Auxiliary contactor for control-circuit switching
The Siemens 3RH1431-1BD40 is a SIRIUS auxiliary contactor in size S00, designed for switching control circuits and signal loads in industrial panels. Its 42 V DC coil draws 3.2 W during both closing and holding, so the coil-supply sizing is straightforward — no inrush peak beyond the steady-state power. The three normally open instantaneous contacts handle 10 A at 24 V and derate to 1 A at 690 V, covering the typical PLC output, relay, and indicator loads found in a control cabinet.
Mounting and wiring constraints
Mounts via screw and snap-on onto a DIN rail; the 90 mm width and 72 mm depth fit the S00 footprint shared across the SIRIUS contactor family. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, so panel layout is flexible. Solid conductors up to 4 mm² (or 2x 2.5 mm²) terminate in the screw terminals — strip length and ferrule sizing follow standard practice for this terminal class. IP20 on the front means the contactor is protected against finger contact but not washdown; keep it inside a closed enclosure.
Contact ratings and mechanical life
The three NO contacts are rated for 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V — these are the AC-15 / DC-13 utilization categories typical for auxiliary contactors switching solenoid valves, contactor coils, and indicator lamps. Mechanical life is 5 million switching cycles typical; contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V, 1 mA, which covers dry-circuit (low-energy) signal switching without contact wetting current. Shock resistance is 10g for 5 ms and 5g for 10 ms, adequate for most industrial machinery vibration profiles.