Power System MCQ With Answers PDF

41. The booster (a) is a series wound dc generator driven by dc shunt motor.

(b) is a low voltage and high current generator operating on straight or linear portion of its voltage-current characteristic.
(c) is a high voltage and low circuit machine.
(d) both (a) and (b).

42. The booster is inserted in the circuit to

(a) reduce current.
(b) increase current.
(c) reduce voltage drop.
(d) compensate for voltage drop.

43. Floating neutral in a 3-phase supply is considered undesirable as it causes

(a) high voltage across the load.
(b) low voltage across the load.
(c) unequal line voltages across the load.
(d) none of the above.

44. In order to reduce the inductive interference to parallel communication circuits to the minimum.

(a) the conductors are transposed at regular intervals.
(b) bundle conductors are used.
(c) thick conductors are used.
(d) either (a) or (b).

45. When there is interference in an overhead communication line running parallel and in close proximity to an overhead power line, the voltage induced in the communication line in the longitudinal and lateral directions by the power line are due to

(a) magnetic induction and electric induction respectively.
(b) electric induction and magnetic induction respectively.
(c) both magnetic induction and electric induction.
(d) magnetic induction only.

46. A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum electric stress occurs at

(a) the upper surface of the conductor.
(b) the lower surface of the conductor.
(c) the ground surface
(d) midway between the conductor and ground. [GATE E.E. 2002]

47. Extra high voltage transmission means

(a) voltage less than 400 kV.
(b) voltage in the range of 400 – 750 kV.
(c) voltage greater than 750 kV.

48. Bundled conductors are used for EHV transmission lines primarily for reducing the

(a) corona loss.
(b) surge impedance of the line.
(c) voltage drop across the line.
(d) I²R losses.

49. Use of bundled conductors reduces

(a) power loss due to corona.
(b) surge impedance.
(c) radio interference.
(d) line inductance.
(e) all of these.

50. With bundled conductors

(a) the corona inception voltage increases.
(b) the corona inception voltage decreases.
(c) the corona inception voltage remains unaffected.

51. Consider the following statements :

1. By using bundle conductors in an overhead line, the corona loss is reduced.
2. By using bundle conductors, the inductance of transmission line increases and capacitance reduces.
3. Corona loss causes interference in adjoining communication lines.

Which of the these statements are correct ?
(a) 1 and 2.
(b) 2 and 3.
(c) 1 and 3.
(d) 1, 2 and 3.

52. The conductor of an EHV line is selected on the basis of

(a) current carrying capacity.
(b) corona and RI performance.
(c) line voltage.
(d) none of these.

53. Frequency of resonant vibrations lies in the range of

(a) 10 – 20 Hz
(b) 100 – 200 Hz
(c) 50 – 100 Hz
(d) 200 – 300 Hz

54. On what basis is the insulation level of a 400 kV, EHV overhead transmission line decided?

(a) Lightning overvoltage.
(b) Corona inception voltage.
(c) Switching overvoltage.
(d) Radio and TV interference.

55: Series capacitor is used in a transmission line to

(a) compensate the voltage drop.
(b) reduce line loss.
(c) limit short-circuit current.
(d) improve load power factor.

56. Series capacitive compensation in EHV transmission lines is used to

(a) reduce the line loading.
(b) improve the stability of the system.
(c) reduce the voltage profile.
(d) improve the protection of the line.

57. Series capacitors

(a) increase the power transmission capability of an EHV long line.
(b) provide voltage control.
(c) increase the shunt admittance of the line.

58. Series capacitors can be used in distribution lines

(a) to provide reactive power compensation.
(b) to reduce the receiving-end voltage under light load conditions.
(c) to reduce the voltage drop.
(d) to reduce line losses.

59. Shunt compensation in an EHV line is used to improve

(a) stability and fault level.
(b) fault level and voltage profile.
(c) voltage profile and stability.
(d) stability, fault level and voltage profile.

60. The most accurate and versatile method of achieving reactive power compensation is by using

(a) switched capacitors.
(b) fixed capacitor with controlled reactor.
(c) saturable reactor with capacitor bank.
(d) switched capacitor with controlled reactors.