An over excited synchronous motor is used for____________?

Related Mcqs:

1. When load on an over-excited or under excited synchronous*motor is increased, rate of change of its armature current as compared with that of power factor is___________?

   A. more
   B. less
   C. equal
   D. twice

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. An over-excited synchronous motor takes__________?

   A. leading current
   B. lagging current
   C. both A. and (b)
   D. none of the above

4. When the field of a synchronous motor is under-excited, the power factor will be____________?

   A. leading
   B. lagging
   C. unity
   D. zero

5. In a synchronous motor, the armature current has large values for____________?

   A. high excitation only
   B. low excitation only
   C. both high and low excitation
   D. none of the above

6. A synchronous motor can be used as a synchronous capacitor when it is____________?

   A. under-loaded
   B. over-loaded
   C. under-excited
   D. over-excited

7. 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

8. As the load is applied to a synchronous motor, the motor takes more armature current because

   A. the increased load has to take more current
   B. the rotor by shifting its phase backward causes motor to take more current
   C. the back e.m.f. decreases causing an increase in motor current
   D. the rotor strengthens the rotating field casuing more motor current

9. A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased

   A. power factor as well as armature current will decrease
   B. power factor as well as armature current will increase
   C. power factor will increase but armature current will decrease
   D. power factor will decrease and armature current will increase

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