The Magnetic Balance test is conducted on Transformers to identify inter turn faults and magnetic imbalance. The magnetic balance test is usually done on the star side of a transformer. A two phase supply 440V is applied across two phases, say, 1U and 1V. The phase W is kept open. The voltage is then measured between U-V and U-W. The sum of these two voltages should give the applied voltage. That is, 1U1W + 1V1W will be equal to 1U1V.