The Siemens SENTRON 5SU1322-7KC40 is an RCBO — a combined residual-current and miniature circuit breaker in one 2-module-wide package, rated 40 A with a 30 mA Type A residual trip and a C-curve overcurrent characteristic. The 50 kA breaking capacity per EN 60898 (and matching 50 kA per IEC 60947-2) means it can interrupt high fault currents without upstream fuses having to clear first, which simplifies panel coordination. Type A detection catches pulsating DC fault currents from single-phase rectified loads — common with switching power supplies, LED drivers, and variable-speed drives — so it's the right choice for mixed-load final circuits.
What the ratings mean for your panel
At 2 width units and 70 mm installation depth, this RCBO fits standard distribution boards. Terminals accept solid or stranded conductors from 0.75 mm² to 35 mm². Rated ambient is -25 to +55 °C, with storage from -40 to +75 °C. That's wide enough for most indoor panel environments, including non-climate-controlled electrical rooms. The IP20 rating applies only when the distribution board is installed and conductors are connected — so don't leave it exposed during commissioning; the front face offers touch protection (finger-safe terminals per the product feature), but the back and sides rely on the enclosure.