What it is and where it fits
The Siemens 3RH1122-1AN60 is a SIRIUS auxiliary contactor in the compact S00 frame — 45 mm wide, 57.5 mm tall, 72 mm deep. That 45 mm width is a standard 2.5-module DIN-rail footprint, so it slots into a crowded panel without eating up multiple positions. Screw and snap-on mounting means you can pre-wire it on the bench and clip it onto the rail, or mount it directly to a backplate with screws if the rail is full. It carries 2 normally-open instantaneous contacts — no leading, lagging, or delayed switching here. That's a straightforward pair of NO contacts for signaling or pilot-duty switching in a motor starter or control circuit.
Ratings that matter on site
The contact rating at 24 V is 10 A — that's the figure that governs most PLC output and relay coil switching in a typical 24 VDC control loop. At 110 V it drops to 1 A, at 230 V it's 6 A, and at 400 V it's 3 A. These are the thermal current ratings for the auxiliary contacts, so match them to your load's inrush and steady-state draw. The surge voltage resistance is 6 kV, which covers the impulse withstand for most industrial environments (pollution degree 3). Contact reliability is spec'd at one incorrect switching operation per 100 million operations at 17 V, 1 mA — that's the low-energy dry-circuit performance. If you're switching dry contacts or low-level signals, this contactor handles it without the oxide-film issues that plague power-rated contacts at low voltage.
Mounting and environment
Mounting position is flexible: +/-180° rotation on a vertical surface, and you can tilt it forward or backward by +/-22.5°. That's useful when you're retrofitting into an existing panel where the rail isn't perfectly level. The shock resistance is 10g for 5 ms and 5g for 10 ms — enough for most industrial machinery but not for heavy off-road equipment. Operating temperature range is -25 to +60 °C; storage and transport go from -55 to +80 °C. The IP20 front protection means the terminals are finger-safe from the front, but the sides and bottom are open to the panel — standard for a DIN-rail component inside a closed enclosure.
Wiring and conductor sizes
The screw terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid conductors. That covers most control wiring from signal-level pairs up to the heavier 4 mm² for short power runs. No need for ferrules on solid wire, but stranded will want them for a clean termination.