Undervoltage release for 3VM breakers to 630 A
The Siemens SENTRON 3VM9908-0BB25 is an undervoltage release — an auxiliary trip accessory designed for the 3VM molded-case breaker family up to 630 A. It opens the breaker when its coil voltage drops below the dropout threshold, providing a defined trip on loss of control power or undervoltage conditions per the protection scheme. Rated for 208-230 V AC at 50/60 Hz, the release draws a maximum apparent power of 2 VA. Its surge voltage resistance is 4 kV, and it is rated for overvoltage category III with pollution degree 3 — suitable for fixed-installation distribution panels in industrial environments where transient overvoltages and conductive dust or humidity are present.
Mounting and panel integration
The release measures 25.7 mm wide, 65.1 mm high, and 28.8 mm deep. It mounts inside the 3VM breaker accessory slot — no additional DIN-rail space is consumed. The stripped length for wiring is 10 mm (0.4 in). Three accessory slots are available on the 3VM frame; this release occupies one. Verify slot compatibility with any other auxiliary devices (shunt trip, alarm contacts) already installed or planned, as the mechanical interlock within the breaker limits which combinations fit.