Induction motor MCQ Part 5. Multiple choice questions on Induction motor with brief explanatory answers.

## If air gap between rotor and stator of a 3 phase induction motor is increased then

If air gap between rotor and stator of a 3 phase induction motor is increased then:

- Leakage reactance is decreased
- Leakage reactance is increased
- No-load current is decreased
- None of the above

Correct answer: 2. Leakage reactance is increased

## The direction of rotation of field in 3 phase motor depends on which of the following factor

The direction of rotation of field in 3 phase motor depends on which of the following factor:

- Frequency of supply
- Magnitude of supply voltage
- Pole number
- None of the above

Correct answer: 4. None of the above

** The direction of rotation of field in 3 phase motor depends on phase sequence of the supply voltage**.

## The efficiency of induction motor

The efficiency of induction motor:

- Is always greater than 1 – s
- Is sometimes greater than 1 – s
- Cannot be greater than 1 – s
- Is depended on magnitude of supply

Correct answer: 3. Cannot be greater than 1 – s

## The number of rotor bars in squirrel cage induction motor is generally

The number of rotor bars in squirrel cage induction motor is generally:

- A prime number
- An even number
- Equal to stator pole number
- None of the above

Correct answer: 1. A prime number

*The number of rotor bars in squirrel cage induction motor is generally a prime number*

## When of following is the correct statement about rotor reactance of induction motor running at full load

When of following is the correct statement about rotor reactance of induction motor running at full load:

- It is almost zero
- It is comparable to rotor resistance
- It is very large as compared to rotor resistance
- None of above

Correct answer: 2. It is comparable to rotor resistance