laxmmii s innsttittuuttee yooff … · iii perform direct loading test on alternator to find out...

1

LLAAXXMMII IINNSSTTIITTUUTTEE OOFF TTEECCHHNNOOLLOOGGYY,, SSAARRIIGGAAMM

CCOOUURRSSEE FFIILLEE

SSuubbjjeecctt NNaammee :: PPoollyypphhaassee TTrraannssffoorrmmeerrss aanndd RRoottaattiinngg AACC

MMaacchhiinneess

SSuubbjjeecctt CCooddee :: 33334400990011

CCoouurrssee NNaammee :: DDEE

SSeemmeesstteerr :: 44tthh

DDEEPPAARRTTMMEENNTT OOFF DDIIPPLLOOMMAA EELLEECCTTRRIICCAALL EENNGGIINNEEEERRIINNGG

Polyphase Transformers and Rotating AC Machines Course Code: 3340901

GTU/ NITTTR Bhopal/13-14 Gujarat State

GUJARAT TECHNOLOGICAL UNIVERSITY, AHMEDABAD, GUJARAT

COURSE CURRICULUM

COURSE TITLE: POLYPHASE TRANSFORMERS AND ROTATING AC

MACHINES

(Code: 3340901)

Diploma Programme in which this course is offered Semester in which offered

Electrical Engineering 4th

Semester

1. RATIONALE

Polyphase (mainly 3 phase) transformers are widely employed in power grids and

transmissions lines starting from generating station till the consumer end. Every generating

station uses alternators for electricity generation. Induction motors and Synchronous motors

are widely used in industries, farms and domestic applications. It is therefore must for

electrical engineers to posses knowledge and skills required to operate and maintain 3 phase

transformers, induction motors, synchronous motors and alternators. This course attempts to

develop these skills into the students.

2. COMPETENCY

The course content should be taught and implemented with the aim to develop different types

of skills so that students are able to acquire following competency:

Operate and Maintain transformers and rotating AC machines.

3. COURSE OUTCOMES

The theory should be taught and practical should be carried out in such a manner that students

are able to acquire different learning outcomes in cognitive, psychomotor and affective

domain to demonstrate following course outcomes.

i. Conduct various routine tests on 3 phase transformer.

ii. Operate 3- phase transformers in parallel.

iii. Select a 3- phase or 1- phase induction motor for a given application.

iv. Synchronize an alternator with bus bar or another alternator.

v. Use Synchronous machines for power factor improvement.

vi. Maintain rotating AC machines.

4. TEACHING AND EXAMINATION SCHEME

Teaching Scheme

(In Hours)

Total

Credits

(L+T+P)

Examination Scheme

Theory Marks Practical

Marks

Total

Marks

L T P C ESE PA ESE PA

200 4 0 4 8 70 30 40 60

Legends: L-Lecture; T – Tutorial/Teacher Guided Theory Practice; P - Practical; C – Credit, ESE - End Semester Examination; PA -

Progressive Assessment



5. COURSE DETAILS

Unit Major Learning Outcomes (in cognitive domain)

Topics and Sub-topics

Unit – I.

Poly Phase

Transformer

1a. Justify the advantage of using 3-

phase transformer over a bank of 3

single phase transformers

1b. With sketches explain the major parts

of the 3-phase transformer

1c. Sketch the different types of

connections of 3-phase transformer

including vector groups

1d. With sketches the describe the need of

parallel operation of 3 phase

transformers .

1e. State the maintenance procedure and

the transformer oil change process

1.1 Comparison of three phase transformer

with bank of three single phase

transformers.

1.2 Arrangement of Core and windings in

transformer, use of tap changer. Types

of losses in transformers.

1.3 Construction - Accessories of 3 phase

transformer: Main tank, bushings,

conservator with breather, oil level

gauge, radiators, buchholz relay,

explosion vent, temperature indicators,

junction box

1.4 Star delta connections and vector

groups

1.5 Cooling of transformer: Natural

cooling, Forced cooling

1.6 Parallel operation – Essential and

desirable Conditions

1.7 Maintenance of different types of

transformers

Unit– II

Poly Phase

Induction

Motors

2a. Explain how a rotational field is

produced in a 3 phase induction motor.

2b. Differentiate between squirrel cage

and wound rotor induction motor with

their salient features.

2c. Explain the torque slip characteristics

of squirrel cage and wound rotor

induction motor including the

generation operation.

2d. Explain various methods of speed

control of 3 phase induction motor.

2e. State the maintenance procedure of

both squirrel cage and wound rotor

induction motor

2.1 Construction, types - Squirrel cage -

Single and double cage, Wound rotor

2.2 Working principle with Torque-slip

curve, equivalent circuit and phasor

diagram

2.3 Torque equation , Starting, running

and condition for the maximum

torque

2.4 Necessary and types of starters- DOL,

Star delta, autotransformer type and

rotor resistance starter.

2.5 No load test and Blocked rotor test,

Losses and efficiency

2.6 Speed control of squirrel cage and

slip-ring inductionmotor


induction motors

Unit– III

Alternator

3a. Explain the working principle of an

alternator

3b. Differentiate between turbo

generator and hydrogenerators

3c. Derive emf equation

3d. Determine the voltage regulation

of an alternator by synchronous

impedance method

3e. Synchronize an alternator with

infinite bus bar.

3f. State the maintenance requirements

of the alternators including the

different cooling systems of the

alternators

3.1 Principle of working and construction.-

Salient and Cylindrical rotor

3.2 Equivalent circuit and phasor diagram

3.3 Voltage regulation by synchronous

impedance method, OC, SC

characteristics

3.4 Synchronization of alternator with bus

bar/alternator

3.5 Cooling system of alternator


alternators



Unit Major Learning Outcomes (in cognitive domain)

Topics and Sub-topics

Unit–IV

Synchronous

Motor

4a. Connect and operate synchronous

motor using proper starting method

4b. Improve the power factor of the

system using synchronous

condenser 4c. State the maintenance requirements

of the synchronous motor

4d. Differentiate the features between the

synchronous and induction motor

4.1 Principle of working, starting methods

4.2 Equivalent circuit and phasor diagram

4.3 Effect of change in excitation ‘V’-

curves

4.4 Synchronous condenser

4.5 Hunting and its prevention

4.6 Different torque of a synchronous

motor

4.7 Maintenance of synchronous motors

Unit-V

Single Phase

Induction

Motors

5a. Describe the working principle of

different types of single phase

motors.

5b. Describe the working principle of

different types of fractional horse

power motors

5c. Troubleshoot single phase

induction motor in a ceiling fan/

cooler

5d. State the maintenance requirements

of the single phase induction motor

5.1 Working of different types of single-

phase induction motors

5.2 Fractional horse power motors

5.3 Speed torque characteristics


single phase motors

6. SUGGESTED SPECIFICATION TABLE WITH HOURS AND MARKS (THEORY)

Unit

No.

