POLARITY TEST

The voltage induced in secondary winding of transformer either in phase arrangement or a position comparison with primary voltages how the output terminal are consider when the terminal have been (DO).For high voltages and (c,d,a) for low voltage when the voltage induced between d and q in phase with voltage induced between d and q in phase with voltage induced the polarity is said to be subtractive otherwise polarity is addition.
When two corresponding terminals (Dand q) have been interconnected a suitable voltage is connected to one of the winding DO and the voltage assured between other two terminal.Q and q if the voltage connected between the terminals DO. The polarity is subtractive otherwise it is additive.