The Siemens 5SU9306-0KK16 is a 2-pole (1P+N) RCD-operated circuit breaker — an RCBO — that combines overcurrent protection and 30 mA AC residual current detection in a single 18 mm wide module. The 16 A rated current with B-curve tripping characteristic means it protects lighting and general-purpose socket circuits against short-circuit and overload, while the 30 mA residual-current element provides earth-fault protection for personnel.
Current derating and installation constraints
At 40 °C it derates to 15.04 A, at 45 °C to 14.56 A, at 50 °C to 13.92 A, and at 55 °C to 12.96 A. If the distribution board runs warm — common in enclosed or multi-row panels — use the derated figure for the connected load.