The Siemens SENTRON 5SU9346-1CN40 is a 4-pole RCBO — residual current operated circuit breaker with overcurrent protection — rated 40 A at 30 °C ambient, with a 30 mA residual trip threshold and a C tripping characteristic. This is the variant that combines the MCB and RCD functions in a single 7-module-width unit, saving a DIN-rail position compared to separate devices.
The insulation voltage is rated 440 V, matching standard 400 V three-phase networks with headroom. The 40 A rating holds at 30 °C; at 40 °C it derates to 37.2 A, at 45 °C to 35.6 A, at 50 °C to 34.8 A, and at 55 °C to 34 A (–) — so if the panel ambient runs hot, factor the derating into the load schedule. That is fine for general-purpose circuits feeding resistive, inductive, or conventional rectifier loads, but if the downstream equipment includes variable-speed drives, LED drivers, or UPS systems that generate DC fault components, a Type A or Type F RCD would be required.
The IP20 rating is standard for enclosed distribution boards — the touch protection is integral.