The Magnetic Balance test is conducted on Transformers to get inter turn faults and magnetic imbalance. The magnetic balance test is urgently done on the star side of a transformer. supply 440V is applied across two phases, say, R and Y. The phase B is kept open. The voltage is then measured
between R-B and Y-B. The sum of these two voltages should give the applied voltage. That is, V(RY) = V(RB) + V(YB)
For instance, if the voltage applied is 440V between 1U1V, then the voltages obtained can be
V(RY) = V(RB)+ V(YB)
440V = 260V + 180V
The voltages obtained in the secondary will also be proportional to the voltages above.
This indicates that the transformer is magnetically balanced. If there is any inter-turn short circuit that may result in the sum of the two voltages not being equal to the applied voltage.
The Magnetic balance test is only an indicative test for the transformer. Its results are not absolute. It needs to be used in conjunction with other tests.
To test voltage is to be applied across each terminal and measure rest two one. and it should be repeat for other options as below. and take reading
| V(RB) in volt | V(RY) in volt | V(BY) in volt |
| voltage applied | voltage measured | voltage measured |
| voltage measured | voltage applied | voltage measured |
| voltage applied | voltage measured | voltage measured |