Unit Title Teaching

Hours

Distribution of Theory Marks

R

Level

U

Level

A

Level

Total

Marks

I Polyphase Transformer 10 04 04 04 12

II Polyphase Indcution Motors 16 08 06 04 18

III Alternator 12 06 05 05 16

IV Synchronous Motor 10 04 06 04 14

V Single Phase Induction Motors 8 02 02 06 10

Total 56 24 23 23 70 Legends: R = Remember U = Understand; A = Apply and above levels (Bloom’s revised taxonomy)

Note: This specification table shall be treated as a general guideline for students and teachers. The actual

distribution of marks in the question paper may vary slightly from above table.

7. SUGGESTED LIST OF EXERCISES/PRACTICALS

The practical/exercises should be properly designed and implemented with an attempt to

develop different types of skills (outcomes in psychomotor and affective domain) so that

students are able to acquire the competencies/programme outcomes. Following is the list of

practical exercises for guidance.

Note: Here only outcomes in psychomotor domain are listed as practical/exercises. However,

if these practical/exercises are completed appropriately, they would also lead to development

of certain outcomes in affective domain which would in turn lead to development of Course

Outcomes related to affective domain. Thus over all development of Programme Outcomes

(as given in a common list at the beginning of curriculum document for this programme)

would be assured.

Faculty should refer to that common list and should ensure that students also acquire

outcomes in affective domain which are required for overall achievement of Programme

Outcomes/Course Outcomes.



S. No. Unit

No.

Practical Exercises

(outcomes in Psychomotor Domain)

Approx

Hours.

required

1

I Identify various accessories of three phase transformer by

visiting to nearby substation and draw its sketch with

cooling arrangement .

4

2 I Perform parallel operation on three phase transformer. 4

3 II Measure the slip of 3-phase Induction motor by using

Tachometer and by Stroboscopic method. 4

4 II Reverse the direction of rotation of a 3-phase IM. 2

5 II Perform direct load test on three phase induction motor and draw

performance curves 4

6

II Perform no load and blocked rotor test on a three phase induction

motor to obtain various parameters. Also construct circle

diagram to determine its performance characteristics.

4

7

II Make connections of DOL starter / star-delta starter / auto

transformer / rotor rheostat starter for appropriate three phase

induction motor.

8

8

II Perform speed control of squirrel cage induction motor by:

1. By changing the supply voltage.

2. By changing the applied frequency.

2

9

II Perform speed control of slip-ring induction motor by:

1. Rotor rheostat control.

2. Injecting an emf from rotor side.

3. operating two motors in cascade connection.

4

10 III Perform direct loading test on alternator to find out voltage

regulation 4

11 III Find out voltage regulation of alternator by synchronous

impedance method for Unity, lagging and leading power factor. 4

12 III Find out voltage regulation of alternator by ampere turn method

for Unity, lagging and leading power factor. 4

13 III Synchronize a given alternator with bus bar. 2

14 IV Construct V-curves of synchronous motor at different load

conditions to see the effect of variation of excitation 2

15 V Test the circuit of capacitor start capacitor run single phase

induction motor used in a ceiling fan 2

16 V Perform No load test on single phase induction motor to

determine the friction and windage loss 2

Total Hours 56

8. SUGGESTED LIST OF STUDENT ACTIVITIES

Following is the list of proposed student activities such as:

i. Prepare journals based on practical performed in laboratory.

ii. Assignments on solving numericals

iii. Prepare chart displaying various accessories of three phase transformer

iv. Prepare/Download a dynamic animation to illustrate the following:

• Working principle of 3 phase induction motor

• Working principle of 3 phase alternator

• Working of different types of 3 phase induction motor starters

v. Carry out a market survey of local dealers for 1-phase Induction motor and compare

them on following points:

(a) Rating (b) Method of starting (c) Cost (d) Starting torque and (e) Performance



vi. Download the catalogue of three phase transformer, three phase induction motor,

synchronous motor and alternator from websites of reputed manufacturers such as

BHEL, SIMENS, CROMPTON, JYOTI, ABB, VOLTAS etc. to learn the latest

developments

9. SPECIAL INSTRUCTIONAL STRATEGIES (if any)

(i) Arrange visit to nearby transformer and induction motor manufacturer/testing

facilities

(ii) Show video/animation films to explain functioning of induction

motor/synchronous machines/transformers and their accessories.

10. SUGGESTED LEARNING RESOURCES

A) List of Books

S.

No. Title of Book Author Publication

1. Electrical Technology Vol. II B. L. Theraja S Chand and Co., New Delhi

2. Electrical Machines Smarajit Ghosh Pearson Learning, New Delhi

3.

Electrical Machinery A.E.Fitzgerald, Charles

Kingsley, Jr., Stephen D.

Umans

Mc. Graw Hill, New Delhi

4. Theory and performance of

Electrical Machines

J.B.Gupta S.K. Kataria and sons, New

Delhi

5. Electrical Machines Ashfaq Hussain Dhanpat Rai and Company,

New Delhi

B) List of Major Equipment/ Instrument with Broad Specifications

i. Three phase transformer 2KVA, 415V /415V, 50 Hz, 2.8A

ii. Three phase induction motor 5 HP, 440V, 8.0A, 1400 RPM Squirrel cage type

with brake drum arrgangement

iii. Three phase induction motor 5 HP, 440V, 8.0A, 1400 RPM Slip-ring induction

motor

iv. Synchronous motor 3 HP, 415V, 3-phase, 50Hz, 1500 RPM

v. DC shunt motor-Alternator

set :

5HP,220V, 1500 RPM, 18A, Excitation- 220V DC

vi. DC shunt motor Alternator 3KVA,415V, 3-phase,3.5A, 1500RPM, Excitation-

220V DC

vii. Single phase induction motor 1 HP, 220 V, 50Hz, 1440 RPM Drum brake with

spring balances

C) List of Software/Learning Websites

i. www.sskphdmm.com

ii. www.nptel.iitm.ac.in

11. COURSE CURRICULUM DEVELOPMENT COMMITTEE

Faculty Members from Polytechnics

Prof. H.C. Chawda, Lecturer in Electrical Engineering, RC Technical Institute,

Ahmedabad.

Prof. R.D. Panchal, Lecturer in Electrical Engineering, RC Technical Institute,

Ahmedabad



Prof. J.C. Gadani, Lecturer in Electrical Engineering, C.U.Shah Govt.Poly.,

Surendranagar.

Coordinator and Faculty Members from NITTTR Bhopal

Prof. (Mrs.) C S Rajeshwari, Head of Department of Electrical and Electronics

Engineering.

Prof. Joshua Earnest, Professor, Department of Electrical and Electronics

Engineering.

Laxmi Institute of Technology, Sarigam

Electrical Department

Academic Year: 2018-19

ASSIGNMENT: 1

Name of Subject : Polyphase Transformer And AC Rotating Electrical Machines Date:

Subject Code : 3340901

Unit: 2 Polyphase Induction Motor

Sr. No.

