The Siemens 5SU9404-1KK06 is a 1P+N RCD-operated circuit breaker (RCBO) from the SENTRON 5SU9 series, combining overcurrent protection and residual current detection in a single 18 mm wide module. The integrated RCD trips on AC fault currents, so it's suited for circuits where both short-circuit and earth-fault protection are needed in one device. The 10 kA rating is typical for sub-distribution boards in commercial or light industrial panels.
Thermal derating and conductor sizing
The 6 A rating holds at 30 °C ambient; at 40 °C it derates to 5.64 A, at 45 °C to 5.46 A, at 50 °C to 5.22 A, and at 55 °C to 4.86 A.
Halogen-free and silicon-free construction.