What it is and what it does
The Siemens SIRIUS 3RH2122-1AP00-ZX95 is a size S00 auxiliary contactor — the little relay that handles the signal switching in a motor starter or control circuit. It's got two instantaneous contacts and is rated for 10 A at 230 V AC and 10 A at 24 V DC, so it can handle pilot duty and interlocking without breaking a sweat. It mounts with a screw or snaps onto a standard 35 mm DIN rail, and you can spin it ±180° on a vertical surface or tilt it ±22.5° forward or back — handy when you're squeezing it into a tight panel.
What the ratings mean for the panel
The 45 mm width and 73 mm depth tell you it's a standard S00 footprint — takes up one 45 mm slot on the DIN rail, so it's easy to plan your panel layout. The operating temperature range of -25 to +60 °C covers most industrial cabinets, and the -55 to +80 °C storage range means it'll sit on the shelf in a cold warehouse just fine. The pollution degree 3 rating means it's built for a conductive environment — think dusty or damp control rooms — so you don't have to derate it for dirty air.
Wiring and clearance
The terminals accept two conductors per clamp: 2x 0.5 to 1.5 mm² solid or stranded, 2x 0.75 to 2.5 mm², or 2x 4 mm² — plenty of capacity for control wiring. Clearance around the contactor: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the sides. That's tight enough for a dense panel but leaves room for a finger-safe cover.