Short-circuit test

The purpose of a short-circuit test is to determine the series branch parameters of the equivalent circuit of a real transformer.

The test is conducted on the high-voltage (HV) side of the transformer where the low-voltage (LV) side or the secondary is short circuited. A wattmeter is connected to the primary. An ammeter is connected in series with the primary winding. A voltmeter is optional since the applied voltage is the same as the voltmeter reading. The LV side of the transformer is short circuited. Now with the help of variac applied voltage is slowly increased until the ammeter gives reading equal to the rated current of the HV side. After reaching at rated current of HV side, all three instruments reading (Voltmeter, Ammeter and Watt-meter readings) are recorded. The ammeter reading gives the primary equivalent of full load current IL. As the voltage applied for full load current in short circuit test on transformer is quite small compared to the rated primary voltage of the transformer, the iron losses in transformer can be taken as negligible here.

To conduct a short-circuit test on power transformer:

${\displaystyle W}$ is the full-load copper loss

${\displaystyle V_{1}}$is the applied voltage

${\displaystyle I_{1}}$ is the rated current

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