The Siemens 5SU1654-6KK06 is a 2-pole residual-current circuit breaker with overcurrent protection (RCBO) from the SENTRON series, combining a 6 A thermal-magnetic trip (B characteristic) and a 300 mA residual-current detection circuit (Type A) in a single 36 mm-wide module. Type A residual-current detection handles pulsating DC fault currents superimposed on AC — the common waveform from single-phase rectifiers in switched-mode power supplies, LED drivers, and variable-speed drives. The 300 mA sensitivity is a deliberate choice: it provides fire protection (the standard 30 mA would nuisance-trip on leakage from long cable runs or filter capacitors). This is not a personnel-protection device; it is sized for equipment and property protection where the earth-leakage background is known to be above 30 mA. At elevated panel temperatures the rating must be derated per the manufacturer's curve: 5.7 A at 40 °C, 5.4 A at 50 °C, 5.1 A at 60 °C, and 4.62 A at 70 °C.
IP20 rating applies when installed in a distribution board with conductors connected. Touch protection is built into the design.