Transformers

A. 180°
B. 120″
C. 90°
D. 75°

A common method of cooling a power transformer is_______________?

A. natural air cooling
B. air blast cooling
C. oil cooling
D. any of the above

In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are______________?

A. friction and windage losses
B. copper losses
C. hysteresis and eddy current losses
D. none of the above

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

Which winding in a transformer has more number of turns ?

A. Low voltage winding
B. High voltage winding
C. Primary winding
D. Secondary winding

Primary winding of a transformer________________?

A. is always a low voltage winding
B. is always a high voltage winding
C. could either be a low voltage or high voltage winding
D. none of the above

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

A transformer transforms__________________?

A. voltage
B. current
C. power
D. frequency

In the transformer following winding has got more cross-sectional area______________?

A. Low voltage winding
B. High voltage winding
C. Primary winding
D. Secondary winding

While conducting short-circuit test on a transformer the following side is short circuited?

A. High voltage side
B. Low voltage side
C. Primary side
D. Secondary side