Siemens SENTRON 5SL6140-7CC — Type C 40 A MCB, 6 kA
The Siemens 5SL6140-7CC is a SENTRON miniature circuit breaker (MCB) with a C tripping characteristic, rated 40 A at 30 °C and 400 V AC, single-pole design. It carries a 6 kA breaking capacity certified to EN 60898, making it suitable for final-circuit overcurrent protection in residential and light commercial distribution boards. The C-curve (5–10× In) handles moderate inrush loads like small motor-driven appliances or fluorescent lighting banks without nuisance tripping.
Key ratings and what they mean for fit
The 40 A rating (at 30 °C) is the headline figure, but the derating curve is what governs real-world panel fit: at 40 °C ambient the breaker is rated 36.88 A, at 45 °C it drops to 35.22 A, and at 50 °C to 33.48 A. If your enclosure runs warm — common in a crowded DIN-rail panel — size the upstream protection and load to the derated value, not the 30 °C number. The C-curve means magnetic trip occurs between 5 and 10 times rated current, so a 40 A breaker clears short circuits between 200 A and 400 A magnetically; below that threshold the thermal bimetal handles overloads. Rated for overvoltage category III and pollution degree 2, this MCB is designed for fixed-installation distribution boards where transients are controlled by upstream SPDs. The 6 kA breaking capacity per EN 60898 is adequate for most residential and light commercial service-entrance panels where the prospective short-circuit current at the board is under 6 kA. For industrial panels with higher fault levels, a higher-rated MCB or backup fuse would be needed.
Physical integration and mounting
Occupying 1 modular width unit (18 mm), the 5SL6140-7CC snaps onto standard DIN rail (EN 60715). Depth is 76 mm overall, with an installation depth of 70 mm behind the panel face. Mounting position is unrestricted — any orientation is allowed, which simplifies layout in tight enclosures. The IP20 rating (with connected conductors) means it is protected against finger contact but not moisture; install inside a sealed distribution board for damp environments.