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

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

18

EXPERIMENT 2: DIRECT CURRENT MOTOR

26

EXPERIMENT 3: TRANSFORMERS

36

EXPERIMENT 4: ASYNCHROUNOUS MACHINES

63

EXPERIMENT 5: SYNCHROUNOUS MACHINES

87

EXPERIMENT 6: DC MACHINES

110

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

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. B. C. D.

Viva Grading Laboratory Grading Short Report 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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ELECTRICAL MACHINES LAB ECB 3173 ELECTRICAL & ELECTRONICS ENG. PROG.

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. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Never eat, drink, or smoke while working in the laboratory. Open-toed shoes are not allowed in the laboratory. Horseplay will not be tolerated. Read labels carefully. Do not use any equipment unless you are trained and approved as a user by your lab assistant or tutor. 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. Double check circuits for proper connections and polarity prior to applying the power. Never, ever modify, attach or otherwise change any high voltage equipment. After wiring the bench equipment, the tutor must check the circuit before the supply is switched on. No leads are to be removed until the supply has been disconnected and any associated machinery has stopped rotating. Be aware of the location of the emergency “stop” and “trip” buttons. Clean up your work area before leaving Failure to comply with the above guidelines can result in you be ejected from the laboratory.

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

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 work’s 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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ELECTRICAL MACHINES LAB ECB 3173 ELECTRICAL & ELECTRONICS ENG. PROG.

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

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. 7

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

EXPERIMENTS: 1. SINGLE PHASE CAGE ROTOR (Capacitor start & run) 1.1 1.2 1.3 1.4

Objectives Equipment required Conducting of experiment Question & result

2. DIRECT CURRENT MOTOR (Shunt wound) 2.1 2.2 2.3 2.4

Objectives Equipment required Conducting of experiment Question & result

3. TRANSFORMERS LABORATORY (Single phase) 3.1 3.2 3.3 3.4

Measurement of the winding resistance Measurement of the transformation ratio No load test Short circuit test

4. AC ASYNCHRONOUS MACHINES LABORATORY (three phase) 4.1 4.2 4.3

No load test Short circuit test Determination of working characteristics

5. AC SYNCHRONOUS MACHINES LABORATORY (three phase) 5.1 5.2 5.3

No load test Short circuit test Determination of the external characteristics

6. DC MACHINES LABORATORY 6.1 6.2 6.3

Measurement of the winding resistance Magnetic characteristics No load test

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

POWER SUPPLY ELECTRON MODEL A0240 Section PS1 P

Key

A

POI

A

Sections PS2 + 3

Section PS4

A

A

mA

V

V

V

VAK P

Ext. Contact AC Power Outlets

A mA AC Exits AC + DC Exits DC Exits Key P POI AC Power Outlets Ext. Contact (Optional) SES V VAK VS

P SES

VS

AC Exits

VAK

P AC+DC Exits

DC Exits

Ammeters Milli-Ammeter L1, L2, L3, N, Ground (Section PS1) AC L1, N (Section PS2) / Ground / DC +, - (Section PS3) +, -, Ground (Section PS4) Key-Lock Protections Power On Indicator 1 x Three Phase, 2 x Single Phase A normally closed external contact may be used to control the unit, otherwise connect a jumper Start, Emergency, Stop Pushbuttons Voltmeters Voltage Adjust Knobs 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 phaseto-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. 9

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

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

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

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

−

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) 250mm

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

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

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 Newton’s /Meter are obtained by multiplying the load in Newtons (5) by the distance in Meters. (see Fig. 6)

Driving Motor

Zero Position Brake Dynamo

Balancing 5N Weight

Graduated Arm

Measuring 5N Weight

Figure 6 - Multiplying the load in Newton’s (5) by the distance in Meters.

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

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

Ammeter

Voltmeter

+

+

-

Power Analyzer

Current In Out

Voltage

R

U

X

S

V

Y

T

W

Z

N

N RS485

NOTE: The location of the instruments may be different from that illustrated above.

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

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

SETUP

3 DIGITAL DISPLAY

2

ENTER

4

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. 16

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

Display Readings: 1. Line Voltages V1, V2, V3

7. Reactive power VAr1, VAr2, VAr3

2. Phase Voltages V1-2, V2-3, V1-3

8. Integral ΣV, ΣI, ΣPF

3. Line Currents I1, I2, I3

9. Integral ΣVA, ΣW, ΣVar

4. Power Factors PF1, PF2, PF3

10. Frequency Hz

5. Apparent Power VA1, VA2, VA3

11. Energy VarH, Wh

6. Real Power W1, W2, W3

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 LAB ECB 3173 ELECTRICAL & ELECTRONICS ENG. PROG.

ELECTRICAL MACHINES ECB 3173 SINGLE PHASE CAGE ROTOR

Name

: : : :

Group No Lab Session Date Lecturer Gas

: : : : :

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

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LAB STAMP

:

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

ECB3173 Electrical Machines 1 Lab Presentation (ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and

Expect result, theoretical knowledge,

Preparation before

calculation and ground work of short

experiment

report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Excellent

Good

Average

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud

Stud.

Stud.

.1

2

3

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (2)

Exceptional (3)









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









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

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

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

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

Punctual

TOTAL

Examiner:

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

Rubric for Short Report Student: Experiment No.:

Course: Lecturer:

Date:

Average (2-3)

Good (4-5)

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.

