What this coupling relay is and where it fits
The Siemens SIRIUS 3RH2122-2KJ80 is a coupling relay for switching auxiliary circuits, sized S00 (45 mm wide, 73 mm deep, 70 mm high). It mounts via screw fixing or snap-on onto 35 mm DIN rail, with ±180° rotation possible on a vertical surface and ±22.5° tilt forward/backward — useful when panel layout forces an unconventional orientation. The built-in suppressor diode handles the DC coil's back-EMF, so you don't need an external flyback diode across the coil terminals.
Switching ratings — what the numbers mean for your circuit
This relay carries 10 A at both 24 V rated value and 230 V rated value — that's the resistive load curve (AC-1 equivalent) for auxiliary contacts. At 60 V it's 4.7 A, at 110 V it's 3 A, and at 400 V it drops to 3 A. For DC switching, the arcing time runs 10 to 15 ms; mechanical life is typical 30 million operations. The AC switching frequency is rated at 10 000 1/h, so it keeps up with rapid-cycle applications like conveyor interlocking or valve sequencing.
Panel integration — DIN rail and clearance
Snap it onto 35 mm DIN rail or screw-mount it. Clearance to adjacent components: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side. The S00 footprint (45 mm wide) fits standard 45 mm-wide DIN-rail slots — one module per position. Wiring accepts 2x (0.5 to 4 mm²) solid or stranded conductors. Operating temperature range is -25 to +60 °C; storage range -55 to +80 °C.
Environmental and compliance notes
Pollution degree 3 (industrial environment). Relative humidity minimum 10%. RoHS compliance date: 10/01/2009 (substance prohibition date). The relay is rated for operation in typical control panel conditions — no special derating needed for most industrial atmospheres.