This turns ratio value dictates the operation of the . If the secondary winding has half the number of turns of the primary winding, then the secondary voltage will be half the voltage across the primary winding. The transformer turns ratio test, or TTR test, confirms that the transformer has the correct ratio of primary turns to secondary turns. Using this test correctly can help to identify tap changer performance, shorted turns, open windings, incorrect winding connections and other faults inside transformers.
The turns ratio is defined as the ratio of turns of wire in the primary winding to the number of turns of wire in the secondary winding.
The ideal transformer identity shown in eq.
With it, we can easily multiply or divide voltage and current in AC circuits.
The question that you have asked refers to third type. As the name suggests, the use of transformers with unity turns ratio is to isolate two circuits operating at .