The Siemens 5SJ4140-7HG40 is a 1-pole miniature circuit breaker from the SENTRON 5SJ4 series, with a C-curve trip characteristic that trips between 5 and 10 times rated current — the standard choice for mixed resistive and moderate inductive loads like small motor circuits, lighting banks, and control transformers. Rated 400 V AC, 60 V DC, it fits single-phase branch circuits in 230/400 V networks.
Snap-on mounting to standard DIN rail (35 mm per EN 60715). The 70 mm depth (installation depth) is the dimension from rail back to the front of the toggle — check enclosure depth clearance, especially in shallow gland-plate boxes.