The Siemens SENTRON 5SM3746-5 is a 4-pole selective residual current circuit breaker (RCCB) rated 63 A at 400 V AC, 50/60 Hz. The Type B residual-current detection means it trips on AC, pulsating DC, and smooth DC fault currents — the full spectrum you get from variable-speed drives, UPS systems, or photovoltaic inverters. The 500 mA rated tripping fault current is higher than a standard 30 mA RCD, so it's sized for selective coordination: it lets downstream 30 mA devices clear a ground fault first, only tripping this upstream unit if the fault persists or exceeds its threshold.
IP20 with conductors connected, so it's intended for enclosed panels only, not washdown or outdoor exposure.
Thermal derating — the real-world current
Above that, it steps down: 60.48 A at 50 °C, 57.96 A at 55 °C, 55.44 A at 60 °C, 52.92 A at 65 °C, and 50.4 A at 70 °C.