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

Related Mcqs:

1. 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...

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. 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...

5. In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?

   A. 5 percent B. 10 percent C. 15 percent D. 30 percent E. none of the above...

6. 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...

7. Power transformers have rating_______________?

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

8. The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?

   A. 0.5 to 0.8 Wb/m2 B. 0.8 to 1.0 Wb/m2 C. 1.1 to 1.35 Wb/m2 D. 1.4 to 1.8 Wb/m2...

9. Multi-layer helical windings are commonly used in the transformers as high voltage windings_______________?

   A. upto 20 kV B. upto 50 kV C. upto 80 kV D. for 110 kV and above...

10. Cylindrical windings using circular conductors, employed in transformers, are_____________?

    A. single layered B. double layered C. multi-layered D. none of the above...