When the 3-phase system is not grounded and if Single Line to Ground fault occurs, the voltage of the other two healthy phases will

A. Increases
B. Decreases
C. Remains unaffected
D. none of the above

Answer: Option A

If The line to ground voltage is V then line to line voltage will be √ 3 times V. Now if one line is grounded due to ground fault. Then voltage between this line and faulted line becomes double the voltage between line to ground. I. E from line to ground and from ground to faulted phase voltage will be added

Generally grounding is provided for

A. only for the safety of the equipment
B. only for the safety of the operating personnel
C. both (A) and (B)
D. none of the above

Answer: Option C
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Ground resistance should be designed such that

A. grounding resistance should be as low as possible
B. grounding resistance should be as high as possible
C. grounding resistance should be always zero
D. none of the above

Answer: Option A
@power_system_engineering

The objective of earthing or grounding is

A. to provide as low resistance possible to the ground
B. to provide as high resistance possible to the ground
C. to provide flow of positive, negative and zero sequence currents
D. none of the above

Answer: Option A
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Factors on which soil resistance depends

A. depth of the electrode
B. moisture
C. Nacl
D. all the above

Answer: Option D
@power_system_engineering

Average resistance of human body is

A. 500 ohms
B. 1000 ohms
C. 1500 ohms
D. 2000 ohms

Answer: Option B

about 10,000 ohms
Human resistance is about 10,000 ohms on the high side and as little as 1,000 ohms if the person is wet. Remember, ohms is the unit of measure of a material's resistance or impedance to current flow.

====End of mcqs_earthing_or_grounding (Page -1)====

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Components of an electrical substation site (Pict -8),
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Engine Control Room (Pict -9),
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Overhead system can be designed for operation up to

A. 11 kV
B. 33 kV
C. 66 kV
D. 400 kV

Answer: Option D

The underground system cannot be operated above 66 kV because of insulation difficulties but overhead system can be designed for operation up to 400 kV or higher even.
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By which of the following a bus-bar is rated?

A. Current only
B. Current and voltage
C. Current, voltage and frequency
D. Current, voltage, frequency and short time current

Answer: Option D

The frequency of voltage generated, in case of generators, can be increased by

A. Using reactors
B. Increasing the load
C. Adjusting the governor
D. Reducing the terminal voltage

Answer: Option C

In aluminium conductors, steel core is provided to

A. Compensate for skin effect
B. Neutralise proximity effect
C. Reduce line inductance
D. Increase the tensile strength

Answer: Option D
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A 3-phase 4-wire system is commonly used on

A. Primary transmission
B. Secondary transmission
C. Primary distribution
D. Secondary distribution

Answer: Option D

Which of the following is usually not the generating voltage?

A. 6.6 kV
B. 8.8 kV
C. 11 kV
D. 13.2 kV

Answer: Option B
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When the interconnector between two stations has large reactance

A. The transfer of power will take place with voltage fluctuation and noise
B. The transfer of power will take place with least loss
C. The stations will fall out of step because of large angular displacement between the stations
D. None of the above

Answer: Option C

====End of mcqs_transmission_and_distribution (Page -1)====