ABILITY TO WITHSTAND SHORT CIRCUIT CURRENTS
IEC 60076-5 Power transformers – Part 5: Ability to withstand short circuit identifies the
requirements for transformers to sustain without damage the effects of overcurrents originated by
external short circuits.
For three-phase transformers with two separate windings, the r.m.s. value of the symmetrical shortcircuit
current is calculated as:

OIL TYPE POWER TRANSFORMER,

DRY TYPE POWER TRANSFORMER,