What this RCBO is and what the ratings mean for fit
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. The B-curve trips between 3 and 5 times rated current (18–30 A magnetic release), which is the standard choice for resistive and general-purpose loads where inrush is modest — lighting circuits, small heaters, control transformers. The 10 kA breaking capacity per EN 60898 means it can safely interrupt a short-circuit fault up to that level without damage to itself or upstream gear, assuming the prospective fault current at the installation point does not exceed that figure. 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. The 6 A rating is the continuous current at 30 °C ambient. 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. If the panel ambient runs above 40 °C, the connected load must be reduced accordingly or the next higher rating selected.
Mounting and integration
The 5SU1654-6KK06 occupies 2 modular-width units (36 mm) on a standard DIN rail. Installation depth is 70 mm; overall depth including the housing is 77 mm. The supply cord can enter from either top or bottom, and the mounting position is unrestricted — any orientation is permitted. IP20 rating applies when installed in a distribution board with conductors connected. Touch protection is built into the design. The device is halogen-free and silicon-free, which matters for installations in clean-room or corrosive environments where outgassing could contaminate contacts or optics.