1. Open-Circuit Test Determine core-loss – R fe, X M Energize the low-voltage side

2. Equivalent Circuit

3. Open-Circuit Test continued Meter readings at rated low-side voltage V = V oc = applied voltage with output open I = I o = magnetization current =  I 2 fe + I 2 M P oc = core loss = V oc I fe >>> R fe = V oc /I fe X M,LS = V oc /I M

4. Short-Circuit Test Determine equivalent resistance, equivalent leakage reactance, and equivalent impedance of the transformer windings Energize the high-side via an autotransformer or VARIAC.

5. Short-Circuit Test continued Adjust the VARIAC until the high-side current is at the rated value. Measure P sc, V sc, I sc.

6. Equivalent Circuit

7. Short-Circuit Test continued Z eq,HS = V sc /I sc P sc = I 2 sc R eq,HS >>> R eq,HS = P sc /I 2 sc Z eq,HS =  R 2 eq,HS + X 2 eq,HS X eq,HS =  Z 2 eq,HS – R 2 eq,HS