Power Systems Questions and Answers – Distribution Systems – 2

This set of Power Systems Questions and Answers for Aptitude test focuses on “Distribution Systems – 2”.

1. For the given circuit diagram for the substation the voltage between the two outer conductors is
__________
The substation voltage between the two outer conductors is √2 V for figure
View Answer

Answer: b
Explanation: The maximum voltage levels between the two outer conductors is double the supply fed to it and the its rms is √2 V.

2. For the given circuit diagram for the substation fed with 315 kV, the voltage between the two outer conductors is ____________
a) 445.5 kV
b) 890 kV
c) 630 kV
d) 223 kV
View Answer

Answer: a
Explanation: The maximum voltage levels between the two outer conductors are double the supply fed to it and its rms is √2V.
Voltage between the two outer conductors is √2*315 kV = 445.5 kV.

3. If a 2-wire ac single phase distribution system operating at ‘P’ MW and ‘V’ kV, operating at the power factor of 0.8, then the current in the outer wire in kA is ______
a) 0.8P/V
b) 1.131P/V
c) 1.88P/V
d) 0.088P/V
View Answer

Answer: a
Explanation: I = P/(√2 V Cos Ø) = 0.88P/V.
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4. If a 2-wire ac single phase distribution system operating at ‘30’ MW and ‘315’ kV, operating at the power factor of 0.8, then the current in the outer wire in kA is _____
a) 0.0838
b) 83.8
c) 8.38
d) 1.131
View Answer

Answer: a
The current in the outer wire in kA is 0.0838 for operating at the power factor of 0.8

5. For a 2-wire ac single phase distribution system operating at ‘30’ MW and ‘315’ kV, operating at the power factor of 0.8 having 15Ω of resistance of each wire, then the copper loss at the substation in kW will be ___________
a) 210.67
b) 105.33
c) 240.87
d) 108.27
View Answer

Answer: a
Explanation: Current in the line, Copper loss at substation in kW will be 210.67 operating at power factor of 0.8
Power losses = 2*I2*R = 2*83.822*15 = 210.673 kW.
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6. For a 2-wire ac single phase distribution system operating at ‘30’ MW and ‘315’ kV, operating at the power factor of 0.8 having 15Ω of resistance of each wire, then the power received at the consumer end will be ____________
a) 29.79 MW
b) 29.895 MW
c) 29.76 MW
d) 29 MW
View Answer

Answer: a
Explanation: Current in the line, Copper loss at substation in kW will be 210.67 operating at power factor of 0.8
Power losses = 2*I2*R = 2*83.822*15 = 210.673 kW
Power received = 30-210.67 = 29.79 MW.

7. For a 2-wire ac single phase distribution system operating at ‘P’ MW and ‘V’ kV, operating at the power factor of 0.8. The copper losses of the system will be proportional to ___________
Find the copper losses of the system for operating at the power factor of 0.8
View Answer

Answer: a
The copper losses of the system for operating at the power factor of 0.8 is 1/(VCos)2
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8. The maximum rms voltage between one phase and ground neutral for a three phase 4-wire ac system will be ____________
a) 221.32 kV
b) 313 kV
c) 442 kV
d) 127 kV
View Answer

Answer: a
Explanation: The maximum rms phase voltage = Vph/√2 = 313/√2 = 221.32 kV.

9. The maximum rms voltage between one phase and ground neutral for a three phase 4-wire ac system will be ___________________
a) 171.46 kV
b) 242.5 kV
c) 221 kV
d) 127 kV
View Answer

Answer: a
Explanation: The maximum rms phase voltage = Vph/√2 = 420/√(2*3) = 221.32 kV.
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10. For the circuit diagram as depicted in the figure, the current per phase under balanced condition with a consumer end load of 90 kW, 414V operating at a power factor of 0.65 is ___________
a) 157.66 A
b) 152 A
c) 111.4 A
d) 193.1 A
View Answer

Answer: a
Explanation: Current per phase in the line, I = P/(√2 V/√3 CosØ) = 90000/(√2*414/√3*0.65) = 157.66 A.

Sanfoundry Global Education & Learning Series – Power Systems.

To practice all areas of Power Systems for Aptitude test, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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