Transmission and Distribution MCQ PDF

41. Consider the following statements: Surge impedance loading of a transmission line can be increased by

1. increasing its voltage level.
2. addition of lumped inductance in parallel.
3. addition of lumped capacitance in series.
4. reducing the length of the line.

Of these statements
(a) 1 and 3 are correct.
(b) 1 and 4 are correct.
(c) 2 and 4 are correct.
(d) 3 and 4 are correct.

42. A lossless radial transmission line with surge impedance loading

(a) takes negative VAR at sending end and zero VAR at receiving end.
(b) takes positive VAR at sending end and zero VAR at receiving end.
(c) has flat voltage profile and unity power factor at all points along it.
(d) has sending-end voltage higher than receiving-end voltage and unity power factor at sending end.

43. What does the standing wave ratio (SWR) of unity imply ?

(a) Transmission line is open-circuited.
(b) Transmission line is short-circuited.
(c) Transmission line’s characteristic impedance is equal to load impedance.
(d) Transmission line’s characteristic impedance is not equal to load impedance. I.E.S. 2007]

44. Consider the following statements:

1. Equivalent-T circuit of a long line is preferred to equivalent-π circuit.
2. The nature of reactive power compensation is different for peak load and off-peak load conditions.
3. Ferranti effect is significant only on medium and long lines.

Which of the statements given above are correct?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

45. For a good voltage profile under no-load condition, a long line needs

(a) shunt capacitors at receiving end.
(b) shunt reactors at the receiving end.
(c) shunt resistance at receiving end.

46. No-load compensation of a high voltage line involves

(a) shunt capacitors.
(b) shunt reactors.
(c) series capacitors.

47. Full-load compensation in a line requires

(a) shunt capacitors.
(b) series capacitors.
(c) transformers.
(d) shunt reactors.

48. Use of additional shunt capacitor can be made for increasing the capability of line as it

(a) reduces surge impedance Z_o.
(b) increases phase shift β.
(c) increase in α.
(d) all of the above.

49. To increase the transmission capability of a high voltage long line

(a) the resistance can be increased.
(b) the resistance can be decreased.
(c) the series reactance can he reduced.
(d) the shunt admittance can be reduced.

50. Power dispatch through a line can be increased by

(a) installing series capacitors.
(b) installing shunt capacitors.
(c) installing series reactor.
(d) installing shunt reactor.

51. The power transmitted will be maximum when

(a) line reactance is high.
(b) corona losses are minimum.
(c) sending-end voltage is more.
(d) receiving-end voltage is more.

52. For constant voltage transmission, the voltage drop along the line is maintained constant by installing

(a) capacitors.
(b) inductors.
(c) resistors.
(d) synchronous phase modifiers at the receiving end.

53. Constant voltage transmission has the drawback(s) of

(a) increase of short-circuit current of the system.
(b) lower reserve of lines in case of line trouble.
(c) increased risk of interruption of supply due to falling of synchronous motors out of synchronism.
(d) all of the above.

54. Constant voltage transmission has the advantage(s) of

(a) availability of steady voltage at all loads at the receiving end.
(b) possibility of better protection for the line due to possible use of higher terminal reactances.
(c) possibility of carrying increased power for a given conductor size in case of long distance heavy power transmission.
(d) all of the above.

55. Constant voltage transmission has the advantage(s) of

(a) increase of short-circuit current of the system.
(b) large reserve of lines in case of line trouble.
(c) improvement of power factor at the times of moderate and heavy loads.
(d) all of the above.

56. A synchronous compensator absorbs inductive reactive power. It is

(a) overexcited.
(b) normally excited.
(c) underexcited.
(d) none of these.

57. A synchronous phase modifier supplies

(a) both active and reactive powers.
(b) both lagging and leading reactive power.
(c) inductive reactive power only.

58. A synchronous phase modifier as compared to synchronous motor of the same rating has

(a) larger shaft diameter and higher speed.
(b) smaller shaft diameter and higher speed.
(c) larger shaft diameter and smaller speed.
(d) smaller shaft diameter and smaller speed.

59. Phase modifier is normally installed in case of

(a) short transmission lines.
(b) medium length lines.
(c) long lines.
(d) for any length of lines.

60. Which of the following statements is not true ?

(a) Synchronous phase modifiers are installed at sending end
(b) Synchronous phase modifiers are installed at load end.
(c) Synchronous phase modifiers are nothing but synchronous motors (specially designed).
(d) Synchronous phase modifiers do not carry load.