Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 4th Sem New 2140906 Ac Machines Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?IV (NEW) EXAMINATION ? WINTER 2018
Subject Code:2140906 Date:01/12/2018
Subject Name:AC Machines
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain working principle of Induction Generator. 03
(b) Derive the EMF equation of an alternator. 04
(c) Mention different starters for three phase induction motor and
explain Auto- transformer starter in details.
07
Q.2 (a) Compare squirrel cage and slip ring Induction Motor. 03
(b) Write a short note on auto synchronous motor. 04
(c) Explain the phenomena of crawling and cogging in induction motor.
07
OR
(c) Explain the procedure to construct the circle diagram of induction
motor. Also describe the method to determine losses, efficiency and
slip at full load condition using circle diagram.
07
Q.3 (a) Derive the torque equation for 3phase Induction Motor. 03
(b) List out the methods of speed control of Induction Motor.
Explain any one in detail.
04
(c)
Define and describe the effect of Armature reaction in an alternator.
07
OR
Q.3 (a) Explain with reason why synchronous motor is not self starting. 03
(b) Discuss the methods of starting of synchronous motor. 04
(c) Explain V-curves and its importance for synchronous motor. 07
Q.4 (a) Explain the determination of direct axis and quadrature axis
synchronous reactance using slip test.
03
(b) Explain the construction and working of universal motor.
04
(c) List the methods of determination of voltage regulation of an alternator.
Explain any one in detail.
07
OR
Q.4 (a) State the conditions to be satisfied for putting a 3 phase alternator in
parallel with infinite bus.
03
(b) Briefly describe the construction and working of linear induction
motor.
04
(c) Explain any one method for starting of 3phase squirrel cage induction
motor.
07
Q.5 (a) Define the pitch factor and distribution factor in case of synchronous
.motor
03
(b) Derive the condition for maximum starting torque for three phase
induction motor.
04
(c)
Discuss the procedure to perform no load and blocked rotor tests on a three
phase induction motor.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?IV (NEW) EXAMINATION ? WINTER 2018
Subject Code:2140906 Date:01/12/2018
Subject Name:AC Machines
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain working principle of Induction Generator. 03
(b) Derive the EMF equation of an alternator. 04
(c) Mention different starters for three phase induction motor and
explain Auto- transformer starter in details.
07
Q.2 (a) Compare squirrel cage and slip ring Induction Motor. 03
(b) Write a short note on auto synchronous motor. 04
(c) Explain the phenomena of crawling and cogging in induction motor.
07
OR
(c) Explain the procedure to construct the circle diagram of induction
motor. Also describe the method to determine losses, efficiency and
slip at full load condition using circle diagram.
07
Q.3 (a) Derive the torque equation for 3phase Induction Motor. 03
(b) List out the methods of speed control of Induction Motor.
Explain any one in detail.
04
(c)
Define and describe the effect of Armature reaction in an alternator.
07
OR
Q.3 (a) Explain with reason why synchronous motor is not self starting. 03
(b) Discuss the methods of starting of synchronous motor. 04
(c) Explain V-curves and its importance for synchronous motor. 07
Q.4 (a) Explain the determination of direct axis and quadrature axis
synchronous reactance using slip test.
03
(b) Explain the construction and working of universal motor.
04
(c) List the methods of determination of voltage regulation of an alternator.
Explain any one in detail.
07
OR
Q.4 (a) State the conditions to be satisfied for putting a 3 phase alternator in
parallel with infinite bus.
03
(b) Briefly describe the construction and working of linear induction
motor.
04
(c) Explain any one method for starting of 3phase squirrel cage induction
motor.
07
Q.5 (a) Define the pitch factor and distribution factor in case of synchronous
.motor
03
(b) Derive the condition for maximum starting torque for three phase
induction motor.
04
(c)
Discuss the procedure to perform no load and blocked rotor tests on a three
phase induction motor.
07
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2
OR
Q.5 (a) What is hunting? How to minimize it? 03
(b) What is synchronization? Explain two bright one dark lamp method of
Synchronization.
04
(c) What is the role of commutator in A.C. commutator motor? Explain
working of Schrage Motor.
07
*************
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This post was last modified on 20 February 2020