The Siemens 5SU9404-1KK25 is a SENTRON RCBO (RCD-operated circuit breaker) combining overcurrent and residual current protection in a single 18 mm wide module. The 1P+N configuration protects one live pole while switching the neutral, fitting standard distribution boards with a 1-module width.
The 25 A rating is the continuous current at 30 °C ambient; at elevated panel temperatures the load must be derated — 23.5 A at 40 °C, 22.75 A at 45 °C, 21.75 A at 50 °C, and 20.25 A at 55 °C (–). The Type C characteristic trips at 5–10× rated current, suited for motor and transformer inrush where a Type B would nuisance-trip.
Rated IP20 with the distribution board installed and conductors connected. Touch protection is provided. Halogen-free and silicon-free construction.