Name of Question Remarks

1 Define Synchronous speed and Slip.

2 Explain function of starter.

3 Compare between Slip ring and Squirrel cage Induction Motor.

4 Write short note on Torque-Slip characteristic of 3-phase I.M.

5 Explain various power losses in Induction Motor.

6 Write methods of speed control of three phase induction motor. Explain any one method.

7 Why starter is required to start three phase Induction motor? State the different types of starter used.

8 Explain D.O.L. starter for polyphase induction motor.

9 Derive the equation of starting torque for 3-ø induction motor and obtain condition of maximum starting torque from it.

10 Write the application of 3 phase induction motor.

11 For a 4 pole, 50 Hz, 3-phase star connected Induction Motor, full load slip is 3 %. Calculate the full load speed.

Date of Submission:-

Name & Sign of Subject In-charge :




ASSIGNMENT: 2



Unit: 4 Synchronous Motor

Sr. No.


1 Why synchronous motor is not self starting? Explain role of the damper winding for starting the synchronous motor.

2 Draw and explain the vector diagram of synchronous motor on load.

3 Derive the equation of mechanical power developed by synchronous motor and obtain the condition for maximum power from it.

4 State the different methods of starting of synchronous motor. Explain any two.

5 Why synchronous motor is a constant speed motor?

6 Explain what is hunting of synchronous motor . How it is prevented.

7 Explain the effect of change of excitation of a synchronous motor on its armature current and power factor.

8 Explain the procedure of plotting V- curve of synchronous motor with circuit diagram.

9 Compare induction motor with synchronous motor.






ASSIGNMENT: 3



Unit: 1 Polyphase Transformer

Sr. No.


1 Explain the function of tank, conservator and breather in Transformer.

2 Why transformer ratings are in KVA?

3 Why the tapping is placed on high voltage side?

4 Explain Star-Delta and Delta-Star connection of Transformer.

5 Explain type of losses in Transformer.

6 Write the specification on name plate of transformer.

7 Draw the sketch showing the construction of Buchholz relay and explain its working.

8 Explain Natural Oil cooled Air cooling-ONAF and Forced Oil Forced Air Cooling-ODAF system in transformer.

9 Compare a bank of three 1-phase transformer with a single 3-Ø transformer.

10 State conditions for parallel operation of two 3-phase Transformer.






ASSIGNMENT: 4



Unit: 3 Alternator

Sr. No.


1 Explain construction of Alternator.

2 State the difference between rotating armature and rotating field type alternator.

3 Derive the emf equestion of alternator.

4 Explain the coil span factor and distribution factor.

5 List various methods of synchronizing alternator with bus bar. Explain any one.

6 Explain armature reaction and its effects.

7 State the method of determining of voltage regulation. Explain Direct loading.

8 What is infinite Bus bar? Explain the condition of connecting alternator with infinite bus bar.

9 Explain hydrogen cooling system of alternator with advantages and disadvantages.

10 Explain the synchronous impedance method of voltage regulation of an Alternator by performing O.C and S.C tests.






ASSIGNMENT: 5



Unit: 5 Single Phase Induction Motor

Sr. No.


1 Explain two field rotating theory of 1- phase Induction Motor with diagram.

2 Why 1- phase Induction Motor is not self starting?

3 What is the function(role) of centrifugal switch in 1- phase Induction Motor?

4 List the methods of starting of 1-ø induction motor.

5 Explain construction and working of Shaded Pole I.M.

6 Explain capacitor start and capacitor run single phase induction motor.

7 Write the application of 1- phase Induction Motor.



Name of Subject : Polyphase Transformer And AC Rotating Electrical Machines Subject Code : 3340901

QUESTION BANK

UNIT -1 Polyphase Transformer

1. Explain the function of tank, conservator and breather in Transformer. 2. Why transformer ratings are in KVA? 3. Why the tapping is placed on high voltage side? 4. Explain Star-Delta and Delta-Star connection of Transformer. 5. Explain type of losses in Transformer. 6. Write the specification on name plate of transformer. 7. Draw the sketch showing the construction of Buchholz relay and explain its

working. 8. Explain Natural Oil cooled Air cooling-ONAF and Forced Oil Forced Air Cooling-

ODAF system in transformer. 9. Compare a bank of three 1-phase transformer with a single 3-Ø transformer. 10. State conditions for parallel operation of two 3-phase Transformer. 11. Delta star transformer is preferred for distribution. 12. State reason why the transformer winding is immersed in mineral oil. 13. Draw the transformer accessories. 14. Write the ratings of 3 phase transformer.

UNIT -2 Polyphase Induction Motors

1. Define Synchronous speed and Slip. 2. Explain function of starter. 3. Compare between Slip ring and Squirrel cage Induction Motor. 4. Write short note on Torque-Slip characteristic of 3-phase I.M. 5. Explain various power losses in Induction Motor. 6. Write methods of speed control of three phase induction motor. Explain any one

method. 7. Why starter is required to start three phase Induction motor? State the different

types of starter used. 8. Explain D.O.L. starter for polyphase induction motor. 9. Derive the equation of starting torque for 3-ø induction motor and obtain

condition of maximum starting torque from it. 10. Write the application of 3 phase induction motor.

11. For a 4 pole, 50 Hz, 3-phase star connected Induction Motor, full load slip is 3 %. Calculate the full load speed.

12. Explain the squirrel cage induction motor(SCIM). 13. Explain the slip ring induction motor(SRIM). 14. Explain how synchronously rotating magnetic field is generated by interaction of

three phase induction motor. 15. Explain the application of three phase induction motor. 16. Explain the working of 3 phase induction motor. 17. Explain the types of 3 phase induction motor. 18. Write the short note on Linear induction motor with advantages and

disadvantages. 19. Explain the circle diagram of three phase induction motor.

UNIT -3 Alternator

1. Draw and explain construction of alternator. 2. State the difference between rotating armature and rotating field type alternator. 3. Describe the projected pole type alternator. 4. Express the emf equation of alternator. 5. Explain the coil span factor and distribution factor. 6. Define the voltage regulation of alternator. 7. The stator of 3phase ,20 p alternator has 120 slots .and there are 4

conductor/slots, if the speed of alternator is 300rpm . calculate the emf induced /phase. Assume gap flux as 50mwb/pole and coil span is 15 deg. electrical.

8. In a 10 pole,3 phase, 50 Hz alternator with 2 slots/pole/phase and 4 9. Conductors per slot in two layers having 160◦ coil span and flux per pole is 0.1

Weber. Calculate induced emf per phase. 10. Explain the alternator on’ ON LOAD’ condition and draw &Explain the vector

diagram of ‘ON LOAD’ condition f different power factor. 11. Explain the different method to find the voltage regulation. 12. Define voltage regulation of an alternator. Explain ZPF method of determining

voltage regulation of an alternator. 13. What is the phase difference? Explain different method to check phase

difference. 14. State the conditions for connecting three phase alternators in parallel. Explain the

combined dark and bright lamp method. 15. Explain ‘One dark & two bright’ lamps method of synchronizing with diagram.

