The Siemens SIRIUS 3RH1122-2KF40-0LA4 is an auxiliary contactor in the S00 frame size, designed for switching control and auxiliary circuits in industrial panels. It carries a 110 V DC coil and provides four normally-open and two normally-closed instantaneous contacts, rated at 10 A at 24 V and derated to 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V — a curve that tracks the standard AC-15 / DC-13 load profiles for contactor duty.
Mounting and integration
Fastens via screw and snap-on mounting onto a 35 mm DIN rail, occupying a 45 mm wide footprint with a depth of 123 mm and height of 60 mm. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward or backward, giving flexibility in tight enclosures. Solid and stranded conductors from 0.25 to 2.5 mm² (2x per terminal) fit the clamp terminals.
Coil and surge suppression
The DC coil draws 11 W closing power and holds at 4 W — a low-hold design that reduces heat buildup in a densely packed panel. A built-in varistor provides surge suppression across the coil, rated for 6 kV surge voltage resistance, which protects the PLC output or relay driving it from back-EMF spikes.
Environmental and reliability ratings
Rated for operation from -40 to +70 °C, storage and transport from -55 to +80 °C. Shock resistance tested to 10g at 5 ms and 5g at 10 ms. Contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V, 1 mA — a critical spec for PLC-level signal switching where dry-contact reliability matters. Pollution degree 3 suits industrial environments with conductive dust or condensation. IP20 on the front protects against finger contact.