The Siemens 5SN6416-8CP is a 4-pole miniature circuit breaker from the SENTRON 5SN series, designed for 400 V AC, 50 Hz systems.
The 6 kA per EN 60898 is the domestic standard; if your panel is built to that code, the lower figure governs. The 440 V AC maximum for multi-phase operation means it's rated for 400 V class systems with headroom for voltage swell. The 72 V DC maximum is a hard limit — do not use this breaker on DC circuits above that voltage. Power loss is 1.6 W per pole at rated current in hot state, so a 4-pole unit dissipates about 6.4 W; factor that into enclosure thermal calculations if the panel is densely packed.
DIN-rail footprint and conductor sizing
Depth is 76 mm overall; installation depth (the projection behind the panel face) is 70 mm. Accepts solid conductors up to 35 mm² — enough for the incoming feed on a sub-distribution board. The 10 000 mechanical operating cycles is typical for this class; it is not a high-cycle switching device, so do not use it for frequent load switching in a process line.