Switchgear protections

41. A transmission line is protected by

Inrush protection
Distance protection
Time graded and current graded over current protection
Both (B) and (C)

Detailed SolutionA transmission line is protected by

42. Arc in a circuit behaves as

a capackive reactance
an inductive reactance
a resistance increasing with voltage rise across the arc
a resistance decreasing with voltage rise across the arc

Detailed SolutionArc in a circuit behaves as

43. Distance relays are generally

split-phase relays
reactance relays
impedance relays
none of the above

Detailed SolutionDistance relays are generally

44. The material used for fuse must have

low melting point and high specific resistance
low melting point and -low specific resistance
high melting point and low specific resistance
low melting point and any specific resistance

Detailed SolutionThe material used for fuse must have

45. Insulation resistance of high voltage circuit breakers is more than

1 mega ohms
10 mega ohms
100 mega ohms
500 mega ohms

Detailed SolutionInsulation resistance of high voltage circuit breakers is more than

46. The single phasing relays are used for the protection of

single phase motors only
two phase motors only
two single phase motors running in parallel
three phase motors

Detailed SolutionThe single phasing relays are used for the protection of

47.

Load flow
Load flow and short-circuit
network analyzer is used to solve problems of A. Load flow B. Load flow and short-circuit C. Load flow and stability
Load flow, short-circuit and stability

Detailed Solution

48. A differential relay measures the vector difference between

two currents
two voltages
two or more similar electrical quantities
none of the above

Detailed SolutionA differential relay measures the vector difference between

49. To reduce short circuit fault currents are used.

reactors
resistors
capacitors
none of the above

Detailed SolutionTo reduce short circuit fault currents are used.

50. Protection by fuses is generally not used beyond

20 A
50 A
100 A
200 A

Detailed SolutionProtection by fuses is generally not used beyond

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