Switchgear protections Archives

31. A fuse is never inserted in

neutral wire

negative of D.

circuit C. positive of

phase dine

Detailed SolutionA fuse is never inserted in

32. Circuit breakers usually operate under

transient state of short-circuit current

sub-transient state of short-circuit current

steady state of short-circuit current

after D. C. component has ceased

Detailed SolutionCircuit breakers usually operate under

33. Thermal overload relays are used to protect the motor against over current due to

short-circuits

heavy loads

grounds

all of the above

Detailed SolutionThermal overload relays are used to protect the motor against over current due to

34. The torque produced in induction type relay (shaded pole structure) is

inversely proportional to the current

inversely proportional to the square of the current

proportional to the current

proportional to square of the current

Detailed SolutionThe torque produced in induction type relay (shaded pole structure) is

35. The fuse wire, in D.C. circuits, is inserted in

negative circuit only

positive circuit only

circuits, is inserted in A. negative circuit only B. positive circuit only C. both (A) and (B)

either (A) or (B)

Detailed SolutionThe fuse wire, in D.C. circuits, is inserted in

36. H.R.C. fuse, as compared to a rewirable fuse, has

no ageing effect

high speed of operation

fuse, as compared to a rewirable fuse, has A. no ageing effect B. high speed of operation C. high rupturing capacity

all of the above

Detailed SolutionH.R.C. fuse, as compared to a rewirable fuse, has

37. The under voltage relay can be used for

generators

busbars

transformers

motors E. all of the above

Detailed SolutionThe under voltage relay can be used for

38. The ground wire should not be smaller than No ______ copper.

Detailed SolutionThe ground wire should not be smaller than No ______ copper.

39. Air blast circuit breakers for 400 kV power system are designed to operate in

100 microsecond

50 millisecond

0.5 sec

0.1 sec

Detailed SolutionAir blast circuit breakers for 400 kV power system are designed to operate in

40. The arc voltage produced in

In phase with the arc current

Lagging the arc current by 90Â°

circuit breaker is always A. In phase with the arc current B. Lagging the arc current by 90Â° C. Leading the arc current by 90Â°

None of the above

Detailed SolutionThe arc voltage produced in

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