The Siemens SENTRON 5SL4340-7RC is a 3-pole miniature circuit breaker with a C tripping characteristic, rated 40 A at 415 V AC and a 10 kA breaking capacity per EN 60898. That 10 kA rating means it can safely interrupt a fault current up to 10,000 amps without welding its contacts or failing — the threshold that decides whether this breaker clears a dead short or the upstream device has to step in.
Snaps onto a standard 35 mm DIN rail — one modular width unit (18 mm wide) per pole, so this 3-pole unit occupies 18 mm of rail space. Depth is 76 mm, which leaves clearance behind most standard enclosure gland plates. Mounting position is unrestricted; the breaker works in any orientation.
Rated for 50/60 Hz supply, overvoltage category III, pollution degree 2 — standard for fixed-installation distribution boards. Halogen-free and silicon-free construction, sealable with a lead seal for tamper-proofing in metered or secured installations.