The Siemens SIRIUS 3RH1140-1BM40-0AA6 is a size S00 auxiliary contactor with four normally open instantaneous contacts, designed for control-circuit switching in panels where you need to multiply contact sets from a single coil signal. It carries a 10 A rated operational current in AC-12 duty at 400 V, which covers most 24 V to 230 V control loads you'd hang on a PLC output or a larger contactor's auxiliary. The coil is rated for 220 V DC, drawing 3.2 W both on pickup and hold — no extra inrush to size your power supply around.
It snaps onto a DIN rail or screws directly to a mounting plate — the fastening method covers both. The 45 mm width fits a standard 45 mm slot in a SIRIUS modular system, and the 72 mm depth leaves room for wiring in a shallow enclosure. Mounting position is flexible: you can rotate it ±180° on a vertical surface and tilt it ±22.5° forward or backward, which helps when you're squeezing it into a crowded panel. IP20 on the front means it's protected against finger contact, but keep it inside a cabinet — it's not rated for washdown or outdoor exposure.
The contact block is field-expandable — the product extension auxiliary switch is supported, so you can add more contact sets later without swapping the base unit. Wire sizes accepted range from 0.5 mm² up to 4 mm², with solid or ferruled stranded conductors. The 6 kV rated surge voltage resistance means it's comfortable in industrial environments with moderate transient activity, and pollution degree 3 rating confirms it's suited for conductive-pollution conditions typical in control panels.