Electrical Power Transmission MCQs Part 7

1. Which one the following is not a standard voltage in European grids:

1. 130 kV
2. 275 kV
3. 322 kV
4. 400 kV

Correct answer: 3. 322 kV

2. The most obvious and foremost requirement for connected lines:

1. Operational flexibility should be present
2. They should operate at the same frequency
3. They should operate at EHV
4. None

Correct answer: 2. They should operate at the same frequency

3. A counterpoise is buried under a transmission line when:

1. Soil resistance is high
2. Soil resistance is low
3. Stones are absent in soil
4. The height of ground is above sea level

Correct answer: 1. Soil resistance is high

4. Kelvin law helps to calculate:

1. Losses of HVDC lines
2. Impact of mechanical strength on working of lines
3. The accurate values of depreciation
4. None of these

Correct answer: 4. None of these

5. Surge impedance of long transmission line is of the order:

1. 100 Ω
2. 200 Ω
3. 400 Ω
4. 800 Ω

Correct answer: 3. 400 Ω

6. Compared to normal alternators, the superconducting alternators are:

1. 20% smaller in size
2. 40% smaller in size
3. 60% smaller in size
4. 80% smaller in size

Correct answer: 2. 40% smaller in size

7. The visual critical voltage (Vv) for corona occurrence in a polished conductor is 100 kV. Keeping all other parameters constant, the Vv for rough conductors is:

1. 50 – 62 kV
2. 72 – 82 kV
3. 98-118 kV
4. 130 – 144 kV

Correct answer: 2. 72 – 82 kV

8. The desired safety factor of insulators:

1. 0.1
2. 3
3. 5
4. 8

Correct answer: 4. 8

9. A 3 wire dc system provides the number of voltages:

1. One
2. Two
3. Three
4. Four

Correct answer: 2. Two

10. As compared to the overhead system the underground system is:

1. More likely to experience faults
2. Less likely to experience faults
3. Equally likely to experience faults

Correct answer: 2. Less likely to experience faults

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