RCBO for final-circuit protection
The Siemens SENTRON 5SU1324-7KX20 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) combining Type A residual current detection with a curve C overcurrent trip in a single 3-module-width (54 mm) package. Rated 20 A at 30 °C, it provides both earth-leakage and short-circuit/overload protection for final circuits in distribution boards. Breaking capacity is 10 kA per EN 60898 and 20 kA per IEC 60947-2, giving selectivity headroom for most commercial and light-industrial installations. The curve C characteristic (magnetic trip between 5 and 10 × In) suits mixed loads with moderate inrush — lighting, small motors, socket outlets.
Thermal derating and installation flexibility
Rated current derates with ambient temperature: 20 A at 30 °C, 18.8 A at 40 °C, 17.4 A at 50 °C, 16.2 A at 55–60 °C, and 14.6 A at 70 °C. In a crowded enclosure or high-ambient panel, size the load circuit to the derated figure at the expected internal temperature. Mounts in any position (vertical, horizontal, inverted) and accepts supply from top or bottom. Installation depth is 70 mm plus the 77 mm overall depth. IP20 rated when installed in a distribution board with conductors connected. Touch protection is built in. Halogen-free and silicon-free construction — relevant for installations with sensitive contacts or clean-room requirements.