The Siemens SENTRON 5SV3646-4 is a 4-pole residual current circuit breaker (RCCB) — Type B, short-time delayed — rated 63 A with a 300 mA residual operating current on a 400 V AC supply. Type B detection covers AC, pulsating DC, and smooth DC fault currents up to 300 mA, which means it handles variable-speed-drive leakage and UPS-fed circuits where a standard Type A would miss a pure DC fault. The short-time delayed characteristic (SIGRES function) prevents nuisance tripping when upstream surge arrestors or downstream MCBs cause a brief inrush; it holds through a 10 kA prospective fault current without welding or rupturing.
Snaps onto a DIN rail (REG) in any orientation — 4 modular width units at 60 mm grid spacing, so it occupies four standard 18 mm slots in a distribution board. Depth is 70 mm, matching the installation depth; the 72 mm width and 90 mm height fit within a standard enclosure cutout. IP20 with conductors connected, which is the norm for enclosed distribution boards. Silicon-free construction, so it won't outgas and foul contacts in sealed panels.