In induction motors, the length of air gap in kept as small as mechanically possible is order to have____________?

Related Mcqs:

1. The length cf air gap to be provided in __________ is primarily determined by power factor consideration?

   A. d.c. series motor . B. d.c. shunt motor C. induction motor D. synchronous motor...

2. D.C. machines designed with a large value of air gap length have_____________?

   A. worst, ventilation B. poor ventilation C. better ventilation D. none of the above...

3. The operation of a D.C. machine with large air gap lengths is comparatively_____________?

   A. quiet B. noisy C. either of the above D. none of the above...

4. Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors ?

   A. Copper B. Aluminium C. Steel D. Cast-iron...

5. In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?

   A. 2 to 3 times greater B. 3 to 4 times greater C. 4 to 5 times greater D. none of the above...

6. Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits ?

   A. Increased I R losses B. Increased core losses C. Poor commutation D. Change in motor parameters E. All of the above...

7. Which of the following in an application of D.C. motors?

   A. Traction B. Drives for process industry C. Battery driven vehicles D. Automatic control E. All of the above...

8. The efficiency of a machine should be as ____________ as possible to reduce the operating cost?

   A. high B. low C. either of the above D. none of the above...

9. With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?

   A. 50 MW B. 100 MW C. 200 MW D. none of the above...

10. With direct water cooling it is possible to have ratings of about_____________?

    A. 200 MW B. 300 MW C. 400 MW D. 600 MW...