The Siemens SIRIUS 3RH1131-2BA40 is a size S00 auxiliary contactor with a 12 VDC coil and 3 normally open (NO) instantaneous contacts. It mounts via screw or snap-on onto a DIN rail, fitting into a 45 mm wide slot in the panel — standard for this frame size. The IP20 front protection means it is intended for installation inside an enclosure, not exposed to washdown or dust.
Ratings and what they mean for fit
The 12 VDC coil draws 3.2 W closing and holding — a steady-state load that the control transformer or PLC output must supply continuously. The contact reliability spec (one incorrect switching per 100 million operations at 17 V, 1 mA) tells you this contactor is built for dry-circuit or low-energy signal switching, not just power auxiliaries. Switching capacity varies by voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V — derate accordingly for your load voltage. The surge voltage resistance of 6 kV gives coordination confidence in panels with nearby contactors or drives.
Mounting and wiring
Screw terminals accept 2x (0.25 to 2.5 mm²) solid or 2x (24 to 14 AWG) stranded. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when fitting into a crowded backpanel. Depth is 73 mm, height 60 mm. Shock rated at 10g / 5 ms and 5g / 10 ms, so it holds up in mobile or high-vibration sections of the line.