Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect?

Related Mcqs:

1. 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

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. The voltage transformation ratio of a transformer is equal to the ratio of_______________?

   A. primary turns to secondary turns
   B. secondary current to primary current
   C. secondary induced e.m.f. to primary induced e.m.f
   D. secondary terminal voltage to primary applied voltage

4. 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

5. Which type of winding is used in 3 phase shell-type transformer?

   A. Circular type
   B. Sandwich type
   C. Cylindrical type
   D. Rectangular type

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

   A. 0.2 to 0.5 per cent
   B. 2 to 5 per cent
   C. 12 to 15 per cent
   D. 20 to 30 per cent

7. 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

8. If the supply frequency to the transformer is increased,”the iron loss will__________?

   A. not change
   B. decrease
   C. increase
   D. any of the above

9. If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be___________?

   A. R2/VK
   B. R2IK2
   C. R22!K2
   D. R22/K

10. Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is_________________?

    A. approximately equal to one
    B. less than one
    C. great than one
    D. none of the above