The Siemens 3RV1901-1G is an electronics-compatible transverse auxiliary switch from the SIRIUS family, designed as a snap-on accessory for SIRIUS 3RV circuit breakers in frame sizes S00, S0, S2, and S3. It provides a single changeover (CO) contact rated at 0.3 A at 24 V, 48 V, and 60 V — suitable for signaling the breaker's tripped or ON/OFF status back to a PLC or indicator lamp.
What the Ratings Mean for Fit
The 1 CO contact (one normally-open plus one normally-closed in a single changeover package) means this switch occupies one auxiliary position on the breaker and provides both a closed-when-tripped and open-when-tripped signal from the same terminal block — useful for dual-indication circuits. The 0.3 A rating at 24 V through 60 V is a low-energy signal rating, not a load-switching rating; it is intended for PLC digital inputs or 24 VDC pilot lamps, not for driving contactor coils directly. The screw-type terminals accept 2 x (0.5 to 1.5 mm²) solid or 2 x (0.75 to 2.5 mm²) stranded, with AWG 18–14 for the auxiliary contact wiring. The IP20 front protection and finger-safe design per IEC 60529 mean it is safe for use in open control panels where operators may reach toward the breaker face, but it is not rated for washdown or outdoor environments.
Panel Integration
Mounts via plug-in fixing directly onto the front of SIRIUS 3RV circuit breakers in sizes S00, S0, S2, and S3. The transverse design places the terminals on the side of the breaker, allowing the auxiliary switch to sit alongside other front-mounted accessories without increasing the DIN-rail footprint. At 45 mm wide, 12 mm high, and 17 mm deep, it adds minimal projection beyond the breaker face. No additional DIN-rail space is consumed.