Download GTU BE/B.Tech 2018 Winter 7th Sem Old 170903 Power System Protection Question Paper

Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 7th Sem Old 170903 Power System Protection Previous Question Paper

1
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER ?VII (OLD) EXAMINATION ? WINTER 2018
Subject Code: 170903 Date: 26/11/2018

Subject Name: Power System Protection

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) With neat diagram explain basic protection circuit with function of all elements. 07
(b) Describe principle of differential protection with need of restraining coil. 07

Q.2 (a) Derive torque equation of induction disc type electromagnetic relay with
diagram.
07
(b) Discuss advantages and disadvantages of Numerical relays. Why more and more
numerical relays are used nowadays.
07
OR
(b) Define: PSM, TSM, Plug setting, Reset, Backup protection 07

Q.3 (a) What protective scheme is used for the protection of Parallel Feeders and Ring
main system.
07
(b) How IDMT relay is provided with directional feature. Explain with diagram. 07
OR
Q.3 (a) Why are 30?, 60? and 90? connections required in directional relays. Draw vector
diagram of the 90? connection finding what is the maximum torque angle.
07
(b) What is importance of Busbar in substation. Explain Busbar protection scheme. 07

Q.4 (a) What are the limitations found in the simple differential protection of
transformer? How are they overcome?
07
(b) Explain restricted earth fault protection of transformer. 07
OR
Q.4 (a) Explain characteristics of different types of distance relays: Impedance, reactance
and mho ralay.
07
(b) Explain with neat sketch power line carrier current protection. 07

Q.5 (a) Discuss protection employed against loss of excitation of alternator. 07
(b) Explain the protection of large induction motor. 07
OR

Q.5 (a) Write short note on micro processor based over current relay. 07
(b) Write brief note on type tests carried out on relays. 07

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