Integrator note: 34 V DC SIRIUS auxiliary contactor
The Siemens SIRIUS 3RH1122-2KV80-0LA0 is a size S00 auxiliary contactor with a 34 V DC coil, built for control-circuit switching in panels where the main contactor or motor starter already handles the power path. Coil pull-in draws 11 W DC, holding at 4 W DC — the holding power is the steady-state load the PLC output or relay sees, so a 24 V DC output driving this through a dropper resistor or DC/DC converter needs to source that 4 W continuously. The built-in varistor surge suppressor clips the inductive kick on coil de-energization, which keeps transients off the backplane and extends the life of solid-state outputs. Rated surge voltage resistance at 6 kV aligns with IEC 60947-1 coordination requirements for basic insulation in industrial control panels.
Contact ratings and switching capability
This auxiliary contactor carries 2 NO + 2 NC instantaneous contacts. The contact reliability spec is one incorrect switching per 100 million operations at 17 V, 1 mA — that low-level switching capability matters for directly driving PLC inputs or signal lamps without a separate interface relay. AC-15 / DC-13 switching capacities are given at several voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. The 110 V DC rating is 1 A, dropping to 0.27 A at 220 V DC. For an integrator, the 690 V AC rating means this contactor can switch control transformer primaries or small heater loads at line voltage without derating. Mechanical life is 30 million operations typical — that is the contactor body, not the contacts under load; actual electrical life depends on the switched current and duty cycle.
Panel integration and mounting
Mounting is screw and snap-on — snaps onto 35 mm DIN rail per EN 60715, or can be screwed directly to a backplate. The size S00 footprint is 45 mm wide × 60 mm high × 73 mm deep. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when the contactor sits on a swing frame or angled sub-panel. The IP20 front protection means it is finger-safe from the front but not sealed against dust ingress; install inside a panel with a door. Terminal capacity accepts 2 × (0.25 … 2.5 mm²) solid or stranded — standard for control wiring up to 14 AWG. Pollution degree 3 suits industrial environments with conductive dust or occasional condensation, provided the panel enclosure maintains at least IP54.