Synchronous Motors Mcqs

This set of Electrical engineering Multiple Choice Questions & Answers (MCQs) focuses on study of “Synchronous Motors”. These questions are chosen from a collection of most authoritative and best reference books on Electrical engineering. Our aim is to prepare an individual for competitive exams like NTS, GAT, ECAT, University and College entrance exams, Jobs and interviews. One should practice our MCQS to assimilate Synchronous Motors Mcqs comprehensively.

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A synchronous motor can develop synchronous torque:

When under loaded

While over-excited

Only at synchronous speed

Below or above synchronous speed

The maximum power developed in a synchronous motor will depend on__________?

The rotor excitation only

The supply voltage only

The rotor excitation and supply volt-age both

The rotor excitation, supply voltage and maximum value of coupling angle (90°)

In a synchronous motor, the breakdown torque is__________?

Directly proportional to the square of the applied voltage

Directly proportional to applied voltage

Inversely proportional to applied voltage

None of the above

A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as_________?

Static condenser


Synchronous condenser

None of the above

If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then_____________?

The stator current will be zero

The stator current will be very small

The stator current will be very high

The back e.m.f. will be more than the supply voltage

The coupling angle or load angle of synchronous motor is defined as the angle between the__________?

Rotor and stator teeth

Rotor and the stator poles of opposite polarity

Rotor and the stator poles of the same polarity

None of the above

The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as__________?

Locked-rotor torque

Synchronous torque

Pull up torque

Reluctance torque

If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will__________?


Run as induction motor

Function as static condenser

Burn with dense smoke

A synchronous machine with low value of short-circuit ratio has___________?

Lower stability limit

High stability limit

Good speed regulation

Good voltage regulation

The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as___________?

Pull-up torque

Pull-in torque

Pull-out torque

None of the above

The construction of a synchronous motor resembles____________?

A series motor

An induction motor

An alternator

A rotary converter

For power factor correction, synchronous motors operate at____________?

No-load and greatly over-excited fields

No-load and under-excited fields

Normal load with minimum excitation

Normal load with zero excitation

Which of the following losses is not dissipated by the stator core surface in a synchronous motor?

Eddy current losses in the conductors

Iron losses in the stator

Copper losses in the slot portion of the conductors

Windage losses

The size of a synchronous motor decreases with the increase in___________?

Flux density

Horse power rating


All of the above

Which of the following losses, in a synchronous motor, does not vary with load?

Windage loss

Copper losses

Any of the above

None of the above

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