Railway-rated contactor relay with varistor suppression
The Siemens 3RH2431-1XF40-0LA2 is a SIRIUS contactor relay built for railway rolling stock and trackside equipment, with a coil rated at 72-125 V DC and a built-in varistor for surge suppression across the coil terminals. It carries 3 instantaneous NO contacts rated for DC switching: 10 A at 24 V, 3 A at 110 V, and 1.2 A at 220 V — the DC arc limits are what set the switching capacity, not the contact material alone. The coil draws 4.5 W during closing and holds at 0.75 W, which keeps the temperature rise inside a sealed railway enclosure manageable.
Mounting and integration into a railway panel
Size S00 means it fits the standard 35 mm DIN rail with screw and snap-on fastening — no adapter plate needed for a typical railway control cabinet. The mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward/backward, so it can be oriented to match the cable entry layout in a cramped relay cabinet. Side-by-side mounting is allowed, with a 6 mm gap at the side and 10 mm clearance upward, forward, and downward — this matters when packing multiple relays into a single row.
Lifecycle and compliance for procurement
Compliance documentation includes RoHS substance prohibition dated 10/01/2009 and a wide operating temperature range of -40 to +70 °C, with storage from -55 to +80 °C. The auxiliary switch block is field-extendable, so you can add NO/NC contacts without replacing the relay — a standardisation benefit for MRO spares holding.