The ABB XT5SU340ATFF000XXX is a 400 A breaking part for the XT5S molded-case switch platform, configured as a 3-pole unit with F F (fixed-front) terminals and UL/CSA+TU certification. This is the replaceable contact-and-arc-chamber assembly that fits into the XT5S 400 frame — the part that actually interrupts current when the switch operates. It is the component a panel builder or maintenance team swaps when the main contacts are worn or after a fault interruption, rather than replacing the entire switch.
Rated for 400 A continuous current in the XT5S frame, this breaking part is sized for the full ampacity of that switch platform. The 3P designation confirms three poles, so it fits three-phase applications. The F F terminal code indicates fixed-front connections — the switch's line and load terminals are at the front face, which is the standard arrangement for panel-mount XT5S switches. UL/CSA+TU certification means the assembly carries both North American (UL/CSA) and Turkish Standards Institution (TÜ) approvals, covering installations in those regulatory jurisdictions.