The Siemens SENTRON 3VA9908-0BB10 is an undervoltage release accessory designed for the 3VA1 and 3VA20 through 3VA25 molded-case breaker frames. It trips the breaker when the control voltage drops below its dropout threshold, protecting downstream equipment from brownout or phase-loss conditions. Rated for 12 V DC with a maximum active power consumption of 2.5 W, it carries a surge voltage resistance of 4 kV and is classified for overvoltage category III with pollution degree 3 — suitable for industrial panel environments where transient immunity matters.
The release occupies a 25.7 mm width × 65.1 mm height × 28.8 mm depth footprint and fits into the three accessory slots on the 3VA breaker frame. Wire termination requires a stripped length of 10 mm (0.4 in).