Siemens SIRIUS 3RH1140-1BW40 is a size S00 auxiliary contactor — four normally open instantaneous contacts, 48 V DC coil. The screw and snap-on mounting fits standard DIN rail; the IP20 front face protects against tool probes in an enclosed panel.
Contact ratings and what they mean for your circuit
The four NO contacts are rated for AC switching at several voltage levels: 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. For DC control circuits, the contacts carry 1 A at 110 V and 0.27 A at 220 V. These are the thermal current ratings — derate if you are switching inductive loads or running multiple contacts in series. The contact reliability figure (one incorrect switching per 100 million operations at 17 V, 1 mA) means this part is suitable for low-level signal switching, not just power.
Coil and environmental limits
The DC coil draws 3.2 W both during pickup and hold — no power drop after closure, so factor that into your 24 VDC supply budget if the contactor is held continuously. Operating temperature range is -25 to +60 °C; storage and transport tolerate -55 to +80 °C. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) is standard for industrial control panels. The unit withstands 6 kV surge voltage, which covers most installation categories up to 300 V phase-to-earth.
Wiring and mechanical fit
Terminals accept solid conductors: two wires of 0.5–1.5 mm², two of 0.75–2.5 mm², or a single 4 mm² per clamp. The 45 mm width, 57.5 mm height, and 72 mm depth match the SIRIUS S00 footprint — it occupies one standard 45 mm module on a DIN rail. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, so panel layout is flexible. Shock resistance is rated at 10g for 5 ms and 5g for 10 ms.