What it is and where it fits
The Siemens 3RH1122-2AP00-0TK0-ZX95 is a SIRIUS auxiliary contactor in the Size S00 frame — the smallest block in the series, built for control-circuit switching inside a motor starter or contactor assembly. It carries 2 NO instantaneous contacts rated 10 A at AC-12 (resistive load at 24 V), which is the practical limit for pilot-duty and PLC output isolation. The 45 mm width and 73 mm depth let it snap onto a DIN rail or screw-mount alongside a 3RT2 power contactor of the same frame size, sharing the same panel footprint.
What the ratings mean for the panel
The AC-12 rating of 10 A at 24 V defines the resistive switching capacity — that's the current it can make and break on control transformers, indicator lamps, or solenoid valves without contact welding. At 230 V AC-15 (the inductive pilot-duty curve) it derates to 6 A, and at 400 V to 3 A, so a buyer wiring a 400 V control circuit through these contacts needs to check the load current against the 3 A ceiling. The 2 NO instantaneous contacts close without delay when the coil picks up — no timing, no overlap — which matters for safety circuits where a make-before-break or delayed action would create a race condition. Pollution degree 3 means the contactor is rated for conductive environments typical of industrial panels, not clean-room or sealed enclosures.
Mounting and environmental constraints
Screw and snap-on mounting onto a 35 mm DIN rail is the standard install — the 45 mm width occupies one slot in a typical motor-starter row. The mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward or backward, so it fits in panels where the rail is angled or the enclosure is shallow. IP20 on the front means finger-safe but not washdown-rated; keep it inside a closed panel. Operating temperature range of -25 to +60 °C covers most indoor industrial environments, and the storage range of -55 to +80 °C is fine for unheated warehouses. Shock resistance at 10g for 5 ms and 5g for 10 ms is typical for Size S00 — it will hold through a nearby contactor slam or a forklift bump, but not a direct hammer blow.