Iec 949 Pdf __link__ -

The adiabatic model assumes that the short-circuit duration is so brief (typically under 5 seconds) that no heat energy escapes the conductor. The entire thermal surge is absorbed by the metal, causing an immediate spike in temperature. While this method is highly conservative and simple to calculate, it neglects the physics of thermal conduction. The Non-Adiabatic Enhancement of IEC 60949 IEC 60949:1988

The metallic screens and armour wires are equally critical safety components. For these, a different temperature model applies. The initial temperature is taken as the cable's maximum operating temperature (often 90°C). The maximum permissible short-circuit temperature depends on the sheath material—for PVC and LSOH, it's 200°C; for MDPE, it's a higher 250°C. iec 949 pdf