SYNCHRONOUS MOTORS QUIZ

While running, a synchronous motor is compelled to run at synchronous speed because of _______

Compulsion due to lenz's law

Induced emf in rotor field winding by stator flux

Magnetic locking between stator and rotor poles

Damper winding in its pole faces

TRUE ANSWER : ?
YOUR ANSWER : ?

Synchronous motor always run at

Less than synchronous speed

None of the listed here

More than synchronous speed

The synchronous speed

TRUE ANSWER : ?
YOUR ANSWER : ?

The direction of rotation of a synchronous motor can be reversed by reversing,

None of the listed here

Supply phase sequence

Polarity of rotor poles

Current to field winding

TRUE ANSWER : ?
YOUR ANSWER : ?

The magnitude of field flux in a 3-phase synchronous motor

Varies with the load

Remains constant at all loads

Varies with power factor

Varies with speed

TRUE ANSWER : ?
YOUR ANSWER : ?

In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then

the torque generated is maximum

the excitation is said to be zero per cent

the motor is said to be fully loaded

the excitation is said to be hundred per cent

TRUE ANSWER : ?
YOUR ANSWER : ?

Hunting in a synchronous motor cannot be due to

windage friction

variable frequency

variable supply voltage

variable load

TRUE ANSWER : ?
YOUR ANSWER : ?

While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by

induction motor torque in field winding

induction motor torque in damper winding

eddy current and hysteresis torque in pole faces

All of the listed here

TRUE ANSWER : ?
YOUR ANSWER : ?

The rotor of a synchronous motor is

None of the listed here

Salient pole type

Nonsalient pole type

Identical to that of a dc motor

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For the same active power consumed, the stator current of a synchronous motor is ______ that of a 3 phase induction motor.

Less than

None of the listed here

The same as

More than

TRUE ANSWER : ?
YOUR ANSWER : ?

When pull-out torque occurs in a synchronous motor, the poles of the rotor are _______

Coincident with statorbpoles

45° (electrical) behind stator poles

Mid way between N and S poles of stator

None of the listed here

TRUE ANSWER : ?
YOUR ANSWER : ?

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