Helps in selecting and setting protective devices like circuit breakers to ensure they trip before the cable reaches dangerous temperatures. Where to Find the Standard IEC 60949:1988
Ensures that cable conductors and screens can handle fault currents without melting or damaging insulation. iec 60949 pdf free download exclusive
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. Helps in selecting and setting protective devices like
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 : Initial and final temperatures ( ∘Craised to
): This assumes no heat is lost to the surrounding environment (adiabatic conditions). It is calculated using the formula:
For faults of longer duration, the standard introduces a correction factor to account for heat dissipation into the cable's insulation or sheath.
САБИР Фахим 
КАДИРИ Хомаюн 
ИСКАНДАРОВ Косимшо 
Дмитрий МИЛОСЕРДОВ 
МЕХДИ Михяуддин 
МОХАММАД Дауд