The Siemens 5SM2822-8 is a selective residual-current device (RCD unit) from the SENTRON series, designed as a companion module for 5SY miniature circuit breakers. It is a 2-pole, type A unit rated at 40 A with a 1000 mA tripping fault current, operating on AC 230 V at 50/60 Hz. The selective design (time-delayed) means it coordinates with downstream RCDs — it holds during a fault long enough for the closest device to clear, so only the faulted branch drops out, not the whole sub-distribution board.
What the ratings mean for fit
The 1000 mA residual current rating (IΔn) is not a typo — this is a selective (time-delayed) RCD, not a standard 30 mA personnel-protection device. It is sized for fire protection or equipment protection in a distribution sub-main, where the upstream RCD must coordinate with downstream 30 mA units. The 40 A rated current matches a 40 A 5SY MCB upstream; the module snaps onto the same DIN rail and connects to the MCB via the busbar and integrated link. Type A detection covers AC sinusoidal and pulsed DC residual currents, which covers most modern electronics and single-phase rectified loads. Overvoltage category III and pollution degree 2 are standard for fixed-installation distribution boards. The IP20 rating applies only when the distribution board is installed with conductors connected — so this is a panel-internal component, not a standalone outdoor device. The 2-module-width (36 mm) footprint and 70 mm depth fit standard SENTRON enclosures and 5SY comb bars.
Panel integration notes
Mounts in any position on DIN rail (REG fastening method). The 2-pole design occupies 2 modular width units (36 mm). Supply can enter from top or bottom. The unit is not sealable. Mechanical service life is 10 000 operating cycles typical. Power dissipation per pole at rated current is 1.9 W — factor that into enclosure thermal calculations if the board is densely populated.