Readings:

1. Line Voltages V1, V2, V3 2. Phase Voltages V1-2, V2-3, V1-3 3. Line Currents I1, I2, I3 4. Power Factors PF1, PF2, PF3 5. Apparent Power VA1, VA2, VA3 6. Real Power W1, W2, W3

7. Reactive power VAr1, VAr2, VAr3 8. Integral V, I, PF 9. Integral VA, W, Var 10. Frequency Hz 11. Energy VarH, Wh 12. 15 minutes average power VAr, W

The parameters are always computed, even when they are not displayed. They are computed on 4 quadrants: this means that power may be negative. Three connection methods are possible: single phase, 4 and 3 wires. In the latter case the parameters are measured correctly only if there is no current on the neutral: that is if the load is balanced.

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ELECTRICAL MACHINES ECB 3173

SINGLE PHASE CAGE ROTOR

SHORT REPORT : ----------CUT HERE----------------------------------------------------------------------------------------------------------------------

Name Group No

: : : :

Lab Session : Date : Lecturer : Gas : :

NAME : : :

DATE OF SUBMITTED:

SHORT REPORT : LAB STAMP :

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ECB3173 Electrical Machines 1

Lab Presentation (ViVa) Marking Scheme No Students Name ID

1

2

3

4

Experiment No / Topic: . Date/Time:..

Category Criteria for Judging Excellent Good Average Poor Bad

Score

Stud

. 1 Stud.

2 Stud.

3

Punctuality Attend the viva session on time as

agreed. (2) (1.5) (1) (0.5) (0)

Analysis and

Preparation before

experiment

Expect result, theoretical knowledge,

calculation and ground work of short

report. (35) (27) (22) (10) (0)

Knowledge &

Understanding

(Comprehension)

Understanding of the topic and

accurate answer to questions posed

by instructor. (50) (38) (32) (15) (0)

Clarity of speaking and

confident

Clarity of and accuracy of the words &

sentences and confident in answering

questions. (13) (10) (8) (3) (0)

Total Score

Approved by, .. Lab Instructor Name: Date:

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Rubric For Lab Assesment

Topic

(Weight) Unacceptable

(0) Marginal

(1) Acceptable

(2) Exceptional

(3) Points

Execution of Procedures

(2)

Demonstrated little or no ability to conduct experiments. Did not collect meaningful data

Demonstrated some ability to conduct experiments. Collected some meaningful data

Demonstrated adequate ability to conduct experiments. Collected most of the needed data

Demonstrated superior ability to conduct experiments. Collected all the appropriate data

Focus of Results and Discussion

(3)

No insight. Entirely missed the point of the experiment

Little insight. Analyzed only the most basic points

Adequate insight. Missed some important points

Excellent insight. Results and discussion well focused

Safety & Health Issues

(1)

No understanding or appreciation of safety and health related issues

Serious deficiencies in addressing health and safety issues leading to a unsupported and/or infeasible result

Sound understanding of health and safety issues. Mostly effective in achieving supported results

Complete understanding of health and safety issues leading to sound and supported results

Participation in Teamwork (If applicable)

(3)

Demonstrated little or no ability to function effectively as leader/team member during experimental work

Demonstrated some ability to function effectively as leader/team member during experimental work

Demonstrated adequate ability to function effectively as leader/team member during experimental work

Demonstrated superior ability to function effectively as leader/team member during experimental work

Punctuality

(1) >10 minutes late

6-10 minutes late

1-5 minutes late

Punctual

TOTAL

Examiner:

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Rubric for Short Report

Student: Course: Date: Experiment No.:

Lecturer:

Item

Assessed Low (0-1)

Average (2-3)

Good (4-5)

Score

Objective, and scope of experiment

Objective and scope are not clear or minimum discussed.

Objective and scope are explained but lack of understanding.

Objective and scope are clearly explained. Interesting presentation.

Results and analysis

No results or plagiarized are presented

Results are presented but some have minor problems or could still be improved

Results and analysis are clearly explained using relevant tool such as graph ,table or etc.