Item Assessed

Low (0-1)

Objective, and scope of experiment

Score

21

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

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

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

CONNECTION DIAGRAM 23

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

3) 4) 5) 6)

1.4

Connect power and note the action of the rotor and the current drawn. What is the current drawn at (a) start-up and (b) 5 seconds after startWhat is the direction of rotation? 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. 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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ELECTRICAL MACHINES LAB ECB 3173 ELECTRICAL & ELECTRONICS ENG. PROG.

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

ELECTRICAL MACHINES ECB 3173

DIRECT CURRENT MOTOR (SHUNT WOUND) Name

: : : : : : : : :

Group No Lab Session Date Lecturer Gas

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

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LAB STAMP

:

26

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

ECB3173 Electrical Machines 1 Lab Presentation (ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and

Expect result, theoretical knowledge,

Preparation before

calculation and ground work of short

experiment

report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Excellent

Good

Average

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud

Stud.

Stud.

.1

2

3

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

Page 27 of 129

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (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









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

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

Exceptional (3)

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

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

Punctual

TOTAL

Examiner:

Page 28 of 129

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

Rubric for Short Report Student: Experiment No.:

Course: Lecturer:

Date:

Average (2-3)

Good (4-5)

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.

Item Assessed

Low (0-1)

Objective, and scope of experiment

Score

Page 29 of 129

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

2. DIRECT CURRENT MOTOR (SHUNT WOUND) 2.1

OBJECTIVES

To connect up, start and run a DC shunt motor 2.2

EQUIPMENT REQUIRED

1) 2) 3) 4) 5) 6) 7) 8) 9) 10)

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

2.3

CONDUCTING THE EXPERIMENT

1) 2) 3) 4) 5) 6) 7)

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

8) 9)

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

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

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

12) 13) 14)

15) 16) 17) 18) 19)

Call your instructor and check all connections are correct. Double check your circuit connection with your instructor to make the power connections. 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. Under no circumstances stop the rotation of the rotor with your hands or adjust the brush position with power connected. Repeat step 14 until the sparking at the brushes is at minimum. Why does the current reduce as the speed of the motor increases? Note the direction of the motor and the starting torque of the shunt connected motor. Switch off

Page 32 of 129

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

Connection Diagram Page 33 of 129

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

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

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

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

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

ELECTRICAL MACHINES ECB 3173 TRANSFORMER EXPERIMENT

Name

: : : : : : : : :

Group No Lab Session Date Lecturer Gas

SHORT REPORT : LONG REPORT :

----------CUT HERE----------------------------------------------------------------------------------------------------------------------

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LONG REPORT : LAB STAMP :

Page 36 of 129

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

ECB3173 Electrical Machines 1 Lab Presentation (ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and

Expect result, theoretical knowledge,

Preparation before

calculation and ground work of short

experiment

report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Excellent

Good

Average

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud

Stud

Stud.

.1

.2

3

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

Page 37 of 129

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (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









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

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

Exceptional (3)

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

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

Punctual

TOTAL

Examiner:

Page 38 of 129

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

Rubric for Short Report Student: Experiment No.:

Course: Lecturer:

Date:

Average (2-3)

Good (4-5)

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.

Item Assessed

Low (0-1)

Objective, and scope of experiment

Score

Page 39 of 129

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

Rubric for Long Report Course :

Date:

Student:

Student ID:

Topic (Weight) Introduction • Background • Objective • Scope

Unacceptable (0)

(3)

Results/Findings/Analysis (3)

Report Organization (2)

Acceptable (2)































Unable to state the introduction clearly

Not explained or not related to the project

No results or plagiarized work are presented

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

State the introduction with limited information

Not clearly explained or partially related to the project

Minimum results are presented and analyzed

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

Able to state the introduction with minor error

Important knowledge are covered but still missing some important concept

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

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

Points

Exceptional (3)



(2) Theoretical Knowledge/ Literature Review

Marginal (1)

Able to state the introduction clearly

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

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

Report very well written and easy to understand

TOTAL

Examiner:

Page 40 of 129

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

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

3.1.4

FORMULAE PARAMETER

SYMBOL

UNIT

Winding Voltage Winding Current Winding Resistance

V I R

Volts Amperes Ohms

R=V/I

for single phase transformer

R=V/I * 2

for STAR connected three phase transformers

COMPONENTS

Single Phase Transformer Power Supply Cables Cables Support Ammeter (A) Voltmeter (V)

Model A4110 Model A0240 Model A4890 Model A4891 With adequate range for this test With adequate range for this test

Page 41 of 129

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

3.1.5

CIRCUIT DIAGRAMS

Single Phase Transformer Primary + DC 0-24V

Secondary

A V

_

Page 42 of 129

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

Connection Diagram

V

A

A4110

Figure 1 . Connection Diagram

Page 43 of 129

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

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.

Page 44 of 129

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

3.1.7

WORKSHEETS Parameter

Symbol

Unit

Value

PRIMARY Winding Voltage

220V

%

Winding Voltage

V

V

Winding Current

I

A

Winding Resistance

R

Ω

2

4

6

8

9

2

4

6

8

9

2

4

6

8

9

SECONDARY Winding Voltage

160V

%

Winding Voltage

V

V

Winding Current

I

A

Winding Resistance

R

Ω

Winding Voltage

220V

%

Winding Voltage

V

V

Winding Current

I

A

Winding Resistance

R

Ω

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

Page 45 of 129

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

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 24Vac

160v

> 230Vac 0v

AC

110v

DC ┼

┼

┴

V

220v

A 0v

0v

Figure 3 . Connection Diagram

Page 53 of 129

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

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)

