The Siemens SENTRON 5SM3647-0 is a 4-pole residual current circuit breaker (RCCB) rated for 80 A at 40 °C ambient, tripping at 300 mA residual current, AC type, for 400 V AC 50 Hz systems. It carries a 10 kA short-circuit current rating and mounts on DIN rail (REG) — standard for panel integration in distribution boards.
What the ratings mean for fit
The 80 A rating holds at 40 °C and 45 °C without derating; at 50 °C it drops to 76.8 A, and at 70 °C to 64 A — so if the panel runs hot, the continuous load must be reduced accordingly. The 300 mA AC-type trip is instantaneous (no short-time delay), meaning it clears earth faults fast but will nuisance-trip on equipment with high-frequency leakage (VFDs, switching supplies). For those loads, an AC-type RCCB is not the right choice — you would need an A or B type. The 10 kA SCCR at 400 V means it safely interrupts faults up to that level without cascading upstream, provided the prospective fault current at the installation point does not exceed that value.
Mounting and integration
Snaps onto DIN rail (REG), occupies 4 width units (72 mm wide), with an installation depth of 70 mm and overall depth of 77 mm. Accepts solid or stranded conductors from 1.5 mm² up to 25 mm². Rated IP20 once installed in a distribution board with conductors connected — suitable for dry indoor enclosures only. Supply can enter from top or bottom. Mounting position is any, so it fits in tight enclosures without orientation restrictions.