Related Questions

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
While starting a synchronous motor by induction motor action, field winding is usually
A connected to D.C. supply
B short-circuited by low resistance
C kept open-circuited
D none of the above
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
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
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
An important advantage of a synchronous motor over wound round induction motor is that
A its power factor may be varied at will
B its speed is independent of supply frequency
C its speed may be controlled more easily
D none of the above
If Bashar can run around a ground four times in 20 minutes and Rahim can run around the same ground three times in 12 minutes, who can run around that ground more times in an hour, and how many times more can he run around ?
A Bashar, three times more
B Rahim , three times more
C They both go around 12 times
D Bashar, eight times more
A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
A Slop speed operation
B High starting torque
C Low windage losses
D All of the above
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

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