What this selective RCCB does on the line
The Siemens 5SV3617-8 is a 2-pole selective residual current circuit breaker (RCCB) from the SENTRON family, rated 80 A with a 300 mA type A residual trip. Selective means it delays tripping on transient earth faults — so a downstream RCD can clear the fault first, keeping this device closed and the rest of the feeder alive. That selectivity is the whole point: you use it as the main incoming RCD in a distribution board where you have sub-circuits with their own 30 mA RCDs. It prevents a nuisance trip on the main from taking out the entire panel. Rated for 230/400 V AC at 50/60 Hz, with a short-circuit current rating of 10 kA per IEC 61008-1. The 10 kA SCCR means it can safely interrupt a fault up to that level without welding contacts or cascading failure upstream — critical for coordination in a panel fed from a transformer with that fault capacity.
Mounting and panel fit
Snaps onto standard DIN rail (REG profile), occupies 2 modular width units (36 mm wide), and mounts in any position. Depth is 70 mm — sits flush in a standard 2-row enclosure. The IP20 rating applies once installed in a distribution board with conductors connected; the front terminals accept top or bottom feed, which simplifies busbar routing in a crowded panel. Silicon-free construction matters for environments where silicone outgassing can contaminate contacts or optics — common in automotive paint shops or semiconductor fabs. The -25 °C to +45 °C operating range covers most indoor industrial and commercial installations; storage range extends to -40 °C.