SYNCHRONOUS MOTORS QUIZ

When a synchronous motor is on no load, the torque angle is about ________

30° electrical

90° electrical

45° electrical

0° electrical

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The pull out torque of a synchronous motor is generally ______ times its full-load torque.

0.5

1.25 to 3.5

6 to 9

5 to 10

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A synchronous machine with low value of short-circuit ratio has

lower stability limit

good voltage regulation

high stability limit

good speed regulation

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The mechanical power developed by a synchronous motor is independent of _________.

Applied stator voltage

Field excitation

Torque angle

Speed

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The armature current of the synchronous motor has higher values for

Both higher and low excitation

Higher excitation only

None of the listed here

Low excitation only

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An under excited synchronous motor behaves as_______

None of the listed here

An inductor

A resistor

A capacitor

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A synchronous motor can be started by

Dc compound motor

Provinding damper winding

All of the listed here

Pony motor

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A synchronous machine with large air gap has

a higher synchronizing power which makes the machine less sensitive to load variations

a small value of inherent regulation

all of the listed here

a higher value of stability limit

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When a synchronous motor is pulled out of synchronism, the stator current ________

Remains unchanged

Is decreased too much

Is increased too much

Become zero

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

None of the listed here

Current to field winding

Polarity of rotor poles

Supply phase sequence

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