Slip rings are usually made of__________? - PakMcqs

Related Mcqs:

1. Slip-rings in a synchronous motor carry____________?

   A. direct current B. alternating current C. no current D. all of the above...

2. The percentage slip in case of a synchronous motor is____________?

   A. 1% B. 100% C. 0.5% D. zero...

3. The duration of sudden snort-circuit test on a synchronous motor is usually about_____________?

   A. one hour B. one minute C. one second D. none of the above...

4. The efficiency of a properly designed synchronous motor will usually fall in range___________?

   A. 60 to 70% B. 75 to 80% C. 85 to 95% D. 99 to 99.5%...

5. If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor__________?

   A. become more B. become less C. remain constant D. none of the above...

6. The armature current of the synchronous motor

   A. has large values for low excitation i niy B. has large values for high excitation only C. has large values for low and high excitation D. any of the above...

7. The operating speed of a synchronous motor can be changed to new fixed value by___________?

   A. changing the load B. changing the supply voltage C. changing frequency D. using brakes...

8. Under which of the following conditions hunting of synchronous motor is likely to occur?

   A. Periodic variation of load B. Over-excitation C. Over-loading for long periods D. Small and constant load...

9. 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...

10. A synchronous machine with low value of short-circuit ratio has___________?

    A. lower stability limit B. high stability limit C. good speed regulation D. good voltage regulation E. none of the above...