The final permissible current is the product of the adiabatic current and the modifying factor. Primary Calculation Formula (Adiabatic)
This is the base rating, assuming no heat escapes the conductor during the short-circuit event. Calculate the Modifying Factor ( iec 949 pdf work
The standard covers several key aspects of machinery safety, including: The final permissible current is the product of
Or, rearranged to find the minimum conductor size required to withstand a specific fault current: : Material constants for conductors (Copper or Aluminum)
The standard specifies different maximum permissible temperatures ($\theta_f$) depending on the insulation type (e.g., PVC, XLPE, EPR). For instance:
IAD=K⋅St×ln(θf+βθi+β)cap I sub cap A cap D end-sub equals the fraction with numerator cap K center dot 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 ( mm2m m squared ). : Duration of short circuit (seconds). : Final and initial temperatures ( ∘Craised to the composed with power C ). : Material constants for conductors (Copper or Aluminum). Non-Adiabatic Factor ( ) The factor