The LV846555 is a MasterPact MTZ2 fixed air circuit breaker from the MasterPacT range, rated 2500 A at 40 °C and built for power distribution protection in industrial and commercial switchboards. It's a 4-pole unit with rear connections top and bottom, designed for Category B selectivity — meaning it holds through a downstream fault and only opens when the fault is on its own bus. That selectivity is the key for a plant engineer coordinating a multi-level distribution scheme: you size the main breaker so a feeder fault doesn't take the whole line down.
Rated making capacity (Icm) hits 105 kA at 1150 V AC, so it closes against a full bolted fault without welding contacts. For a site electrical engineer, the Icw at 3 seconds is the number that decides whether your coordination study passes.
Physical integration and environmental limits
Fixed mounting on rails or base plate, with a 115 mm connection pitch. IP30 protection means it's suited for indoor switchboards where tools or fingers are the main concern, not hose-down.
Also listed to IEC 61557-12 for IT system monitoring. Impulse withstand voltage is 12 kV (Uimp), which covers typical surge environments in industrial distribution.
Durability and maintenance
Mechanical durability is 20,000 cycles with periodic preventive maintenance; electrical durability is 500 cycles at 1150 V AC, 50/60 Hz per IEC 60947-2. Maximum breaking time is 25 ms, closing response time 70 ms.