The Siemens 3RH1122-2JB40-0LA0 is a SIRIUS auxiliary contactor in the Size S00 frame, designed for switching control and signaling circuits rather than motor loads directly. It carries a 24 V DC coil with a built-in diode surge suppressor, and its contact arrangement is 2 normally-open plus 2 normally-closed instantaneous contacts. Rated operational currents vary by voltage and duty: 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 — these are the values to use when sizing for your specific control voltage. The coil draws 11 W on pickup and holds at 4 W.
The 45 mm width and 60 mm height are standard for the S00 frame; depth is 73 mm including terminals. Terminals accept solid or stranded wire from 0.25 to 2.5 mm² (2 conductors per clamp). The front face carries an IP20 protection class, meaning finger-safe but not washdown-rated — keep it inside the enclosure.
Shock resistance is 10g / 5 ms and 5g / 10 ms. Contact reliability is rated at one incorrect switching operation per 100 million cycles at 17 V, 1 mA — useful for low-signal applications. RoHS compliance date is July 1, 2006. Surge voltage resistance is rated at 6 kV.