Which of the following does not change in a transformer ?

A. Current
B. Voltage
C. Frequency
D. All of the above

In a transformer the energy is conveyed from primary to secondary_________?

A. through cooling coil
B. through air
C. by the flux
D. none of the above

A transformer core is laminated to__________?

A. reduce hysteresis loss
B. reduce eddy current losses
C. reduce copper losses
D. reduce all above losses

The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?

A. tightness of clamping
B. gauge of laminations
C. size of laminations
D. all of the above

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

No-load on a transformer is carried out to determine______________?

A. copper loss
B. magnetising current
C. magnetising current and loss
D. efficiency of the transformer

The dielectric strength of transformer oil is expected to be______________?

A. lkV
B. 33 kV
C. 100 kV
D. 330 kV

Sumpner’s test is conducted on transformers to determine_____________?

A. temperature
B. stray losses
C. all-day efficiency
D. none of the above

The permissible flux density in case of cold rolled grain oriented steel is around__________?

A. 1.7 Wb/m2
B. 2.7 Wb/m2
C. 3.7 Wb/m2
D. 4.7 Wb/m2

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