A common method of cooling a power transformer is_______________?

Related Mcqs:

1. 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

2. 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

3. Efficiency of a power transformer is of the order of________________?

   A. 100 per cent
   B. 98 per cent
   C. 50 per cent
   D. 25 per cent

4. The power transformer is a constant______________?

   A. voltage device
   B. current device
   C. power device
   D. main flux device

5. The maximum load that a power transformer can carry is limited by its________________?

   A. temperature rise
   B. dielectric strength of oil
   C. voltage ratio
   D. copper loss

6. 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

7. Natural oil cooling is used for transformers up to a rating of____________?

   A. 3000 kVA
   B. 1000 kVA
   C. 500 kVA
   D. 250 kVA

8. A transformer cannot raise or lower the voltage of a D.C. supply because_______________?

   A. there is no need to change the D.C. voltage
   B. a D.C. circuit has more losses
   C. Faraday’s laws of electromagnetic induction are not valid since the rate of change of flux is zero
   D. none of the above

9. No-load current of a transformer has_____________?

   A. has high magnitude and low power factor
   B. has high magnitude and high power factor
   C. has small magnitude and high power factor
   D. has small magnitude and low power factor

10. The transformer ratings are usually expressed in terms of______________?

    A. volts
    B. amperes
    C. kW
    D. kVA