16. Why we need parallel operation of alternator ? Describe the procedure for synchronizing the alternator on infinite bus bar.

17. Give application of alternator.

UNIT -4 Synchronous Motor

1. Why synchronous motor is not self starting? Explain role of the damper winding for starting the synchronous motor.

2. Draw and explain construction and working of synchronous motor. 3. Draw and explain the vector diagram of synchronous motor on load. 4. Draw the phasor diagrams of Synchronous Motor for lagging, leading and unity

power factor conditions. 5. Explain the effect of change of excitation of a synchronous motor on its armature

current and power factor. 6. Derive the equation of mechanical power developed by synchronous motor and

obtain the condition for maximum power from it. 7. State the different methods of starting of synchronous motor. Explain any two. 8. Explain what is hunting of synchronous motor . How it is prevented. 9. What is V-curve? Explain the procedure of plotting V- curve of synchronous motor

with circuit diagram. 10. Compare induction motor with synchronous motor. 11. State the applications of Synchronous Motor. 12. How synchronous motor is used for power factor correction? 13. Explain why the synchronous motor is constant speed motor.

UNIT -5 1- Phase Induction Motor

1. Why single phase Induction motor is not self starting? Which modification are required to make it self starting .

2. Write the applications of 1-ø induction motors. 3. Explain two field rotating theory of 1-ø induction motor with diagram. 4. List the methods of starting of 1-ø induction motor. Draw and explain construction

and working of shaded pole induction motor. 5. Explain Resistance start induction run type single phase induction motor. 6. Explain any one type of single phase induction motor for fan application.

Laxmi Institute of Technology , Sarigam Approved by AICTE, New Delhi; Affiliated to Gujarat Technological University, Ahmadabad

Academic Year 2018-19 Centre Code: 691 Examination : Mid Exam I Semester: IV

Branch: Electrical Date: 28.01.2019 Sub Code: 3340901

Sub: PTACM Time: 10.30 AM to 11.30 AM Marks: 20

Q-1 Answer any three. 6 1. Define Slip Speed and Slip. 2. Calculate Synchronous speed of 3-phase, 4-pole, 60 Hz Induction Motor. 3. Explain principal of Star-Delta starter. 4. Explain how the Rotating Magnetic Field produced in 3-phase Induction Motor. Q-2 (A) Compare squirrel cage Induction Motor and slip ring Induction Motor. 3 OR (A) Obtain the equation of starting torque and obtain the condition for maximum starting torque. (B) Draw and explain slip-torque characteristic of 3-phase Induction Motor. 4 OR (B) Explain various power losses in Induction Motor. Q-3 (A) For a 6 pole, 60 Hz, 3-phase star connected Induction Motor, full load slip is 4 %. Calculate the

full load speed. 3

(B) Write methods of speed control of three phase induction motor. Explain any one method. 4

OR (A) Explain construction and working of star-delta starter.

(B) Explain DOL starter for 3-phase Induction Motor.

-૧ કોઈપણ પાંચના જવાબ લખો ૬ ૧. લીપ પીડ અને લીપ સમ વો. ૨. ૩-ફઇઝ, 4 પોલ, 60 હટઝ ઇ ડ શન મોટરની િસ ોનસ પીડ ગણો. ૩. ટાર-ડ ટા ટાટરનો િસ ધાતં સમ વો. ૪. ૩-ફઇઝ ઇ ડ શન મોટરમા ંરોટ ટગ મે નેટ ક ફ ડ કઈ ર તે ઉ પ થાય છે સમ વો. -૨ (અ) વીરલ કજ ઇ ડ શન મોટર અને લીપ રગ ઇ ડ શન મોટરની સરખામણી કરો. ૩

અથવા

(અ) ઇ ડ શન મોટર માટ ટા ટગ ટોક ુ ં ૂ મેળવો અન ેમહતમ ટા ટગ ટોકની કં ડશન મેળવો.

(બ) 3-ફઇઝ ઇ ડ શન મોટરની લીપ-ટોક લા ણ તા દોરો અને સમ વો. ૪

અથવા (બ) ઇ ડ શન મોટરમા ંથતા પાવર લોસ સમ વો. -૩

(અ) ૬ પોલ, ૬0 હટઝ, 3 ફઈઝ ટાર જોડણ વાળ ઇ ડ શન મોટરની લ લોડ લીપ ૪ % છે.તો ત ેમોટરની લ લોડ ગિત શોધો.

૩

(બ) 3 ફઈઝ ઇ ડ શન મોટરની પીડ કં ોલની પ ધિતઓ લખો. કોઈ પણ એક સમ વો. ૪

અથવા (અ) ટાર-ડ ટા ટાટરની રચના અને કાય સમ વો.

(બ) 3 ફઈઝ મોટર માટ DOL ટાટર સમ વો.

Laxmi Institute of Technology , Sarigam Approved by AICTE, New Delhi; Affiliated to Gujarat Technological University, Ahmadabad

Academic Year 2018-19 Centre Code: 691 Examination : Mid Exam I Semester: IV

Branch: Electrical Date: 28.01.2019 Sub Code: 3340901

Sub: PTACM Time: 10.30 AM to 11.30 AM Marks: 20

Q-1 Answer any three. 6

1. Define Slip Speed and Slip. 2. Calculate Synchronous speed of 3-phase, 4-pole, 60 Hz Induction Motor. 3. Explain principal of Star-Delta starter. 4. Explain how the Rotating Magnetic Field produced in 3-phase Induction Motor. Q-2 (A) Compare squirrel cage Induction Motor and slip ring Induction Motor. 3 OR (A) Obtain the equation of starting torque and obtain the condition for maximum starting torque. (B) Draw and explain slip-torque characteristic of 3-phase Induction Motor. 4 OR (B) Explain various power losses in Induction Motor. Q-3 (A) For a 6 pole, 60 Hz, 3-phase star connected Induction Motor, full load slip is 4 %. Calculate the

full load speed. 3

(B) Write methods of speed control of three phase induction motor. Explain any one method. 4

OR (A) Explain construction and working of star-delta starter. (B) Explain DOL starter for 3-phase Induction Motor.

