76. For the same resistance of line the ratio, weight of copper conductor/ weight of aluminium conductor , is
77. The function of steel wire in a ACSR conductor is
(A) to take care of surges
(B) to prevent corona
(C) to reduce inductance and hence improve power factor
(D) to provide additional mechanical strength.
78. In high voltage transmission lines the top most conductor is
(A) R-phase conductor
(B) Y- phase conductor
(C) B-phase conductor
(D) Earth conductor.
79. For 11 kV line the inductance per km per phase will be of the order of
(A) 1 H
(B) 0.1 H
(C) 1 mH
(D) 0.1 mH.
80. For 11 kV. line the capacitance per km per phase will be of the order of
(A) 1 Farad
(B) 0.1 Farad
(C) 0.01 Farad
(D) 0.01 microF.
81. If 3000 kW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will be
(A) 11 kV
(B) 33 kV
(C) 66 kV
(D) 132 kV.
82. The permissible voltage variation in transmission and distribution system is
(A) ± 0.1%
(B) ± 1%
83. The voltage of transmission can be regulated by
(A) use of tap changing transformers
(B) switching in shunt capacitors at the receiving end during heavy loads
(C) use of series capacitors to neutralize the effect of series reactance
(D) any of the above methods.
84. The most economic voltage for transmitting given power over a known distance by overhead transmission line is approximately
(A) 3.6 kV/km
(B) 1.6 kV/km
(C) 2.6 kV/km
(D) 3.6 kVkm.
85. String efficiency is given by
(A) (voltage across the string) / ((numbers of discs on the string) x (voltage across disc nearest to the conductor))
(B) ((voltage across the string) x (numbers of discs on the string)) / (voltage across disc nearest to the conductor)
(C) ( (voltage across disc nearest to the conductor) x (numbers of discs on the string)) / (voltage across the string)
(D) (voltage across disc nearest to the conductor))/ ((numbers of discs on the string) x (voltage across the string)
86. For a 66 kV line having span of 200 meters between towers the approximate sag will be
(A) 0.02 m
(B) 0.2 m
(C) 2 m
(D) 20 m.
87. In the above case if the span is doubled, the sag will be
(A) 2 m
(D) 1 m.
88. The reflection coefficient for a short circuit line is
(D) - 1.
89. In case the height of transmission tower is increased
(A) the line capacitance and inductance will not change
(B) the line capacitance will decrease but line inductance will decrease
(C) the line capacitance will decrease and line inductance will increase
(D) the line capacitance will decrease but line inductance will remain unaltered.
90. In a transmission line if booster transformer are to be used, preferred location will be
(A) at the receiving end
(B) at the sending end
(C) at the intermediate point
(D) any where in the line.