The LV839026 is a Schneider Electric MasterPact MTZ3 fixed-mount, 3-pole circuit breaker rated for 4000 A continuous at 40 °C. It carries an H3 breaking capacity code, delivering 100 kA Icu at 254 V AC and 508 V AC, and 85 kA Icu at 635 V AC per ANSI C37.50.
Ratings that govern the real decision
Rated short-time withstand current (Icw) is 85 kA for 0.5 s per ANSI C37.50. Integral instantaneous protection trips between 171 kA and 209 kA, so it clears hard bolted faults fast while letting lower-level overcurrents ride through for the downstream breaker to handle. Mechanical durability is 10,000 cycles; electrical durability is 1,000 cycles under ANSI C37.50. For a 4000 A frame, that electrical endurance is typical for the class — plan your maintenance intervals around it if the breaker sees frequent switching, not just fault protection.
Fixed-mount on a base plate with rails. The footprint is 30.2 in wide by 13.9 in tall by 11.7 in deep. Connection pitch is 9.06 in. That's a big frame — verify your enclosure depth and bus bar spacing before committing the cutout. No DIN-rail option on this one; it bolts directly to the panel floor.