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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING SEMESTER IV • EXAMINATION SUMMER- 2017
Subject Code: 340902 Date: 01- 05 -2017
Subject Name: Electrical machine-II
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. Each question carry equal marks (14 marks)
Q.1

Explain how rotating magnetic field is produced when a supply is given to winding.
07





Why Starter is necessary for Induction motor? Explain types of starter explain any one in detail.
07



Q.2

Derive the equation for starting torque and condition for maximum starting torque.
07





State the types of induction motor, explain the difference between two.
07



OR

Write the Steps to draw Circle Diagram.
07



Q.3

Draw explain construction working of shaded pole induction motor.
07





Explain Double field revolving theory of induction motor.
07



OR
Q.3

Derive the emf equation of an Alternator.
07





Explain the procedure to find voltage regulation of an alternator by synchronous impedance method.
07



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Q.4

State different methods of starting of synchronous motor, Explain any one .
07





What is "V" Curve of synchronous motor? How it is obtained in a laboratory.
07



OR
Q.4

A 50 Hz 16 Pole star connected alternator has 192 armature slot with coil span of 150° electrical. Calculate Distribution Factor Pitch factor Synchronous Speed.
07


Hz ,16


What is Synchronizing? Write the condition for Synchronizing, one alternator with infinite bus bar or another alternator. Explain "One dark two Bright" lamps method of Synchronizing with Bus bar.
07

. "

Q.5

Draw and explain vector diagram of Synchronous motor with load.
07





Compare Synchronous with Induction Motor.
07



OR
Q.5

Explain construction and working of Schrage Motor.
07





Explain what is Hunting of Synchronous motor. How it is prevented.
07

.