University question paper of Power system protection and SwitchGear Nov/Dec 2011 for final year EEE students. Engineering students can download this question paper. This Power system protection and SwitchGear question paper is only for 2008 regulation students.
ANNA UNIVERSITY OF TECHNOLOGY,
B.E / B.TECH, DEGREE EXAMINATIONS : NOV / DEC 2011
REGULATIONS : 2008
SEVENTH SEMESTER : EEE
080280074 – POWER SYSTEM PROTECTION AND SWITCHGEAR
Time : 3 Hours Max. Marks : 100
PART – A
( 10 * 2 = 20 MARKS )
ANSWER ALL QUESTIONS
1) What is the difference between a protective relay and a fuse ?
2) What is meant by dead spot ?
3) Give two methods of protection of transformer.
4) State the advantages of static relaying.
5) Give two methods of arc quenching in circuit breaker.
6) What is current chopping ?
7) Give the advantages of SF6 circuit breaker.
8) What is the difference between type and routine tests in circuit breaker ?
9) State the uses of Ground wires.
10) What are the causes for over voltages ?
PART – B
( 5 * 16 = 80 MARKS )
ANSWER ALL QUESTIONS
11) (a). Describe with neat diagrams, the construction, working and applications of induction type directional over current relay.
(b). What is meant by percent bias? How is this achieved in practice in a differential relay? Under what circumstances is a percentage differential relay preferred over the differential relay for (i) internal fault and (ii) through fault.
12) (a). Explain with a neat sketch Buchholz relay used for transformer protection.
(b). Explain principle of carrier current protection of a transmission line. Describe phase comparison carrier current protection of a transmission system.
13) (a). i) Explain DC circuit breaking method. (8)
ii) Explain the phenomena of current chopping. (8)
(b). i) Explain high resistance method and current zero interruption method of arc interruption. (8)
ii) Explain the terms “Restriking voltage and “rate of rise of restriking voltage”. What is their significance in the operation of circuit breaker ? (8)
14) (a). With neat diagram describe the functioning of SF6 circuit breaker. State the advantages of the breaker.
(b). i) Explain the various tests conducted on circuit breakers. (8)
ii) A circuit breaker is rated at 1200 amps, 1500 MVA, 33kV, 3phase 3 sec oil circuit breaker. What are its normal current braking current, making current and short time rating. (8)
15) (a). i) Discuss the harmful effects of lightning. (8)
ii). Explain with diagram Peterson coil earthing of a generator and give the merits of this earthing over other types of earthing. (8)
(b). i) Explain in detail how ground wires can be used for protecting transmission lines against lightning. Discuss the practical aspects of its locations and applications. (12)
ii) Distinguish between surge absorber and surge diverter. (14)