What this RCBO is and what the ratings mean
The Siemens 5SU1656-6KV06 is a combined residual-current circuit breaker with overcurrent protection (RCBO) — a single module that does the job of an RCD and an MCB in one DIN-rail unit. The 'FI/LS' label is the German shorthand for this combo device. Type A sensitivity (300 mA IΔn) means it detects pulsating DC fault currents on top of sinusoidal AC — the standard for circuits feeding single-phase electronics, inverters, or variable-speed drives where a pure AC-sensing RCD might not trip on a half-wave fault. The 6 kA breaking capacity (IEC 60898) tells you it can safely interrupt a short-circuit fault up to 6,000 A at the rated voltage; that's the standard domestic and light-commercial SCCR for a final subcircuit in most European installations. The B-curve 6 A overcurrent characteristic trips instantaneously at 3–5× rated current (18–30 A), so it's sized for resistive and general-purpose loads like lighting, small appliance circuits, or control transformers — not high-inrush motor or welding loads where a C or D curve would be needed.
Panel fit and deployment context
This RCBO snaps onto a standard 35 mm DIN rail in a consumer unit or distribution board. The 70 mm depth (D=70 mm) is the standard for Siemens 5SU6 series devices, so it fits alongside other Siemens modular protection gear without a step-out. The 1+N-pole format switches the live and monitors neutral; the neutral is switched internally but not protected against overcurrent.