In which of the following motors the stator and rotor fields rotate simultaneously? A. D.C. motor B. Reluctance motor C. Universal motorD. Synchronous motor E. Induction motor
If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then A. it runs at a slower speedB. the motor stops C. it continues to run at the same speed D. it runs at a very high…
A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because A. speed of the motor is reduced B. power factor is decreased C. Eb (back e.m.f.) becomes less than…
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor A. will become moreB. will become less C. will remain…
Stability of a synchronous machine: A. decreases with increase in its excitationB. increases with increase in its excitation C. remains unaffected with increase in excitation D. any of the above
If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to____________? A. increase in both armature current and power factor angle B. increase in back e.m.f.…
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerating torque is produced by_____________? A. induction motor torque in field winding B. induction motor torque in damper winding C.…
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…
Which of the following motors will be used in electric clocks? A. D.C. shunt motor B. D.C. series motor C. A.C. induction motorD. A.C. synchronous motor
Power factor of a synchronous motor is unity when_____________? A. the armature current is maximumB. the armature current is minimum C. the armature current is zero D. none of the above