What it is and what it does
The ABB XT5NU340ABFN000AXX is a 3-pole molded case circuit breaker from the XT5N 400 series, fitted with a TMA 400-4000 A trip unit and FF (fixed front) terminals, UL listed. The TMA trip unit provides thermal-magnetic protection with an adjustable continuous current range from 400 A to 4000 A, covering a wide band of overload and short-circuit settings for feeder or main breaker duty in distribution panels and motor control centers.
Lifecycle and sourcing reality
For a BOM line that calls out XT5NU340ABFN000AXX, the current lifecycle status means no last-time-buy pressure and no forced substitute search — the part is specified into new designs and stocked for ongoing production support.
Integration and deployment context
The XT5N 400 frame mounts in a standard panel cutout and connects via fixed-front terminals, which simplifies bus-bar and cable routing in switchboard or MCC construction.