Efficiency of a power transformer is of the order of________________?

Related Mcqs:

1. Which of the following is the main advantage of an auto-transformer over a two winding transformer?

   A. Hysteresis losses are reduced
   B. Saving in winding material
   C. Copper losses are negligible
   D. Eddy losses are totally eliminated

2. The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?

   A. Conservator
   B. Breather
   C. Bushings
   D. Buchholz relay

3. The efficiency of a transformer will be maximum when_____________?

   A. copper losses = hysteresis losses
   B. hysteresis losses = eddy current losses
   C. eddy current losses = copper losses
   D. copper losses = iron losses

4. In a transformer routine efficiency depends upon_____________?

   A. supply frequency
   B. load current
   C. power factor of load
   D. both B. and (c)

5. The maximum efficiency of a distribution transformer is____________?

   A. at no load
   B. at 50% full load
   C. at 80% full load
   D. at full load

6. An ideal transformer will have maximum efficiency at a load such that?

   A. copper loss = iron loss
   B. copper loss iron loss
   D. none of the above

7. The efficiency of a transformer, under heavy loads, is comparatively low because_______________?

   A. copper loss becomes high in proportion to the output
   B. iron loss is increased considerably
   C. voltage drop both in primary and secondary becomes large
   D. secondary output is much less as compared to primary input

8. For a transformer, operating at constant load current, maximum efficiency will occur at______________?

   A. 0.8 leading power factor
   B. 0.8 lagging power factor
   C. zero power factor
   D. unity power factor

9. A common method of cooling a power transformer is_______________?

   A. natural air cooling
   B. air blast cooling
   C. oil cooling
   D. any of the above

10. In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?

    A. to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
    B. to absorb the line surge voltage and save the winding of transformer from damage
    C. to reflect the line surge and save the winding of a transformer from damage
    D. none of the above