-૧ કોઈપણ પાંચના જવાબ લખો ૬

૧. લીપ પીડ અને લીપ સમ વો. ૨. ૩-ફઇઝ, 4 પોલ, 60 હટઝ ઇ ડ શન મોટરની િસ ોનસ પીડ ગણો. ૩. ટાર-ડ ટા ટાટરનો િસ ધાતં સમ વો. ૪. ૩-ફઇઝ ઇ ડ શન મોટરમા ંરોટ ટગ મે નેટ ક ફ ડ કઈ ર તે ઉ પ થાય છે સમ વો. -૨ (અ) વીરલ કજ ઇ ડ શન મોટર અને લીપ રગ ઇ ડ શન મોટરની સરખામણી કરો. ૩

અથવા (અ) ઇ ડ શન મોટર માટ ટા ટગ ટોક ુ ં ૂ મેળવો અન ેમહતમ ટા ટગ ટોકની કં ડશન મેળવો. (બ) 3-ફઇઝ ઇ ડ શન મોટરની લીપ-ટોક લા ણ તા દોરો અને સમ વો. ૪

અથવા

(બ) ઇ ડ શન મોટરમા ંથતા પાવર લોસ સમ વો. -૩

(અ) ૬ પોલ, ૬0 હટઝ, 3 ફઈઝ ટાર જોડણ વાળ ઇ ડ શન મોટરની લ લોડ લીપ ૪ % છે.તો ત ેમોટરની લ લોડ ગિત શોધો.

૩

(બ) 3 ફઈઝ ઇ ડ શન મોટરની પીડ કં ોલની પ ધિતઓ લખો. કોઈ પણ એક સમ વો. ૪

અથવા

(અ) ટાર-ડ ટા ટાટરની રચના અને કાય સમ વો.

(બ) 3 ફઈઝ મોટર માટ DOL ટાટર સમ વો.

1

1/3

Seat No.: ________ Enrolment No.______________

GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER –IV• EXAMINATION – SUMMER – 2017

Subject Code: 3340901 Date: 27-04 - 2017

Subject Name: Poly Phase Transformer and Rotating A.C. Machine

Time: 10:30 AM TO 01:00 PM Total Marks: 70 Instructions:

1. Attempt all questions.

2. Make Suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

4. Use of programmable & Communication aids are strictly prohibited.

5. Use of only simple calculator is permitted in Mathematics.

6. English version is authentic.

Q.1 Answer any seven out of ten. દશમ ાંથી કોઇપણ સ તન જવ બ આપો. 14

1. A 3-Φ Transformer is superior compared to 3-single phase transformer

૧. ૩ સસિંગલ ફેઝ ટ્ર ન્સફોમમરની સરખ મણી મ ાં ૩ ફેઝ ટ્ર ન્સફોમમર વધ રે ક ર્મક્ષમ છે ક રણ આપો.

2. Explain function of breather.

૨. બ્રિધર ન ાં ક ર્મ સમજાવો.

3. Explain use of oil in transformer.

૩. ટ્ર ન્સફોમમર મ ાં ઓઈલન ાં ક ર્મ સમજાવો.

4. Explain Distribution factor in alternator.

૪. અલ્ટરનેટરમ ટે ડીસ્ટરીબ્ય શન ફેકટર સમજાવો.

5. Explain “slip” related to induction motor.

૫. ઇન્ડકશન મોટરન સદર્મ સ્લીપ સમજાવો.

6. Explain use of centrifugal switch.

૬. સેન્ટ્રીફય ગલ સ્વીચ ની ઉપર્ોગીત જણ વો.

7. Give name of methods for finding voltage regulation of alternator.

૭. અલ્ટરનેટરન ાં વોલ્ટેજ રેગ્ય લેશન શોધવ મ ટેની રીતો જણ વો.

8. Give application of alternator.

૮. અલ્ટરનેટરન ઉપર્ોગો જણ વો.

9. Why transformer rating is in KVA?

૯. ટ્ર ન્સફોમમર ન ાં રેટટિંગ KVA મ ાં કેમ હોર્ છે?

10. Explain the function of Damper winding.

૧૦. ડેમ્પર વ ઈન્ડીંગન ાં ક ર્મ સમજાવો.

Q.2 (a) Explain essential condition required for parallel operation of 3-phase

transformer.

03

પ્રશ્ન. ર (અ) થ્રી ફેઝ ટ્ર ન્સફોમમરને પેરેલલમ ાં જોડવ ની જરૂરી શરતો જણ વો.

૦૩

OR

(a) Write the specification on name plate of transformer. 03

(અ) થ્રી ફેઝ ટ્ર ન્સફોમમરની નેમ પ્લેટ પર લખેલ સ્પેસીફીકેશન જણ વો. ૦૩

2/3

(b) Explain the vector diagram of Dy11 group in 3-phase transformer. 03

(બ) થ્રી ફેઝ ટ્ર ન્સફોમમર મ ટે Dy11 ગ્ર પન ાં વેક્ટરડ ર્ ગ્ર મ સમજાવો. ૦૩

OR

(b) Explain construction of 3-phase transformer. 03

(બ) થ્રી ફેઝ ટ્ર ન્સફોમમર ની રચન સમજાવો. ૦૩

© Explain the squirrel cage induction motor. 04

(ક) સ્ય રેલ કેજ ઇન્ડકશન મોટર સમજાવો. ૦૪

OR

(c) Explain the slip-ring induction motor. 04

(ક) સ્લીપ રીંગ ઇન્ડકશન મોટર સમજાવો ૦૪

(d) Explain two field rotating theory for 1-phase Induction motor. 04

(ડ) સસિંગલ ફેઝ ઇન્ડકશન મોટરમ ટે બે ફેઝ ફરત ચ ાંબકીર્ ક્ષેત્ર ની થીર્રી સમજાવો.

૦૪

OR

(d) Explain the power stages in three phase induction motor. 04

(ડ) થ્રી ફેઝ ઇન્ડકશન મોટરમ ાં સવસવધ પ વર સ્ટેજ સમજાવો ૦૪

Q.3 (a) Explain the working of three phase induction motor. 03

પ્રશ્ન. 3 (અ) થ્રી ફેઝ ઇન્ડકશન મોટર ક ર્મ સમજાવો ૦૩

OR

(a) Write advantages and dis-advantages of linear induction motor. 03

(અ) લીનીર્ર ઇન્ડકશન મોટરન ન ફ ર્દ અને ગેરફ ર્દ જણ વો. ૦૩

(b) Explain the D.O.L Starter of 3-phase induction motor. 03

(બ) થ્રી ફેઝ ઇન્ડકશન મોટર મ ટે ડી.ઓ.એલ. સ્ટ ટમર સમજાવો. ૦૩

OR

(b) Explain the star-delta Starter of 3-phase induction motor. 03

(બ) થ્રી ફેઝ ઇન્ડકશન મોટરમ ટે સ્ટ ર ડેલ્ટ સ્ટ ટમર સમજાવો. ૦૩

(c) Explain application of three phase induction motor. 04

(ક) થ્રી ફેઝ ઇન્ડકશન મોટરન ઉપર્ોગો જણ વો ૦૪

OR

(c) A four pole ,50 Hz 3-phase star connected Induction motor has slip of 4%.

Calculate the full load speed of motor. Also calculate rotor frequency.

