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

Related Mcqs:

1. The forced oil and air circulation method is usual one for transformers of capacities____________?

   A. upto 5 MVA B. upto 10 MVA C. upto 20 MVA D. 30 MVA upwards...

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. 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...

4. For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?

   A. 1.0 Wb/m2 B. 1.1 Wb/m2 C. 1.3 Wb/m2 D. 1.6 Wb/m2 E. None of the above...

5. 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...

6. 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...

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

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

8. Power transformers should be designed to have maximum efficiency________________?

   A. at one-fourth load B. at one-half load C. at or near full load D. any of the above...

9. Power transformers have rating_______________?

   A. equal to 50 kVA B. equal to 100 kVA C. above 200 kVA D. none of the above...

10. Aluminium when adopted as a conductor material in __________ transformers, decreases the overall cost of the transformer?

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