Open-Circuit Test

• Determine core-loss – Rfe , XM

• Energize the low-voltage side

Equivalent Circuit

Open-Circuit Test continued

• Meter readings at rated low-side voltage

• V = Voc = applied voltage with output open• I = Io = magnetization current = I2

fe + I2M

• Poc = core loss = VocIfe >>> Rfe = Voc/Ife

• XM,LS = Voc/IM

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.

Short-Circuit Test continued

Adjust the VARIAC until the high-side current is at the rated value.

Measure Psc , Vsc , Isc .

Equivalent Circuit

Short-Circuit Test continued

• Zeq,HS = Vsc/Isc

• Psc = I2scReq,HS >>> Req,HS = Psc/I2

sc

• Zeq,HS = R2eq,HS + X2

eq,HS

• Xeq,HS = Z2eq,HS – R2

eq,HS