The Siemens SENTRON 5SJ4105-7HG42 is a 1-pole miniature circuit breaker with a C-curve tripping characteristic, rated at 0.5 A at 30 °C. It is designed for standard DIN-rail mounting and occupies one modular width unit (18 mm). The C-curve means it trips between 5 and 10 times rated current, making it suitable for protecting circuits with moderate inrush — typical for control transformers, contactor coils, and general industrial loads in mechanical engineering and industry applications.
Ratings and fit
Rated 0.5 A at both 30 °C and 40 °C ambient, it derates to 0.48 A at 45 °C, 0.46 A at 50 °C, 0.44 A at 55 °C, and 0.42 A at 60 °C. If the panel ambient runs above 40 °C, the load must be reduced accordingly or the breaker may nuisance-trip. The 18 mm width (1 MW) and 70 mm installation depth let it drop into any standard modular enclosure. It snaps onto a standard mounting rail in any orientation and accepts combined terminals top and bottom for daisy-chaining busbars or ring-tongue lugs. Rated for AC/DC operation, with a maximum DC voltage of 60 V. The IP20 rating applies with connected conductors; the handle area is rated IP40, which keeps dust out of the toggle mechanism in industrial cabinets. Overvoltage category 3 and pollution degree 3 mean it is rated for fixed installations within building distribution panels and industrial control panels where transient overvoltages and conductive dust are expected.
Lifecycle and sourcing
The 5SJ4105-7HG42 is halogen-free and silicon-free, which matters for applications sensitive to outgassing — such as sealed relay cabinets or medical-adjacent environments where corrosion of silver contacts is a concern.