The Siemens SIRIUS 3RH6122-1KF40 is a coupling relay for switching auxiliary circuits, built into the S00 contactor footprint. It carries 2 normally-open and 2 normally-closed contacts, controlled by a 110 V DC coil that draws 2.8 W for both closing and holding. The relay snaps onto a 35 mm DIN rail or screws directly to a mounting plate, and the screw-terminal connections accept up to 2x 4 mm² solid or 2x 2.5 mm² stranded wire — clean terminations in a packed enclosure.
The contacts are rated for AC-12 and DC-12/DC-13 duty. At 230 V AC, the maximum operational current is 10 A; at 400 V AC it drops to 3 A, and at 690 V AC to 1 A. For DC loads at 110 V, the relay switches 3 A; at 220 V, 1.2 A. These numbers define the actual load you can break — not just carry — at each voltage. The 6 kV rated surge voltage resistance means the relay withstands line transients common in industrial panels without flashover.
The 45 mm wide body fits the S00 contactor footprint, so it shares the same DIN-rail spacing and panel cutouts. The screw terminals accept 2x (0.5…1.5 mm²), 2x (0.75…2.5 mm²), or 2x 4 mm² solid/stranded, and for AWG: 2x (20…16), 2x (18…14), or 2x 12.