What it is and what it does
The SENTRON 5SU9354-8KK32 is a 2-pole (1P+N) RCD-operated circuit breaker — an RCBO that combines overcurrent protection and residual current detection in a single 36 mm wide (2-module) package. It's rated 32 A with a D tripping curve, meaning it's built for loads with high inrush currents like small motors, transformers, or discharge lighting where a B or C curve would nuisance-trip on startup. The Type A fault current detection handles pulsating DC residual currents, which is what you get from single-phase rectifiers in VFDs, switching power supplies, and LED drivers.
Breaking capacity and standards
Breaking capacity is 10 kA per both EN 60898 and IEC 60947-2 — that's the standard for domestic and light commercial distribution boards. It's rated for overvoltage category III, which covers fixed-installation downstream of the utility meter. The energy limiting class is 3, meaning it lets through less fault energy than a class 1 or 2 device, so downstream components see less stress during a short circuit.
Thermal derating and ambient limits
The 32 A rating holds at 30 °C ambient. At 40 °C it derates to 30.08 A, at 45 °C to 29.12 A, at 50 °C to 27.84 A, and at 55 °C to 25.92 A. Operating ambient range is -25 to +45 °C; storage range is -40 to +75 °C. If your panel runs hot — say a packed enclosure near a furnace line — factor the derating into your load calculation. Power dissipation is 1.5 W, which is modest for a 32 A RCBO.
Panel fit and wiring
Width is 36 mm (2 width units), depth 77 mm, installation depth 70 mm. Mounts on DIN rail in any position. Accepts solid or stranded conductors from 0.75 to 35 mm². Supply can enter from top or bottom. IP20 with conductors connected and distribution board installed — standard for enclosed distribution boards. Touch protection is built in.