The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?

Related Mcqs:

1. In direct cooled system using hydrogen both stator and rotor conductors are made____________?

   A. solid B. hollow C. perforated D. any ofthe above...

2. 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...

3. The density of hydrogen is __________ times the density of air?

   A. 0.07 B. 1.5 C. 2.5 D. 3.5...

4. 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...

5. Machines cooled by direct cooling method may be called_____________?

   A. “supercharged” B. “inner cooled” C. “conductor cooled” D. any of the above...

6. Direct water cooling of rotor winding presents_____________?

   A. no mechanical difficulties B. lesser mechanical difficulties C. greater mechanical difficulties D. none of the above...

7. 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...

8. Commercial available medium size machines have a speed range of __________ ?

   A. 200 to 400 r.p.m B. 600 to 1000 r.p.m C. 1000 to 1500 r.p.m D. 2000 to 2500 r.p.m...

9. cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?

   A. Direct B. Indirect C. Conventional D. Any of the above...

10. Which of the following brushes can be used for high values of current density ?

    A. Metal graphite brushes B. Hard carbon brushes C. Electro-graphitic brushes D. Natural graphite brushes...