What it is and what it does
The Siemens 3RH1140-1BG40-0AA6 is a SIRIUS auxiliary contactor — a control-circuit device that provides four normally-open (NO) instantaneous contacts for signaling, interlocking, or extending the contact count of a main contactor or starter. It is sized as a Size S00 unit, the smallest frame in the SIRIUS family, and mounts via screw or snap-on to a DIN rail. Rated operational current is 10 A at 24 V, derating to 6 A at 230 V and 1 A at 690 V. The contacts are rated for a surge voltage resistance of 6 kV and a pollution degree of 3, meaning they tolerate the conductive contamination typical of industrial control panels.
Mounting and integration
The 3RH1140-1BG40-0AA6 occupies a 45 mm wide by 57.5 mm high by 72 mm deep footprint on the DIN rail. The mounting position is flexible — it can be rotated ±180° on a vertical surface and tilted forward or backward by ±22.5°, which simplifies layout in crowded enclosures. Screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². The front face carries IP20 protection, so the terminals are finger-safe once wired but the contactor itself is not sealed against moisture or dust ingress — it belongs inside a panel, not in a washdown zone.
Electrical and environmental ratings
The DC magnet coil draws 3.2 W for both closing and holding, so the coil suppression circuit sees a steady load. Operating temperature range is -25 to +60 °C; storage and transport range extends to -55 to +80 °C. Shock resistance is rated at 10g for 5 ms and 5g for 10 ms. Contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V and 1 mA, which is the low-energy test condition that matters for PLC input signals. Mechanical endurance is typical 30 million switching cycles.