Siemens 3RH1921-1DA20 Auxiliary Contact Screw Terminal

Siemens 3RH1921-1DA20 Auxiliary Contact Screw Terminal is a signaling accessory for Siemens 3RT1 contactors. This auxiliary contact block adds additional contacts to the contactor assembly and uses screw terminals for secure field wiring. It is designed to mount on compatible 3RT1 contactors and is part of the 3RH1921 family of auxiliary switches. The family includes variants such as 3RH1921-1EA20 with two normally open contacts and 3RH1921-1DA11, a first-lateral switch with 1 normally open and 1 normally closed contact, illustrating the range of configurations available for signaling, interlocking, and feedback in control circuits. Typical applications include machine automation, control panels, and safety interlocks where monitoring the status of the main contactor is beneficial. The compact form factor and screw-terminal wiring support straightforward integration into existing Siemens panel installations, enabling reliable, easy-to-maintain auxiliary signaling without altering the primary switching hardware.