Discussion and conclusion

Very incomplete or incorrect interpretation of trends and comparison of data indicating a lack of understanding of results

The discussion and conclusion are clearly explain but less related with objective.

The conclusion is clearly explained with interesting discussion. Student shows his/her understanding on the subject of discussion.

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1. SINGLE PHASE CAGE ROTOR

(CAPACITOR START & RUN) 1.1 OBJECTIVES To determine by experiment, different methods of starting and running single phase induction motors using a capacitor permanently wired in series with the auxiliary winding and an additional capacitor paralleled with the permanent capacitor via the centrifugal switch. 1.2 EQUIPMENT REQUIRED 1) 1 x Cage rotor-ADM109 2) 1 x Centrifugal switch-ADM113 3) 1 x Rotating mechanism - ADM113A 4) 1 x Mechanical brake drum ADM115 5) 1 x Single phase stator (Capacitor stator) - ADM104 6) 1 x End shield with brake slot and tachometer receptacle - ADM101A 7) 1 x Endshield-ADM102 8) 1 x Set allen keys-ADM118 9) 1 x Set bolt/nut assembly - ADM 116 10) 1 x Tacho meter 11] 1 x Set connecting leads 1.3 CONDUCTING THE EXPERIMENT

1) Assemble the motor according to the assembly diagrams and the following instructions: Install the rotor into the stator. Clip the centrifugal switch assembly into the end housing and terminate the connections on the binding posts. Mount and secure the end housings onto the stator.

2) Connect up the circuit as illustrated in Fig. 1.

FIG 1 - WIRING DIAGRAM

22


CONNECTION DIAGRAM 23


3) Connect power and note the action of the rotor and the current drawn. 4) What is the current drawn at (a) start-up and (b) 5 seconds after start- 5) What is the direction of rotation? 6) Give reasons to support your observation of what the changes to the circuit have

achieved by comparing these observations to those obtained previously in fig 1. 1.4 ANSWERS TO METHOD QUESTIONS (RESULTS)

1) Current drawn at start-up. _____________________________________________________________________

2) Current drawn 5 seconds after start-up

_____________________________________________________________________

3) Is there a difference between the initial and running currents? _____________________________________________________________________

4) Did the rotor start spinning on its own? _____________________________________________________________________

5) In what direction did the rotor spin?

_____________________________________________________________________

6) Why did the rotor spin in this direction?

_____________________________________________________________________

7) What net result changing the circuit configuration from that of fig 1? _____________________________________________________________________

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CONCLUSION

Here the student should tabulate in point form what they have learnt from doing the experiment. They should also state whether the experiment was of any value to them or not, and if so, why? ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________

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DIRECT CURRENT MOTOR (SHUNT WOUND)

SHORT REPORT : ----------CUT HERE----------------------------------------------------------------------------------------------------------------------

Name Group No

: : : :


NAME : : :

DATE OF SUBMITTED:

SHORT REPORT : LAB STAMP :

26




1

2

3

4



Score

Stud

. 1 Stud.

2 Stud.

3


agreed. (2) (1.5) (1) (0.5) (0)

Analysis and

Preparation before

experiment



report. (35) (27) (22) (10) (0)

Knowledge &

Understanding

(Comprehension)



by instructor. (50) (38) (32) (15) (0)


confident



questions. (13) (10) (8) (3) (0)

Total Score


Page 27 of 129



Topic

(Weight) Unacceptable

(0) Marginal

(1) Acceptable

(2) Exceptional

(3) Points


(2)






(3)






(1)






(3)





Punctuality


6-10 minutes late

1-5 minutes late

Punctual

TOTAL

Examiner:

Page 28 of 129




Lecturer:

Item

Assessed Low (0-1)

Average (2-3)

Good (4-5)

