Most Important Synchronous Motor MCQs

1. Sort The advantages of amortisseur winding:

1. It increases stability
2. It develops torque which is useful for fast machine
3. It develops torque which is useful for slow machines
4. All of these

Correct answer: d. All of these

2. The correct statement about the speed of synchronous motor:

1. It remains constant from no load to full load
2. It increases from no load to full load
3. It decreases from no load to full load
4. It is pulsating and change at irregular intervals

Correct answer: a. It remains constant from no load to full load

3. The synchronous motor is not a self starting motor because:

1. It uses damper winding
2. No stator is present
3. The slip is zero in the motor
4. The rotor’s instantaneous torque reverses after half cycle

Correct answer: d. The rotor’s instantaneous torque reverses after half cycle

4. The overexcited synchronous motor is used to:

1. Support the variable loads
2. Support loads which have low torque
3. Supply reactive power
4. None of these

Correct answer: c. Supply reactive power

Explanation: The overexcited synchronous motor provides reactive power to the power system and it can be used for the power factor correction

5. The method which can be used to start a synchronous motor:

1. Use an external prime mover
2. Reduce the stator frequency to safe point
3. Use Amortisseur windings
4. All of these

Correct answer: d. All of these

6. Speed regulation of synchronous motor is:

1. 0
2. 1
3. 10
4. 100

Correct answer: a. 0

7. The maximum pullout torque in a synchronous motor occurs at:

1. 0º
2. 45º
3. 60º
4. 90º

Correct answer: d. 90º

8. Synchronous motors are self-starting, the statement is:

1. True
2. False

Correct answer: b. False

9. The power factor of under excited synchronous motor is:

1. Leading
2. Lagging
3. Unity
4. Zero

Correct answer: b. Lagging

10. The percent slip of synchronous motor is:

1. 0
2. 0.5
3. 99.5
4. 100

Correct answer: a. 0 is the right answer