Related Questions

The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as
A pull-up torque
B pull-in torque
C pull-out torque
D none of the above
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
Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?
A High field current
B Low short circuit ratio
C High core losses
D Low field current
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
The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as
A locked-rotor torque
B synchronous torque
C pull up torque
D reluctance torque
The ratio of starting torque to running torque in a synchronous motor is
A zero
B one
C two
D infinity
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
A induction motor torque in field winding
B induction motor torque in damper winding
C eddy current and hysteresis torque in pole faces
D reHetance motor torque due to saliency of the rotor
E all of the above methods
When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
A inductor motor torque
B induction generator torque
C synchronous motor torque
D d.c. motor toque
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
In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
A One-third
B Twice
C Thrice
D Six times

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