The Siemens 3RH2122-2GG20 is a SIRIUS auxiliary contactor, size S00, with 2 normally open (NO) instantaneous contacts. It is designed for signal switching and control-circuit isolation inside motor starter assemblies or general control panels, not for direct motor load switching — that is the job of the main contactor it follows. Rated for a 24 VDC coil (10 A at 24 V), it also carries switching capacity at higher voltages: 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, and 0.26 A at 600 V. The mechanical life is typical 30 million operations, making it a fast mover on spares shelves for high-cycle applications.
The 10 A rating at 24 V is the headline switching current for control circuits. The 30 million mechanical cycles mean it can handle high-speed production lines without frequent replacement. Physical footprint: 73 mm deep, 45 mm wide, 70 mm high. The size S00 form factor is compact — it occupies roughly the same panel space as a small contactor. Relative humidity minimum 10%.