what is the polarity test of a transformer?

The polarity test of a transformer is conducted to determine the relative polarity of the windings, which is crucial for proper connection in parallel operation. This test involves applying a low voltage to one winding and measuring the voltage induced in the other winding. By observing the phase relationship between the applied and induced voltages, engineers can confirm whether the transformer windings are in phase (same polarity) or out of phase (opposite polarity).