What it is and what the ratings mean
The Siemens SENTRON 5SL4103-6 is a 1-pole miniature circuit breaker rated 3 A with a B tripping characteristic, designed for 230/400 V AC systems and a 10 kA breaking capacity per EN 60898 and IEC 60947-2. The B curve means it trips at 3–5× rated current — standard for resistive and general-purpose loads in residential and light commercial panels where inrush is low. The 10 kA SCCR tells you it can safely interrupt a fault current up to that level without welding contacts or cascading failure upstream, which is the standard interrupting rating for most final subcircuits in a 400 V distribution board.
Panel fit and deployment context
Occupies 1 modular width unit (18 mm) on a DIN rail — standard 1P spacing. Depth is 76 mm with 70 mm installation depth, so it clears a standard 80 mm deep enclosure backplate. IP20 with connected conductors, meaning it's protected against finger contact but not washdown; this is a dry indoor panel part. Mounting position is any, which simplifies layout in tight sub-distribution boards. Sealable design allows the installer to lock the toggle position after commissioning.