Switchgear and protection. Part – 4

31. The normal current in power line is 100A. If a short-circuit fault occurs on the line, then one can expect the short-circuit current to be

A. 200 A       

B. 300 A

C. More than 1000 A

D. 100 A

32. A short circuit between one line and ground, very often caused by physical contact is known as

A. Single line-to-ground fault

B. Line-to-line fault

C. Double line-to-ground fault

D. None of the above

33. Merz-price circulating current principles is more suitable for

A. Generators                 

B. Transformers

C. Both a and b

D. None of the above

34. In the following bus active and reactive powers are not specified

A. Load bus

B. Generator bus

C. Slack bus

D. None of the above

35. If the fault current is 2000A, the relay setting 50% and C.T. Ratio is 400/5, the plug setting multiplier will be

A. 15

B. 10

C. 25

D. 50

36. A low oil circuit breaker has the following advantage over a bulk oil circuit breaker

A. It requires a small space

B. The degree of carbonization is increased

C. Maintenance problems are increased

D. None of the above

37. If the percentage reactance of the system up to the fault point is 20% and base KVA is 10000, then short-circuit KVA is

A. 10000KVA

B. 50000KVA

C. 500KVA

D. 30000KVA

38. The time-current graph of a fuse

A. Has linear characteristic

B. Is a circle

C. Has inverse characteristic

D. None of the above

39. The medium used for arc extinction in ABCB is

A. Oil

B. Air

C. SF₆

D. Vacuum

40. Which of the following relays is used on long transmission lines?

A. Impedance relay

B. Mho’s relay

C. Reactance relay

D. None of the above