CALCULATION OF PERCENTAGE IMPEDENCE

Percentage relative to what?

Perhaps you can restate your question.

You do not calculate the % impedance of a transformer. The MFG has a procedure in which they measure the % impedance.

Dear All,

To measure the % impedance of a transformer,

1 To short circuit Low voltage terminals (secondary terminals).

2 Apply voltage to the high voltage terminals (primary terminals).

3 Adjust the applied voltage so that the primary current is rated full load current of the transformer.

4. % impedance of the transformer = applied voltage / rated primary voltage.

Regards

dear sir

My Answer is as follows

% impedance is calculated by conducting short circuit test on Transformer.

1)short LV terminals r,y,b and n.

2)apply LT 3 phase volatge on primary side and note down the voltage measured using multimeter.the voltage is "V".

3)Measure the current on LV side using tong tester which is short circuited current.convert the current to the primary side using transformation ratio.It is "Isc"

3)now percentage impedance is ,

%Z = (Rated HV current/Rated HV Voltage)*(V/Isc)*100

Cheers

gova