04

(ક) ૪ પોલ, ૫૦ હટમઝ, થ્રી ફેઝ સ્ટ ર જોડ ણ વળી ઇન્ડકશન મોટરની ફૂલ લોડ સ્લીપ ૪% છે તો તેની ફૂલલોડ સ્પીડ શોધો અને રોટર ની આવસૃિ શોધો.

૦૪

(d) Write the specification written on the name plate of 3-phase induction motor. 04

(ડ) થ્રી ફેઝ ઇન્ડકશન મોટરની નેમ પ્લેટ પર લખેલ સ્પેસીફીકેશન જણ વો. ૦૪

OR

(d) Give application of 1-phase induction motors. 04

(ડ) સસિંગલ ફેઝ ઇન્ડકશન મોટરન ઉપર્ોગો જણ વો ૦૪

Q.4 (a) Why the Synchronous Motor is not self starting? 03

પ્રશ્ન. ૪ (અ) સસિંક્રોનસ મોટર કેમ સ્વર્મ સાંચ બ્રલત નથી? ૦૩

OR

(a) Explain method for obtaining “V” curve in laboratory. 03

3/3

(અ) પ્રર્ોગશળ મ ાં “વી” કવમ મેળવવ ની રીત સમજાવો. ૦૩

(b) State the advantages for keeping alternator armature system stationary. 04

(બ) અલ્ટરનેટરમ ાં આમેચર સીસ્ટમને સ્થીર ર ખવ ન ફ ર્દ ઓ લખો. ૦૪

OR

(b) List various methods of synchronizing alternator with busbar. Explain any

one.

04

(બ) અલ્ટરનેટરને અનાંત બસબ રમ ાં જોડવ ની રીતો જણ વો. તેમ ાંની કોઇપણ એક સમજાવો.

૦૪

(c) Explain the circle diagram of three phase induction motor. 07

(ક) થ્રી ફેઝ ઇન્ડકશન મોટરનો સકમલ ડ ર્ગ્ર મ સમજાવો. ૦૭

Q.5 (a) Explain, why the single phase induction motor are not self starting? 04

પ્રશ્ન. ૫ (અ) શ મ ટે સસિંગલ ફેઝ ઇન્ડકશન મોટર સેલ્ફ સ્ટ ટીગ નથી? સમજાવો. ૦૪

(b) Explain in brief advantages of hydrogen cooling system of alternator, 04

(બ) અલ્ટરનેટરમ ાં હ ઇડ્રોજન ક લીંગ રીતન ફ ર્દ ઓ ટ ાંકમ સમજાવો. ૦૪

(c) State the application of synchronous motor. 03

(ક) સસિંક્રોનસ મોટર ન ઉપર્ોગો લખો. ૦૩

(d) Derive E.M.F equation for alternator. 03

(ડ) અલ્ટરનેટર મ ટે “ઇ.એમ.ફ.” ન ાં સ ત્ર ત રવો. ૦૩

************

1/3


GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER – 4(NEW) • EXAMINATION – SUMMER 2018

Subject Code: 3340901 Date: 28-Apr-2018

Subject Name: Polyphase Transformers And Rotating Ac Machines

Time: 10:30 AM TO 01:00 PM Total Marks: 70 Instructions:








1. Write down different name of accessories used in 3-phase transformer.

૧. 3 ફેઈઝ ટ્ર ન્સફોમમર મ ાં ઉપયોગ થત ાં એક્સેસરીઝન ન મ લખો.

2. Explain the need of starter in 3-phase Induction motor.

૨. થ્રી ફેઈઝ ઇન્ડક્શન મોટરમ ાં સ્ટ ટમર ની જરૂરરય ત સમજાવો.

3. Define “slip” related to Induction Motor.

૩. ઇન્ડક્શન મોટરન સાંદર્મ મ ાં “સ્લીપ” સમજાવો.

4. Why armature winding is kept in stator in case of alternator?

૪. ઓલ્ટરનેટરમ ાં શ મ ટે આમેચર વ ઇંરડિંગ ને સ્ટેટરમ ાં ર ખવ મ આવે છે?

5. In the case of 3-phase transformer, which type of winding (coil) is used for low

voltage and high voltage side?

૫. 3 ફેઈઝ ટ્ર ન્સફોમમરમ ાં લો વોલ્ટેજ અને હ ઇ વોલ્ટેજ બ જુએ કઈ વ ઇંરડિંગ (કોઈલ) નો ઉપયોગ થ ઈ છે?

6. State the following statements as TRUE OR FALSE

(1) A squirrel cage induction motor has a poor starting torque.

(2) Reversal of rotation of 3 phase induction motor is impossible.

(3) 3 phase induction motor can be connected to unbalance 3 phase load.

(4) An induction motor is variable speed motor.

૬. નીચેન વવધ નો સ ચ છે કે ખોટ છે તે જણ વો. 1) સ્ક્વીરલ કેઈજ ઇન્ડક્શન મોટરનો સ્ટ રટિંગ ટોકમ નબળો છે.

2) થ્રી ફેઈઝ ઇન્ડક્શન મોટરની ફરવ ની રદશ બદલવી અશકય છે.

3) થ્રી ફેઈઝ ઇન્ડક્શન મોટરને અનબેલેન્સ લોડ(ર્ ર) સ થે જોડ ઈ શક ય.

4) ઇન્ડક્શન મોટર વેરરએબલ સ્પીડ મોટર છે.

7. Write down different losses in electrical machines.

૭. વવદ્યતુ મશીનોમ ાં થત ાં જુદ જુદ લોસ લખો.

8. Explain function of damper winding.

૮. ડેમ્પર વ ઈડીગ નુાં ક યમ સમજાવો.

9. Why single phase induction motor is not self starting?

૯. વસિંગલ ફેઈઝ ઇન્ડકશન મોટરશ મ ટે સ્વચ લલત નથી?

2/3

10. Why synchronous motor is a constant speed motor?

૧૦. સીન્કોનસ મોટર અચળ ગતી વ ળી મોટર શ મ ટે છે?

Q.2 (a) Draw Dy1 group of winding in 3 phase transformer. 03

પ્રશ્ન. ર (અ) 3 ફેઈઝ ટ્ર ન્સફોમમરન Dy1 જોડ ણ દોરો. ૦૩

OR

(a) Compare the bank of three single-phase transformers with single three phase

transformer.

03

(અ) એક થ્રી ફેઈઝ ટ્ર ન્સફોમમર અને ત્રણ સીંગલ ફેઈઝ ટ્ર ન્સફોમમરની બેન્કની સરખ રેટીંગ

મ ટે સરખ ાંમની કરો. ૦૩

(b) Derive the condition for maximum starting torque of Induction Motor.

03

(બ) ઇન્ડક્શન મોટરમ ાં મહત્તમ સ્ટ રટિંગ ટોકમ મ ટેની શરતો મેળવો. ૦૩

OR

(b) For a 4 pole, 60 Hz, 3-phase star connected Induction Motor, full load slip is 3 %.

