What the 3RH2140-2LF40 is and what it switches
The Siemens 3RH2140-2LF40 is a SIRIUS coupling relay — a size S00 auxiliary contactor designed for switching auxiliary circuits, not motor loads directly. Its four NO instantaneous contacts handle control signals, interlocks, and PLC outputs in panels where the main contactor stays dedicated to the power path. The 110 V AC coil includes an integrated varistor surge suppressor, which clips voltage spikes from the coil's magnetic field collapse — one less component to wire on the DIN rail.
Rated 10 A at both 24 V and 230 V, the contacts carry full current at the two most common control voltages in industrial panels. At 110 V — the coil voltage of this unit — the switching capacity is 3 A.
Lifecycle and sourcing — active production, quoted to order
Pollution degree 3 means it tolerates conductive pollution in typical industrial environments.