Synchronous Motor MCQ Part 4.

Under: *Synchronous motor multiple choice questions*

## The speed regulation of a synchronous motor is always

The speed regulation of a synchronous motor is always:

- Positive
- Negative
- 50%
- Zero

Correct answer: 4. Zero

Speed regulation is mathematically defined as:

**SR = (η _{nl} – η_{fl})/η_{fl} * 100%**

*Since in synchronous motor the speed essentially remains same from no load to full load, the speed regulation of synchronous motor is zero.*

## The maximum value of torque angle in synchronous motor (expressed in electrical degrees is

The maximum value of torque angle in the synchronous motor (expressed in electrical degrees is:

- 22.5
- 45
- 90
- 120

Correct answer: 3. 90

## In synchronous motor the loss of synchronization after the pullout torque is exceeded is termed as

In synchronous motor the loss of synchronization after the pullout torque is exceeded is termed as:

- Hunting
- Slipping poles
- Crawling
- None of above

Correct answer: 2. Slipping poles

## The larger the field current of synchronous motor

The larger the field current of synchronous motor:

- The greater the maximum torque of the motor
- The lower the maximum torque of the motor
- Any of above
- None of above

Correct answer: 1. The greater the maximum torque of the motor

*In synchronous motor, the larger is the field current of synchronous motor the greater will be the maximum torque of motor*

## An increase in load of synchronous motor will increase armature current for which of the following conditions

An increase in load of synchronous motor will increase armature current for which of the following conditions:

- When motor is under excited
- When motor is normally excited
- When motor is over excited
- All of above

Correct answer: 4. All of above