The Siemens 5SL6650-6 is a SENTRON miniature circuit breaker (MCB) in a 4-pole 3P+N configuration, rated 50 A at 400 V AC with a B tripping characteristic. The neutral pole is switched, so this unit suits single-phase or three-phase panels where the neutral needs to be disconnected with the phases.
The 50 A rating at 30 °C is the headline figure, but the derating curve matters in a warm enclosure: at 40 °C the breaker is good for 46.97 A, at 45 °C for 46 A, and at 55 °C for 42.01 A. It avoids nuisance trips on moderate inrush from lighting or heating circuits, but it is not intended for motor starting (use C or D curve for that). The same 6 kA rating under IEC 60947-2 confirms it for industrial panel applications with similar fault levels.
Halogen-free and silicon-free construction reduces toxic smoke in a fire and avoids silicone outgassing that can foul relay contacts in the same enclosure.