Which of the following methods is used for air cooling of turbo-alternators ?

Related Mcqs:

1. 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...

2. 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...

3. 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...

4. 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...

5. Which of the following is an advantage of hydrogen cooling ?

   A. Increase in efficiency B. Increase in ratings C. Increase in life D. Smaller size of coolers E. All of the above...

6. 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...

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

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

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. A current density of __________ is ilsed for large power transformers with forced circulation of oil or with water cooling coils?

    A. 1.5 to 2.5 A/mm2 B. 3.5 to 4.5 A/mm2 C. 4.0 to 5.0 A/mm2 D. 5.4 to 6.2 A/mm2...