RCBO for 50 Hz distribution boards
The Siemens 5SU1354-0KK40 is a 2-pole residual current operated circuit breaker (RCBO) from the SENTRON series, combining overcurrent protection and residual current detection in a single 36 mm wide (2 modular width units) package for 50 Hz systems. Energy limitation class 3.
The higher IEC figure applies when the device is used as an industrial molded-case equivalent; the EN figure governs residential and commercial distribution board coordination. Energy limitation class 3 means the let-through energy is low enough to protect downstream wiring and loads under fault conditions — relevant for selectivity studies with upstream SENTRON NH fuse-links or SENTRON 3VA breakers.
Thermal derating and installation constraints
Derate to 37.6 A at 40 °C, 36.4 A at 45 °C, 34.8 A at 50 °C, 32.4 A at 55 °C and 60 °C, 30.8 A at 65 °C, and 29.2 A at 70 °C. Panel builders must apply these values when grouping multiple RCBOs in a confined enclosure. Mounting position is unrestricted, and the supply can enter from either top or bottom — simplifies busbar routing in a crowded distribution board. IP20 applies once the board is closed with conductors connected.