DC Motor MCQs Part 2

Contents

- 1 Which of following is a variable speed DC motor
- 2 When the speed of a DC motor increases, the armature current
- 3 With respect to the direction of rotation, the interpoles on a DC motor should have the same polarity as the main poles
- 4 Once a shunt motor is up to speed, the speed can be increased considerably by
- 5 The field poles and armature of a DC motor are laminated in order to
- 6 Hot bearings of DC can happen due to
- 7 The back EMF in DC motor
- 8 DC shunt motors find practical applications where

## Which of following is a variable speed DC motor

Which of following is a variable speed DC motor:

- Cumulatively compounded DC Motor
- Differentially compounded DC Motor
- Shunt DC Motor
- 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:

- Remains constant
- Increases
- Decreases
- 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:

- Ahead of them
- Behind them
- Both of these
- 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:

- Decreasing field circuit resistance
- Increasing armature circuit resistance
- Increasing field circuit resistance
- Reducing the load

Correct answer: 3. Increasing 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:

- Decrease the speed
- Reduce eddy currents
- Reduce the weight of the machine
- 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:

- Dirty lubricant or lack of lubricant
- Poor ventilation
- Deviation from rated voltage
- None of above

Correct answer: 1. Dirty lubricant or lack of lubricant

## The back EMF in DC motor

The back EMF in DC motor:

- Aids the applied voltage
- Aids the armature current
- Opposes the applied voltage
- 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:

- Practically constant speed is required
- High starting torque is required
- High no-load speed is required
- Variable speed is required

Correct answer: 1. Practically constant speed is required