Induction Motor MCQ Part 3

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Induction Motor MCQ Part 3

Multiple choice questions on Induction Motor

If one phase from three-phase supply to a three-phase induction motor is interchanged what happens to the flux and direction

If one phase from three-phase supply to a three-phase induction motor is interchanged what happens to the flux and direction:

  1. Flux decreases and direction changes
  2. Flux increases and direction remains same
  3. Flux remains same while direction reverses
  4. Flux increases and direction also reverses

Correct answer: 3. Flux remains same while direction reverses

If one phase from three phase supply to a three phase induction motor is changed what happens to the flux and direction then the direction of motor reverses while flux remains same.

Which of the following statement about friction and winding losses of 3 phase induction motor is correct

Which of the following statement about friction and winding losses of 3 phase induction motor is correct:

  1. They are minimum at no-load
  2. They are maximum at no-load
  3. They are the same at all loads
  4. They are maximum at full load

Correct answer: 2. They are maximum at no-load

Friction and winding losses of 3 phase induction motor are maximum at no-load

Which of the following starting method is not preferred for starting large induction motors

Which of the following starting method is not preferred for starting large induction motors:

  1. Direct on-line
  2. Star-delta starting
  3. Autotransformer
  4. None of above

Direct on-line

Which of the following starting method is not preferred for starting large induction motors since it results in very high starting current. Rather some starter is used for reducing the amount of current.

The power factor of an induction motor on no load is around

The power factor of an induction motor on no load is around:

  1. 0.1-0.2
  2. 0.7
  3. 0.85
  4. 1

Correct answer: 1. Low

The power factor of an induction motor on no load is low.

At no load, the induction motor takes a very high no-load current (that is lagging the applied voltage by a large angle). For this reason, the power factor of an induction motor on no load is low.

When loaded an induction motor can be thought of a transformer whose secondary is

When loaded an induction motor can be thought of a transformer whose secondary is:

  1. Short circuited
  2. Open circuited
  3. Supplying a variable resistive load
  4. None of above

Correct answer: 3. Supplying a variable resistive load

When loaded an induction motor can be thought of a transformer whose secondary is Supplying a variable resistive load

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