For faults of longer duration, the standard introduces a correction factor to account for heat dissipation into the cable's insulation or sheath.
The standard utilizes a three-step approach to determine the permissible short-circuit current ( Calculate Adiabatic Current ( IADcap I sub cap A cap D end-sub iec 60949 pdf free download exclusive
Accounting for non-adiabatic effects allows engineers to sometimes use smaller conductor cross-sections for specific fault durations, potentially reducing material costs. For faults of longer duration, the standard introduces
IAD=K×St×ln(θf+βθi+β)cap I sub cap A cap D end-sub equals the fraction with numerator cap K cross cap S and denominator the square root of t end-root end-fraction cross the square root of l n open paren the fraction with numerator theta sub f plus beta and denominator theta sub i plus beta end-fraction close paren end-root : Cross-sectional area of the conductor ( mm2m m squared : Duration of the short circuit ( : Material constant. : Initial and final temperatures ( ∘Craised to the composed with power cap C : Temperature constant for the material. : Initial and final temperatures ( ∘Craised to