The Siemens 5SU9356-1CR50 is a 2-pole 1P+N RCBO — a combined RCD and MCB in one 36 mm wide module, part of the SENTRON 5SU9 family. It protects a single-phase AC circuit against overload, short-circuit, and earth leakage (AC type, 30 mA trip threshold). The C tripping characteristic means it holds magnetic trips for 5–10× rated current, so it's sized for motor and lighting circuits with moderate inrush, not pure resistive loads.
Rated 50 A at 30 °C ambient, derated to 45 A at 50 °C — that thermal curve is what you size against if the panel runs warm. Terminal accepts solid or stranded conductors from 0.75 to 35 mm² — enough for the 50 A load on a 10 mm² cable. Power dissipation maxes at 1.5 W, so it won't cook adjacent devices in a densely packed sub-distribution board. Halogen- and silicon-free construction matters if this panel lives in a clean room or a zone where off-gassing during a fault could contaminate optics or electronics.
Touch protection is built in, so no extra finger-safe shrouds needed.