Low Voltage Cable Short Circuit Rating Calculator (up to 1kV)
Calculate the maximum permissible short circuit current of cables up to 1kV with copper conductors.
Formula:
\[\displaystyle I_{(kA)} = \frac{S}{\sqrt{t}} \cdot K\]Variables:
- \(I\) = Short Circuit Rating (kA) - Maximum fault current the cable can withstand
- \(S\) = Conductor Cross-sectional Area (mm²) - Cable size
- \(t\) = Duration of Short Circuit (sec) - Typically matching circuit breaker clearing time
- \(K\) = Material Constant - Depends on insulation type
K Values by Insulation Type:
XLPE & XLSZH Cables:
\(K = 0.143\) (Higher thermal stability)
PVC Insulated Cables:
- \(K = 0.115\) for \(S \leq 300\text{ mm}^2\)
- \(K = 0.103\) for \(S > 300\text{ mm}^2\)
Important Notes:
- Values are for copper conductors only
- Applicable for low voltage cables up to 1kV
- Short circuit duration typically ranges from 0.1 to 5 seconds
- Consider derating factors for ambient temperature and installation conditions