Score













Page 29 of 129


2. DIRECT CURRENT MOTOR (SHUNT WOUND)

2.1 OBJECTIVES

To connect up, start and run a DC shunt motor

2.2 EQUIPMENT REQUIRED

1) 1 x DC armature (Large) ADM108A 2) 1 x Mechanical brake drum ADM 115 3) 1 x DC stator ADM103 4) 1 x Endshield with brake slot and tachometer receptacle ADM 101A 5) 1 x Endshield ADM102 6) 1 x DC brushgear (2 x brush holders) ADM111 7) 1 x Set Allen keys - ADM118 8) 1 x Set bolt/nuts assembly - ADM116 9) 1 x 50 R 250W resistor module ADM 212 10) 1 x Set connecting leads

2.3 CONDUCTING THE EXPERIMENT

1) By examining, determine how many sets of windings exist within DC stator. 2) Measure the resistance of each winding set. 3) List the windings and respective resistances. 4) Note the laminated construction of the stator. Why are laminations used? 5) Note the construction of the DC rotor. What is the function of the commulator? 6) How many windings does the DC rotor comprise? 7) In what configuration are the windings of the DC rotor (Lap or Wave wound). Give a

reason for your answer. 8) Measure the resistance of each winding of the DC rotor. 9) Assemble the motor according to the assembly diagrams and the following instructions:

Install the rotor into the stator. Clip the brush gear assembly into one end housing and terminate the connections to the binding posts. Mount and secure the end housing onto stator. Note: Owning to the high torque of the DC motor it must be connected to a load. Do not run this motor without a load for more than 1min.

Page 30 of 129


10) Position of the brush gear as follows:

11) Connect up the circuit illustrated in Fig 1. Note that the interpoles are connected in series with the shunt windings in order to provide the required starting resistance. Do not couple the circuit to the power supply at this stage.

Page 31 of 129


12) Call your instructor and check all connections are correct. 13) Double check your circuit connection with your instructor to make the power

connections. 14) Turn the power on and note the action of the rotor. If smooth rotation is not achieved,

disconnect the power to the motor and increase the load via mechanical brake to stop the rotation. Disconnect all power and adjust the position of the brushes. Connect the power and observe the rotor action and sparking at the brushes. Excessive brush sparking indicates that they are incorrectly positioned.

15) Under no circumstances stop the rotation of the rotor with your hands or adjust the brush position with power connected.

16) Repeat step 14 until the sparking at the brushes is at minimum. 17) Why does the current reduce as the speed of the motor increases? 18) Note the direction of the motor and the starting torque of the shunt connected motor. 19) Switch off

Page 32 of 129


Connection Diagram

Page 33 of 129


2.4 ANSWERS TO METHOD QUESTIONS (RESULTS)

1) Number of sets of windings in the DC stator.

________________________________________________________________________

2) Resistance of each winding set.

________________________________________________________________________

3) What is the purpose of the laminations of this shape in the stator?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

4) What is distinctive about the DC rotor and what is the winding configuration?

________________________________________________________________________

5) Why is the rotor wound in this configuration?

________________________________________________________________________

6) Winding resistance of rotor?

________________________________________________________________________

7) What causes excess sparking at the brushes?

________________________________________________________________________

8) Current drawn at start up and rotor action.

________________________________________________________________________

9) Rotor direction?

________________________________________________________________________

10) Rotor speed?

________________________________________________________________________

11) Current drawn with load?

________________________________________________________________________

Page 34 of 129


CONCLUSION

Here the pupil/student should tabulate in form what they have learnt from doing experiment. They should also state whether the experiment was of any value to them or what, and if so why?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Page 35 of 129



TRANSFORMER EXPERIMENT

SHORT REPORT : LONG REPORT : ----------CUT HERE----------------------------------------------------------------------------------------------------------------------

Name Group No

: : : :


NAME : : :

DATE OF SUBMITTED:

SHORT REPORT : LONG REPORT : LAB STAMP :

Page 36 of 129




1

2

3

4



Score

Stud

. 1 Stud

. 2 Stud.

