The LV839229 is a Schneider Electric MX communicating opening voltage release for MasterPact MTZ drawout circuit breakers. It's the coil that trips the breaker on loss of control voltage or remote command — a control function, not a protection relay. Control circuit voltage is 200-250 V AC 50/60 Hz or 200-250 V DC, with a tripping threshold of 0.7 to 1.1 Un. Holding power sits at 4.5 VA / 4.5 W, so the control transformer or DC supply needs to sustain that continuously.
This part is marked obsolete by Schneider Electric. That means the factory line is closed — no last-time-buy window remains open. If you're maintaining an MTZ fleet, this is the kind of spare that gets harder to find each quarter; a cross-reference to a non-communicating MX coil or a third-party equivalent may be worth evaluating for new builds.
Drawout mounting means this coil plugs into the MasterPact MTZ cradle — it's not for fixed-mounted breakers. The 50 ms ±10% response time applies across MTZ1, MTZ2, and MTZ3 frames; that's the mechanical opening time once the coil sees the trip threshold. The 0.7-1.1 Un tripping window means it releases when the control voltage drops to 70% of nominal — useful for undervoltage protection schemes — and holds in up to 110% without nuisance tripping. The MX 'com' variant adds communication capability, so it can be tripped remotely via the breaker's control bus, not just by hardwired contacts.