What it is and what it does
The Siemens 3RH1140-1BE40 is a SIRIUS auxiliary contactor — a compact switching block that mirrors the main contactor's armature position to drive status feedback, interlocking, or pilot-duty loads in a motor control center. It carries 4 normally-open instantaneous contacts rated 10 A at 24 V and 10 A in AC-12 duty, which covers resistive and solid-state loads typical of PLC inputs, indicator lamps, and small relays. The coil pulls 3.2 W DC both inrush and hold, so the power supply doesn't need to differentiate pick vs. seal current. Size S00 keeps the footprint at 45 mm wide, 57.5 mm tall, 72 mm deep — it clips onto a DIN rail or screws directly to a backplate. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, which helps when the panel layout forces a non-standard orientation.
Ratings that govern the fit
The 10 A AC-12 rating is the headline figure for pilot-duty switching — it's the current the contacts can make and break for resistive loads like contactor coils and signal lamps. For inductive DC loads, the voltage-specific ratings tell the real story: 10 A at 24 V, 1 A at 110 V, 0.27 A at 220 V — the DC arc extinction limits the current as voltage climbs. At 230 V AC the contacts handle 6 A, at 400 V AC 3 A, at 690 V AC 1 A. That span covers most control-voltage levels in European and North American panels. The screw terminals accept 2x 0.5…1.5 mm², 2x 0.75…2.5 mm², or 2x 4 mm² solid conductors — enough for daisy-chaining the common rail through multiple auxiliary blocks. IP20 on the front means finger-safe in an enclosed panel; pollution degree 3 confirms it tolerates conductive dust in industrial environments. Ambient operating range is -25 to +60 °C, storage -55 to +80 °C. Shock tested to 10g / 5 ms and 5g / 10 ms — fine for machine-mounted cabinets near presses or conveyors.