Objective Type Question or MCQ of B. Economics of Operation page-5

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41. If the inductance and capacitance of a system are 1.0 H and 0.01 μF respectively and the instantaneous value of current interrupted is 10 amp, voltage across the breaker contacts will be

a) 50 kV
b) 100 kV
c) 60 kV
d) 57 kV

Ans: (b)

42. In case of a 3-phase short circuit in a system, the power fed into the system is

a) Mostly reactive.
b) Mostly active.
c) Active and reactive both equal.
d) Reactive only.

Ans: (a)

43. Standard impulse testing of a power transformer requires

a) Two applications of chopped wave followed by one application of a full wave.
b) One application of chopped wave followed by one application of a full wave.
c) One application of chopped wave followed by two applications of a full wave.
d) None of the above.

Ans: (a)

44. Phase modifier is normally installed in the case of

a) Short transmission lines.
b) Medium length lines.
c) Long length lines.
d) For all length lines.

Ans: (c)

45. In order to eliminate sheath losses, a successful method is

a) To transpose the cable along with cross bonding.
b) Transpose the cable only.
c) Cross bonding the cables is enough.
d) None of the above effective.

Ans: (a)

46. Capacitance of a 3-core cable between any two conductors with sheath earthed is 2 μF. The capacitance per phase will be

a) 1 μF
b) 4 μF
c) 0.667 μF
d) 1.414 μF

Ans: (b)

47. For the system shown in diagram below, a line-to-ground fault on the side of the trans-former is equivalent to

a) A line-to-ground fault on the generator side of the transformer.
b) A line-to-line fault on the generator side of the transformer.
c) A double line-to-ground fault on the generator side of the transformer.
d) A 3-phase fault on the generator side of the transformer.

Ans: (b)

48. For a synchronous phase modifier the load angle is

a) 0°
b) 25°
c) 30°
d) None of the above

Ans: (a)

49. Size of conductor on modern EHV lines is obtained based on

a) Voltage drop
b) Current density
c) Corona
d) Above (a) and (b)

Ans: (c)

50. The insulation resistance of a cable of length 10 km is 1 MΩ, its resistance for 50 km length will be

a) 1 MΩ
b) 5 MΩ
c) 0.2 MΩ
d) None of the above

Ans: (c)

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Objective Type Question or MCQ of B. Economics of Operation page-5

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