The Siemens SENTRON 5SM3646-4 is a 4-pole residual current circuit breaker (RCCB) — type B, short-time delayed — rated 63 A at 300 mA sensitivity on a 400 V AC supply at 50/60 Hz. The short-time delay (SIGRES function) lets it ride through nuisance trips from surge currents or brief inrush without dropping the circuit — useful on motor or capacitor bank feeds where a standard RCCB would false-trip. That figure is the withstand for the device itself; the downstream load's available fault current needs to stay under it. The 400 V AC rated voltage is line-to-line on a three-phase system, which is the standard European low-voltage distribution voltage.
IP20 with connected conductors.