Phasing Out Test Carried Out on Transformer

Phasing Out Test Carried Out on Transformer

Q. With the help of neat figure explain phasing out test carried out on transformer.

Phasing out test :

This test is carried out only on 3Φ transformer to identify primary and secondary winding belonging to the same phase. As shown in figure A all the phases of 3 Φ transformer are short circuited except a primary and supposed secondary. A low voltage D.C. supply is given through a battery to the primary winding. The galvanometer is connected to the terminals of secondary winding which is not shorted.

The key "K" is connected shown. Now the keys pressed and deflection of galvanometer is observed carefully. Similarly galvanometer is connected to the other secondaries and procedure is repeated. The winding across which maximum deflection occurs is the secondary phase winding that corresponds to primary winding to which source connected.

Repeat the same procedure for other primary winding and find the corresponding was secondary side.