Switchgear and Protection MCQs Part 3

Switchgear and Protection MCQs Part 3. Multiple choice questions on Switchgear and Protection.

Commonly the making current of the circuit breaker is expressed in terms of

Commonly the making current of circuit breaker is expressed in terms of:

  1. Average value
  2. Peak value
  3. RMS value
  4. None of these

Correct answer: 2. Peak value

The rating of fuse is expressed in terms of

The rating of fuse is expressed in terms of:

  1. Amperes
  2. Volts
  3. Volt-amperes
  4. kVAR

Correct answer: 1. Amperes

Under normal operating conditions the contacts of the circuit breaker remain

Under normal operating conditions the contacts of the circuit breaker remain:

  1. Semi-closed
  2. Closed
  3. Open
  4. None of above

Correct answer: 2. Closed

In case of forced blast circuit breaker, the speed of circuit interruption is

In case of forced blast circuit breaker, the speed of circuit interruption is:

  1. Fast
  2. Medium
  3. Slow
  4. None of these

Correct answer: 1. Fast

On switching off the load sparking occurs due to high current

On switching off the load sparking occurs due to high current:

  1. Resistance
  2. Capacitance
  3. Inductance
  4. Skin effect

Correct answer: 3. Inductance

The circuit breaker must be able to perform the action of

The circuit breaker must be able to perform the action of:

  1. Breaking fault current
  2. Opening faulty circuit
  3. Carrying fault current for short time
  4. All of these

Correct answer: 4. All of these

An isolator is designed to open a circuit under condition of

An isolator is designed to open a circuit under condition of:ยท

  1. Nom1al flow
  2. Full load
  3. No load
  4. None of these

Correct answer: 3. No load

If length of the arc in a circuit breaker increases, its resistance

If length of the arc in a circuit breaker increases, its resistance:

  1. Increases
  2. Decreases
  3. Remains same
  4. None of above

Correct answer: 1. Increases

The time-current graph of a fuse

The time-current graph of a fuse

  1. Is a straight line
  2. Has inverse characteristic
  3. Is a circle
  4. None of these

Correct answer: 2. Has inverse characteristic

For the same power, which of following circuit breaker has least size

For the same power, which of following circuit breaker has least size:

  1. Vacuum circuit breaker
  2. SF6 circuit breaker
  3. Oil circuit breaker
  4. Air-blast circuit breaker

Correct answer: 2. SF6 circuit breaker

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