Short-circuit test

Calculations

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

${\displaystyle V_1}$ is the applied voltage

${\displaystyle I_1}$ is the rated current

${\displaystyle R_{01}}$ is the resistance as viewed from the primary

${\displaystyle Z_{01}}$ is the total impedance as viewed from the primary

${\displaystyle X_{01}}$ is the reactance as viewed from the primary

${\displaystyle W={I_1}^2{R}_{01}}$

${\displaystyle R_{01}=\frac{W}{{I_1}^2}}$

${\displaystyle Z_{01}=\frac{V_1}{I_1}}$

${\displaystyle X_{01}=\sqrt{{Z_{01}}^2-{R_{01}}^2}}$

High-power tests

A short-circuit test for determination of transformer impedance and losses is carried out with relatively low power applied to the transformer, and with winding currents of the same magnitude as in operation. A different form of short-circuit testing is done to assess the mechanical strength of the transformer windings, and their ability to withstand the high forces produced if an energized transformer experiences a short-circuit fault. Currents during such events can be several times the normal rated current. The resultant forces can distort the windings or break internal connections. For large utility-scale power transformers, high-power test laboratories have facilities to apply the very high power levels representative of a fault on an interconnected grid system.