Search
.Management Sciences
Category: Synchronous Motors
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
A. the motor is said to be fully loaded
B. the torque generated is maximum
C. the excitation is said to be zero per cent
D. the excitation is said to be hundred per cent
The size of a synchronous motor decreases with the increase in___________?
A. flux density
B. horse power rating
C. speed
D. all of the above
. In a synchronous motor which loss varies with load ?
A. Windage loss
B. Bearing friction loss
C. Copper loss
D. Core loss
Change of D.C. excitation of a synchronous motor changes:
A. applied voltage of the motor
B. power factor of power drawn by the motor
C. motor speed
D. none of the these
E. all of the these
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
In a synchronous motor, the breakdown torque is__________?
A. directly proportional to the square of the applied voltage
B. directly proportional to applied voltage
C. inversely proportional to applied voltage
D. none of the above
The ratio of starting torque to running torque in a synchronous motor is____________?
A. zero
B. one
C. two
D. infinity
The effect of increasing the load on a synchronous motor running with normal excitation is to___________?
A. decrease both armature current and power factor
B. decrease armature current but increase power factor
C. increase armature current but decrease power factor
D. increase both its armature current and power factor
In which of the following motors the stator and rotor fields rotate simultaneously?
A. D.C. motor
B. Reluctance motor
C. Universal motor
D. Synchronous motor
E. Induction motor
Synchronous motor always runs at______________?
A. the synchronous speed
B. less than synchronous speed
C. more than synchronous speed
D. none of the above
Recent Comments