SYNCHRONOUS MOTORS QUIZ

An over excited synchronous motor behaves as _____

None of the listed here

A capacitor

A resistor

An inductor

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In a 3-phase synchronous motor, the negative phase sequence exists when the motor is

None of these

under-loaded

over-loaded

supplied with unbalanced voltage

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The back emf in the stator of a synchronous motor depends on

Rotor speed

Flux density

Rotor excitation

None of the listed here

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A synchronous motor runs at speed ranging from ______

150 to 1800 rpm

None of the listed here

3600 to 6000 rpm

1800 to 3600 rpm

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A rotary converter can also be run as a

Synchronous motor

Dc series generator

Dc shunt generator

Dc compound generator

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

minimum

None of the listed here

Maximum

Zero

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An important advantage of a synchronous motor over wound round induction motor is that

None of these

its speed is independent of supply frequency

its power factor may be varied at will

its speed may be controlled more easily

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Change of D.C. excitation of a synchronous motor changes

Motor speed

Applied voltage of the motor

Power factor of power drawn by the motor

Any of the above

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If one phase of a 3 phase synchronous motor is short circuited, motor

Will refused ro start

Will overheat in spots

Will not come upto speed

Will fail to pull into step

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The operating speed of a synchronous motor can be changed to new fixed value by

changing the supply voltage

changing the load

using brakes

changing frequency

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