The Siemens 5SM2623-0 is a 2-pole residual current circuit breaker (RCCB) from the SENTRON family, designed as a plug-in RC unit for the 5SL4 miniature circuit breaker series. It carries a 40 A rated current and a 300 mA tripping fault current, Type AC, for 230 V AC systems. The 300 mA sensitivity is typical for fire protection or circuits feeding equipment with higher leakage, rather than personnel protection (which usually calls for 30 mA). The 40 A rating is at 40 °C ambient; the part derates to 32 A at 70 °C, so panel builders need to check the thermal curve when packing breakers into a warm enclosure.
Occupies 2 modular width units (MW) on a DIN rail, with a 70 mm depth that matches the standard 5SL4 breaker footprint. The 70 mm × 70 mm × 90 mm envelope (W×D×H) means it fits the same cutout as the companion MCB. Fastening method is REG (regular DIN-rail clip).