Switchboard fault-rating check - Icu (ultimate breaking capacity) ≥ calculated I_k’’ with 10 % margin.
Formula
$$ I_{cu} \geq 1.1 \cdot I_k'' $$Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $I_cu$ | Ultimate breaking capacity | kA | breaker spec |
| $I_k''$ | Initial symmetrical fault current | kA | short-circuit study |
Sources
- IEC 61363 / IEC 60947-2.