Open circuit and short circuit test for transformer iron loss and copper loss.

Transformer known low loss among the electrical machine, hence efficiency of transformer about 98% at full load operation.
But some lossless have,it is determined by open circuit test and short circuit test.

Open circuit test of transformer.
Open circuit test of transformer determine iron loss as a eddy current loss and hysteresis loss.
in open circuit test HT(high tension) side of transformer open and testing done with LT side (low tension) by apply rated voltage.
Watt meter connected in the circuit measured all lossless of transformer. but HT side open current through the winding flow very less hence copper loss neglected,it is 2 to 3 % of full load copper loss.

Short circuit test of transformer.

Short circuit test done to determine copper loss in transformer.
in short circuit test Low tension(LT) windings short circuit and high tension (HT) winding supply 10 % voltage,but due to LT short full load current achieve, hence full load copper shown in watt meter,here iron loss neglected because very small .