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

Related Mcqs:

1. The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?

   A. minimum B. maximum C. nil D. none of the above...

2. The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?

   A. minimum B. maximum C. nil D. none of the above...

3. 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...

4. 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...

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. 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...

7. 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...

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

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

9. The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

   A. Corrugations B. Fins C. Tubes D. Radiator tanks E. All of the above...

10. Hot rolled sheets have ___________ value of permeability?

    A. zero B. low C. high D. none of the above...