DC Motor MCQs Part 2

DC Motor MCQs Part 2

Which of following is a variable speed DC motor

Which of following is a variable speed DC motor:

  1. Cumulatively compounded DC Motor
  2. Differentially compounded DC Motor
  3. Shunt DC Motor
  4. Series DC Motor

Correct answer: 4. Series DC Motor

When the speed of a DC motor increases, the armature current

When the speed of a DC motor increases, the armature current:

  1. Remains constant
  2. Increases
  3. Decreases
  4. None of the above

Correct answer: 3. Decreases

With respect to the direction of rotation, the interpoles on a DC motor should have the same polarity as the main poles

With respect to the direction of rotation, the interpoles on a DC motor should have the same polarity as the main poles:

  1. Ahead of them
  2. Behind them
  3. Both of these
  4. None of these

Correct answer: 2. Behind them

Once a shunt motor is up to speed, the speed can be increased considerably by

Once a shunt motor is up to speed, the speed can be increased considerably by:

  1. Decreasing field circuit resistance
  2. Increasing armature circuit resistance
  3. Increasing field circuit resistance
  4. Reducing the load

Correct answer: 1. Decreasing field circuit resistance

The field poles and armature of a DC motor are laminated in order to

The field poles and armature of a DC motor are laminated in order to:

  1. Decrease the speed
  2. Reduce eddy currents
  3. Reduce the weight of the machine
  4. Reduce armature reaction

Correct answer: 2. Reduce eddy currents

Hot bearings of DC can happen due to

Hot bearings of DC can happen due to:

  1. Dirty lubricant or lack of lubricant
  2. Poor ventilation
  3. Deviation from rated voltage
  4. None of above

Correct answer: 1. Dirty lubricant or lack of lubricant

The back EMF in DC motor

The back EMF in DC motor:

  1. Aids the applied voltage
  2. Aids the armature current
  3. Opposes the applied voltage
  4. None of the above

Correct answer: 3. Opposes the applied voltage

DC shunt motors find practical applications where

DC shunt motors find practical applications where:

  1. Practically constant speed is required
  2. High starting torque is required
  3. High no-load speed is required
  4. Variable speed is required

Correct answer: 1. Practically constant speed is required

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