The Siemens 5SL6463-6RC is a SENTRON 5SL6 miniature circuit breaker rated 63 A with B tripping characteristic, 4 poles, and a 7.5 kA breaking capacity per EN 60898. It's designed for residential and infrastructure branch-circuit protection on 415 V AC three-phase systems.
The B characteristic means magnetic trip occurs at 3–5× In (189–315 A), so it won't nuisance-trip on moderate motor starts but will clear a hard short fast. Four poles let you switch all three phases plus neutral in a single unit, though the neutral conductor is not switched internally — it's a 4-pole breaker with solid-neutral switching. The 415 V AC rated supply voltage matches standard three-phase European distribution; single-phase operation is rated at 250 V AC per pole. Maximum voltage in multi-phase operation is 440 V AC, giving a bit of headroom on a nominal 400 V system. For the panel builder, the 72 mm width (4 width units at 18 mm each) and 76 mm depth mean it occupies standard DIN-rail space; the 70 mm installation depth accounts for the busbar and wiring behind the rail. Mounting position is any, so vertical or horizontal panel layouts work.