The Siemens 5SU1324-1KK82 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) from the SENTRON family, rated 125 A at AC with a 30 mA residual fault current and C-curve trip characteristic. It breaks fault currents up to 10 kA per EN 60898 and IEC 60947-2, so it handles typical commercial and industrial branch-circuit faults without upstream coordination issues.
Thermal derating and installation constraints
At 40 °C ambient the 125 A rating derates to 115.62 A; at 50 °C it drops to 106.25 A, and at 60 °C to 96.25 A. That means a panel running near 50 °C loses roughly 15% of the headline capacity — factor that into the load schedule before committing the BOM line. The unit occupies 7 modular width units (roughly 126 mm) on a DIN rail and mounts in any position, with a 70 mm installation depth. Supply can enter from top or bottom.
Environmental and compliance
Halogen-free and silicon-free construction suits installations where outgassing or contamination risk matters (e.g., clean rooms, medical environments). The housing is rated IP20 when installed in a distribution board with connected conductors. Overvoltage category III and pollution degree 2 cover fixed-installation mains supply. Operating temperature range spans -40 °C to 75 °C, with max 95% humidity influence.