Switchgear protections

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.

2
4
6
10

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 90°
circuit breaker is always A. In phase with the arc current B. Lagging the arc current by 90° C. Leading the arc current by 90°
None of the above

Detailed SolutionThe arc voltage produced in

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