The maximum power developed in a synchronous motor occurs at a coupling angle of

A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will

A

remain same

B

go down

C

improve

D

none of the above

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

A

rotor and stator teeth

B

rotor and the stator poles of opposite polarity

C

rotor and the stator poles of the same polarity

D

none of the above

The power developed by a synchronous motor will be maximum when the load angle is

A

zero

B

45°

C

90°

D

120°

In a synchronous motor, the maximum power developed depends on all of the following except

A

rotor excitation

B

maximum value of coupling angle

C

direction of rotation

D

supply voltage

The maximum power developed in a synchronous motor will depend on

A

the rotor excitation only

B

the supply voltage only

C

the rotor excitation and supply volt-age both

D

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

A synchronous motor develops maximum power when load angle is

A

45°

B

60°

C

90°

D

120°

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

A

under-loaded

B

over-loaded

C

under-excited

D

over-excited

A synchronous motor can develop synchronous torque

A

when under loaded

B

while over-excited

C

only at synchronous speed

D

below or above synchronous speed

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because

A

synchronous motor has no slip

B

stator supply is not required to produce magnetic field

C

mechanical load on the rotor remains constant

D

synchronous motor has large airgap

The power factor of a synchronous motor is better than that of induction motor because

A

stator supply is relieved of responsibility of producing magnetic field

B

mechanical load on the motor can be adjusted

C

synchronous motor runs at synchronous speed

D

synchronous motor has large air gap

The maximum power developed in a synchronous motor occurs at a coupling angle of

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