If you'd like more information or a copy of the standard, I recommend checking the IEC website or contacting a local standards organization.

The winding's ability to withstand the heat generated by the massive overcurrent without the insulation melting or degrading.

IEC 60076-5 applies to all oil-immersed power transformers—from small distribution units (typically > 630 kVA) to massive generator step-up (GSU) transformers exceeding 1,000 MVA. The standard explicitly covers:

Unlike steady-state calculations, short-circuit currents are asymmetrical due to the DC component. IEC 60076-5 provides the standard formula for maximum instantaneous asymmetrical peak current: