What it is and where it fits
The Siemens SIRIUS 3RH1122-1KE40 is a coupling relay built for switching auxiliary circuits in control panels. It mounts on a DIN rail via screw and snap-on fastening, sized for the S00 contactor footprint at 45 mm wide and 72 mm deep. Rated at 60 V with a 10 A switching capacity at 24 V, it handles the auxiliary loads common in motor starter and PLC output isolation circuits. The 6 kV surge voltage resistance means it can sit on the same rail as contactors without coupling noise back into the control logic.
Key ratings and what they mean for the buyer
The 10 A at 24 V rated value is the headline switching current for DC auxiliary circuits — enough for multiple solenoid valves or indicator lamps in a typical panel slice. At higher voltages the current drops: 1 A at 110 V, 0.27 A at 220 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. These are the AC-15 / DC-13 style derating curves you need when sizing for mixed-voltage control circuits. Contact reliability is one incorrect switching operation per 100 million operations at 17 V, 1 mA. The typical mechanical life is 30,000,000 operations. The built-in varistor surge suppressor (design of the surge suppressor: with varistor) clamps coil transients at source, so you don't need an external flyback diode or RC snubber on the relay coil. Coil closing and holding power is a steady 2.3 W DC.
Environmental and mounting constraints
Operating temperature spans -25 to +60 °C, with storage and transport range of -55 to +80 °C. Pollution degree 3 means it's rated for industrial environments with conductive pollution — no conformal coating needed for most panel conditions. Mounting position is flexible: ±180° rotation possible on a vertical surface, plus ±22.5° forward/backward tilt. Shock resistance is 10g at 5 ms and 5g at 10 ms — adequate for machine-mounted panels but not for direct hammer-mill attachment without isolation. IP20 on the front means finger-safe but not washdown-rated; keep it inside the enclosure. The screw terminals accept solid conductors from 0.5 mm² up to 4 mm² (2x 0.5...1.5 mm², 2x 0.75...2.5 mm², 2x 4 mm²).