The Siemens 5SU9326-1CR25 is a SENTRON RCBO — a residual-current-operated circuit breaker that combines overcurrent protection (MCB function) with earth-leakage protection (RCD function) in a single 4-module-wide (72 mm) DIN-rail device. The 6 kA breaking capacity is certified to both EN 60898 and IEC 60947-2, so it handles fault currents up to that level in a 230/400 V distribution board without cascading upstream.
Temperature derating — the real-world rating
At 40 °C it derates to 23.3 A, at 45 °C to 22 A, at 50 °C to 21.5 A, and at 55 °C to 20.8 A.
The supply can enter from either top or bottom, and the mounting position is unrestricted — no orientation restrictions in the enclosure.