Page 576 - Basic Electrical Engineering

Example 6.6 The no-load input power to a transformer is 100 W. The no-

load current is 3 A when the primary applied voltage is 230 V at 50 Hz. The
resistance of the primary winding in 0.5 Ω. Calculate the value of iron loss

and no-load power factor.

Solution:

2
At no-load, the input power is lost as a small amount of I R loss in the
winding and as core loss.

In an ac circuit, power = VI cos ϕ

Let No-load input power be W 0