Siemens 3RH1921-1EA20 Controller

The Siemens 3RH1921-1EA20 is a first lateral auxiliary switch block designed for SIRIUS 3RT1 series contactors. It provides 2 Normally Open (NO) contacts with screw terminal connections, allowing the contactor to switch additional control circuits beyond its main power contacts. This auxiliary switch is mounted on the side (laterally) of the contactor and is compatible with a wide range of 3RT1 contactor sizes, from S0 through S12. The snap-on mounting design enables quick installation without tools, while the screw terminals ensure reliable, vibration-resistant wiring for control and signaling circuits.