Page 54 of 129

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

3.3.7

WORKSHEETS Parameter

Symbol

Unit

220V

%

Winding Voltage

V

V

Current

A

A

Wattmeter

W

W

Input Voltage

Power Factor

Value

1

2

3

4

5

Cos ϕ

Reactance

Ω

Impedance

Ω

Resistance

Ω Table 3 . Short Circuit Test

Transformer Model:

Page 55 of 129

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

Cos ϕ P V

I (Amp) Graph 1 . Short Circuit Test

Page 56 of 129

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

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 Current Input Power Power Power Factor

V I P W Cosϕ

Volts Amperes Watts Watts

Single phase transformers:

3.4.4

P= I = Cosϕ =

W P/(V * Cosϕ) P/(V * I)

COMPONENTS

Single Phase Transformer Power Supply Cables Cables Support Ammeters (A) Wattmeters (W) Voltmeter (V)

Model A4110 Model A0240 Model A4890 Model A4891 With adequate range for this test With adequate range for this test With adequate range for this test

Page 57 of 129

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

3.4.5

CIRCUIT DIAGRAMS

Single Phase Transformer Primary A AC 0-220V

Secondary

W1 V

Page 58 of 129

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

Connection Diagram

Digital Multimeter

Transformer

A

Power supply

220v

>24Vac

>230Vac

160v

0v

AC

110v

220v

DC

┼

┼

┴

V

A 0v

0v

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)

Page 59 of 129

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

3.4.7

WORKSHEETS

Parameter

Symbol

Unit

220V

%

Winding Voltage

V

V

Current

A

A

Wattmeter

W

W

Input Voltage

Power Factor

Value

20

40

60

80

100

Cos ϕ Table 4 .No Load Test

Transformer Model:

Page 60 of 129

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

P

V Graph 2 . No Load Test

Transformer Model:

Page 61 of 129

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

I

V Graph 3. No Load Test Transformer Model:

Page 62 of 129

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

ELECTRICAL MACHINES ECB 3173

ASYNCHROUNOUS MACHINES EXPERIMENT Name

: : : : : : : : :

Group No Lab Session Date Lecturer Tutor(s) GAs

SHORT REPORT : LONG REPORT :

----------CUT HERE----------------------------------------------------------------------------------------------------------------------

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LONG REPORT : LAB STAMP :

Page 63 of 129

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

ECB 3173 Electrical Machines 1 Lab Presentation(ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and

Expect result, theoretical knowledge,

Preparation before

calculation and ground work of short

experiment

report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Excellent

Good

Average

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud.

Stud.

Stud.

1

2

3

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

Page 64 of 129

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (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









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

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

Exceptional (3)

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

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

Punctual

TOTAL

Examiner:

Page 65 of 129

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

Rubric for Short Report Student: Experiment No.:

Course: Lecturer:

Date:

Average (2-3)

Good (4-5)

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.

Item Assessed

Low (0-1)

Objective, and scope of experiment

Score

Page 66 of 129

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

Rubric for Long Report Course :

Date:

Student:

Student ID:

Topic (Weight) Introduction • Background • Objective • Scope

Unacceptable (0)

(3)

Results/Findings/Analysis (3)

Report Organization (2)

Acceptable (2)































Unable to state the introduction clearly

Not explained or not related to the project

No results or plagiarized work are presented

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

State the introduction with limited information

Not clearly explained or partially related to the project

Minimum results are presented and analyzed

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

Able to state the introduction with minor error

Important knowledge are covered but still missing some important concept

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

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

Points

Exceptional (3)



(2) Theoretical Knowledge/ Literature Review

Marginal (1)

Able to state the introduction clearly

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

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

Report very well written and easy to understand

TOTAL

Examiner:

Page 67 of 129

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

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 Power 2 Power 3 Armature Voltage Armature Current No Load Power Factor

W1 W2 W3 V I Cosϕ

Watts Watts Watts Volts Amperes

Three Phase Motor:

P= I = Cosϕ =

W1 + W2+W3 P/( 3 * V * Cosϕ) P/( 3 * I * V)

Page 68 of 129

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

4.1.4

COMPONENTS

Squirrel Cage Asynchronous Motor Power Supply Cables Cables Support Three phase analyzer

4.1.5

Model Model Model Model Model

A4220 A0240 A4890 A4891

A4750D

CIRCUIT DIAGRAMS

Three Phase Motors Squirrel Cage Motor.

PS1

Three Phase Analyzer

M 3 Phases

Page 69 of 129

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

Connection Diagram

A0240

Section PS1 P

A

A

Sections PS2 - 3 A

A V

Key

POI

Section PS4 mA

V

V

VAK

VAK

P Overspeed AC Power Outlets

P SES

VS

AC Exits

Ammeter Analyzer

P AC + DC Exits

DC Exits

Voltmeter

Power

R

U

X

S

V

Y

T

W

Z

N

N

A4220

RS485

U1 V1 W1

V2 W2 U2

Figure 1 . Connection Diagram Page 70 of 129

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

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

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

4.1.7

WORKSHEETS

Three Phase Parameter

Symbol

Unit

220V

%

Winding Voltage

V

V

Armature Current

I

A

Wattmeter 1

W1

W

Wattmeter 2

W2

W

Wattmeter 3

W3

W

P

W

Armature Voltage

No Load Power No Load Power Factor

Value

120

100

80

60

40

20

Cos ϕ Table 1 . No Load Test

Motor Model :

Page 72 of 129

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

I P Cos ϕ

V Graph 1. No Load Test

Motor Model:

Page 73 of 129

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

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 Power 2 Power 3 Armature Voltage Armature Current Short Circuit Power Factor

