The Siemens 5SM2845-2 is a 4-pole selective residual-current device (RCD) from the SENTRON series, designed as an add-on unit for the 5SY miniature circuit breaker range. Selective design (type S) means it incorporates a short time delay so that downstream RCDs trip first during a fault, keeping this unit as the backup — critical for panel coordination in distribution boards where you want only the branch circuit to drop, not the whole submain.
Rated at 63 A continuous. The 1000 mA residual trip threshold is for fire or equipment protection, not personnel protection. Rated insulation voltage (Ui) is 460 V, surge voltage resistance is 4 kV, and overvoltage category III — all consistent with 400 V three-phase distribution panels where it's installed downstream of the main switch. The IP20 rating (with conductors connected, in an installed distribution board) is standard for enclosed panel mount — no washdown rating here.
Occupies 4 modular width units. Installation depth is 70 mm. Designed as a clip-on RCD unit for the 5SY MCB series — it's not a standalone device; it mounts to the right of the corresponding 5SY breaker and connects via the busbar and a mechanical trip link. If you're replacing a failed unit in an existing 5SY panel, this drops in without rewiring the load side. The OFF-delay is not adjustable, and the rated fault current is fixed at 1000 mA — no field tweaks. False-tripping protection is built in (suppression of nuisance trips from transient surges).