GTU BE 6th Semester 162403 Switch Gear and Fault Analysis Summer 2018 Question Paper

1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE – SEMESTER ?VI (OLD) – EXAMINATION ? SUMMER 2018
Subject Code:162403 Date:28/04/2018
Subject Name:Switch Gear & Fault Analysis
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. Notations used have usual meaning.
Q.1 (a) Define ?fault? in power system. Discuss the types of faults and causes of fault.
How the faults can be minimized?
07
(b) Discuss the necessity of protection system and explain fault clearing process. 07

Q.2 (a) Explain the following term: (1) Isolator (2) Lightning Arrester (3) Recovery voltage
07
(b) Explain the principle of circulating current differential protection. Discuss the
difficulties with it.
07
OR
(b) Write a brief note on IDMT relay. 07

Q.3 (a) Discuss Air blast circuit breaker with neat diagram. 07
(b) Explain construction and working of electromagnetic induction disc type relay.
Also discuss Plug setting and Time setting in induction disc relay.
07
OR
Q.3 (a) Explain the effect and derive the expression of current due to sudden short circuit
of R-L series circuit.
07
(b) Explain the construction of vacuum circuit breaker with neat diagram. 07

Q.4 (a) Discuss the construction and working of HRC fuse with its advantages and
disadvantages.
07
(b) Explain the double line to ground fault on an unloaded generator. 07
OR
Q.4 (a) Explain the attracted armature relay with necessary diagram. 07
(b) Discuss SF6 – circuit breaker with necessary diagram. 07

Q.5 (a) Explain Auto-reclosure. 07
(b) Explain the principle of distance protection by R-X diagram and explain the
operating characteristics of an impedance relay.
07
OR
Q.5 (a) Explain Resistance Switching and Current Chopping with neat sketch. 07
(b) Write a short note on micro-controller based digital relay. 07
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