Calculate the full load speed.

03

(બ) 4 પોલ, 60 હટ્ઝ, 3- ફેઈઝ સ્ટ ર જોડણ વ ળી ઇન્ડક્શન મોટરની ફુલ લોડ સ્લીપ 3 % છે. તો તે મોટરની ફુલ લોડ લગત શોધો.

૦૩

(c) State essential conditions for parallel operation of two 3-phase Transformer.

04

(ક) બે થ્રી ફેઈઝ ટ્ર ન્સફોમમરને સમ ાંતર મ ાં જોડવ મ ટે ની જરૂરી શરતો. ૦૪

OR

(c) Draw and explain the following types of cooling methods of 3-phase Transformer.

1) ONAF 2) ONON

04

(ક) થ્રી ફેઈઝ ટ્ર ન્સફોમમર મ ાં નીચ ેદશ વેલ પ્રક ર શીતન આકૃવત દોરીને સમજાવો. 1) ONAF 2) ONON

૦૪

(d) Draw the sketch of Buchholz Relay in 3-phase Transformer and explain its

construction and working.

04

(ડ) થ્રી ફેઈઝ ટ્ર ન્સફોમમર મ ાં બકુોલ્ઝ રીલ ેની આકૃવત દોરો અને એની રચન અને ક યમ સમજાવો.

૦૪

OR

(d) State different types of Tap Changing in 3-Phase Transformer. Explain any One in

detail.

04

(ડ) થ્રી ફેઈઝ ટ્ર ન્સફોમમર મ ાં અલગ અલગ પ્રક ર ન ટેપ ચેંજજિંગ લખો. કોઈ પણ એક

વવગતવ ર સમજાવો. ૦૪

Q.3 (a) Compare between Squirrel cage and Slip ring Induction motor. 03

પ્રશ્ન. 3 (અ) સ્ક્વીરલ કેઈજ અને સ્લીપ રીંગ ઇન્ડક્શન મોટર વચ્ચેની સરખ મણી કરો. ૦૩

OR

(a) Explain various application of 3- Phase Induction motor. 03

(અ) થ્રી ફેઈઝ ઇન્ડક્શન મોટર ન વવવવધ ઉપયોગો જણ વો. ૦૩

(b) State the advantages for keeping armature system stationary in Alternator.

03

(બ) ઓલ્ટરનેટરમ ાં આમેચર સીસ્ટમને સ્થીર ર ખવ ન ફ યદ ઓ લખો. ૦૩

OR

(b) Explain in brief advantages of hydrogen cooling system of alternator.

03

(બ) ઓલ્રનેટરમ ાં હ ઈડ્રઓલ્ટરનેટરમ ાં હ ઇડ્રોજન કલૂીંગ રીતન ફ યદ ઓ સમજાવો. ૦૩

(c) Draw and explain slip-torque characteristic of 3-phase Induction Motor.

04

3/3

(ક) થ્રી ફેઈઝ ઇન્ડક્શન મોટરની સ્લીપ- ટોકમ લ ક્ષણીકત દોરો અને સમજાવો.

૦૪

OR

(c) State the methods of speed control from stator side of 3-phase induction motor.

Explain any two.

04

(ક) થ્રી ફેઈઝ ઇન્ડક્શન મોટરની સ્ટેટર બ જુ થી સ્પીડ કાંટ્રોલ કરવ ની રીતો લખો.કોઈ પણ

બે સમજાવો. ૦૪

(d) State Different types starter use in 3-phase Induction Motor. Explain D.O.L. starter. 04

(ડ) થ્રી ફેઈઝ ઇન્ડક્શન મોટરન અલગ અલગ પ્રક રન સ્ટ ટમર લખો. D.O.L. સ્ટ ટમર સમજાવો.

૦૪

OR

(d) State the methods of speed control from rotor side of 3-phase induction motor.

Explain cascading control method.

04

(ડ) થ્રી ફેઈઝ ઇન્ડક્શન મોટરની રોટર બ જુ થી સ્પીડ કાંટ્રોલ કરવ ની રીતો લખો. કોસ્કેટીંગ

કાંટ્રોલ ની રીત સમજાવો. ૦૪

Q.4 (a) Explain the method for obtaining “V” curve in laboratory.

03

પ્રશ્ન. ૪ (અ) પ્રયોગશ ળ મ ાં “વી” કવમ મેળવવ ની રીત સમજાવો. ૦૩

OR

(a) Explain advantages and disadvantages of synchronous motor. 03

(અ) સીન્કોનસ મોટર ન ફ યદ અને ગેર ફ યદ લખો. ૦૩

(b) Derive EMF equation of alternator. 04

(બ) ઓલ્ટરનેટર મ ટે ઈ.એમ.એફ. નુાં સતૂ્ર ત રવો. ૦૪

OR

(b) Explain any one of method for synchronization of 3 phase alternator with infinite

busbar.

04

(બ) થ્રી ફેઈઝ ઓલ્ટરનેટરને અનાંત બસબ ર સ થે સીન્કોન ઇઝીંગની કોઈ એક રીત

સમજાવો. ૦૪

(c) Explain how the rotating magnetic field is produced when three phase supply is

given to the stator of 3-phase induction motor.

07

(ક) 3 ફેઈઝ ઇન્ડકશન મોટર ન સ્ટેટર ને 3 ફેઈઝ સપ્લ ય આપવ મ આવે તો રોટેરટિંગ

મેગ્નેટીક ફીલ્ડ કેવી રીતે પેદ થ ય છે તે સમજાવો. ૦૭

Q.5 (a) State conditions for parallel operation of two Alternators.

04

પ્રશ્ન. ૫ (અ) બે ઓલ્ટરનેટર ને સમ ાંતર જોડ ણ મ ટે ની શરતો લખો. ૦૪

(b) Explain the construction and working of a shaded pole Induction motor.

04

(બ) શેડેડ પોલ ઇન્ડક્શન મોટર ની રચન અને ક યમ સમજાવો. ૦૪

(c) State the different methods of starting of synchronous motor. Explain any one. 03

(ક) સીન્કોનસ મોટર ને ચ લ ુકરવ ની જુદી જુદી રીતો લખો. કોઈ પણ એક સમજાવો. ૦૩

(d) Explain the construction and working of the motor used in the ceiling fan. 03

(ડ) સીલલિંગ ફેનમ ાં વપર તી ઇન્ડકશન મોટરની રચન તથ ક યમ સમજાવો. ૦૩

************

1/3


GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER – IV EXAMINATION –WINTER - 2018

Subject Code:3340901 Date: 20-11-2018

Subject Name: POLYPHASE TRANSFORMERS AND ROTATING AC MACHINES

Time:02:30 PM TO 05:00 PM Total Marks: 70 Instructions:








1. What is use of Transformer oil?

૧. ટ્ ાંસ્ફોમમર ઓઇલનો ઉપયોગ શુ છે?