3


agreed. (2) (1.5) (1) (0.5) (0)

Analysis and

Preparation before

experiment



report. (35) (27) (22) (10) (0)

Knowledge &

Understanding

(Comprehension)



by instructor. (50) (38) (32) (15) (0)


confident



questions. (13) (10) (8) (3) (0)

Total Score


Page 37 of 129



Topic (Weight)

Unacceptable (0)

Marginal (1)

Acceptable (2)

Exceptional (3) Points


(2)






(3)






(1)






(3)





Punctuality


6-10 minutes late

1-5 minutes late

Punctual

TOTAL

Examiner:

Page 38 of 129




Lecturer:

Item

Assessed Low (0-1)

Average (2-3)

Good (4-5)

Score













Page 39 of 129


Rubric for Long Report

Course : Date: Student: Student ID:

Topic (Weight)

Unacceptable (0)

Marginal (1)

Acceptable (2)


Introduction Background Objective Scope

(2)

Unable to state the introduction clearly

State the introduction with limited information

Able to state the introduction with minor error

Able to state the introduction clearly

Theoretical Knowledge/ Literature Review

(3)

Not explained or not related to the project

Not clearly explained or partially related to the project

Important knowledge are covered but still missing some important concept

Clearly explained the knowledge and concept. Student capable of discussing the theory and simulated results

Results/Findings/Analysis

(3) No results or plagiarized work are presented

Minimum results are presented and analyzed

Results are presented but with minor error and could still be improved

Results and analysis are clearly explained using relevant tool such as graph , table, etc.

Report Organization

(2) Report is too difficult to understand with many grammatical error and not well organized

Report is easy to understand with few grammatical error and moderately organized

Report well written but occasionally some points are difficult to understand. Minor grammatical error

Report very well written and easy to understand

TOTAL

Examiner:

Page 40 of 129


3. TRANSFORMERS LABORATORY

3.1 MEASUREMENT OF THE TRANSFORMER WINDINGS RESISTANCE 3.1.1 OBJECTIVES Measure the primary and secondary windings resistance of single phase transformers with the Volt-Ampere method (Ohm's Law). 3.1.2 THEORETICAL REVIEW The transformers' windings resistance cause internal voltage drops that reduces their efficiency. Therefore, it must be as low as possible. It is calculated by applying known DC voltage and measuring the resulting current flow. 3.1.3 FORMULAE

PARAMETER SYMBOL UNIT Winding Voltage V Volts Winding Current I Amperes Winding Resistance R Ohms R=V/I for single phase transformer R=V/I * 2 for STAR connected three phase transformers

3.1.4 COMPONENTS Single Phase Transformer Model A4110 Power Supply Model A0240 Cables Model A4890 Cables Support Model A4891 Ammeter (A) With adequate range for this test Voltmeter (V) With adequate range for this test

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3.1.5 CIRCUIT DIAGRAMS Single Phase Transformer Primary Secondary DC 0-24V

A

V

+ _

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Connection Diagram

Figure 1 . Connection Diagram

A

A4110

V

Page 43 of 129


3.1.6 Conducting the experiment The components must be connected as shown in the connection diagrams as shown in Fig. 1 and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS - Set the DC windings voltage PS3 = 0 V. - Switch on the power supply.

Increase input voltage gradually by operating on the front knob power supply. It must be increased in 2% steps up to 10 % max. Do not exceed 10 % of nominal winding voltage to avoid overheating of the windings.

- Measure the voltage and current for any step and enter them in the worksheet tables.

( Tables 1). - Repeat the above steps for all primary and secondary windings and calculate their

resistance with the formulae given above.

- Now calculate the average value of the resistance for each primary and secondary winding. Similar windings should have similar resistance.

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3.1.7 WORKSHEETS

Parameter Symbol Unit Value

PRIMARY

Winding Voltage 220V % 2 4 6 8 9

Winding Voltage V V

Winding Current I A

Winding Resistance R

SECONDARY


Winding Voltage V V

Winding Current I A



Winding Voltage V V

Winding Current I A


Table 1. Measurement of the Transformer Windings Resistance Transformer Model:

Page 45 of 129


3.2 MEASUREMENT OF THE TRANSFORMATION RATIO 3.2.1 OBJECTIVES Calculate the transformation ratio of single phase transformers. 3.2.2 THEORETICAL REVIEW The transformation ratio is a characteristic value of every transformer and can be calculated either as a ratio between primary and secondary windings turns or voltages. It is therefore >1 in a step-down transformer and


3.2.5 CIRCUIT DIAGRAMS Single Phase Transformer Primary Secondary AC 0-230V

V1 V2

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Connection Diagram


A4110

V1 V2

Page 48 of 129


3.2.6 Conducting the experiment The components must be connected as shown in the connection diagrams as shown in Fig. 2 and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS - Set the AC input voltage PS2 or PS1 = 0 V. - Switch on the power supply.

