SYNCHRONOUS MOTORS QUIZ

When the synchronous motor runs at synchronous speed, the voltage induced in the damper winding is _____

None of the listed here

Zero

minimum

Maximum

TRUE ANSWER : ?
YOUR ANSWER : ?

In order to to reverse the direction of a synchronous motor, _______

Change supply frequency

None of the listed here

Interchange any two stator lines

Reduce dc field excitation to zero

TRUE ANSWER : ?
YOUR ANSWER : ?

The speed of a synchronous motor

Increases as the load increases

None of the listed here

Always remains constant

Decreases as the load decreases

TRUE ANSWER : ?
YOUR ANSWER : ?

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

None of the listed here

Mid way between N and S poles of stator

Coincident with statorbpoles

45° (electrical) behind stator poles

TRUE ANSWER : ?
YOUR ANSWER : ?

When the field of a synchronous motor is under-excited, the power factor will be

lagging

unity

leading

zero

TRUE ANSWER : ?
YOUR ANSWER : ?

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

Damper winding in its pole faces

Compulsion due to lenz's law

Magnetic locking between stator and rotor poles

Induced emf in rotor field winding by stator flux

TRUE ANSWER : ?
YOUR ANSWER : ?

The speed of a synchronous motor can be changed by varying _______

None of the listed here

Mechanical load

Supply frequency

Field excitation

TRUE ANSWER : ?
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A synchronous machine with low value short circuit ratio has

High stability limit

Lower stability limit

Good voltage regulation

Good speed regulation

TRUE ANSWER : ?
YOUR ANSWER : ?

A synchronous motor can be used as a synchronous capacitor when it is

Over excited

Under excited

Under loaded

Over loaded

TRUE ANSWER : ?
YOUR ANSWER : ?

If the field of a synchronous motor is underexcited, the power factor will be

zero

lagging

unity

leading

TRUE ANSWER : ?
YOUR ANSWER : ?

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