For a 3-phase transformer:
A simplified version of the Ohmic method often used by contractors to calculate fault currents at various distances along a run of cable or busway. Step-by-Step Calculation (Transformer Example) short ckt current calculation
Create a single-line diagram and reduce the network to a single equivalent impedance ($Z_{eq}$) seen from the fault point. For a 3-phase transformer: A simplified version of
This is the most straightforward approach, using Ohm's Law ( ). You calculate the total resistance ( ) and reactance ( short ckt current calculation