Transmission and Distribution Mcq

81. The inductance of single-phase two-wire power transmission line per km gets doubled when the

(a) distance between the wires is doubled.
(b) distance between the wires is increased four fold.
(c) distance between the wires is increased as square of the original distance.
(d) radius of the wire is doubled.

82. Inductance of an overhead line, in comparison to that of a cable of same capacity is

(a) larger.
(b) smaller.
(c) of the same order.

83. The inductance of a power transmission line increases with

(a) decrease in line length.
(b) increase in diameter of conductor.
(c) increase in spacing between the phase conductors.
(d) increase in load current carried by the conductors.

84. The inductance of a transmission line is minimum when

(a) GMD is high.
(b) GMR is high.
(c) both GMD and GMR are high.
(d) GMD is low and GMR is high.

85. For a given conductor the value of GMR is

(a) larger for capacitance calculation.
(b) larger for inductance calculation.
(c) same for both capacitance and inductance calculation.

86. The self GMD of a conductor with three strands each of radius r and touching each other is

(a) r (0.7788 x 2 x 2)1/3
(b) r (0.7788 x 2 x 2 x 2)
(c) r (0.7788 x 2 x 2 x 2)3
(d) r (0.7788 x 2 x 2)3

87. Hollow conductors are used in transmission lines to

(a) reduce weight of copper.
(b) improve stability.
(c) reduce corona.
(d) increase power transmission capacity.

88. Bundled conductors arc employed to improve

(a) appearance of the transmission line.
(b) mechanical stability of the line.
(c) current carrying capacity of the line.
(d) corona performance of the line.

(a) 20 cm
(b) 40 cm
(c) 80 cm
(d) 3.5 cm

90. For a stranded conductor, the ratio of GMR to actual radius is

(a) equal to 1.
(b) more than 1.
(c) equal to 0.7788.
(d) less than 0.7788

91. Bundled conductors in EHV transmission system provide

(a) reduced capacitance.
(b) increased capacitance.
(c) increased inductance.

92. Which one of the following statements is not correct for the use of bundled conductors in transmission lines?

(b) Reduction in corona loss.
(d)  Increase in interference with communication lines.

93. Bundled conductors are mainly used in high voltage overhead transmission lines to

(a) reduce transmission line losses.
(b) increase mechanical strength of the line.
(c) reduce corona.
(d) reduce sag.

94. Ds, is the GMR of each sub-conductor of a four sub-conductor bundle conductor and d is the bundle spacing. What is the GMR of the equivalent single conductor?

(a) 1.09 √(Ds x d3)
(b) 1.09 √(Ds3 x d3)
(c) 1.09 (Ds3 x d3)1/4
(d) 1.09 (Ds X d3)1/4

95. Proximity effect

(a) is more pronounced for large conductors, high frequencies and close proximity.
(b) increases the resistance of the conductors and reduces the self reactance.
(c) is substantially eliminated with stranded conductors.
(d) all of the above.

96. Following effects are associated with transmission lines

1. Skin effect. 2. Corona effect. 3. Proximity effect.

The effective resistance of a conductor is increased by
(a) 1 only.
(b) 2 and 3 only.
(c) 1 and 3 only.
(d) 1, 2 and 1.

97. Capacitance in equivalent circuit of a transmission line is due to

(a) current in the line.
(b) difference in potential of line.
(c) leakage of current.
(d) presence of magnetic flux.

98. if the separation between the three phases of a transmission line is increased then

(a) the inductance will increase and capacitance will remain unchanged.
(b) both the inductance and capacitance will increase.
(c) the inductance will increase and the capacitance will decrease.
(d) the inductance will decrease and the capacitance will increase.

99. The capacitance of an overhead transmission line increases with

1. increases in mutual geometrical mean distance.
2. increase in height of conductors above ground.

Select the correct answer from the following:
(a) Both 1 and 2 are true.
(b) Both 1 and 2 are false.
(c) Only 1 is true.
(d) Only 2 is true.

(a) 1500 Ω
(b) 3000 Ω
(c) 750 Ω
(d) 600 Ω