What it is and where it fits
The Siemens 3VM9908-0BB22 is an undervoltage release accessory for the SENTRON 3VM molded-case circuit breaker family, rated for breakers up to 630 A. It trips the breaker when control voltage drops below the dropout threshold, providing undervoltage protection for motor feeders, conveyor drives, or any load that must not auto-reclose after a supply dip. The release operates on a 60 V AC control supply at 50/60 Hz, drawing a maximum apparent power of 2 VA. Its rated insulation voltage is 690 V, with a surge voltage resistance of 4 kV and overvoltage category III — suitable for fixed-installation distribution panels where transient overvoltages are expected.
Mounting and panel integration
The 3VM9908-0BB22 occupies three accessory slots on the 3VM breaker. Its dimensions — 25.7 mm wide, 65.1 mm high, 28.8 mm deep — fit within the standard breaker footprint; no additional DIN-rail space is needed beyond the breaker itself. Wire stripping length is 10 mm (0.4 in) for the control connections. Pollution degree 3 rating means the release is designed for industrial environments where conductive pollution or dry non-conductive pollution that becomes conductive due to condensation may occur. This aligns with typical panel environments in factories, mills, and processing plants.
Lifecycle and sourcing
As a current-production accessory, the 3VM9908-0BB22 is sourced to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.