What it is and what it does
The Siemens 3RH1122-2AU00 is a SIRIUS auxiliary contactor, size S00, with 2 normally-open instantaneous contacts and no delayed or make-before-break switching. It carries 10 A at 24 V rated value and handles surge voltage resistance up to 6 kV. The front face is IP20-protected, and the unit mounts via screw or snap-on onto a DIN rail or mounting plate.
What the ratings mean for fit
The 10 A at 24 V rating governs the contactor's switching capacity in low-voltage control circuits — typical for PLC outputs, relay coils, or signal lamps. The 6 kV surge voltage resistance means the contacts can withstand transient overvoltages common in industrial panels without welding or arcing across. The IP20 front protects against finger contact but not moisture; this part is intended for dry, enclosed cabinet use, not washdown zones. The 2 NO instantaneous contacts switch within the same cycle as the coil — no intentional delay. That makes the 3RH1122-2AU00 a straight signal repeater or interlock element, not a timer or sequencing block.
Mounting and integration
Size S00 (45 mm wide, 60 mm tall, 73 mm deep) fits the standard Siemens S00 contactor footprint. Screw and snap-on mounting lets you clip it onto a DIN rail or fasten it with screws to a backplate. The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward — useful when panel space is tight or the rail is angled. Solid connections accept 2x conductors from 0.25 to 2.5 mm² — enough for daisy-chaining control wiring without extra terminals. The contact reliability spec (one incorrect switching per 100 million operations at 17 V, 1 mA) means this contactor can handle dry-contact logic levels, not just power circuits.