It protects a single-phase final subcircuit against overload, short-circuit, and earth leakage, with a C-curve trip characteristic that handles motor-start inrush and moderate switching loads without nuisance tripping. Rated 20 A at 30 °C ambient, it derates to 18.8 A at 40 °C and 16.2 A at 55 °C — the thermal curve matters when the device lives in a crowded enclosure. It is a 1P+N design — the switched pole is protected; the neutral pole is switched but not fused. IP20 with the distribution board installed and conductors connected.
If the load is purely resistive (heater, incandescent), a B-curve would be faster; if it is a heavy motor or transformer with high inrush, a D-curve might be needed. The 1-module-wide footprint (18 mm) saves rail space in a distribution board compared to a 2-module RCBO. The halogen-free and silicon-free construction is relevant for clean-room or high-reliability environments where outgassing must be minimised.