What it is
The Siemens 3RH1140-2BF40 is a SIRIUS auxiliary contactor in Size S00 — a compact switching block meant to extend the control-circuit contacts on a main contactor or to serve as a standalone signal relay in a panel. It carries four normally-open (4 NO) instantaneous contacts with zero delayed, lagging, or make-before-break switching, so every contact closes at the same instant the coil pulls in.
Key ratings and what they mean for fit
The magnet coil is rated 110 V DC, drawing 3.2 W on both pickup and hold — no power drop after sealing, so the coil dissipation is constant and the supply must be sized for the full 3.2 W continuously. The main contact rating is 10 A at AC-12 (resistive loads up to 400 V), which is the standard auxiliary contactor duty for control transformers, indicator lamps, and PLC digital inputs. At 110 V the contacts are rated 1 A, at 230 V it drops to 6 A, and at 690 V to 1 A — the AC-12 curve is linear with voltage, so for a given load voltage interpolate between these points. Surge voltage resistance is rated 6 kV, and the pollution degree is 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation) — this is standard for industrial control panels not in a sealed, climate-controlled environment. Contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V, 1 mA — this is the low-level signal reliability figure, meaning the contacts are gold-flashed or silver-nickel and can be trusted for PLC input switching without wetting current concerns.
Where it goes in the panel
Mounts via screw or snap-on onto a DIN rail. The Size S00 footprint is 45 mm wide, 60 mm tall, 73 mm deep. IP20 on the front means finger-safe but no protection against water ingress — keep it inside a cabinet or an IP54-rated enclosure. The product extension auxiliary switch is available (field-addable), so the 4 NO base can be expanded with additional contact blocks if the control scheme needs more than four signals.
Lifecycle and compliance
RoHS compliance date is marked as 07/01/2006. No UL or CSA listing is explicitly stated in the evidence.