The Siemens 3VA9908-0BB22 is an undervoltage release accessory for the SENTRON 3VA series of molded-case circuit breakers. It trips the breaker when supply voltage on the release coil drops below its dropout threshold, protecting connected loads from undervoltage conditions or providing a remote shunt-trip function.
This release slides into one of the three accessory slots on the left side of the 3VA1 or 3VA20 through 3VA25 breaker frame. The dimensions are compact — 65.1 mm tall, 25.7 mm wide, and 28.8 mm deep — so it fits within the breaker's existing envelope without stealing DIN-rail space from adjacent devices. Wire stripping length is 10 mm (0.4 in) for the coil connections.