Question

The efficiency of a transformer is 90%. The maximum loss has occured in

• A. resistance of primary and secondary coils
• B. eddy current
• C. hysteresis loss
• D. magnetostriction loss.

Answer 1

Answer: (A)

resistance of primary and secondary coils

losses consist of $I^{2}R$ losses in the primary and secondary windings, and hysteresis and eddy-current losses in core.
Hysteresis losses are minimized by the use of iron having a narrow hysteresis loop; and eddy currents are minimized by laminating the core; nothing much can be done about the $I^{2}R$, other than using wires of low resistivity.
Maximum losses occurs as the $I^{2}R$ losses compared to the hysteresis and eddy currents loss which are controlled by the mentioned ways.