W1 W2 W3 V I Cosϕ

Watts Watts Watts Volts Amperes

P

=

Cosϕ =

W1 + W2+W3 = P/

3 * V * I * Cosϕ

3 *V*I

Page 74 of 129

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

4.2.4

COMPONENTS

Asynchronous Motor Power Supply Cables Cables Support Three phase analyzer Rotor Mechanical Lock 4.2.5

Model Model Model Model Model

A4220 A0240 A4890 A4891

A4750D

CIRCUIT DIAGRAMS Theoretical Diagram

Squirrel Cage Motor Rotor Mechanical Lock

PS1

Three Phase Analyzer

Asynchronous Motor

Page 75 of 129

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

Connection Diagram

A0240

Section PS1 P

A

Sections PS2 - 3 A

A

A V

Key

POI

Section PS4 mA

V

V

VAK

VAK

P Overspeed AC Power Outlets

P SES

VS

AC Exits

Ammeter Analyzer

P AC + DC Exits

DC Exits

Voltmeter

Power

R

U

X

S

V

Y

T

W

Z

N

N

A4220

RS485

U1 V1 W1

Rotor Mechanical Lock V2 W2 U2

Figure 2 . Connection Diagram

* The rotor must be locked with the Rotor Mechanical Lock device provided. Page 76 of 129

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

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

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

4.2.7

WORKSHEETS Parameter

Symbol

Unit

Armature Current

0.6Amp

%

Armature Voltage

V

V

Armature Current

I

A

Wattmeter 1

W1

W

Wattmeter 2

W2

W

Wattmeter 3

W3

W

Value

100

85

70

55

40

25

Table 2 . Short Circuit Test Motor Model:

Page 78 of 129

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

I sc Psc Cosϕ

V Graph 2 . Short Circuit Test

Motor Model:

Page 79 of 129

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

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

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

4.3.3

FORMULAE

PARAMETER

SYMBOL

UNIT

Armature Voltage Armature Curent Arm Length Weight Torque Speed Excitation Curent Input Power Output Power Power 1 Power 2 Power 3 Efficiency

V I a G T n Ie Pi Po W1 W2 W3 η

Volts Ampères m N Nm min-1 Ampères Watts Watts Watts Watts Watts

T =G*a Po = 2 π n T/60 Pi = W1 + W2 + W3 = Cosϕ = Pi / ( 3 * V * I) η = Po / Pi

3 * V * I * Cosϕ For three phase motor

Page 81 of 129

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

4.3.4

COMPONENTS

Three Phase Squirrel Cage Motor Braking DC Generator Coupling Base Power Supply Resistive Load Cables Cables Support Three phase analyzer RPM meter 4.3.5

Model Model Model Model Model Model Model Model

A4220 A4430 A4840 A0240 A4510 A4890 A4891

A4750D

CIRCUIT DIAGRAMS Theoretical Diagram

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

PS1

Three Phase Analyzer

M 3 Phase

G

A2

PS4

Page 82 of 129

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

Connection Diagram

A0240

Section PS1

Sections PS2 - 3

Section PS4

Figure 3 . Connection Diagram Page 83 of 129

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

4.3.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 3) and must be grounded. The motor must be coupled to the brake dynamo. MANUAL DATA COLLECTION AND ANALYSIS Calibrate the torque meter as shown in Fig. 3.1.

Fig. 3.1 - Set-up for full scale adjustment using a magnetic brake (Example) Hang a 5 N weight on the torque arm at a distance of exactly 110 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. Adjust the Full Scale trimmer for an indication calculated as follows: T = torque = 5 N x 0.11 m = 0.55

Nm

Remove the 5 N weights and avoid excessive stress of the load cell so that the calibration remains stable.

Page 84 of 129

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

Connect the circuit as shown in Fig. 3.

Set the excitation voltage PS4 to nominal output voltage 220V and drive motor voltage PS1 380V is reached. Step up the three resistive (A4510) load rotary switches by one position at a time. Enter the read values in the worksheet table.( Table 3) Plot the graphs of the load characteristics.(Graph 3) Notes: Measurements should be made as quick as possible to avoid overheating. 4.3.7

WORKSHEETS

Three Phase Parameter

Symbol

Load / Nominal Load

Unit Step

Armature Voltage

PS1

V

Armature Current

A

A

Arm Length

a

m

Torque

T

Nm

Speed

n

rpm

PS4

A

Power Input

Pi

W

Power Output

Po

W

Power 1

W1

W

Power 2

W2

W

Power 3

W3

W

Excitation Current

Efficiency

Value 6

5

4

3

2

1

η Table 3 . Determination of Working Characteristics

Machine Model:

Page 85 of 129

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

I n T η

Pi Graph 3 . Determination of Working Characteristics

Machine Model:

Page 86 of 129

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

ELECTRICAL MACHINES ECB 3173

SYNCHROUNOUS MACHINES EXPERIMENT Name

: : : :

Group No Lab Session Date Lecturer Tutor(s)

: : : : : :

SHORT REPORT : LONG REPORT :

----------CUT HERE----------------------------------------------------------------------------------------------------------------------

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LONG REPORT : LAB STAMP : Page 87 of 129

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

ECB 3173 Electrical Machines 1 Lab Presentation(ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and

Expect result, theoretical knowledge,

Preparation before

calculation and ground work of short

experiment

report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Excellent

Good

Average

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud.

Stud.

Stud.

1

2

3

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

Page 88 of 129

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (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









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

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

Exceptional (3)

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

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

Punctual

TOTAL

Examiner:

Page 89 of 129

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

Rubric for Short Report Student: Experiment No.:

Course: Lecturer:

Date:

Average (2-3)

Good (4-5)

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.

