Monday, 15 February 2016

SGP BITS

1. Oil immersed type reactors are used for voltages __________.
2. A circuit breaker is essentially _________.
3. The arcing contacts for a circuit are made up of ______.
4. The fault clearing time of a circuit breaker is usually of ________.
5. For modern circuit breakers, the time of closing the cycle is _______.
6. The pressure of air used in air blast circuit breakers is around _____.
7. The rating of circuit breaker is usually determined on the basis of ____.
8. Busbars are usually made of _______.
9. A fuse is normally a ___________.
10. Buchholz relay is a ___________.
11. Mho relays have an R-X  plane characteristic depicted by __________.
12. Under voltage relays are mostly used for _______.
13. Differential relays are used for protection of equipment against _________.
14. Earth fault relays are _____________.
15. Reactance relay are employed for phase fault in ____________.
16. Location of lightning arrestor is near a ___________.
17. Grounding is done generally at _______.
18. A relay used on short transmission line is ___________.
19. In tap changing transformers, the tappings are provided on _______.
20. Which of the following is a static excitor?
21. Which of the following equipment is not installed in a substation?
22. The recovery voltage will be maximum for power factor of ____.
23. Arc chutes are used in _______________.
24. Breaking capacity of circuit breakers is usually expressed in ___________.               
25. Earth wire is made of ______.
26. A Buchholz relay protect a transformer from__________
27. In Mertz –Price protection, the CT’s  secondary of delta – star power transformer will be in______________
28. For transformer protection, a differential relay is biased to avoid mal operation due to_____________
29.The percentage bias for a generator protection lies between____
30.For the protection of transformers, harmonic restraint is used to guard against_________________
31.The bus-bar zone faults are generally__________
32.A line trap in a long transmission line is used to _________
33.First zone distance relay protects a transmission line section up to   full length.___________
34.The over voltage surges in the power systems may be caused by___________
35.Location of lightning arrestors is near a___________
36.The reflection coefficient of a short circuited line is ___________
37.In railway applications  Circuit Breakers is used__________
38.Arc is initiated due to___________
39.Current zero interruption method used in________
40.Minimum oil circuit breakers use oil for_____________
41.Making capacity of a circuit breaker is equal to_____________
42.Arc in a circuit behaves as a____________
43.Differential relays are used for protection of___________
44.The relay used on short transmission lines____________
45.Both voltage and current signals are required for____________
46.Differential relays used for the protection of equipment against________
47.Auto reclosure improves  what type of stability.___________
48.what is the power factor of an arc?_________
49.Peterson coil has a reactance called?__________
50.what is the rating of SF6?___________

 KEY

1. above 33kv                                                                     

2. arc extinguisher                                                                   

3. copper tungsten alloy                                                    

4. few cycles of supply voltage                                          

5. 0.003 sec                                                                        

6. 20kg/cm2                                                                                                                         

7. symmetrical faults

8.copper

9current limiting devices

10. gas actuated relay

11.a circle passing through origin

12 motor protection

13. internal faults

14. directional relay

15. short lines

16  transformer

17 supply end

18 reactance relay

19 secondary winding

20 rectifier

21. exiters

22  unity

23 air blast CB

24 MVA

25 galvanised standered steel

26 internal faults

27 star – delta

28 inrush currents

29 5-10

30 swithing over voltages

31 single line to ground

32  confined the carrier signals in the line

33  80%

34 switching

35 transformer

36 -1

37 air blast

38 current between contacts

39 AC circuit breakers

40 arc quenching

41 2.55 times of symmetrical breaking capacity

42 resistance increases voltage increases

43 transformers

44 reactance relay

45 directional relay

46 internal faults
47 transient

48 unity

49 inductance

50. above 132kv

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