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K FACTOR CALCULATOR

Adiabatic Equation for Short Circuit Protection

BS 7671 / BS 7454 Compliant
Cable Configuration
°C
°C
Standard K Values (BS 7671)
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Formula
BS 7671 / IEC 60364-5-54 Formula
K = √[Qc(β+20)/ρ₂₀ × ln((β+θf)/(β+θᵢ))]
Where:
Qc = Volumetric heat capacity (J/K·cm³)
β = Reciprocal of temp coefficient (K)
ρ₂₀ = Resistivity at 20°C (μΩ·cm)
θᵢ = Initial temperature (°C)
θf = Final temperature (°C)
Calculated Results
K Factor
0
A²s/mm²
For adiabatic equation:
S = √(I²t) / k
Material Properties
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Standard Comparison
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BS 7671 Table
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