Item Assessed

Low (0-1)

Objective, and scope of experiment

Score

Page 90 of 129

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

Rubric for Long Report Course :

Date:

Student:

Student ID:

Topic (Weight) Introduction • Background • Objective • Scope

Unacceptable (0)

(3)

Results/Findings/Analysis (3)

Report Organization (2)

Acceptable (2)































Unable to state the introduction clearly

Not explained or not related to the project

No results or plagiarized work are presented

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

State the introduction with limited information

Not clearly explained or partially related to the project

Minimum results are presented and analyzed

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

Able to state the introduction with minor error

Important knowledge are covered but still missing some important concept

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

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

Points

Exceptional (3)



(2) Theoretical Knowledge/ Literature Review

Marginal (1)

Able to state the introduction clearly

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

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

Report very well written and easy to understand

TOTAL

Examiner:

Page 91 of 129

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

5. AC SYNCHRONOUS MACHINES LABORATORY 5.1

NO LOAD TEST

This experiment is performed on a Synchronous Machine. 5.1.1

OBJECTIVES

Plot the magnetization characteristics of a synchronous generator. 5.1.2

THEORETICAL REVIEW

This experiment shows the electromotive force Eo against the excitation current Ie. The resulting graph shows that for the same value of excitation current there are two different values of electromotive force, one for the ascending and one for the descending curves. Usually the medium value of Eo is considered. The area enclosed in the magnetization loop represents the power losses for magnetic hysteresis (residual magnetism) in the armature iron. 5.1.3

FORMULAE PARAMETER

SYMBOL

UNIT

Voltage Excitation Current Pair of Poles Speed Frequency Theoretical Frequency Theoretical Speed Theoretical Voltage

E 01 Ie p n1 F1 f n E0

Volts Amperes rpm Hz Hz rpm Volts

E 0 /E 01 = n/n 1 E 0 =E 01 * (n/n 1 ) = E 01 * (f/F 1 ) n 1 = (60 * f)/p

5.1.4

COMPONENTS

Three Phase Synchronous Machine

Model

A4223 Page 92 of 129

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

Squirrel Cage Three Phase Drive Motor Power Supply Cables Cables Support Coupling Base Three Phase Analyzer RPM meter 5.1.5

Model Model Model Model Model Model

A4220 A0240 A4890 A4891 A4840 A4750D

CIRCUIT DIAGRAMS

V Generator 3 Phase

PS4

Three Phase Analyzer F

A

PS1

Motor PS1 3 Phase

Page 93 of 129

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

Connection Diagram

A0240

Section PS1

Sections PS2 - 3

Section PS4

Figure 1 . Connection Diagram

Page 94 of 129

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

5.1.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 1) and must be grounded. The synchronous machine is mechanically coupled to the driving asynchronous motor. MANUAL DATA COLLECTION AND ANALYSIS -

Set the excitation voltage PS4 and drive motor voltage PS1 = 0

-

Switch on the power supply and adjust PS1 to nominal motor voltage (380V). When the motor is up to speed gradually increase the excitation current from 0% to 100% in 10% steps.

-

At each step enter in the worksheet table the values of the excitation current I e , voltage E 01 and frequency F 1 .(Table 1)

-

Repeat the above steps while decreasing Ie from 100% to 10%

-

If during the experiment the frequency F 1 varies, adjust it to the theoretical value (f) with the above formula. Do the same for voltage E 01 to the theoretical value (E 0 )

-

To stop the machines turn back the PS 4 to ‘0’ position first and PS 1 to ‘0’ position.

-

Press Stop Button.

Plot the graph.(Graph 1)

Page 95 of 129

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

5.1.7

WORKSHEETS

Parameter

Symbol

Unit

Excitation Current

0.2Amp

%

Excitation current

Ie

A

Eo1

V

F1

Hz

Excitation Current

0.2Amp

%

Excitation Current

Ie

A

Eo1

V

F1

Hz

Voltage Frequency

Voltage Frequency

Value

10

20

30

40

50

60

70

80

90

100

100

90

80

70

60

50

40

30

20

10

Table 1. No Load Test Machine Model:

Page 96 of 129

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

Eo

Ie Graph 1. No Load Test Machine Model:

Page 97 of 129

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

5.2

SHORT CIRCUIT TEST

This experiment is performed on a Synchronous Machine. 5.2.1

OBJECTIVES

Plot the short circuit characteristics of a synchronous generator. The short circuit diagram shows the output current versus the excitation current when the armature windings are short circuited. 5.2.2

THEORETICAL REVIEW

This test is performed by driving the generator to a speed close to nominal and by measuring the short circuit current while stepping up the excitation current. It is not necessary to measure the output frequency as the short circuit current is largely independent from speed when the generator is running close to nominal RPM. 5.2.3

MEASUREMENTS PARAMETER

SYMBOL

UNIT

Excitation Current Current 1 Current 2 Current 3 Short Circuit Current

A1 A2 A3 A4 Isc

Amperes Amperes Amperes Amperes Amperes

Page 98 of 129

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

5.2.4

COMPONENTS

Three Phase Synchronous Machine Squirrel Cage Three Phase Drive Motor Power Supply Coupling Base Cables Cables Support Coupling Base Three phase analyzer 5.2.5

Model Model Model Model Model Model Model Model

A4223 A4220 A0240 A4840 A4890 A4891 A4840

A4750D

CIRCUIT DIAGRAMS Theoretical Diagram

A1

Generator 3 Phase

PS4

Three Phase A2 Analyzer

A4

PS1

Motor 3 Phase

Page 99 of 129

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

Connection Diagram

A0240

Section PS1

Sections PS2 - 3

Section PS4

Figure 2 . Connection Diagram

Page 100 of 129

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

5.2.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 2) and must be grounded. The synchronous machine is mechanically coupled to the driving asynchronous motor. MANUAL DATA COLLECTION AND ANALYSIS -

Set the excitation voltage PS4 and motor supply voltage PS1 = 0

-

Switch on the power supply. Start the driving motor

-

When the motor reaches nominal speed by adjusting (PS1 to 380V), step up the excitation current (PS4) Ie until nominal current (0.2Amp) is reached.

