The Siemens 3RV1901-1A is a lateral auxiliary switch from the SIRIUS product family, designed as a side-mount accessory for 3RV circuit breakers in frame sizes S00, S0, S2, and S3. It provides one normally-open and one normally-closed instantaneous auxiliary contact, rated for a maximum thermal current of 10 A.
The auxiliary contacts carry voltage-dependent ratings that govern real-world switching: 2 A at 24 V, 0.5 A at 110 V, 0.25 A at 220 V, 4 A at 230 V, 3 A at 400 V, and 10 A at 690 V. The AC-15 rating at 690 V is 1 A, which is the utilization category for switching electromagnetic loads (contactors, relays) — that's the figure to use when sizing for inductive control circuits at that voltage.
Mounting is plug-in fixing onto the side of the breaker — no DIN rail footprint, no tools required for attachment. The screw-type terminals accept solid or finely stranded conductors: 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²), with the same range for wire ends with core-end processing. AWG equivalents are 2x (18... 14).
Environmental limits
Lifecycle status and sourcing
The 3RV1901-1A is a phased-out product. The official Siemens successor is the SIRIUS 3RV2901-1A, which is the preferred replacement type.