The Siemens 5SL1301-7MB is a 3-pole miniature circuit breaker from the SENTRON series, rated 1 A with a C tripping characteristic. It protects branch circuits in residential and light commercial infrastructure panels, interrupting faults up to 3 kA per IEC 60947-2 at 230/400 V AC.
For a 3-pole breaker on a 230/400 V three-phase system, that's 1 A per phase — enough for a small control transformer or a few pilot lights, not for motor or heater circuits. The 3 kA breaking capacity per IEC 60947-2 tells you the breaker can safely interrupt a fault current up to 3 kA without welding contacts or cascading failure upstream. In a residential panel with typical available fault current below 3 kA, that's adequate; if your service entrance has higher fault current, you'll need a breaker with a higher interrupting rating.
Panel integration and physical fit
The 5SL1301-7MB snaps onto a standard DIN rail (mounting position any) and occupies 3 modular width units (54 mm wide). Depth is 76 mm, installation depth 70 mm — it clears a standard 80 mm deep enclosure.