-

At each step enter in the worksheet table the values of the excitation and generator currents.(Table 2)

-

Calculate the short circuit current as the average of the generator currents.

-

Plot the graph.(Graph 2)

NOTE: Since the short circuit test graph is linear, short circuit current (Isc) can be drawn by measuring only two points.

Page 101 of 129

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

5.2.7

WORKSHEETS

Parameter

Symbol

Unit

Excitation Current

0.2Amp

%

Excitation current

Ie-A4

A

Current 1

A1

A

Current 2

A2

A

Current 3

A3

A

Short Circuit Curr.

Isc

A

Parameter

Symbol

Unit

Excitation Current

0.2Amp

%

Excitation current

Ie-A4

A

Current 1

A1

A

Current 2

A2

A

Current 3

A3

A

Short Circuit Curr.

Isc

A

Value 10

20

30

40

50

60

70

80

90

100

40

30

20

10

Value 100

90

80

70

60

50

Table 2 . Short Circuit Test Machine Model:

Page 102 of 129

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

Isc

Ie Graph 2 . Short Circuit Test

Machine Model:

Page 103 of 129

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

5.3

DETERMINATION OF THE EXTERNAL CHARACTERISTICS

This experiment is performed on a Synchronous Machine 5.3.1

OBJECTIVES

Plot the external characteristics of a synchronous generator with constant excitation current and constant power factor. 5.3.2

THEORETICAL REVIEW

The load of an alternator affects its output voltage. How it is affected depends on the kind of load. With a resistive load the power factor is "1" and the output voltage may drop 8 to 20% from its noload value. An inductive load such as induction motors causes a lagging power factor and an output voltage drop as much as 25 to 50% below its no-load value. A capacitive load causes a leading power factor and an increase in output voltage above the no-load value. These voltage variations are due to: Resistance drops in the armature windings Changes in flux Reactance voltage In fact, when the load current is capacitive the reaction ampere-turns increase the magnetization while when the load current is inductive they decrease it. 5.3.3

FORMULAE PARAMETER

SYMBOL

UNIT

Output Voltage Load Current Excitation Current

V I I2

Volts Amperes Amperes

P=V*I

Page 104 of 129

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

5.3.4

COMPONENTS

DC Motor (or other drive motor) Three Phase Synchronous Machine Power Supply Cables Cables Support Coupling Base Resistive Load (R1) Capacitive Load (C1) Inductive Load (L1) Three phase analyzer 5.3.5

Model Model Model Model Model Model Model Model Model Model

A4244 A4223 A0240 A4890 A4891 A4840 A4510 A4520 A4530

A4750D

CIRCUIT DIAGRAMS Theoretical Diagram

V PS1

M

G

Threephase analyzer F

A2

R Load

C Load

L Load

PS4

Page 105 of 129

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

Connection Diagram

A0240

Section PS1

Sections PS2 - 3 Section PS4

Figure 3 . Connection Diagram

Page 106 of 129

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

5.3.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 3) and must be grounded. The synchronous machine is mechanically coupled to the driving motor. MANUAL DATA COLLECTION AND ANALYSIS 1. Reset the three loads and power supplies PS1 and PS4 to the 0 position. 2. Switch on the power supply. 3. Adjust the motor's speed to about nominal speed by adjusting PS1 to 380V. 4. Adjust the excitation voltageuntil the no-load alternator(Synchronous Generator) nominal output voltage Vo is reached(PS4 to 220V). 5. Step up the three resistive (A4510)load rotary switches by one position at a time 6. At each step enter in the worksheet table the output voltage V and current A1.( Table 3 ) 7. When full load is reached, repeat step no 5 & 6 with the capacitive (A4520)and inductive (A4530) loads. 8. Plot the graph.(Graph 3) NOTE: The experiment must be performed with constant alternator excitation current.

Page 107 of 129

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

5.3.7

WORKSHEETS

Parameter

Symbol

Unit

Load

R

Step

Line Voltage

V

V

Excitation Current

Ie

A

I

A

Symbol

Unit

Load

C

Step

Line Voltage

V

V

Excitation Current

Ie

A

I

A

Symbol

Unit

Load

L

Step

Line Voltage

V

V

Excitation Current

Ie

A

I

A

Line Current

Parameter

Line Current

Parameter

Line Current

Value 1

2

3

4

5

6

5

6

5

6

Value 1

2

3

4

Value 1

2

3

4

Table 3. Determination of the external characteristics Machine Model:

Page 108 of 129

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

V

(R/C/L) Graph 3 . Determination of the external characteristics

Machine Model:

Page 109 of 129

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

ELECTRICAL MACHINES ECB 3173 DC MACHINES EXPERIMENT

Name

: : : :

Group No Lab Session Date Lecturer Tutor(s)

: : : : : :

SHORT REPORT : LONG REPORT :

----------CUT HERE----------------------------------------------------------------------------------------------------------------------

NAME

: : :

DATE OF SUBMITTED: SHORT REPORT : LONG REPORT : LAB STAMP :

Page 110 of 129

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

ECB 3173 Electrical Machines 1 Lab Presentation (ViVa) Marking Scheme No

Students Name

ID

1 2 3 4

Experiment No / Topic: ……………………….

