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.Management Sciences
Category: Synchronous Motors
If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then
A. it runs at a slower speed
B. the motor stops
C. it continues to run at the same speed
D. it runs at a very high speed
The construction of a synchronous motor resembles____________?
A. a series motor
B. an induction motor
C. an alternator
D. a rotary converter
Riunting in a synchronous motor takes place___________?
A. when supply voltage fluctuates
B. when load varies
C. when power factor is unity
D. motor is under loaded
The maximum power developed in a synchronous motor occurs at a coupling angle of____________?
A. 30°
B. 60°
C. 90°
D. 180°
Synchronous motors are_____________?
A. not-self starting
B. self-starting
C. essentially self-starting
D. none of the above
Synchronsizing power of a synchronous machine is_____________?
A. direcly proportional to the synchronous reactance
B. inversely proportional to the synchronous reactance
A. equal to the synchronous reactance
D. none of the above
Slip rings are usually made of__________?
A. carbon or graphite
B. brass or steel
C. silver or gold
D. copper or aluminium
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
Stability of a synchronous machine:
A. decreases with increase in its excitation
B. increases with increase in its excitation
C. remains unaffected with increase in excitation
D. any of the above
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