The Siemens SENTRON 5SY6363-6CC is a 3-pole miniature circuit breaker with a B tripping characteristic, rated 400 V AC and breaking 6 kA per EN 60898.
Under UL 1077 and CSA C22.2 No.235, the same unit is rated 5 kA, so if your BOM specifies North American supplementary protection, that's the figure to coordinate with. The B-curve characteristic means it holds through normal load transients but trips quickly on a hard short — no nuisance tripping on moderate inrush, but fast clearing when it matters.
Mounting and integration notes
Snaps onto a DIN rail — any mounting position works. The 54 mm width (3 modular units) matches standard cutouts.