Date/Time:………………………..

Score Category

Criteria for Judging

Attend the viva session on time as

Punctuality

agreed.

Analysis and Preparation before experiment

Excellent

Good

Averag e

Poor

Bad

(2)

(1.5)

(1)

(0.5)

(0)

(35)

(27)

(22)

(10)

(0)

(50)

(38)

(32)

(15)

(0)

(13)

(10)

(8)

(3)

(0)

Stud.

Stud.

Stud.

1

2

3

Expect result, theoretical knowledge, calculation and ground work of short report.

Knowledge &

Understanding of the topic and

Understanding

accurate answer to questions posed

(Comprehension)

by instructor.

Clarity of speaking and confident

Clarity of and accuracy of the words & sentences and confident in answering questions. Total Score

Approved by,

………………………………….. Lab Instructor Name: Date:

111

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

Rubric For Lab Assesment Topic (Weight)

Execution of Procedures (2)

Focus of Results and Discussion (3)

Safety & Health Issues (1)

Participation in Teamwork (If applicable) (3)

Punctuality (1)

Unacceptable (0)

Marginal (1)

Acceptable (2)

Exceptional (3)









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









No insight. Entirely Little insight. missed the point Analyzed only the of the experiment most basic points

Adequate insight. Missed some important points

Excellent insight. Results and discussion well focused

























No understanding or appreciation of safety and health related issues

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

>10 minutes late

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

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

6-10 minutes late

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

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

1-5 minutes late

Points

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

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

Punctual

TOTAL

Examiner:

112

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

Rubric for Short Report Student: Experiment No.:

Item Assessed

Course: Lecturer:

Low (0-1)

Average (2-3)

Good (4-5)

Date:

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.

Score

113

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

Rubric for Long Report Course :

Date:

Student:

Student ID:

Topic (Weight) Introduction • Background • Objective • Scope (2) Theoretical Knowledge/ Literature Review (3)

Results/Findings/Analysis (3)

Report Organization (2)

Unacceptable (0)

Marginal (1)

Acceptable (2)

Exceptional (3)

































Unable to state the introduction clearly

Not explained or not related to the project

No results or plagiarized work are presented

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

State the introduction with limited information

Able to state the introduction with minor error

Not clearly Important explained or knowledge are partially related to covered but still the project missing some important concept

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

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

Points

Able to state the introduction clearly

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

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

Report very well written and easy to understand

TOTAL

Examiner:

114

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

6. DC MACHINES LABORATORY 6.1

MEASUREMENT OF THE WINDINGS RESISTANCE

6.1.1

OBJECTIVES

Calculate the winding resistance of shunt DC machines with the Volt-Ampere method (Ohm's Law). 6.1.2

THEORETICAL REVIEW

The windings resistance cause internal voltage drops that reduce the machine’s efficiency. Therefore it must be as low as possible. It is calculated by applying known DC voltages and measuring the resulting current flows. 6.1.3

FORMULAE PARAMETER

SYMBOL

UNIT

Winding Voltage Winding Current Winding Resistance

V I R

Volts Amperes Ohms

R=V/ I 6.1.4

COMPONENTS

DC Shunt Excitation Machine Power Supply Cables Cables Support Ammeter Voltmeter

Model A4244 Model A0240 Model A4890 Model A4891 With adequate range for this test With adequate range for this test

115

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

6.1.5

CIRCUIT DIAGRAMS Theoretical Diagram

Shunt Excitation Machine The shunt excitation winding has accessible ends for measuring its resistance

A PS3

V

DC Machine

116

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

Connection Diagram

A0240

Section PS1 P

Key

A

POI

A

Sections PS2 - 3

Section PS4

A

A

mA

V

V

V

VAK P

Overspeed

P

AC Power Outlets

SES

A

VS

VAK

P

AC Exits

AC

DC Exits

DC Exits

V

A4244 A1

G

B1

A2

B2

Figure 1 . Connection Diagram

117

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

6.1.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 1) and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS -

Set the D.C. windings voltage PS3 = 0 V.

-

Switch on the power supply. Increase PS3 gradually by operating on the front knob. It must be increased in 2% steps up to 10 % max. Do not exceed 10 % of nominal winding voltage to avoid excessive winding temperature

-

Measure the voltage and current for any step and enter them in the worksheet tables. ( Table 1)

-

Repeat the above steps for field winding and calculate their resistance with the formula given above. ( Table 2 )

118

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

6.1.7

WORKSHEETS

Parameter

Symbol

Unit

Winding Voltage

220V

%

Winding Voltage

V

V

Winding Current

I

A

Winding Resistance

R

Ω

Value

2

4

6

8

10

Table 1 . Measurement of the windings resistance Machine Model:

Parameter

Winding: Armature

Symbol

Unit

Winding Voltage

220V

%

Winding Voltage

V

V

Winding Current

I

A

Winding Resistance

R

Ω

Value

2

4

6

8

10

Table 2 . Measurement of the windings resistance Machine Model:

Winding: Field

119

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

6.2

MAGNETIC CHARACTERISTICS

This experiment can be performed on shunt excitation DC generators. 6.2.1

OBJECTIVES

Plot the magnetization characteristics of a DC machine. 6.2.2

THEORETICAL REVIEW

This experiment shows the electromotive force Eo against the excitation current Ie. The resulting graph shows that for the same value of excitation current there are two different values of electromotive force, one for the ascending and one for the descending curves. Usually the medium value of Eo is considered. The area enclosed in the magnetization loop represents the power losses for magnetic hysteresis (residual magnetism) in the armature iron. 6.2.3

