What the TMA 400-4000 A rating means for fit
The XT5NU340ABFN000XXX: The TMA designation indicates a thermal-magnetic adjustable trip unit: the thermal element provides overload protection (adjustable from 400 A to 4000 A), while the magnetic element handles short-circuit protection. The 400-4000 A range covers large motor feeders, transformer primaries, or main bus ties in 480 V / 600 V industrial panels. The fixed (non-interchangeable) trip means the breaker is ordered for a specific application — if the load profile changes significantly, the entire breaker is swapped rather than just the trip unit.
Deployment context
This breaker mounts in a standard switchboard or panelboard enclosure. The 3-pole fixed configuration suits main or branch feeder duty where three-phase power is distributed. The UL listing confirms acceptance for North American installations per UL 489.