The Siemens 5SJ4140-7HG42 is a 1-pole SENTRON miniature circuit breaker from the 5SJ4 series, designed for branch-circuit protection in industrial control panels and distribution boards. It carries a C tripping characteristic, meaning it tolerates moderate inrush currents typical of motor starters and small transformers before opening on overload. Rated breaking capacity is 10 kA per EN 60898 and 15 kA per IEC 60947-2 at 400 V AC — enough for most secondary distribution panels where the upstream transformer limits fault current below those levels. The DC rating stops at 60 V, so it is not a candidate for higher-voltage DC bus protection. The 18 mm width (one modular unit) snaps onto standard DIN rail, mounts in any position, and accepts combined top/bottom terminals with a tightening torque of 3.5 Nm. Ambient temperature range from -40 °C to 75 °C covers heated enclosures and outdoor cabinets alike.
Mounting and wiring notes
Depth of 70 mm and height of 121 mm fit standard 1-pole MCB cutouts. The combined terminals (top and bottom) accept copper conductors; torque to 3.5 Nm per the terminal specification. No tunnel terminals are offered, so the combined style is the only termination option. IP20 with connected conductors, IP40 in the handle area — sufficient for enclosed panel use. Pollution degree 3 and overvoltage category 3 suit industrial environments where conductive dust or condensation may be present.