Conductor Short-Circuit Thermal Withstand (Onderdonk / ICEA)
Whether a conductor survives the available fault current for the protective device's clearing time without exceeding its insulation short-circuit temperature, by the public-domain ICEA / Onderdonk adiabatic equation, plus the minimum size for the actual fault. A thermal-withstand screen, not a substitute for an engineered study.
Formula and source
(I/A)^2 x t = K x log10((T2 + B)/(T1 + B)); withstand = area x sqrt(C / t), min size = fault x sqrt(t / C), where C = K log10((T2+B)/(T1+B)). Copper K=0.0297 B=234; aluminum K=0.0125 B=228.
ICEA P-32-382 / Onderdonk adiabatic short-circuit heating equation (public-domain form), by name.
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