The Siemens 3RV1901-1CA00-0FJ0 is an auxiliary switch with two normally-closed contacts, designed for lateral mounting on 3RV circuit breakers in frame sizes S00 through S3. It signals the breaker's trip or manual-off state to a PLC or indicator lamp — a common need in motor control centers and distribution panels where remote status feedback is required.
Deployment context
Snaps onto the side of the 3RV breaker without extra tools — the lateral mounting bracket aligns with the breaker's accessory slot. In a panel, this keeps the wiring tidy and the auxiliary contacts mechanically ganged to the main contacts, so the NC signal is reliable even if the breaker trips mechanically.