Suppose we have a 3-phase system with a voltage of 400 V, a cable length of 50 m, and a fault level of 10 kA. We want to calculate the short circuit current and determine the minimum cable size.
To determine the minimum cross-sectional area (CSA) of a cable such that, under a bolted three-phase short circuit fault, the conductor temperature does not rise beyond the short-circuit rating of the insulation material (e.g., 160°C for PVC, 250°C for XLPE). short circuit calculation for cable sizing
[ \textCable withstand: (k \cdot S)^2 \ge I_sc^2 \cdot t \ (\textlet-through of device) ] Suppose we have a 3-phase system with a
For large cables, some heat escapes into the insulation. IEC 60949 provides a correction factor ( \varepsilon ). However, for most LV applications, the adiabatic formula is conservative and acceptable. [ \textCable withstand: (k \cdot S)^2 \ge I_sc^2