A circuit breaker is a current interruption device that is used in power system for protection purposes. Circuit breakers are everywhere. They can be found in substations, homes, residential, and industrial complexes. Given below are the top 10 Electrical Engineering MCQ Questions on circuit breakers.
A circuit breaker is best defined as
A circuit breaker is best defined as:
- Signaling device
- Current interrupting device
- Sacrificial device
- Manual device
Correct answer: 2. Current interrupting device
The circuit breakers which produces the least arc energy
The circuit breakers which produces the least arc energy:
- Plain oil
- Full oil
- Air blast
- Air break
Correct answer: 3. Air blast
Breaking capacity of a circuit breaker rated 1000 A, 1000 MVA, 33 kV is
Breaking capacity of a circuit breaker rated 1000 A, 1000 MVA, 33 kV is:
- 1000 A
- 1783 A
- 1783 MVA
- 1000 MVA
Correct answer: 4. 1000 MVA
If the rated breaking current of circuit breaker is 500 A @ rated 33 kV service line voltage in three phase circuit, then breaking capacity is
If the rated breaking current of circuit breaker is 500 A @ rated 33 kV service line voltage in three phase circuit, then breaking capacity is:
- 0.0165 MVA
- 0.028 MVA
- 16.5 MVA
- 28.57 MVA
Correct answer: 4. 28.57 MVA
The circuit breaker which is highly reliable as well as requires least maintenance
The circuit breaker which is highly reliable as well as requires least maintenance:
- Plain oil circuit breakers
- Bulk oil circuit breaker
- Airblast
- Vacuum circuit breakers
- SF6 circuit breaker
Correct answer: 5. SF6 circuit breaker
The rupturing capacity of a circuit breaker for 3 phase, 11 kV system having SC current 40 kA will be around
The rupturing capacity of a circuit breaker for 3 phase, 11 kV system having SC current 40 kA will be around:
- 50 MVA
- 100 MVA
- 500 MVA
- 750 MVA
Correct answer: 4. 750 MVA
The device which provides signal to circuit breaker
The device which provides signal to circuit breaker:
- Contactor
- Transformer
- Relay
- Fuse
Correct answer: 3. Relay
The protective relays are the devices which perform fault detection and signal the circuit breaker for switching.
Which one of following circuit is more easy to interrupt
Which one of following circuit is more easy to interrupt:
- AC
- DC
- Both are equally easy
Correct answer: 1. AC
The rated making current of a breaker having rated symmetrical breaking current of 15000 A (r.m.s) is
The rated making current of a breaker having rated symmetrical breaking current of 15000 A (r.m.s) is:
- 25000 A
- 38250 A
- 42984 A
- 53665 A
Correct answer: 2. 38250 A
Making capacity = 2.55 * Rated symmetrical breaking current = 2.55 * 15000 = 38250 A
Resistance of arc in circuit breaker is linked to length as
Resistance of arc in circuit breaker is linked to length:
- Directly related
- Inversely related
- Not related at all
- Any of above
Correct answer: 1. Directly related
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