Machines cooled by direct cooling method may be called_____________?

Related Mcqs:

1. 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

2. In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?

   A. increase
   B. decrease
   C. either of the above
   D. none of the above

3. Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?

   A. 10 MW
   B. 30 MW
   C. 60 MW
   D. 150 MW

4. 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

5. Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?

   A. 2 MVA
   B. 5 MVA
   C. 7.5 MVA
   D. 10 MVA

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

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

7. 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

8. Direct water cooling of rotor winding presents_____________?

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

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

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

10. Electrical machines having a power output up to about 750 W may be called__________machines?

    A. small size
    B. medium size
    C. large size
    D. any of the above