% Impedance of Three Winding Transformer

Do your own homework!

Calculating the percentage impedance of a Transformer

Looks like this one keeps getting passed from interviewee to interviewee, except this time even less information is provided, so the answer is: No we can't.

There are 3 cases to be considered-1)both secondary unloaded,2)one loaded,3)both loaded-for interacting of load currents on primary.

The rating of transformers should have been in MVA. 50 kVA for 132 kV 3 winding transformer seems to be very low. You get the details from the Transformer manufacturer. Percentage impedance of the transformers depend on the design of the transformer and other winding parameters.

The only information for your transformer percentage impendence, is to refer back to your transformer test report. It is not easy to calculate the percentage impedance of your transformer with these data's. What is your transformer fault level. Do you have it? May be if you have the transformer faults level then maybe we can do reverse calculation to find out your transformer impendence.