7-protection-elements-in-power-distribution-networks

Power System Protection MCQs Part 11

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Power System Protection MCQs Part 11.

The most dangerous fault in an alternator is

The most dangerous fault in an alternator is:

  1. Stator winding fault
  2. Failure of field
  3. Unbalanced load
  4. Prime mover failure

Correct answer: 1. Stator winding fault

If failure of alternator takes place in alternator, then it

If failure of alternator takes place in alternator, then it

  1. Draws some current from supply
  2. Runs as a synchronous motor
  3. Goes in inverted running mode
  4. All of these

Correct answer: 4. All of these

Most dangerous voltages in power systems are expected to be induced due to

Most dangerous voltages in power systems are expected to be induced due to:

  1. Resonance
  2. Lightning
  3. Insulation failure
  4. Arcing ground

Correct answer: 2. Lightning

Under normal conditions, a lightning arrestor conducts ___________ current to earth

Under normal conditions, a lightning arrestor conducts ___________ current to earth:

  1. Small
  2. Moderate
  3. Very high
  4. Zero

Correct answer: 4. Zero

A 3-phase induction motor whose stator is delta connected is carrying full load. If one of its fuses blows out then the motor

A 3-phase induction motor whose stator is delta connected is carrying full load. If one of its fuses blows out then the motor:

  1. Will continue running burning its two phases
  2. Will stop and carry heavy current causing permanent damage to its winding
  3. Will continue running without any harm to the winding
  4. Will continue running burning its one phase

Correct answer: 4. Will continue running burning its one phase

Which of following is correct in a transmission line

Which of following is correct in a transmission line:

  1. Inductance < Capacitance
  2. Inductance > Capacitance
  3. Inductance = Capacitance
  4. None of above

Correct answer: 2. Inductance > Capacitance

In an alternator the automatic protection relay is generally not provided for which of following faults

In an alternator the automatic protection relay is generally not provided for which of following faults:

  1. Overcurrent
  2. Overspeed
  3. Field failure
  4. All of these

Correct answer: 4. All of these

The impedance relaying scheme is used for protection of

The impedance relaying scheme is used for protection of:

  1. Alternators
  2. Bus-bars
  3. Transmission lines
  4. Transformers

Correct answer: 3. Transmission lines

A 3-phase delta connected induction motor is carrying too heavy load and one of its fuses blows out. Afterwards the motor

A 3-phase delta connected induction motor is carrying too heavy load and one of its fuses blows out. Afterwards the motor:

  1. Will stop and carry heavy current causing permanent damage to its winding
  2. Will continue running with one burning phase
  3. Will continue running without any harm to the winding
  4. Will continue running burning its two phase

Correct answer: 1. Will stop and carry heavy current causing permanent damage to its winding

If one-phase of a 3-phase synchronous motor is short-circuited, it

If one-phase of a 3-phase synchronous motor is short-circuited, it:

  1. Will overheat in spots
  2. Will not come upto speed
  3. Will fail to pull into step
  4. Will refuse to start

Correct answer: 4. Will refuse to start

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