The Siemens 5SU9304-1KK25 is a 1P+N RCBO from the SENTRON 5SU9 series — an RCD-operated circuit breaker that combines overcurrent and residual current protection in a single 18 mm wide module.
Thermal derating — the real-world current rating
At 40 °C it derates to 23.5 A, at 45 °C to 22.75 A, at 50 °C to 21.75 A, and at 55 °C to 20.25 A. That's the number to use for your load calc, not the 25 A label.
Panel fit and installation
At 18 mm wide (1 width unit), it takes one modular slot in a distribution board. Rated IP20 with the distribution board installed and conductors connected.
Halogen-free and silicon-free construction. Touch protection is provided on the terminals. The device is classified as energy limiting class 3, which means it limits let-through energy in a fault — relevant for downstream component coordination.