The back e.m.f. in the stator of a synchronous motor depends on____________?

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 magnitude of stator back e.m.f. Eb depends on___________?

   A. load on the motor
   B. d.c. excitation only
   C. both the speed and rotor flux
   D. none of the above

3. In a synchronous motor, the magnitude of stator back e.m.f. & depends on_______________?

   A. d.c. excitation only
   B. speed of the motor
   C. load on the motor
   D. both the speed and rotor flux

4. Which of the following losses is not dissipated by the stator core surface in a synchronous motor?

   A. Eddy current losses in the conductors
   B. Iron losses in the stator
   C. Copper losses in the slot portion of the conductors
   D. Windage losses
   E. None of the above

5. 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

6. In a synchronous motor, damper windings are provided on____________?

   A. stator frame
   B. rotor shaft
   C. pole faces
   D. none of the above

7. 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

8. 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

9. 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

10. 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