The Siemens SENTRON 5SL6350-6 is a 3-pole miniature circuit breaker rated 50 A at 400 V AC, with a B-curve trip characteristic and a 6 kA breaking capacity certified to both EN 60898 and IEC 60947-2. It carries an IP20 rating with connected conductors, meaning it's finger-safe only when wired; no gaskets, no outdoor exposure.
What fits alongside it
That means you can add remote tripping or status indication without re-wiring the load side.
The closest functional sibling is the 5SL4363-7 — same 3-pole SENTRON form factor (same 54 mm width, 76 mm depth, 90 mm height), same 400 V AC rating, same 50 A current, but with a C-curve trip characteristic and a 10 kA breaking capacity instead of the B-curve and 6 kA here. If your circuit sees motor inrush or transformer energization, the C-curve sibling is the usual pick to avoid nuisance trips. The physical swap is a straight DIN-rail drop-in: same footprint, same wiring, same auxiliary accessory compatibility. The power loss per pole is 5 W on the C-curve version versus 4 W on this B-curve unit — negligible difference in a distribution board.