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.
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). 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.
That leaves clearance for wiring ducts and adjacent devices. 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.