What it is and what it does
The Siemens 3RH2122-1AQ00 is a SIRIUS auxiliary contactor — a control-circuit switching block, not a main power contactor. It carries 2 normally-open instantaneous contacts in the S00 frame size, meaning it fits the same DIN-rail footprint as the S00 power contactors and can be ganged alongside them for interlocking or signal feedback. The contacts are rated for 10 A at 24 V, 10 A at 230 V, and derate to 0.26 A at 600 V — so the buyer needs to match the switching voltage to the load's control circuit, not assume a single current rating holds across all voltages.
Mounting and integration
Fastens with screw and snap-on onto 35 mm DIN rail. Mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward — useful when the panel layout forces a non-standard orientation. Side clearance of 6 mm and 10 mm upward/downward/forward clearance keeps heat dissipation and wiring access predictable. Accepts solid or stranded wire: 2x (0.5…1.5 mm²), 2x (0.75…2.5 mm²), or 2x 4 mm².