__________is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ?

Related Mcqs:

1. The design of mechanical parts is particularly important in case of __________ speed machines?

   A. low
   B. medium
   C. high
   D. any of the above

2. The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?

   A. heating time constant
   B. cooling time constant
   C. either A. or B.
   D. none of the above

3. The change in flux linkages can be caused in which of the following ways ?

   A. The flux is constant with respect to time and is stationary and the coil moves through it
   B. The coil is stationary with respect to flux and the flux varies in magnitude with respect to time
   C. Both the changes mentioned above occur together, i.e., the coil moves through a time varying field
   D. All of the above

4. 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

5. 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

6. 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

7. 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

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. D.C. machines designed with a large value of air gap length have_____________?

   A. worst, ventilation
   B. poor ventilation
   C. better ventilation
   D. none of the above

10. 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