Induction Motor MCQs Part 3

Induction Motor MCQs Part 3

The operation of induction motor is based on

The operation of induction motor is based on:

1. Ampere’s law
2. Lenz’s law
3. Principle of self-induction
4. Principle of mutual induction

Correct answer: 4. Principle of mutual induction

The no-load speed of induction motor depends on which of following factor

The no-load speed of induction motor depends on which of following factor:

1. Number of poles
2. Supply frequency
3. Both of these
4. None of these

Correct answer: 3. Both of these

If Ns implies speed of rotating flux for three phase induction motor and N is speed of the rotor, the rate at which the flux cuts the rotor conductors is directly proportional to

If Ns implies speed of rotating flux for three phase induction motor and N is speed of the rotor, the rate at which the flux cuts the rotor conductors is directly proportional to

1. Ns
2. Ns-N
3. N
4. N-Ns

Correct answer: 2. Ns-N

The rotor winding of a 3-phase wound rotor induction motor is generally connected in configuration

The rotor winding of a 3-phase wound rotor induction motor is generally connected in configuration

1. Delta
2. Star
3. Partly star and partly delta
4. None of these

Correct answer: 2. Star

A 3-phase induction motor is

A 3-phase induction motor is

1. Almost a constant-speed motor
2. Highly variable speed motor
3. Very expensive motor
4. Not easily maintainable

Correct answer: 1. Almost a constant-speed motor

The size of air-gap between stator and rotor of a 3-phase induction motor ranges between

The size of air-gap between stator and rotor of a 3-phase induction motor ranges between

1. 5 cm to 10 cm
2. 1 cm to 2 cm
3. 4 cm to 6 cm
4. 0·4 mm to 4 mm

Correct answer: 4. 0·4 mm to 4 mm

Provided that, for same kVA rating the leakage flux of induction motor as compared to transformer is

Provided that, for same kVA rating the leakage flux of induction motor as compared to transformer is:

1. Less
2. More
3. Identical
4. None of these

Correct answer: 2. More

A squirrel cage induction motor is not selected for which of the following case

A squirrel cage induction motor is not selected for which of the following case:

1. Maintenance cost is to be kept low
2. Initial cost is the main consideration
3. Higher starting torque is the main consideration
4. All above considerations are involved

Correct answer: 3. Higher starting torque is the main consideration

As compared to squirrel cage induction motor, a wound rotor induction motor is preferred for

As compared to squirrel cage induction motor, a wound rotor induction motor is preferred for:

1. High starting torque
2. Slow speed operation
3. All of the above
4. Low windage losses

Correct answer: 1. High starting torque

Blocked rotor test on induction motors is performed to determine

Blocked rotor test on induction motors is performed to determine:

1. Power factor on short circuit
2. Leakage reactance
3. Short-circuit current under rated voltage
4. All of these

Correct answer: 4. All of these