6.2.4

MEASUREMENTS PARAMETER

SYMBOL

UNIT

Armature Voltage Excitation Current Speed

V Ie n

Volts Ampères rpm

COMPONENTS

DC Shunt Excitation Machine Slip Ring Three Phase Drive Motor Power Supply Cables Cables Support Coupling Base Ammeter Voltmeter RPM Meter

Model A4244 Model A4223 Model A0240 Model A4890 Model A4891 Model A4840 With adequate range for this test With adequate range for this test

120

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

6.2.5

CIRCUIT DIAGRAMS Theoretical Diagram

A

PS1

M 3 Phase

DC Machine

+

V

PS4

_

121

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

Connection Diagram

A0240

Section PS1 P

A

A

Sections PS2 - 3 A

A V

Key

POI

Section PS4 mA

V

V

VAK P

Overspeed AC Power Outlets

P SES

VS

P

AC Exits

AC + DC Exits

DC Exits

V

A4223 A4222

A

A4244

U1 V1 W1 A1

V2 W2 U2

VAK

B1

G

A2 B2

Figure 2 . Connection Diagram

122

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

6.2.6 Conducting the experiment The components must be connected as shown in the in the connection diagrams (Fig. 2) and must be grounded. The DC machine is mechanically coupled to the driving motor (3 Phase squirrel cage motor or single phase split phase/capacitor motor). MANUAL DATA COLLECTION AND ANALYSIS -

Set the excitation voltage PS4 and drive motor supply voltage PS1 = 0

-

Switch on the power supply and adjust PS1 to nominal motor voltage.

-

When the motor is up to speed gradually increase the excitation current from 0% to 100% in 10% steps by adjusting PS4.

-

At each step enter in the worksheet table the values of voltage and excitation current. ( Table 2 )

-

Repeat the above steps while decreasing the excitation current from 100% to 10%

-

Plot of the ascending and descending in the same graph .( Graph 1)

6.2.7

WORKSHEETS

Parameter

Symbol

Unit

Excitation Current

0.2Amp

%

Excitation current

Ie

A

Voltage

V

V

Speed

n

rpm

Excitation Current

0.2Amp

%

Excitation Current

Ie

A

Voltage

V

VA

Speed

n

rpm

Value 10

20

30

40

50

60

70

80

90

100

100

90

80

70

60

50

40

30

20

10

Table 2 . Magnetic characteristics Machine Model:

123

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

V

Ie Graph 1 . Magnetic characteristics

Machine Model:

124

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

6.3

NO LOAD TEST

6.3.1

OBJECTIVES

The experiment is designed to measure the mechanical plus iron losses. 6.3.2

THEORETICAL REVIEW

The mechanical losses are caused by friction on bearings, brushes and ventilation. They are not affected by the load and depend only on rotation speed. Copper losses may be disregarded due to the low current absorbed in these conditions. When in rotation, the rotor is subject to the alternating flux generated by the excitation winding on the stator and this causes the iron losses due to hysteresis and Eddy currents. 6.3.3

FORMULAE PARAMETER

SYMBOL

UNIT

Armature Voltage Armature Current Input Power (no-load) Mechanical Losses Magnetic Losses

Va Ia P Pm Pfe

Volts Amperes Watts Watts Watts

P = Va * Ia = Pm + PFe 6.3.4

COMPONENTS

DC Shunt Excitation Machine Power Supply Cables Cables Support Coupling Base Ammeter Voltmeter RPM Meter

Model A4244 Model A0240 Model A4890 Model A4891 Model A4840 With adequate range for this test With adequate range for this test

125

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

6.3.5

CIRCUIT DIAGRAMS Theoretical Diagram

Shunt Excitation

A

PS4

PS3

V

M

126

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

Connection Diagram

A0240

Section PS1 P

Key

A

POI

A

Sections PS2 - 3

Section PS4

A

A

mA

V

V

V

VAK P

Overspeed AC Power Outlets

P SES

VS

VAK

P

AC Exits

AC

DC Exits

DC Exits

V

A

A4244 A1

M

B1

A2

B2

Figure 3 . Connection Diagram 127

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

6.3.6

Conducting the experiment

The components must be connected as shown in the in the connection diagrams (Fig. 3) and must be grounded. MANUAL DATA COLLECTION AND ANALYSIS -

Set the excitation voltage PS4 and armature voltage PS3 = 0

-

Switch on the power supply and adjust PS4 to nominal voltage (220V). Start the motor by gradually increasing the armature voltage PS3 until reach speed 3000 rpm by using tachometer.

-

When the motor is at speed 3000 rpm , measure the current and voltage and enter the values in the worksheet table. (Table 3)

-

Decrease PS3 (-10 Volt).

-

Decrease PS4 and make sure the motor is still at nominal speed of 3000 rpm. Avoid making the excitation (PS4) current (voltage) too small or zero!!!.

-

The experiment is completed when the armature voltage is so low that the motor begins to slow down.

-

To stop the motor, adjust PS3=0, then after the motor stop, adjust PS4=0.

-

Plot the graph. ( Graph 2 )

128

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

6.3.7

WORKSHEETS

Parameter

Symbol

Unit

Armature Voltage

Va

V

Armature Current

Ia

A

No Load Losses

P

W

Value

Table 3 . No load test Machine Model:

P

Graph 2 . No load test

Va

Machine Model: 129