A Buchholz relay can be installed on______________?

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

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

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

The purpose of providing an iron core in a transformer is to_____________?

A. provide support to windings
B. reduce hysteresis loss
C. decrease the reluctance of the magnetic path
D. reduce eddy current losses

The function of breather in a transformer is___________?

A. to provide oxygen inside the tank
B. to cool the coils during reduced load
C. to cool the transformer oil
D. to arrest flow of moisture when outside air enters the transformer

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

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