What it is and where it fits
The Siemens SIRIUS 3RH1122-1AU60-1AA0 is an auxiliary contactor — a control-circuit switching block that extends the contact set of a main contactor or handles standalone signal routing in a panel. It carries 2 normally-open and 2 normally-closed instantaneous contacts, rated for a maximum operational current of 10 A in AC-12 duty (resistive loads at line frequency). The size S00 footprint (45 mm wide, 57.5 mm tall, 72 mm deep) is the standard compact frame for this class in the SIRIUS family, and the screw and snap-on mounting lets it clip directly onto a DIN rail or fasten with screws into a backplate.
Ratings that decide the fit
The 10 A AC-12 rating is the headline — it governs resistive switching at line voltage. For inductive DC loads the derating is steep: 10 A at 24 V drops to 1 A at 110 V, 0.27 A at 220 V, and 0.1 A at 690 V. That means this contactor is sized for control transformers, pilot lights, and PLC output isolation, not for motor starting. The surge voltage resistance of 6 kV and pollution degree 3 rating confirm it is built for industrial panels where transient spikes and conductive dust are expected. Mechanical life is typical 30 million operations; contact reliability is specified as one incorrect switching per 100 million operations at 17 V, 1 mA — a low-level signal rating that matters for direct PLC input circuits.
Mounting and wiring
Mounting position is standing on a horizontal surface; the screw and snap-on method means it clips onto a DIN rail or can be screw-fastened to a plate. The front carries IP20 protection.