The Siemens 3RH2140-1BW40-0AA6 is a SIRIUS auxiliary contactor in size S00 — a compact 45 mm wide block that adds 4 normally-open instantaneous contacts to a motor starter or contactor assembly. Rated 10 A at 24 V and 10 A at 230 V, it handles signal-level switching across control circuits up to 690 V.
The 4 NO contacts are rated for AC switching at 10 000 operations per hour with an arcing time of 10 to 15 ms, and DC arcing runs 7 to 13 ms — fast enough for relay logic and PLC input isolation. Wire sizes from 0.5 to 4 mm² solid or stranded fit the screw terminals, with dual-wire entry up to 2.5 mm².