Core losses are caused by two factors: hysteresis and eddy current losses. Hysteresis loss is that
energy lost by reversing the magnetic field in the core as the magnetizing AC rises and falls and
reverses direction. Eddy current loss is a result of induced currents circulating in the core.
The efficiency of a transformer can be calculated using Equations (13-8), (13-9), and (13-10).
VS IS x PF
(VS IS x PF)
PF = power factor of the load
A 5:1 step-down transformer has a full-load secondary current of 20 amps. A
short circuit test for copper loss at full load gives a wattmeter reading of 100 W.
If RP = 0.3W, find RS and power loss in the secondary.
To find IP:
To find RS: