The ABB XT5HU340AFYN000XXX is a NEXT5H 400 molded case circuit breaker (MCCB) fitted with an Ekip DIP LSI electronic trip unit, rated 400 A, 3-pole, with FF (flat-front) terminals and UL/CSA certification. The Ekip DIP LSI is a fixed, non-interchangeable trip unit offering L (long-time), S (short-time), and I (instantaneous) protection curves — no ground-fault element on this variant. The 400 A frame and 3-pole construction make it a straight fit for 3-phase feeder or main breaker duty in switchboards and panelboards where UL 489 listing is required.
The 400 A continuous rating on a NEXT5H frame gives headroom for feeder circuits up to that ampacity without nuisance tripping. The Ekip DIP LSI trip unit's L (long-time) setting handles overloads with an adjustable pickup and time delay; S (short-time) provides selectivity with downstream breakers by delaying the trip on moderate faults; I (instantaneous) clears high-level faults fast. No ground-fault protection on this LSI variant — if GF is needed, you'd step to the LSIG version. The FF (flat-front) terminal design accepts standard bus bar or cable connections; the 3-pole format matches 3-phase systems. UL/CSA listing means it's accepted in North American panels without additional agency review.
Mounts in the standard NEXT5H 400 frame footprint — same cutout and drilling pattern as other breakers in the NEXT5H family. The FF terminals are flat-front, so bus bar connections land without special adapters. Verify the line/load lug wire range against your cable size before terminating; the frame accepts copper or aluminum conductors within the UL-listed range. No DIN-rail mounting on this frame size — it bolts directly to the panel backplate or mounting base.