The Siemens 5SU1656-6KK16 is a 2-pole residual current circuit breaker with overcurrent protection (RCBO) from the SENTRON family, combining a 16 A rated current (at 30 °C) with a 300 mA residual current trip, Type A, in a single 36 mm wide module (2 modular width units). The 16 A rating is the thermal current at 30 °C ambient; at 40 °C it derates to 15.2 A, at 50 °C to 14.4 A, and at 70 °C to 12.32 A — so if the panel runs warm, size the load against the derated figure, not the 30 °C headline. The 300 mA residual current sensitivity (Type A) catches pulsating DC fault currents as well as sinusoidal AC, which covers most modern electronic loads — VFDs, LED drivers, switched-mode supplies — without nuisance tripping on the DC component.
Halogen-free and silicon-free construction means it meets the material restrictions common in rail, marine, and high-reliability industrial specs — no halogenated flame retardants that could produce corrosive smoke under fault.
Temperature derating in practice
The RCBO carries a full derating curve from 30 °C to 70 °C in 5 °C steps. At 55 °C it is rated 13.92 A, at 60 °C 13.6 A, at 65 °C 12.96 A. If the panel ambient exceeds 40 °C, use the 40 °C column (15.2 A) as the design limit — the device will trip thermally below its 30 °C rating.