Related Mcqs:

1. The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as___________?

   A. pull-up torque
   B. pull-in torque
   C. pull-out torque
   D. none of the above

2. 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

3. 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

4. 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

5. 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

6. The ratio of starting torque to running torque in a synchronous motor is____________?

   A. zero
   B. one
   C. two
   D. infinity

7. The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of_____________?

   A. zero degree
   B. two degrees
   C. five degrees
   D. ten degrees

8. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor___________?

   A. remains same as the original value
   B. decreases to half the original value
   C. tends to becomes zero
   D. increases to two times the original value

9. 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

10. 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