Iec 60076-5 [best]

In a concentric winding arrangement (LV inside, HV outside), current flow creates radial forces. The inner winding (usually LV) experiences inward crushing forces. The outer winding (HV) experiences outward bursting (hoop) forces, similar to a barrel exploding. IEC 60076-5 mandates that the mechanical strength of conductors, spacers, and the core must withstand these forces without plastic deformation.

IEC 60076-5 specifies requirements and test procedures to verify a power transformer’s mechanical and electrical ability to withstand internal short-circuit forces without catastrophic failure. Its scope covers design, manufacturing and testing provisions intended to ensure transformers remain safe and retain containment of energized parts during and after a short-circuit event. iec 60076-5

For multi-winding transformers, the standard defines specific equivalent circuits for calculating short-circuit currents in each winding pair. In a concentric winding arrangement (LV inside, HV