The Siemens 3RH1122-2BW40 is a SIRIUS auxiliary contactor in size S00, designed to switch control and signal circuits in motor starter and contactor assemblies. It carries a 48 VDC coil and is rated for 10 A in AC-12 duty, which covers resistive and solid-state loads typically found in PLC output circuits and relay logic panels. The contact arrangement is 2 normally-open and 2 normally-closed instantaneous contacts, giving you four isolated poles for feedback, interlock, or permissive signals.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail. The 45 mm width matches the S00 contactor footprint, so it clips directly alongside a 3RT1 contactor without extra spacing. Side clearance is zero — adjacent devices can butt up. Mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward and backward. The IP20 front protection means it's suited for enclosed panels where tools are the only access; no washdown rating. Wire termination accepts solid or stranded conductors from 0.25 to 2.5 mm², two per terminal. The 73 mm depth leaves room for wiring ducts in standard 80 mm deep enclosures.
Switching capacity across voltages
The AC-12 rating at 10 A is the headline figure, but the contactor also carries defined switching capacities at other voltages: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. For DC control circuits, it switches 10 A at 24 V, 1 A at 110 V, and 0.27 A at 220 V. These values define the load-break capability per pole — useful when interposing between 24 VDC PLC outputs and higher-voltage contactor coils.
Environmental and mechanical limits
Operates from -25 to +60 °C, stores from -55 to +80 °C. Shock rated at 10g for 5 ms and 5g for 10 ms. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) — standard for industrial control panels. Surge voltage resistance is 6 kV. Maximum operating altitude is 2 000 m without derating. Mechanical life is typical 30 million operations.
Coil and operating range
The 48 VDC coil draws 3.2 W for both closing and holding — no power drop after pickup. Operating range is 0.8 to 1.1 times rated voltage, so pickup is guaranteed at 38.4 V and the coil withstands 52.8 V continuous.