The LV839259 is a Schneider Electric XF closing voltage release — a control accessory for MasterPact MTZ drawout circuit breakers. It operates on a 380/480 V AC/DC control circuit voltage (50/60 Hz) and is designed for drawout mounting, meaning it installs into the breaker's chassis rather than being hardwired into the panel. This is the part that closes the breaker on command from the control system.
Response time varies by the breaker frame it's paired with: 55 ms ± 10% on a MasterPact MTZ1, 70 ms ± 10% on an MTZ2, and 80 ms ± 10% on an MTZ3. Supply holding power is 4.5 VA / 4.5 W — a modest draw that the breaker's control circuit handles easily.