Increase the input voltage gradually in 20% steps from 0% to 100% of transformers nominal voltage.

- At each step measure the voltage readings of V1 and V2 and enter them in the worksheet table. ( Table 2 ).

- At each step compute the transformation ratio with the formulae given above and enter them in the worksheet tables. ( Table 2 ).

- At this point calculate the average value of the transformation ratio.

Page 49 of 129


3.2.7 WORKSHEETS


Input Voltage 220V % 20 40 60 80 100

Primary Voltage V1 V

Secondary Voltage V2 V

Transformation Ratio K

Table 2 . Measurement of the Transformation Ratio Transformer Model:

Page 50 of 129


3.3 SHORT CIRCUIT TEST 3.3.1 OBJECTIVES Calculate the resistance losses, determine the short circuit voltage and the short circuit power factor, calculate the additional losses, the equivalent resistance and reactance. 3.3.2 THEORETICAL REVIEW With this test the transformer primary windings are fed with up to the nominal current and the secondary windings are short-circuited. The power drawn is very low and therefore it is possible to simulate the leakage fluxes in both primary and secondary windings because the latter depends upon the load current in the two windings. As the transformer is short-circuited, the input voltage must be very low, usually 5% of the nominal rating and the mutual flux is of the same order of magnitude. Since the core losses are approximately proportional to the square of the mutual flux, they are negligible. This means that a wattmeter connected to measure the input power indicates only the copper losses because there are no output power or core losses. 3.3.3 FORMULAE

PARAMETER SYMBOL UNIT Voltage V Volts Current I Amperes Input Power W Watts

Single phase transformers: P = W Cos = P/(V * I) I = P/(V * Cos) R = P/I2 Z = V/I X = Z2 - R2

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3.3.4 COMPONENTS Single Phase Transformer Model A4110 Three Phase Transformer Model A4120 Power Supply Model A0240 Cables Model A4890 Cables Support Model A4891 Ammeters (A) With adequate range for this test Wattmeters (W1, W2) With adequate range for this test Voltmeter (V) With adequate range for this test 3.3.5 CIRCUIT DIAGRAMS Single Phase Transformer Primary Secondary AC 0-24V

W1

V

A

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Connection Diagram


V A

A

AC DC

> 230Vac > 24Vac

0v

220v

0v

160v

0v

110v

220v

Single Phase Transformer

Digital Multimeter

Power supply

Page 53 of 129


3.3.6 Conducting the experiment The components must be connected in the connection diagrams as shown in Fig. 3 and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS - Set the AC input voltage PS2 or PS1 = 0 V. - Switch on the power supply.

Increase the input voltage at 1% steps to about 5% of nominal rating until the nominal current can be read in the primary winding.

- At each step enter the readings in the worksheet tables. ( Table 3 ). - At the end calculate the Equivalent Secondary Reactance, Impedance and Resistance with

the above formulae. - Plot the graph. (Graph 1)

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3.3.7 WORKSHEETS


Input Voltage 220V % 1 2 3 4 5

Winding Voltage V V

Current A A

Wattmeter W W

Power Factor Cos

Reactance

Impedance

Resistance Table 3 . Short Circuit Test

Transformer Model:

Page 55 of 129


I (Amp)

Graph 1 . Short Circuit Test

Cos P V

Page 56 of 129


3.4 NO LOAD TEST 3.4.1 OBJECTIVES Calculate the hysteresis losses, measure the no-load current and calculate the no load Power Factor of single and three phase transformers. 3.4.2 THEORETICAL REVIEW The power absorbed by a transformer with its secondary windings open (no load) is caused by hysteresis losses and eddy currents. To reduce the hysteresis losses a ferromagnetic material is used that has a narrow hysteresis loop, while to reduce the eddy currents the magnetic iron core is laminated and its sheets are insulated by means of special resins. 3.4.3 FORMULAE

