What it is and what it does
The Siemens 3RH1122-1AH10 is a SIRIUS auxiliary contactor in the S00 frame size, designed for switching control and signaling circuits in motor starter and contactor assemblies. It provides 2 normally open and 2 normally closed instantaneous contacts, rated at 10 A for AC-12 resistive loads.
Key ratings and what they mean for fit
The AC-12 rating of 10 A at 24 V means this contactor is built for resistive control loads — think relay coils, indicator lamps, and PLC inputs — not motor starting. The 6 kV rated surge voltage withstand gives it solid isolation coordination for industrial panels with mixed voltage levels. Contact reliability is specified at one incorrect switching operation per 100 million cycles at 17 V, 1 mA — that's the low-energy signal switching threshold. If you're dry-switching PLC-level signals, this contactor handles it without the contact wetting issues you'd see on a standard power contactor.
Panel integration and wiring
Mounts via screw or snap-on onto a DIN rail — the S00 footprint takes 45 mm width and 72 mm depth, leaving room for adjacent devices in a crowded enclosure. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, useful when you're routing wires in a tight gland plate layout. Terminals accept solid conductors from 0.5 mm² up to 4 mm² (or 2x 1.5 mm², 2x 2.5 mm²), with AWG equivalents of 20–16, 18–14, and a single 12 AWG. The IP20 front protection means it's safe for finger-probe access inside a closed panel — no extra shrouding needed.