What it is and where it fits
The Siemens 3RH1140-2BB40-0TK0-ZX95 is a SIRIUS auxiliary contactor in size S00, designed to switch control circuits rather than motor loads directly. Its 24 VDC coil draws 3.2 W both on pickup and hold, so the power supply sizing is straightforward — no inrush spike to budget for. The four instantaneous NO contacts handle 10 A at 24 V rated value, which covers most PLC output interposing and contactor feedback circuits in a panel. Mounting is screw or snap-on onto a DIN rail, and the +/-180° rotation on a vertical surface plus +/-22.5° tilt gives flexibility in tight enclosures. The front face carries IP20 protection, so it's suited for enclosed control panels where no washdown or dust ingress is expected.
Key ratings and what they mean for your BOM
The contact reliability spec — one incorrect switching per 100 million operations at 17 V, 1 mA — tells you this contactor is built for dry-circuit signal switching, not just power-level pilot duty. That matters when your customer's AML specifies gold-flash contacts for low-energy PLC inputs; this part meets that threshold without a separate interface relay. Rated surge voltage resistance is 6 kV, which aligns with IEC 60947-1 overvoltage category III for 300 VAC circuits. Pollution degree 3 means the contactor tolerates conductive pollution typical of industrial control panels — no conformal coating required for normal environments. Wire termination accepts 2x (0.25... 2.5 mm²) solid or 2x (24... 14 AWG) stranded. That covers standard control wiring from 0.5 mm² signal pairs up to 2.5 mm² for longer runs. The 73 mm depth fits standard 80 mm deep enclosures with room for wiring ducts.
Lifecycle and sourcing posture
RoHS compliance date is July 1, 2006, which covers the original EU RoHS directive. The part carries no explicit REACH or UL listing in the evidence, so verify against your customer's compliance matrix — particularly if the end-client requires UL 508 listing for the panel.
Integration notes for the panel builder
The size S00 footprint (45 mm wide, 60 mm tall, 73 mm deep) matches the standard Siemens S00 contactor family. If your panel was laid out for a 3RT1015 motor contactor, this auxiliary contactor shares the same width and mounting hole pattern, so it clips onto the same DIN rail without re-drilling. Operating temperature range is -25 to +60 °C, with storage and transport range from -55 to +80 °C. That covers most indoor industrial environments but check if your panel sees sustained ambient above 60 °C — the contactor's thermal derating curve (not in evidence) would apply. Shock resistance is 10g for 5 ms and 5g for 10 ms. That's adequate for fixed-mount panels on machine frames but not for direct mounting on a vibrating conveyor or press — use vibration dampers if the panel is on the moving part of the machine.