The no-load current drawn by transformer is usually what per cent of the full-load current ?

Related Mcqs:

1. In an actual transformer the iron loss remains practically constant from no load to full load because:____________?

   A. value of transformation ratio remains constant
   B. permeability of transformer core remains constant
   C. core flux remains practically constant
   D. primary voltage remains constant
   C. secondary voltage remains constant

2. 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

3. Which of the following loss in a transformer is zero even at full load ____________?

   A. Core loss
   B. Friction loss
   C. Eddy current loss
   D. Hysteresis loss

4. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of_________________?

   A. less than 15 A
   B. more than 15 A
   C. 15 A
   D. none of the above

5. The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be___________?

   A. 6400 W
   B. 1600 W
   C. 800 W
   D. 400 W

6. The no load current in a transformer lags behind the applied voltage by an angle of about_____________?

   A. 180°
   B. 120″
   C. 90°
   D. 75°

7. 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

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. The magnetising current of a transformer is usually small because it has___________?

   A. small air gap
   B. large leakage flux
   C. laminated silicon steel core
   D. fewer rotating parts

10. 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