PARAMETER SYMBOL UNIT Voltage V Volts Current I Amperes Input Power P Watts Power W Watts Power Factor Cos

Single phase transformers: P = W I = P/(V * Cos) Cos = P/(V * I) 3.4.4 COMPONENTS Single Phase Transformer Model A4110 Power Supply Model A0240 Cables Model A4890 Cables Support Model A4891 Ammeters (A) With adequate range for this test Wattmeters (W) With adequate range for this test Voltmeter (V) With adequate range for this test

Page 57 of 129


3.4.5 CIRCUIT DIAGRAMS Single Phase Transformer Primary Secondary AC 0-220V

W1

V

A

Page 58 of 129


Connection Diagram

Figure 4 . Connection Diagram 3.4.6 Conducting the experiment The components must be connected as shown in the connection diagrams as shown in Fig. 4 and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS - Set the AC input voltage PS2 or PS1 = 0 V. - Switch on the power supply.

Increase the input voltage gradually in 20% steps from 0% to 100% of the transformer nominal voltage

- At each step measure the voltage, current and power readings and enter them in the

worksheet tables. - Calculate the no load input power, power factor and no load current with the above

formulae. - Plot the graphs. (Graph 2 & Graph 3)

V A

A

AC DC

>230Vac >24Vac

0v

220v

0v

160v

0v

110v

220v

Transformer Digital Multimeter

Power supply

Page 59 of 129


3.4.7 WORKSHEETS


Input Voltage 220V % 20 40 60 80 100

Winding Voltage V V

Current A A

Wattmeter W W

Power Factor Cos

Table 4 .No Load Test Transformer Model:

Page 60 of 129


Graph 2 . No Load Test

P

V

Transformer Model:

Page 61 of 129


Graph 3. No Load Test

I

V

Transformer Model:

Page 62 of 129



ASYNCHROUNOUS MACHINES EXPERIMENT

SHORT REPORT : LONG REPORT : ----------CUT HERE----------------------------------------------------------------------------------------------------------------------

Name Group No

: : : :

Lab Session : Date : Lecturer : Tutor(s) : GAs :

NAME : : :

DATE OF SUBMITTED:

SHORT REPORT : LONG REPORT : LAB STAMP :

Page 63 of 129


ECB 3173 Electrical Machines 1

Lab Presentation(ViVa) Marking Scheme

No Students Name ID

1

2

3

4



Score

Stud.

1 Stud.

2 Stud.

3


agreed. (2) (1.5) (1) (0.5) (0)

Analysis and

Preparation before

experiment



report. (35) (27) (22) (10) (0)

Knowledge &

Understanding

(Comprehension)



by instructor. (50) (38) (32) (15) (0)


confident



questions. (13) (10) (8) (3) (0)

Total Score


Page 64 of 129



Topic (Weight)

Unacceptable (0)

Marginal (1)

Acceptable (2)



(2)






(3)






(1)






(3)





Punctuality


6-10 minutes late

1-5 minutes late

Punctual

TOTAL

Examiner:

Page 65 of 129


Rubric for Short Report Student: Course: Date: Experiment No.:

Lecturer:

Item

Assessed Low (0-1)

Average (2-3)

Good (4-5)

Score













Page 66 of 129


Rubric for Long Report

Course : Date: Student: Student ID:

Topic (Weight)

Unacceptable (0)

Marginal (1)

Acceptable (2)


Introduction Background Objective Scope

(2)

Unable to state the introduction clearly

State the introduction with limited information

Able to state the introduction with minor error

Able to state the introduction clearly

Theoretical Knowledge/ Literature Review

(3)

Not explained or not related to the project

Not clearly explained or partially related to the project

Important knowledge are covered but still missing some important concept

Clearly explained the knowledge and concept. Student capable of discussing the theory and simulated results

Results/Findings/Analysis

(3) No results or plagiarized work are presented

Minimum results are presented and analyzed

Results are presented but with minor error and could still be improved

Results and analysis are clearly explained using relevant tool such as graph , table, etc.

