Auxiliary contactor for control-circuit switching
The Siemens 3RH1431-1BM40 is a SIRIUS auxiliary contactor in size S00, built for switching control loads in motor starter and contactor assemblies. It carries 3 instantaneous normally-open contacts and 1 normally-closed contact, rated 10 A at AC-12 (resistive control-circuit duty) and 10 A at 24 V DC. The DC coil pulls 3.2 W to close and holds at 3.2 W — no AC hum, no power drop after pick-up. Rated for 220 V DC coil voltage, it mounts via screw or snap-on onto a DIN rail. The 90 mm width, 57.5 mm height, and 72 mm depth fit the S00 footprint — zero side clearance needed, so you can gang them tight in a panel. IP20 on the front face keeps fingers out; pollution degree 3 means it handles conductive dust in industrial enclosures.
Contact ratings across the voltage range
The contacts are rated for switching at multiple control voltages: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. At 110 V the rating is 1 A, and at 220 V it's 0.27 A. These are the thermal current limits for the contact set — match your control-circuit voltage to the appropriate row to avoid overstressing the contacts. Mechanical endurance is rated at 5 000 000 cycles typical for the contactor size. Shock resistance is 10g / 5 ms and 5g / 10 ms, and the operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Maximum operating altitude is 2 000 m.
Wiring and mounting flexibility
Terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². The mounting position allows +/-180° rotation on a vertical surface and can be tilted forward/backward by +/-22.5° — useful for tight cabinet layouts or angled DIN-rail sections.