The Voltech Handbook of Transformer Testing

2.22 PHAS - Inter-winding Phase Test

Where Used

This test is useful for most types of transformer, although unusual with line frequency transformers and tests for the phase angle between windings.

It is most useful for determining the phase effect of audio and telecommunications transformers when placed in a transmission line.

Measurement Conditions

If you are programming the test from a computer that is connected to the auxiliary port of the tester, you may enter the test conditions in the following way.

Select the test terminals, enter the test frequency, click on the measure button and the editor will select the correct voltage and display the measured phase angle.

You can then use this measured angle as a basis for setting your limits.

If your computer is not connected to the tester, you can choose the test voltage from the following table.

N.B. When selecting your energised winding, check that your transformer does not have a large step-up turns ratio between this winding and any other windings as this may cause high voltages to be present during the test. Energize the winding with the most turns if this is the case.