The Siemens 3VA9908-0BB27 is an undervoltage release for SENTRON 3VA molded-case circuit breakers — specifically the 3VA1 and 3VA20 through 3VA25 frames. Coil burden is 2.5 VA at rated voltage, so the control transformer feeding it needs to cover that draw plus any other loads on the same circuit.
Rated 440–480 V AC 50/60 Hz — this is the coil operating range, not a contact rating. If your control voltage sits outside that band (e.g. 380 V or 500 V), the release won't hold in or may overheat. The 4 kV surge voltage resistance (overvoltage category III) means it's suitable for fixed-installation distribution panels where transient overvoltages from the mains are expected. Pollution degree 3 confirms it's rated for conductive dust and humidity typical of industrial enclosures — not clean-room or residential.
Footprint is 65.1 mm high × 25.7 mm wide × 28.8 mm deep — it clips into the breaker's accessory slot, not onto DIN rail directly. The 10 mm (0.4 in) stripped length is the wire prep for the screw terminals; use ferruled stranded or solid copper. Three accessory slots on the breaker frame mean you can stack this undervoltage release with a shunt trip or auxiliary switch in the same breaker, but check the slot assignment in the 3VA mounting guide.
The 3VA9908-0BB27 carries an active lifecycle status from Siemens.