What it is and where it fits
The Siemens 3RH2122-2XF40-0LA2 is a SIRIUS contactor relay purpose-built for railway applications. It carries a 72–125 VDC coil with a built-in varistor surge suppressor, which clips voltage spikes from the inductive coil — no external free-wheel diode needed on the DC side. Two instantaneous contacts handle the switching; the relay is sized S00, the smallest SIRIUS frame, and mounts via screw or snap-on onto standard 35 mm DIN rail.
Compliance documentation
The substance prohibition date of 10/01/2009 aligns with the EU RoHS and REACH compliance cutover for this product family. The varistor design is a standard component that does not introduce restricted substances. For a full compliance declaration (RoHS, REACH, UL, IEC), the manufacturer provides a declaration of conformity and material data sheet — these are available on request with the RFQ.