Harmonics in transformer result in___________?

Power transformers are designed to have maximum efficiency at___________?

A. nearly full load
B. 70% full load
C. 50% full load
D. no load

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

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

The path of the magnetic flux in transformer should have____________?

A. high reluctance
B. low reactance
C. high resistance
D. low resistance

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

Helical coils can be used on___________?

A. low voltage side of high kVA transformers
B. high frequency transformers
C. high voltage side of small capacity transformers
D. high voltage side of high kVA rating transformers