Type of transformer testing: - (1) Type Tests (2) Routine Tests (3) Special Tests. 1. These tests are done mainly in a prototype unit not in all manufactured units in a lot. Type test of transformer confirms main and basic design criteria of a production lot. 2. Routine tests of transformer are mainly for confirming operational performance of individual unit in a production lot. Routine tests are carried out on every unit manufactured. 3. Special tests of transformer are done as per customer requirement to obtain information useful to the user during operation or maintenance of the transformer.