SIRIUS coupling relay for auxiliary circuit switching
The Siemens 3RH1122-2VB40 is a SIRIUS coupling relay designed for switching auxiliary circuits in control panels.
The size S00 footprint (45 mm wide, 60 mm high, 73 mm deep) is the standard compact relay-contactor format for this class.
Environmental and electrical ratings
Operates from -25 to +60 °C and stores from -55 to +80 °C, with a maximum altitude of 2 000 m. Shock resistance is 10g / 5 ms and 5g / 10 ms, adequate for machine-mounted applications with moderate vibration.
The contacts are rated for switching at multiple voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. The AC-12 rating at 10 A is the headline figure for resistive loads. The built-in diode surge suppressor across the coil means you don't need an external flyback diode for DC switching — just verify polarity matches the circuit.
Terminals accept solid conductors from 0.25 to 2.5 mm², which covers standard control wiring up to 14 AWG. The screw terminals are straightforward for panel builders — no special tooling needed beyond a standard screwdriver.