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.Management Sciences
Category: Synchronous Motors
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 oscillations in a synchronous motor can be damped out by_______________?
A. maintaining constant excitation
B. running the motor on leading power factors
C. providing damper bars in the rotor pole faces
D. oscillations cannot be damped
In which of the following motors the stator and rotor magnetic field rotate at the same speed?
A. Universal motor
B. Synchronous motor
C. Induction motor
D. Reluctance motor
An over excited synchronous motor is used for____________?
A. fluctuating loads
B. variable speed loads
C. low torque loads
D. power factor corrections
A three-phase synchronous motor will have_____________?
A. no slip-rings
B. one slip-ring
C. two slip-rings
D. three slip-rings
The armature current of the synchronous motor
A. has large values for low excitation i niy
B. has large values for high excitation only
C. has large values for low and high excitation
D. any of the above
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
E. none of the above
The magnitude of field flux in a 3-phase synchronous motor?
A. varies with power factor
B. varies with speed
C. varies with the load
D. remains constant at all loads
A synchronous motor will always stop when:______________?
A. supply voltage fluctuates
B. load in motor varies
C. excitation winding gets disconnected
D. supply voltage frequency changes
The shaft of synchronous motor is made of____________?
A. mild steel
B. chrome steel
C. alnico
D. stainless steel
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