The LV839258 is an XF closing voltage release — a solenoid-style coil that, when energized, mechanically closes the breaker contacts. It's designed for MasterPact MTZ drawout circuit breakers, meaning it mounts into the breaker's accessory compartment and connects via the drawout cradle's control wiring.
The coil holds at 4.5 VA / 4.5 W — a low continuous draw that keeps the control transformer sizing modest. The threshold tripping voltage is 0.85 to 1.1 times the rated control voltage (Un), so on a 277 V circuit the coil reliably picks up between about 235 V and 305 V. Below 235 V it drops out, which is the intended undervoltage-release behavior for this accessory type. Response time varies by breaker frame: 55 ms ±10% on the MTZ1, 70 ms ±10% on the MTZ2, and 80 ms ±10% on the MTZ3. That's the mechanical closing time from coil energization to main-contact touch — fast enough for most transfer and sequencing schemes, but not a high-speed closing application.