Electrical Power Transmission MCQs Part 7
1. Which one the following is not a standard voltage in European grids:
- 130 kV
- 275 kV
- 322 kV
- 400 kV
Correct answer: 3. 322 kV
2. The most obvious and foremost requirement for connected lines:
- Operational flexibility should be present
- They should operate at the same frequency
- They should operate at EHV
- None
Correct answer: 2. They should operate at the same frequency
3. A counterpoise is buried under a transmission line when:
- Soil resistance is high
- Soil resistance is low
- Stones are absent in soil
- The height of ground is above sea level
Correct answer: 1. Soil resistance is high
4. Kelvin law helps to calculate:
- Losses of HVDC lines
- Impact of mechanical strength on working of lines
- The accurate values of depreciation
- None of these
Correct answer: 4. None of these
5. Surge impedance of long transmission line is of the order:
- 100 Ω
- 200 Ω
- 400 Ω
- 800 Ω
Correct answer: 3. 400 Ω
6. Compared to normal alternators, the superconducting alternators are:
- 20% smaller in size
- 40% smaller in size
- 60% smaller in size
- 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:
- 50 – 62 kV
- 72 – 82 kV
- 98-118 kV
- 130 – 144 kV
Correct answer: 2. 72 – 82 kV
8. The desired safety factor of insulators:
- 0.1
- 3
- 5
- 8
Correct answer: 4. 8
9. A 3 wire dc system provides the number of voltages:
- One
- Two
- Three
- Four
Correct answer: 2. Two
10. As compared to the overhead system the underground system is:
- More likely to experience faults
- Less likely to experience faults
- Equally likely to experience faults
Correct answer: 2. Less likely to experience faults
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