Power System Protection MCQs Part 2
a. In case of fault it is often desired that frame leakage protection should trip:
- Half the installed breakers
- Only one breaker
- All connected breakers
- Two breakers
Correct answer: 3. All connected breakers
b. The correct equation for an effectively grounded system is:
- X0/X1 < 3.0
- X0/X1 > 3.0
- X0/X1 > 2.0
- 3.0 < X0/X1< 9.0
Correct answer: 1. X0/X1 < 3.0
c. Buchholz relay is used to protect:
- Alternator
- Induction Motors
- Synchronous motors
- Transformers
Correct answer: 4. Transformers
d. Generally, the carrier current protection scheme is recommended for:
- HV cables
- HV transmission lines
- Both of these
- None of these
Correct answer: 2. HV transmission lines
e. SF6 gas is ____________:
- Highly inflammable
- Non-inflammable
Correct answer: 3. Non-inflammable
f. The under-voltage relay is recommended for:
- Transformers
- Motors
- Feeder
- Busbars
Correct answer: 2. Motors
g. ____________________ is/are an instantaneous relay/s:
- PMMC type
- Shaded pole type
- Both of these
- None of these
Correct answer: 1. PMMC type
h. Statement: SF6 circuit breakers have very short arcing time.
Utterance: SF6 circuit breakers are costly.
- Both statement and utterance are correct
- Both are wrong
- The statement is correct, the utterance is wrong
- The statement is wrong, the utterance is correct
Correct answer: 1. Both statement and utterance are correct
i. Plug setting multiplier is defined as the ratio of:
- Fault current in relay coil x Pick up current
- Fault current in relay coil / Pick up current
- Fault current in relay coil x Transformer secondary turns
- Fault current in relay coil / Transformer secondary turns
Correct answer: 2. Fault current in relay coil / Pick up current
j. High-speed circuit breakers result in:
- Increased stability of power systems
- Decreased stability of the power system
Correct answer: 2. Decreased stability of the power system
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