The Siemens 3VM9908-0BB20 is an undervoltage release accessory designed for the 3VM10 through 3VM14 molded-case circuit breaker family. It operates on a 24 V AC control supply at 50/60 Hz, tripping the breaker when the control voltage drops below its dropout threshold. That's a standard fit for panel builders wiring undervoltage protection into a distribution board — the release mounts directly into the breaker's accessory slot, no extra DIN rail space needed.
Compliance & Documentation
RoHS compliant since 01-10-14. REACH Article 33 duty to inform applies — the part contains lead (CAS 7439-92-1) above 0.1% w/w. Export control is AL: N / ECCN: N, no restrictions for most commercial shipments.