Siemens 3RH1122-2JB40 is a SIRIUS coupling relay — a compact auxiliary contactor built for switching control and signal circuits in industrial panels. Size S00 frame, 45 mm wide, snaps onto DIN rail or screws directly to a mounting plate. Coil is 24 V DC, pull-in and hold at 2.3 W. Rated AC-12 at 10 A, so it handles resistive loads like contactor coils and indicator lamps without derating. Surge suppressor built in — a free-wheeling diode across the coil, which means no external snubber needed on DC control circuits.
What the ratings mean for fit
The 10 A AC-12 rating is the continuous thermal current — it governs the contact set's ability to carry resistive loads without welding. For inductive loads (contactors, solenoids), the AC-15 rating drops to 6 A at 230 V. The DC switching capability is lower: 10 A at 24 V, 1 A at 110 V, 0.27 A at 220 V. If you're breaking DC solenoids or brake coils, check the voltage against those curves. The 2 NO + 0 NC contact configuration means this relay makes two independent normally-open circuits; there's no break contact on board. Ambient range is -25 to +60 °C, storage from -55 to +80 °C. Pollution degree 3 — suitable for industrial environments with conductive dust or humidity.
Mounting and integration
Snaps onto DIN rail or screws to a backplate. Mounting position: ±180° rotation on a vertical surface, ±22.5° tilt forward/backward. Side clearances: zero mm.