Report Organization

(2) Report is too difficult to understand with many grammatical error and not well organized

Report is easy to understand with few grammatical error and moderately organized

Report well written but occasionally some points are difficult to understand. Minor grammatical error

Report very well written and easy to understand

TOTAL

Examiner:

Page 67 of 129


4. AC ASYNCHRONOUS MACHINES LABORATORY

4.1 NO LOAD TEST This experiment is performed on three phase squirrel cage motor. 4.1.1 OBJECTIVES The experiment is meant to compute the no-load current and the no-load power factor. 4.1.2 THEORETICAL REVIEW The power absorbed by an unloaded asynchronous motor is only caused by mechanical losses (cooling and friction) and Joule losses in the stator and rotor. The motor absorbs a low current and rotates close to the synchronism speed. Therefore the Joule losses in the rotor are negligible and also its iron losses are low because of the low flux frequency. 4.1.3 FORMULAE

PARAMETER SYMBOL UNIT Power 1 W1 Watts Power 2 W2 Watts Power 3 W3 Watts Armature Voltage V Volts Armature Current I Amperes No Load Power Factor Cos Three Phase Motor: P = W1 + W2+W3 I = P/( 3 * V * Cos) Cos = P/( 3 * I * V)

Page 68 of 129


4.1.4 COMPONENTS Squirrel Cage Asynchronous Motor Model A4220 Power Supply Model A0240 Cables Model A4890 Cables Support Model A4891 Three phase analyzer Model A4750D 4.1.5 CIRCUIT DIAGRAMS Three Phase Motors Squirrel Cage Motor.

M 3 Phases PS1

Three Phase Analyzer

Page 69 of 129


Connection Diagram A0240 Section PS1 Sections PS2 - 3 Section PS4

AC Power Outlets SES VS AC Exits AC + DC Exits DC Exits

Key POI VAK

VAK

P A A A A mA

V V V

P P

P Overspeed



RS485

A4220 U1 V1 W1

V2 W2 U2


Page 70 of 129


4.1.6 Conducting the experiment The components must be connected as shown in the connection diagrams (Fig. 1) and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS Set the supply voltage PS1 = 0. Switch on the power supply. Increase the supply voltage PS1 to 120% of the motor's nominal voltage (220Volt). Gradually decrease the voltage from 120% to 20% in 20% steps (Table 1). At each step record the values of voltage V, current I and input power W1, W2 and W3 into the work-sheet table (Table 1). For each step calculate power P and the no-load power factor with the above formulae and enter the values in the work-sheet table. Plot the graphs. (Graph 1)

Page 71 of 129


4.1.7 WORKSHEETS Three Phase


Armature Voltage 220V % 120 100 80 60 40 20

Winding Voltage V V

Armature Current I A

Wattmeter 1 W1 W

Wattmeter 2 W2 W

Wattmeter 3 W3 W

No Load Power P W

No Load Power Factor Cos

Table 1 . No Load Test Motor Model :

Page 72 of 129


Graph 1. No Load Test

I P Cos

V

Motor Model:

Page 73 of 129


4.2 SHORT CIRCUIT TEST 4.2.1 OBJECTIVES Compute the short circuit current and power factor. 4.2.2 THEORETICAL REVIEW The rotor of the motor is locked and the stator is supplied with the nominal current that requires up to 30% of nominal voltage. The short circuit current graph is linear and can be used to determine the short circuit current at nominal voltage. The short circuit current can also be calculated with the formulae given below. 4.2.3 FORMULAE PARAMETER SYMBOL UNIT Power 1 W1 Watts Power 2 W2 Watts Power 3 W3 Watts Armature Voltage V Volts Armature Current I Amperes Short Circuit Power Factor Cos P = W1 + W2+W3 = 3 * V * I * Cos Cos = P / 3 * V * I

