What it is and where it fits
The Siemens SIRIUS 3RH1122-1KG40-0LA3 is an auxiliary contactor in size S00, designed for control-circuit switching in industrial panels. It carries 2 normally-open and 2 normally-closed instantaneous contacts, rated for a 125 V DC coil. Mounting is via screw fixing or snap-on onto a DIN rail; the unit occupies 45 mm width and 57.5 mm height, with a depth of 72 mm. The front face is IP20 rated, so it suits enclosed panel environments where finger-safe access is needed.
Switching capacity and contact ratings
The contacts are rated for switching at multiple voltage levels: 10 A at 24 V, 1 A at 110 V, 0.27 A at 220 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. These are the thermal current values for the auxiliary contacts — use them to size the control circuit load, not the main power path. The contactor includes a built-in varistor surge suppressor across the coil, which limits voltage spikes when the coil de-energises. Coil closing power is 11 W DC; holding power drops to 4 W DC, so the coil driver must supply the inrush but can settle to a lower continuous draw.
Environmental and mechanical limits
Operating temperature range is -40 to +70 °C; storage and transport tolerate -55 to +80 °C. The unit withstands shock of 10 g for 5 ms and 5 g for 10 ms. Pollution degree 3 means it's suitable for industrial atmospheres with conductive pollution. Contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V, 1 mA — important for low-level signal switching where oxide films on dry contacts can cause intermittents. The mechanical endurance is 30 million operating cycles.
Wiring and connection data
The terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². The screw-type clamping is standard for panel wiring; strip length and torque follow the manufacturer's installation instructions. The auxiliary switch block is field-expandable — the product extension auxiliary switch is listed as yes, so additional contact blocks can be added to the side of the base unit without removing wiring.