Transformer PU referred to HV


Consider a 132/33kV 25 MVA Transformer having leakage impedance 10% (0.1 pu) and let us estimate the current during short circuit test when supply is given on HV side and LV side shorted. But now we will solve this case using pu values
Transformer HV side test voltage applied = 440V. This voltage when converted to pu voltage will be


Here for calculating pu value of supply voltage we have taken base kV as 132kV as supply is from HV side where base kV is rated HV side kV of the transformer.

Hence short circuit current in pu will be
This arrangement is as shown in following figure


HV side base current will be. obviously which is transformer HV side full load current.

Thus actual current will be

We have calculated same short circuit current as using impedance value.

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