# Single Phase Induction Motor MCQs Part 3

Single Phase Induction Motor MCQs Part 3

## For same rating, the size of single-phase induction motor is around how many times that of a corresponding 3-phase induction motor

For same rating, the size of single-phase induction motor is around how many times that of a corresponding 3-phase induction motor:

1. 0.5 ties
2. 1.5 times
3. 3 times
4. Same

See complete list of Induction motor MCQs

## The purpose of starting winding in single phase induction motor is to

The purpose of starting winding in single phase induction motor is to:

1. Limit temperature rise of temperature
2. Produce rotating flux in conjunction with main winding
3. Reduce the losses
4. None of these

Correct answer: 2. Produce rotating flux in conjunction with main winding

## As compared to resistance split induction motors, the capacitor motors are

As compared to resistance split induction motors, the capacitor motors are:

1. Costlier
2. Less costly
3. Any of these
4. None of these

Also see: Amps to kW Conversion formula

## A 4 pole, 250 W, 115 V, 60 Hz capacitor start induction motor takes a full-load line current of 5.5 A when running at 1770 RPM. The full-load efficiency of motor is 65%. The slip is

A 4 pole, 250 W, 115 V, 60 Hz capacitor start induction motor takes a full-load line current of 5.5 A when running at 1770 RPM. The full-load efficiency of motor is 65%. The slip is:

1. 0.7%
2. 1.2%
3. 1.7%
4. 4.7%

Synchronous speed (Ns) = 120f/P = 120*60/4 = 1800 RPM

——————–

Slip (s) = (Ns – N)/Ns = (1800 – 1770)/1800 = 0.017 = 1.7%

## A capacitor start, capacitor-run motor has

A capacitor start, capacitor-run motor has:

1. High starting torque
2. Low power factor
3. High power factor
4. Low efficiency

Correct answer: 3. High power factor

Explanation: The capacitor start, capacitor-run motor is similar to the capacitor-start type with the exception that the stating winding remains in circuit after motor is started. Such a motor, as a result of the aforementioned operates at higher power factor.

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