2. Define Synchronous speed & slip.

૨. સસાંક્રોનસ સ્પીડ અને સ્સ્લપ ની વ્ય ખ્ય આપો.

3. Why transformer is rated in KVA?

૩. ટ્ ાંસ્ફોમમરનુ રેટીંગ કેમ KVAમ ાં હોય છે?.

4. Write the methods for finding Voltage regulation of an Alternator.

૪. અલ્ટનેટરનુ વોલ્ટેજ રેગ્યુલેશન શોધવ ની રીતો લખો.

5. Write applications of a Synchronous motor.

૫. સસાંક્રોનસ મોટરની ઉપયોસ્ગત લખો.

6. Draw V-curve of a Synchronous motor.

૬. સસાંક્રોનસ મોટરન વી-કવમ દોરો.

7. Why starter is required in an Induction motor?

૭. ઇંડક્શન મોટરમ સ્ટ ટમર કેમ જોઇએ છે?

8. Give difference between projected pole rotor & salient pole rotor.

૮. પ્રોજેક્ટેડ પોલ અને સેસ્લઅાંટ પોલ રોટરનો તફ વત આપો.

9. Write methods of cooling of a transformer.

૯. ટ્ ાંસ્ફોમમરની કુસલાંગની પધ્ધસ્તઓ લખો.

10. Give specifications of an alternator.

૧૦. અલ્ટનેટરન સ્પેસ્સફફકેશન આપો.

Q.2 (a) Which are essential conditions for parallel operation of 3- phase

transformers? 03

પ્રશ્ન. ર (અ) 3-Ø ટ્ ાંસ્ફોમમરને પેરેલલમ જોડવ ની જરૂરી શરતો કઇ છે? ૦૩

OR

(a) Write the specifications on the name plate of a 3-phase transformer. 03

(અ) 3-Ø ટ્ ાંસ્ફોમમરની નેમપ્લેટ પરન સ્પસે્સફફકેશન લખો. ૦૩

(b) Explain construction of a Buchholz relay. 03

(બ) બુખોઝ રીલેની રચન સમજાઓ. ૦૩

2/3

OR

(b) Draw vector diagram for Dy11 group of a transformer. 03

(બ) ટ્ ાંસ્ફોમમરન Dy11 ગ્રુપનો વેક્ટર ડ ય ગ્ર મ દોરો. ૦૩

(c) Explain construction of a 3-phase transformer. 04

(ક) 3-Ø ટ્ ાંસ્ફોમમરની રચન સમજાઓ. ૦૪

OR

(c) Explain construction of a squirrel cage induction motor. 04

(ક) સ્ક્વીરલ કેજ ઇંડક્શન મોટરની રચન સમજાઓ. ૦૪

(d) Explain power stages of a 3-phase induction motor. 04

(ડ) ઇંડક્શન મોટરન પ વર સ્ટેજીશ સમજાઓ. ૦૪

OR

(d) Explain slip ring induction motor. 04

(ડ) સ્લીપરીંગ ઇંડક્શન મોટર સમજાઓ. ૦૪

Q.3 (a) Write about shaded pole induction motor. 03

પ્રશ્ન. 3 (અ) શેડેડ ઇંડક્શન મોટર સ્વશ ેલખો. ૦૩

OR

(a) Explain 2-phase rotating field theory of a 1- Ø induction motor. 03

(અ) 1- Ø ઇંડક્શન મોટરમ ાં બે ફેજ ફરત ચુમ્બકીય ક્ષેત્રની થીયરી સમજાઓ. ૦૩

(b) Explain construction of an Alternator. 03

(બ) અલ્ટનેટરની રચન સમજાઓ. ૦૩

OR

(b) Derive emf equation of an alternator. 03

(બ) અલ્ટનેટર મ ટે ઇ.એમ.એફનુાં સુત્ર ત રવો. ૦૩

(c) Explain any one method for synchronization of a 3- Ø Alternator with

infinite

busbar.

04

(ક) 3- Ø અલ્ટનેટરને અન ાંત બસબ ર જોડે જોડવ ની કૉઈ એક રીત સમજાઓ.

૦૪

OR

(c) Explain armature reaction in case of a 3-phase alternator. 04

(ક) 3- Ø અલ્ટનટેરમ ાં આમેચર રીએક્શન સમજાઓ. ૦૪

(d) Explain damper winding in a Synchronous motor. 04

(ડ) સીંક્રોનસ મોટરમ ાં ડેમ્પર વ ઇંડીંગ સમજાઓ. ૦૪

OR

(d) Explain use of synchronous motor for power factor improvement. 04

(ડ) પ વર ફેક્ટર સુધ રવ સીંક્રોનસ મોટરનો ઉપયોગ સમજાઓ. ૦૪

Q.4 (a) Why Synchronous motor is not self starting? 03

પ્રશ્ન. ૪ (અ) સીંક્રોનસ મોટર કેમ સ્વયાં ચ લ ુથતી નથી? ૦૩

OR

(a) Explain method of obtaining V-curve in a laboratory. 03

(અ) પ્રયોગશ ળ મ ાં વી-કવમ મેળવવ ની રીત સમજાઓ. ૦૩

(b) Explain Star-delta transformer starter in a 3- Ø induction motor. 04

3/3

(બ) 3- Ø ઇંડક્શન મોટરમ ાં સ્ટ ર-ડેલ્ટ ટ્ ાંસ્ફોમમર સ્ટ ટમર સમજાઓ. ૦૪

OR

(b) Explain DOL starter in a 3- Ø induction motor. 04

(બ) 3- Ø ઇંડક્શન મોટરમ ાં ડી.ઓ.લ. સ્ટ ટમર સમજાઓ. ૦૪

(c) Explain cooling of a 3- Ø alternator. 07

(ક) 3- Ø અલ્ટનેટરનુાં કુલીંગ સમજાઓ. ૦૭

Q.5 (a) Give applications of a synchronous motor. 04

પ્રશ્ન. ૫ (અ) સીંક્રોનસ મોટરન ઉપયોગો આપો. ૦૪

(b) Explain Capacitor start capacitor run motor . 04

(બ) કેપેસીટર સ્ટ ટમ કેપેસીટર રન મોટર સમજાઓ. ૦૪

(c) Explain Torque-slip characteristics of a 3- Ø induction motor. 03

(ક) 3- Ø ઇંડક્શન મોટરમ ાં ટોકમ-સ્લીપ લ ક્ષસ્ણકત ઓ સમજાઓ. ૦૩

(d) Give advantages of stationary armature system in a 3- Ø alternator. 03

(ડ) 3- Ø અલ્ટનેટરમ ાં સ્સ્થર આમેચર પધ્ધસ્તન ફ યદ આપો. ૦૩

************

laxmmii s innsttittuuttee yooff … · iii perform direct loading test on alternator to find out...

Documents