The Siemens 5SM3647-5 is a 4-pole selective RCCB (residual current circuit breaker) from the SENTRON series, rated 80 A at 40 °C with a 300 mA Type B residual current trip. The selective design (time-delayed) means it coordinates with downstream RCDs — the 5SM3647-5 holds during a fault on a sub-circuit so only the closest device trips, keeping the rest of the panel live. That matters for a molding cell or a conveyor line where a single ground fault shouldn't drop the whole zone. Type B detection covers AC, pulsating DC, smooth DC, and high-frequency residual currents — the kind you get from VFDs, rectifiers, and switched-mode supplies common on modern automation panels.
Above that it derates linearly: 76.8 A at 50 °C, 73.6 A at 55 °C, 70.4 A at 60 °C, 67.2 A at 65 °C, and 64 A at 70 °C.