What it is and where it fits
The Siemens 3RH1131-2JC40 is a SIRIUS coupling relay rated for switching auxiliary circuits — think interposing relays in control panels, signal isolation between PLC outputs and motor contactor coils, or pilot-duty loads. It sits in the S00 contactor frame, which means it occupies the same 45 mm wide DIN footprint as the S00 contactors, so it drops into the same panel layout without extra rail space. Mounting is screw or snap-on (the evidence says both), and the enclosure is IP20 on the front — fine for a clean panel, not for washdown.
Key ratings — what they mean for your BOM
The headline rating is 10 A at AC-12 duty, which covers resistive and solid-state loads at 24 V. That 10 A is the maximum continuous current the contacts are rated to carry and break under AC-12 conditions — if you are driving contactor coils or small transformers, that is the number to size against. For higher voltages the rating drops: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, 1 A at 690 V. The coil power is 2.3 W DC for both closing and holding, so the coil draw is modest and consistent. The surge suppressor is built in with a diode, which means you don't need an external flyback diode for DC coil suppression — saves a component and a wiring step.
Mounting and environmental limits
Operating temperature range is -25 to +60 °C, storage/transport -55 to +80 °C. Shock resistance is 10g for 5 ms and 5g for 10 ms — adequate for most industrial panels, not for extreme mobile or high-vibration applications. The mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward. That takes the guesswork out of panel layout — you can orient it to fit wire routing. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive due to condensation) is typical for industrial control panels. Maximum altitude is 2 000 m without derating.
Connections and wiring
The solid connection accepts 2 x (0.25... 2.5 mm²) — that is two conductors per terminal, solid or stranded, in the range from 0.25 to 2.5 mm². No special ferrules required for stranded if you strip cleanly. The contact configuration is 3 NO instantaneous contacts (no delay, no make-before-break, no lagging). No auxiliary switch. Depth is 73 mm, height 60 mm — standard S00 dimensions that match the contactor line.