The winding's ability to withstand the heat generated by the massive overcurrent without the insulation melting or degrading.
IEC 60076-5 is the international standard that specifies the requirements for power transformers to withstand the thermal and dynamic effects iec 60076-5
To comply with IEC 60076-5 , transformers must meet several technical benchmarks during a fault: Symmetrical Short-Circuit Current ( Isccap I sub s c end-sub The winding's ability to withstand the heat generated