The Siemens 3RV1901-1DA00-0FJ0 is a transverse auxiliary switch rated at 1 W, designed to mount on SIRIUS 3RV circuit-breakers in frame sizes S00 through S3. It signals the breaker's tripped or ON/OFF state back to a PLC or indicator lamp — a common addition when remote status monitoring is needed on a motor feeder or distribution panel.
Integration Note
The switch clips onto the left or right side of the 3RV breaker housing — no tools needed, but verify the actuator alignment with the breaker's toggle mechanism before snapping it home. The 1 W rating covers the signal contact's switching capacity; keep the load within that limit to avoid contact welding on inductive DC loads.