SIRIUS auxiliary contactor, 24 V DC, 10 A — what fits and what doesn't
The Siemens 3RH1122-2QB40-0LA0 is a SIRIUS auxiliary contactor in size S00, designed for 24 V DC coil operation with a rated current of 10 A at 24 V. It carries 2 normally open instantaneous contacts and no delayed or lagging switching — straight make/break for auxiliary circuits in motor starters, contactor banks, or PLC output isolation. The coil draws 11 W on pick-up and holds at 4 W, so the control transformer or DC supply needs to handle that inrush without droop. Mounting is screw-fixed or snap-on onto a DIN rail; the 45 mm width fits a standard 45 mm slot in a panel layout. The IP20 front protection means it's safe for finger contact inside an enclosure — no washdown rating, so keep it behind a gland plate or cabinet door. Mechanical life is rated at 30 million operations, and contact reliability is specified as one incorrect switching operation per 100 million at 17 V, 1 mA — that's a dry-circuit capability for low-level signal switching, not just power contacts.
Lifecycle and sourcing posture
RoHS compliance is documented with a substance prohibition date of 07/01/2006, covering the EU directive. The surge suppressor design uses diode assemblies, which means polarity matters on the DC coil — verify orientation before wiring.
Ratings that govern the real application
The 10 A rating at 24 V is the headline figure, but the contactor also carries switching capacities across higher voltages: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. That covers most control-voltage standards in a mixed-voltage panel — just watch the derating curve above 40 °C ambient (operating range -40 to +70 °C). Surge voltage resistance is 6 kV. Shock resistance is 10g at 5 ms and 5g at 10 ms — enough for machine-mounted applications on conveyors or presses, but not rated for continuous high-G environments like engine test cells. The screw terminals accept 2x (0.25 to 2.5 mm²) solid or stranded wire. That's standard for control wiring up to 14 AWG; fine-stranded wire should use ferrules to avoid strand breakout under the screw head.
Panel integration notes
Size S00 means the contactor occupies a 45 mm wide footprint on the DIN rail, with a depth of 73 mm and height of 60 mm. That leaves clearance for wiring ducts and adjacent devices. Mounting position allows +/-180° rotation on a vertical surface and can be tilted forward/backward by +/-22.5°. That flexibility helps in tight retrofit panels where the rail orientation isn't perfectly plumb. The product extension auxiliary switch is available as an add-on, so you can stack additional contact blocks on the side without changing the base unit.