Download Open-Circuit Test

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 = I2fe + 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/I2sc
• Zeq,HS = R2eq,HS + X2eq,HS
• Xeq,HS = Z2eq,HS – R2eq,HS