# Power Systems Questions and Answers – Electric Field and Potential of a Long Straight Conductor – 1

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This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Electric Field and Potential of a Long Straight Conductor – 1”.

1. Shunt admittance of a transmission line comprises of ______
a) capacitance with conductance
b) capacitance with inductance
c) resistance with inductance
d) capacitance with susceptance

Explanation: Shunt admittance is capacitance with conductance in the branch.

2. Conductance is the result of the leakage over the surface of insulators.
a) True
b) False

Explanation: Conductance comes into the picture due to the leakage current over the conductor’s surface.

3. Charging current in the transmission line is _______________
a) drawn at open as well as closed end of the transmission line
b) drawn at closed end of the transmission line
c) drawn at open end of the transmission line
d) drawn at the shunt capacitance at closed end of transmission line.

Explanation: Charging current in transmission line is drawn even when the far end of the TL is open.

4. A three phase 50 Hz transmission line has flat horizontal spacing with 3.5 m between adjacent conductors. The conductors are No. 2/0 hard drawn copper (outside diameter = 1.05cm). The voltage f the line is 110 kV. The capacitance to neutral per kilometre of line is
a) 0.00826 μF/km
b) 0.0826 μF/km
c) 0.01652 μF/km
d) 0.1652 μF/km

5. A three phase 50 Hz transmission line has flat horizontal spacing with 3.5 m between adjacent conductors. The conductors are No. 2/0 hard drawn copper (outside diameter = 1.05cm). The voltage f the line is 110 kV. The capacitive reactance to neutral per kilometre of line is ____________
a) 0.384 x 106 Ω/km to neutral
b) 0.768 x 106 Ω/km to neutral
c) 0.284 x 106 Ω/km to neutral
d) 0.642 x 106 Ω/km to neutral

6. A three phase 50 Hz transmission line has flat horizontal spacing with 3.5 m between adjacent conductors. The conductors are No. 2/0 hard drawn copper (outside diameter = 1.05cm). The voltage f the line is 110 kV. The line charging current per km of the line is _______________
a) 0.17 A/km
b) 0.34 A/km
c) 0.24 A/km
d) 0.48 A/km

7. A three phase 50 Hz transmission line has flat horizontal spacing with 3.5 m between adjacent conductors. The conductors are No. 2/0 hard drawn copper (outside diameter = 1.05cm). The voltage f the line is 110 kV. The line charging current per conductor of the line is _____________
a) 0.085 A/km
b) 0.17 A/km
c) 0.12 A/km
d) 0.24 A/km

Explanation: Cn = 0.00826 μF/km
Xn = 1/ωCn
Xn = 1/(100π* .284 *10-6)
Xn = 0.384 x 106 Ω/km to neutral
Charging current = Vn/Xn
Charging current = (110/√3)*1000/(0.384 *106)
Charging current = 0.17 A/km
Charging current per conductor = I/2
Charging current per conductor = 0.17/2
Charging current per conductor = 0.085 A/km.

8. A three phase 50 Hz transmission line has flat horizontal spacing with 3.5 m between adjacent conductors. The conductors are No. 2/0 hard drawn copper (outside diameter = 1.05cm). The voltage f the line is 110 kV. The reactive volt amperes generated by the line is
a) 31.4 kVAR
b) 62.8 kVAR
c) 42 kVAR
d) 56 kVAR

Explanation: Cn = 0.00826 μF/km
Xn = 1/ωCn
Xn = 1/(100π* .284 *10-6)
Xn = 0.384 x 106 Ω/km to neutral
Reactive volt amperes generated by the line = (VL)2/Xc
Reactive volt amperes generated by the line = 31.4 kVAR.

Sanfoundry Global Education & Learning Series – Power Systems.

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