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Gujarat Technological University

This document is an exam for an Electrical Machines course, consisting of 5 questions covering various topics relating to transformers, induction motors, synchronous machines, DC generators and motors, and power transmission. The exam contains multiple choice and written answer questions worth a total of 70 marks. It provides instructions to attempt all questions, make assumptions where needed, and indicates the mark value for each question.

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Rajeshree Singh
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95 views1 page

Gujarat Technological University

This document is an exam for an Electrical Machines course, consisting of 5 questions covering various topics relating to transformers, induction motors, synchronous machines, DC generators and motors, and power transmission. The exam contains multiple choice and written answer questions worth a total of 70 marks. It provides instructions to attempt all questions, make assumptions where needed, and indicates the mark value for each question.

Uploaded by

Rajeshree Singh
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Seat No.: ________ Enrolment No.

___________

GUJARAT TECHNOLOGICAL UNIVERSITY


BE - SEMESTER– III (NEW) EXAMINATION – SUMMER 2015

Subject Code: 2131005 Date: 04/06/2015


Subject Name: ELECTRICAL MACHINES
Time: 02.30pm-05.00pm Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1 (a) Explain working of single phase transformer under no load condition with the 07
help of vector diagram.
(b) What is the constructional difference between core type and shell type 07
transformer? What are the merits and demerits of each?
Q.2 (a) How can you perform open circuit test on transformer? Which parameter you 07
can obtain from this test?
(b) Why are we connecting two transformers in parallel? What are the different 07
conditions for parallel operation of transformer?
OR
(b) What is autotransformer? Derive its equation for saving in copper. 07

Q.3 (a) Explain Sumpner’s test performed on transformer. 07

(b) How can we convert three phase to two phase in transformer? 07

OR
Q.3 (a) Explain torque-slip curve of induction motor. 07

(b) What is difference between squirrel cage and slip ring induction motor? 07

Q.4 (a) What do you mean by distribution factor and pitch factor in synchronous 07
machine?

(b) Explain ZPF method to find out regulation of alternator. 07

OR
Q.4 (a) What is the basic principle and construction of synchronous motor? 07

(b) Derive the e.m.f equitation of D.C.Generator. 07

Q.5 (a) Explain different type of D.C.Generator with diagram. 07

(b) Explain different method of speed control of D.C Motor. 07

OR
Q.5 (a) What do you mean by power factor? How can we improve power factor? 07

(b) What is Ferranti effect? How is it effect voltage of transmission line? 07

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