Power System Protection MCQs Part 3
a. The rate of rise of restriking voltage is usually expressed in terms of:
- V / s
- kV / ms
- kV / µs
- MV/ns
Correct answer: 3. kV / µs
b. It is desired to chop 20 A current in a circuit having L = 4 mH, C = 0.2 µC. Find the induced voltage.
- 10 kV
- 3.72 kV
- 2.8 kV
- 1.7 kV
Correct answer: 3. 2.8 kV
Solution = i √(L/C) = 20 A * √(4 mH/0.2 uC) = 2.8 kV
c. Fault diverter is actually a:
- Fuse
- Circuit breaker
- Relay
- Switch
Correct answer 4. Switch
3. The fault diverter is actually a fast switch.
d. The major advantage associated with the static digital relay is:
- Less sensitive
- Performance speed is slow
- It is expensive
- It is not accurate
Correct answer: 3. It is expensive
e. Fusing factor of a fuse is mathematically defined by the equation:
- Current rating of fuse * 4.44
- 1/Current rating of the fuse
- Min fusing current / Current rating of the fuse
- Min fusing current * Current rating of the fuse
Correct answer: 3. Min fusing current / Current rating of the fuse
f. The correct statement about Sulphur Hexaflouride gas:
- It provides free electrons to the breaker
- It absorbs free electrons
- It increases current flow the through the arc
- None of these
Correct answer: 2. It absorbs free electrons
g. The correct equation which explains the breaking capacity of single phase circuit breaker:
- V × I × 10−1 MVA
- V × I × 10−3 MVA
- V × I × 10−6 MVA
- V × I × 10−9 MVA
Correct answer: 3. V × I × 10−6 MVA
h. The __________ the current, the ___________ is the time required by fuse to blow up:
- Greater, smaller
- Greater, Greater
- Smaller, Smaller
- All of these are possible
Correct answer: 1. Greater, smaller
i. Usually the earth relays have ___________ current settings:
- Lower
- Higher
- Both
- None
Correct answer: 1. Lower
j. The correct equation which explains the breaking capacity of 3 phase circuit breaker:
- √3 × V × I × 10−1 MVA
- √3 × V × I × 10−3 MVA
- √3 × V × I × 10−6 MVA
- √3 × V × I × 10−9 MVA
Correct answer: 3. √3 × V × I × 10−6 MVA
Continue reading:
- Power System Protection MCQs Part 1
- Power System Protection MCQs Part 2
- Power System Protection MCQs Part 3
- Power System Protection MCQs Part 4
- Power System Protection MCQs Part 5
- Power System Protection MCQs Part 6
- Power System Protection MCQs Part 7
- Power System Protection MCQs Part 8
- Power System Protection MCQs Part 9
- Power System Protection MCQs Part 10