The Siemens SENTRON 5SL3140-7 is a 1-pole miniature circuit breaker rated 40 A at 400 V AC with a C tripping characteristic. It breaks 4.5 kA per EN 60898 and 5 kA per IEC 60947-2, so it handles typical residential and light commercial fault levels without cascading upstream. The C curve means it tolerates moderate inrush — fine for general-purpose loads like lighting, receptacles, and small motor circuits.
Derating and ambient range
At 30 °C ambient the breaker carries its full 40 A. At 40 °C it derates to 37.57 A, at 45 °C to 36.8 A, and at 55 °C to 33.61 A. If your panel runs warm — common in a crowded enclosure — factor the derating into the load schedule. The operating range spans -40 °C to 75 °C, so outdoor or unheated installations are within spec.
Mounting and integration
The 5SL3140-7 occupies one modular width (18 mm) on a DIN rail. Depth is 76 mm, installation depth 70 mm. Mounting position is any — no derating for orientation. IP20 with connected conductors, so it belongs inside a panel, not in a washdown zone. The housing is halogen-free and silicon-free, which matters for environments sensitive to outgassing (e.g., clean rooms or sealed enclosures).