The Siemens SIRIUS 3RH1122-1BB40-0TK0-ZX95 is an auxiliary contactor, size S00, with a 24 VDC coil and a contact configuration of 2 normally-open and 2 normally-closed instantaneous contacts. It carries a 10 A rating at AC-12 duty, which means it's suited for switching resistive loads and control circuits in a panel — the AC-12 rating covers the load curve for resistive and solid-state loads, not motor inrush. The coil pulls 3.2 W on both pick-up and hold, so there's no power drop after engagement; the DC holding power matches the closing power, which simplifies thermal budgeting in a crowded DIN-rail enclosure.
Mounts via screw or snap-on onto a DIN rail — the 45 mm width and 57.5 mm height fit the standard S00 footprint, so it occupies the same slot as a S00 contactor. Clearance at the side is 0 mm, meaning it can sit flush against adjacent devices without derating for heat buildup at the sides. Wire capacity accepts 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm² solid, covering most control-circuit wiring gauges without needing ferrules.
The auxiliary contacts are rated for AC-12 at 10 A, but the switching capacity drops with voltage: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. For DC switching, the contacts handle 10 A at 24 V, 1 A at 110 V, and 0.27 A at 220 V. Mechanical life is typical 30 million operations, so it'll outlast most contactors it's paired with in cyclic service.