What it is and what it does
The Siemens 3RH1122-1BB40-ZX95 is a SIRIUS auxiliary contactor in the size S00 frame — the smallest of the SIRIUS contactor family, built for control-circuit switching rather than motor loads. It carries 2 normally-open and 2 normally-closed instantaneous contacts, rated for AC-12 duty at 10 A, meaning it's designed for switching resistive loads like relay coils, PLC inputs, and signal lamps inside a control panel. The coil is 24 VDC with a holding power draw of 3.2 W — the same as its inrush closing power, so there's no drop in consumption after pickup. That steady draw simplifies DC-supply budgeting on a 24 V bus.
Panel fit and mounting
Width is 45 mm, height 57.5 mm, depth 72 mm — a compact footprint that fits standard DIN-rail enclosures. Mounting is screw-and-snap-on, so it clips onto the rail without tools and can be removed with a screwdriver for service. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward or backward, giving flexibility in tight gland-plate layouts. Zero side clearance is required — the part can be butted directly against adjacent devices on the rail. Front face is IP20, which is standard for dry indoor panels; no washdown rating, so keep it inside the enclosure.
Switching capacity by voltage
The auxiliary contacts are rated for different currents depending on the switching voltage — a detail that matters when you're using this contactor to switch loads at non-standard voltages. At 24 V the contacts handle 10 A; at 110 V it drops to 1 A; at 230 V it's 6 A; at 400 V it's 3 A; at 500 V it's 2 A; and at 690 V it's 1 A. The 230 V figure (6 A) is higher than the 110 V figure (1 A) because the ratings follow the AC-12 utilization category curve, not a simple inverse-voltage rule.