Auxiliary circuit coupling relay, S00 frame
The Siemens 3RH2131-2MB40-0KT0 is a SIRIUS coupling relay designed for switching auxiliary circuits — it handles the logic-level and pilot-duty loads that the main contactor's auxiliary contacts might not cover, or that need electrical isolation from the power circuit. Rated 10 A at both 24 V and 230 V, it carries three instantaneous contacts that close without delay, so it suits interlocking, status feedback, and PLC input isolation in a motor control centre. The coil consumes 1.6 W DC for both closing and holding — the same figure means no inrush spike to size the control transformer around, and the holding power stays low enough to keep the panel temperature rise within the enclosure's thermal budget.
DIN-rail fit and panel clearance
Width is 45 mm, depth 73 mm, height 70 mm — the S00 frame occupies three standard 15 mm DIN-rail module positions, so a row of these relays packs tightly without wasted rail space. A panel designer who ignores the 6 mm side clearance risks tracking across the pollution layer (pollution degree 3) under humid conditions.
Environmental and compliance envelope
RoHS substance prohibition date is 10/01/2009 — the relay complies with the EU RoHS directive as amended, and the date is the compliance cut-off, not a production end date.