The Siemens 5SM3448-6 is a SENTRON residual current operated circuit breaker (RCCB) — 4-pole, Type A, rated 100 A at 400 V AC, 50 Hz, with a 100 mA trip threshold. It's an instantaneous (short-time-delay-free) device meant for standard distribution boards where you need ground-fault protection on a 4-wire system. The 100 mA sensitivity suits circuits feeding equipment where a 30 mA device would nuisance-trip — think sub-mains, large fixed machinery, or distribution sub-panels in commercial or industrial buildings.
What the ratings mean for fit
The 100 A continuous rating (at AC, resistive load) means this RCCB can carry the full current of a heavy sub-feed or large fixed load. The 100 mA residual sensitivity is a deliberate choice — it's above the 30 mA threshold for personal shock protection, so it's used where the goal is equipment and fire protection on circuits with higher natural leakage (long cable runs, heaters, drives). The 10 kA short-circuit current rating (SCCR) per IEC 61008-1 tells you it can safely interrupt a fault up to that level without welding contacts or rupturing the case, provided the upstream device limits the let-through energy. The 1 kA rating per EN 60898 is a coordination figure for domestic-type MCBs upstream — the RCCB is expected to see only limited fault current in that scenario.
Where it goes in the panel
Snaps onto a DIN rail (REG per EN 60715), occupies 4 modular width units (72 mm wide), and can be mounted in any orientation. The 70 mm installation depth fits standard distribution boards. Supply can come from top or bottom — no orientation restriction. IP20 with conductors connected, so it's intended for enclosed distribution boards, not open washdown areas. Silicon-free construction matters if this panel is in a coating or painting environment where silicone outgassing could cause adhesion failures.