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

Related Mcqs:

1. 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...

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

   A. low power factor B. high power factor C. high over load capacity D. any of the above...

3. 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...

4. For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?

   A. 1.0 to 1.2 A/mm2 B. 1.5 to 2.0 A/mm2 C. 2.2 to 3.2 A/mm2 D. 3.2 to 4.2 A/mm2...

5. 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...

6. The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?

   A. heating time constant B. cooling time constant C. either A. or B. D. none of the above...

7. In a D.C. machine the current per brush arm should not be more than_____________?

   A. 100 A B. 200 A E. 300 A D. 400 A...

8. In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?

   A. 10 m/s B. 20 m/s C. 30 m/s D. 40 m/s...

9. In a D.C. machine the number of brush arms is _________ the number of poles?

   A. less than B. equal to C. greater than D. none of the above...

10. The laminations of the armature of a D.C. machine are usually ___________ thick?

    A. 0.1 to 0.2 mm B. 0.2 to 0.3 mm C. 0.3 to 0.4 mm D. 0.4 to 0.5 mm...