What it is and what it does
The Siemens 5SU9356-1KK63 is a SENTRON RCBO — a residual-current-operated circuit breaker that combines overcurrent and earth-fault protection in a single 2-module-wide (36 mm) package. It's a 1P+N design, meaning it switches and protects the line conductor only, with the neutral switched but not protected. The C-curve tripping characteristic means it holds up to 5–10× rated current for short-duration inrush (typical for motor-starting or transformer loads) before tripping magnetically. Rated 63 A at 30 °C ambient, it derates to 59.22 A at 40 °C, 57.33 A at 45 °C, 54.81 A at 50 °C, and 51.03 A at 55 °C. That derating curve matters when you're packing this into a warm enclosure — the 40 °C figure is the one to design to for a standard panel. Breaking capacity is 6 kA per EN 60898 (the residential / light commercial standard) and 10 kA per IEC 60947-2 (the industrial standard). The higher 10 kA figure gives you headroom for industrial distribution boards with higher prospective fault currents.
Mounting and integration
Snaps onto DIN rail, 2 modular width units (36 mm wide, 77 mm deep, 90 mm tall). Installation depth is 70 mm. Mounting position is any orientation. Supply can come from either top or bottom — no mandatory orientation for the line feed. IP20 rated when installed in a distribution board with conductors connected — standard for enclosed panel gear, not for exposed washdown areas.