Auxiliary contactor for control-circuit switching
The Siemens 3RH1140-1AH10 is a SIRIUS auxiliary contactor in size S00, carrying four normally-open instantaneous contacts for switching control circuits up to 10 A in AC-12 duty (resistive loads at 24 V). Rated operational current drops with voltage: 6 A at 230 V, 3 A at 400 V, 1 A at 690 V — so the 10 A figure applies only at 24 V, not across the full range. Snap-on mounting onto a 35 mm DIN rail, or screw-fixed to a panel; the 45 mm width fits standard S00 contactor spacing and leaves room for auxiliary switch blocks.
Rated switching capacity and contact reliability
AC-12 rating of 10 A is the headline number, but the contactor also carries 1 A at 110 V and 0.27 A at 220 V for DC control circuits — the DC curve is much lower than the AC curve, so don't assume the AC rating transfers. Contact reliability is specified at one incorrect switching operation per 100 million cycles at 17 V, 1 mA — a dry-circuit rating that matters for PLC inputs or low-level signal switching where oxide films can block conduction. Mechanical life is 30 million operating cycles typical, which is standard for the S00 frame in auxiliary duty.
Environmental and mounting flexibility
Operating temperature range is -25 to +60 °C; storage and transport extend to -55 to +80 °C — the wider storage range governs handling, not running. Shock resistance of 10g / 5 ms and 5g / 10 ms covers most industrial panel vibration; the mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, so it fits tight enclosures without derating. IP20 on the front means finger-safe but not washdown — keep it inside a closed panel, not on a machine exterior.
Wiring and terminal data
Screw terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid/stranded; AWG equivalents are 2x (20–16), 2x (18–14), and 1x 12. Degree of pollution 3 per IEC 60947-1 means the contactor is rated for conductive pollution environments typical of industrial control panels — no additional conformal coating needed for normal use. Surge voltage resistance is 6 kV, which coordinates with standard 400 V motor circuits and upstream Type 2 surge arrestors.
Lifecycle and compliance
Reference code per IEC 81346-2 is K — the standard designation for contactors and relays in system documentation.