A. the supply voltage and the back e.m.f.
B. magnetising current and back e.m.f.
C. the rotating stator flux and rotor poles
D. none of the above
Related Mcqs:
- 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 coupling angle or load angle of synchronous motor is defined as the angle between the__________?
A. rotor and stator teeth
B. rotor and the stator poles of opposite polarity
C. rotor and the stator poles of the same polarity
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 - 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 - If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is__________?
A. 2
B. 3
C. 4
D. 6 - 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
E. nine times - 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. eddy current and hysteresis torque in pole faces
D. reHetance motor torque due to saliency of the rotor
E. all of the above methods - In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?
A. 3000 r.p.m.
B. 1500 r.p.m.
C. 750 r.p.m.
D. none of the above - When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?
A. V
B. V312
C. V2
D. 1/V - The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as_____________?
A. slip torque
B. pull-out torque
C. breaking torque
D. synchronising torque
