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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-II EXAMINATION WINTER 2018
Subject Code:X20903 Date: 09/01/2019
Subject Name: Electrical Machines I II
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt Any five questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Explain classification of dc generator.
07

Explain Principle of Operation of a DC Generator and also explain types of armature winding in brief.
07
Q.2

Derive Torque equation of a dc motor.
07

Explain armature reaction.
07
Q.3

Difference between core type and shell type transformer.
07

Derive EMF equation of a Transformer.
07
Q.4

Difference between transformer and induction motor and also explain torque slip characteristics of induction motor.
07

Why single phase induction motor is not self starting? Explain any one method to make itself starting.
07
Q.5

Explain coil span factor and spread factor in details.
07

What is voltage regulation in alternator? State various methods to find voltage regulation and explain any one method in detail.
07
Q.6

Explain open circuit test and short circuit test in single phase transformer.
07

Difference between three point starter and four point starter.
07
Q.7

Explain working principle of 1-phase transformer in details.
07

Explain various losses taking place in a DC machine.
07