When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?

Related Mcqs:

1. 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

2. 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

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

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

4. 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

5. 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

6. The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as__________?

   A. locked-rotor torque
   B. synchronous torque
   C. pull up torque
   D. reluctance torque

7. 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

8. 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

9. When the voltage applied to a synchronous motor is increased, which of the following will reduce?

   A. Stator flux
   B. Pull in torque
   C. Both A. and (b)
   D. None of the above

10. 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