The Siemens 3RV1901-1GA00-0FJ0 is a transverse auxiliary switch designed for electronic compatibility, rated at 1 W, and fits circuit-breaker frames from size S00 through S3. It provides high contact reliability for signaling and control circuits within the breaker's enclosure.
Mounts transversely within the circuit-breaker's accessory slot — no additional DIN rail space required. The electronic-compatible design means it switches reliably at the low-energy levels typical of PLC inputs and electronic overload relays, without the contact-wetting issues common to standard auxiliary switches.