Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 6th Sem Old 160901 Electrical Machine Iii Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI(OLD) ? EXAMINATION ? SUMMER 2019
Subject Code:160901 Date:27/05/2019
Subject Name: Electrical Machine - III
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.
Q.1 (a) Describe the Hopkinson?s test to find efficiency of DC machines. 07
(b) Define distribution factor and derive its equation. 07
Q.2 (a) Explain V and inverted V curve of synchronous motor. 07
(b) Explain field?s test for finding the efficiency of DC series machine. 07
OR
(b) Define pitch factor and derive its equation. Also give its advantage and
disadvantage.
07
Q.3 (a) State the condition of synchronizing of an alternator with bus bar. Explain one dark
and two bright lamp methods with necessary electrical circuit diagram.
07
(b) What do you mean by SCR (short circuit ratio) of a synchronous machine? What is
its significance?
07
OR
Q.3 (a) Explain armature reaction and its effects at different power factor in alternator. 07
(b) Why synchronous motor is not self-starting? Explain the methods of starting of
synchronous motor.
07
Q.4 (a) Define voltage regulation of alternator and explain ZPF method. 07
(b) Write a short note on auto synchronous motor. 07
OR
Q.4 (a) Write short note on DC servo motor. 07
(b) Explain hunting of synchronous machine and method of its prevention. 07
Q.5 (a) Explain the operation of AC servo motor. 07
(b) Write a short note on Switched Reluctance Motor. 07
OR
Q.5 (a) Explain working of PMBLDC motor with schematic diagram. 07
(b) Explain the construction and working of an induction regulator. 07
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This post was last modified on 20 February 2020