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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