Cable Short-Circuit Thermal Check
Compute the minimum allowable cross-section from short-circuit current, protection clearing time, conductor, and insulation; check cable thermal withstand.
Key points
Cable Short-Circuit Thermal Check: Compute the minimum allowable cross-section from short-circuit current, protection clearing time, conductor, and insulation; check cable thermal withstand. Formula: S_min = I_sc·√t / k ｜ I_allow = k·S/√t. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. Thermal withstand ensures conductor temperature during a fault stays within insulation limits; k depends on conductor and insulation, and this tool uses common values. Use the actual clearing time (including breaker opening and protection delay), not just the instantaneous setting.
Inputs
S_min = I_sc·√t / k ｜ I_allow = k·S/√tCalculation model (updates with parameters)
| Thermal coefficient k | 143 | 铜 / XLPE |
| Minimum thermal cross-section S_min | 55.28 mm² | I_sc·√t/k |
| Actual cable cross-section S | 70 mm² | needs ≥ S_min |
| Recommended standard cross-section | 70 mm² | 按常用电缆Cross-section档向上取整 |
| Allowable short-circuit current for this section | 31.65 kA | k·S/√t，对应动作Time 0.100 s |
| Thermal withstand check | 通过 ✓ | Actual cross-sectionmet短路热稳定 |
| Short-circuit thermal effect I²t | 62.5 kA²·s | 用于and厂家允许Value对比 |
Engineering notes
- Thermal withstand ensures conductor temperature during a fault stays within insulation limits; k depends on conductor and insulation, and this tool uses common values.
- Use the actual clearing time (including breaker opening and protection delay), not just the instantaneous setting.
- Use the maximum short-circuit capacity at the installation point; for parallel cables, check total section and current sharing, not a single cable.
FAQ
- What is Cable Short-Circuit Thermal Check for?
- Compute the minimum allowable cross-section from short-circuit current, protection clearing time, conductor, and insulation; check cable thermal withstand.
- What is the formula for Cable Short-Circuit Thermal Check?
- Core formula: S_min = I_sc·√t / k ｜ I_allow = k·S/√t. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using Cable Short-Circuit Thermal Check?
- Thermal withstand ensures conductor temperature during a fault stays within insulation limits; k depends on conductor and insulation, and this tool uses common values. Use the actual clearing time (including breaker opening and protection delay), not just the instantaneous setting. Use the maximum short-circuit capacity at the installation point; for parallel cables, check total section and current sharing, not a single cable.