The Siemens 5SP3750-2 is a 1-pole SENTRON miniature circuit breaker rated 50 A at 230 V AC, 50 Hz, with tripping characteristic E and a breaking capacity of 25 kA per EN 60898. Characteristic E is a delayed thermal-magnetic curve designed for motor circuits and other loads with high inrush current. It trips magnetically at 10 to 20 times rated current (500–1000 A for this 50 A unit), so it won't nuisance-trip on a motor start but clears fast on a bolted fault.
Rated for the panel environment
Mounts on a 40-mm busbar system per DIN 43870 Part 2 — the standard meter-panel busbar grid. It occupies 1.5 width units (about 27 mm on a DIN rail), so panel density is decent. Depth is 89.5 mm including the enclosure, with 76.3 mm enclosure depth; that fits most meter cabinets without hitting the cover. Infeed is via box terminal, outgoing via spring-loaded terminal, which speeds wiring on a production panel build. IP40 with conductors connected; fine for a dry indoor meter board, not for washdown.