Download GTU B.Tech 2020 Winter 5th Sem 3150910 Electrical Machine Ii Question Paper

Enrolment No.

Subject Code:3150910

GUJARAT TECHNOLOGICAL UNIVERSITY

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BE- SEMESTER-V (NEW) EXAMINATION - WINTER 2020

Subject Name:Electrical Machine- 11

Time:10:30 AM TO 12:30 PM

Date:27/01/2021

Total Marks: 56

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Instructions:

1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

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1. 1. What is slip? Explain torque-slip characteristics of an induction motor. [03]
   2. Define pitch factor and distribution factor with respect to an alternator. [04]
   3. Explain the procedure to construct the circle diagram of three-phase induction motor. Also, discuss how the losses, efficiency and slip of three-phase induction motor are calculated at full load condition using circle diagram. [07]
2. 1. Explain cogging and crawling in case of three-phase induction motor. [03]

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   2. Discuss the procedure to perform no load and blocked rotor tests on a three-phase induction motor. [04]
   3. List out the methods of speed control of three-phase Induction Motor. Explain any one in detail. [07]
3. 1. Why synchronous motor is not self-starting? Describe in brief. [03]
   2. Derive the maximum running torque condition in case of three-phase induction motor. [04]

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   3. Define voltage regulation of an alternator. List out the methods to find out the voltage regulation of the alternator. Explain any one in detail. [07]
4. 1. Discuss working of Repulsion motor. [03]
   2. Write a note on double cage induction motor. [04]
   3. Mention different starters for three-phase Induction motor and explain star-delta starter in detail. [07]

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5. 1. Explain the construction of a salient pole synchronous machine. [03]
   2. What is synchronization in case of alternator? Explain two bright one dark lamp method of synchronization. [04]
   3. Write a short note on auto synchronous motor. [07]

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6. 1. Briefly describe the construction and working of linear induction motor. [03]
   2. Briefly explain V-curves of synchronous motor. [04]
   3. Explain construction, working and applications of Permanent magnet brushless DC motor. [07]
7. 1. How direct axis and quadrature axis reactance can be measured for salient pole machine? [03]

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   2. Explain the construction and working of universal motor. [04]
   3. Mention the types of single-phase AC motors. Explain the construction and working of shaded pole single phase motor. [07]
8. 1. Derive the emf equation of an alternator. [03]
   2. Draw and explain the equivalent circuit of three-phase induction motor. [04]

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   3. Define and describe the effect of armature reaction in an alternator. [07]

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