Page 74 of 129


4.2.4 COMPONENTS Asynchronous Motor Model A4220 Power Supply Model A0240 Cables Model A4890 Cables Support Model A4891 Three phase analyzer Model A4750D Rotor Mechanical Lock 4.2.5 CIRCUIT DIAGRAMS

Theoretical Diagram Squirrel Cage Motor Rotor Mechanical Lock PS1

Asynchronous Motor


Page 75 of 129


Connection Diagram

A0240 Section PS1 Sections PS2 - 3 Section PS4

AC Power Outlets SES VS AC Exits AC + DC Exits DC Exits

Key POI VAK

VAK

P A A A A mA

V V V

P P

P Overspeed



RS485

A4220 U1 V1 W1

V2 W2 U2

Figure 2 . Connection Diagram * The rotor must be locked with the Rotor Mechanical Lock device provided.

Rotor Mechanical Lock

Page 76 of 129


4.2.6 Conducting the experiment The components must be connected as shown in the in the connection diagrams (Fig. 2) and must be grounded. The rotor must be locked with the Rotor Lock device provided. MANUAL DATA COLLECTION AND ANALYSIS Set the supply voltage PS1 = 0. Switch on the power supply. Adjust the stator input current PS1 to 0.6 Ampere so that nominal current flows in the stator windings. Gradually decrease PS1from 100% to 25% of nominal armature current in 15% steps(Table 2). At each step record the values of voltage, current and input power W1, W2 and W3 into the worksheet table.( Table 2) For each step calculate power P and the short circuit power factor with the above formulae and enter the values in the worksheets.( Table 2) Plot the graphs .(Graph 2)

Page 77 of 129


4.2.7 WORKSHEETS


Armature Current 0.6Amp % 100 85 70 55 40 25

Armature Voltage V V

Armature Current I A

Wattmeter 1 W1 W

Wattmeter 2 W2 W

Wattmeter 3 W3 W

Table 2 . Short Circuit Test Motor Model:

Page 78 of 129


Graph 2 . Short Circuit Test

I sc Psc Cos

V

Motor Model:

Page 79 of 129


4.3 DETERMINATION OF WORKING CHARACTERISTICS 4.3.1 OBJECTIVES Find the motor's load characteristics by loading it with a brake dynamo. Measure the torque and mechanical power at various load conditions. Calculate the motor efficiency. Plot the load characteristics for analysis. 4.3.2 THEORETICAL REVIEW The motor drives a loaded brake dynamo whose stator is mounted on bearings and capable of rotating. Since the torque between its stator and rotor is proportional to the generated electrical power, a dynamometer installed on its stator to counteract its rotation gives a reading of the motor's torque. The torque's value can be read in two ways:

- by a load cell connected to a torque meter - by an arm and weights system

The torque can be varied by varying the dynamo's electric load. The measured torque includes the losses on bearings, ventilation and on collector brushes. However, they are small and do not affect significantly the experiment's results.

Page 80 of 129


4.3.3 FORMULAE PARAMETER SYMBOL UNIT Armature Voltage V Volts Armature Curent I Ampres Arm Length a m Weight G N Torque T Nm Speed n min-1 Excitation Curent Ie Ampres Input Power Pi Watts Output Power Po Watts Power 1 W1 Watts Power 2 W2 Watts Power 3 W3 Watts Efficiency T = G * a Po = 2 n T/60 Pi = W1 + W2 + W3 = 3 * V * I * Cos Cos = Pi / ( 3 * V * I) For three phase motor = Po / Pi

Page 81 of 129


4.3.4 COMPONENTS Three Phase Squirrel Cage Motor Model A4220 Braking DC Generator Model A4430 Coupling Base Model A4840 Power Supply Model A0240 Resistive Load Model A4510 Cables Model A4890 Cables Support Model A4891 Three phase analyzer Model A4750D RPM meter 4.3.5 CIRCUIT DIAGRAMS

Theoretical Diagram Three Phase Squirrel Cage and Slip Ring Motor (on slip ring motor short circuit ring brushes) PS1

M 3 Phase

A2 G

PS4


Page 82 of 129

Electrical Machines 1 Lab Manual May 2015

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