The ABB XT5NU340ABFFBB0XXX is a 3-pole molded case circuit breaker from the XT5N 400 family, fitted with a TMA 400-4000 A electronic trip unit and fixed front terminals (FF). The UL listing is built into the base variant — the suffix confirms it. The TMA trip unit covers a 400–4000 A continuous current range, adjustable via the front dials. That makes it a feeder breaker sized for the main distribution board in an industrial plant, not a branch-circuit device. The 400 A frame is the smallest in the XT5N class, so the breaker body itself is rated for the full 400 A without needing a larger frame.
What the TMA trip unit means for coordination
The TMA is a solid-state trip offering adjustable long-time (Ir), short-time (Isd), and instantaneous (Ii) pickup, plus ground-fault protection if the neutral sensor is wired. For a site electrical engineer building a selective coordination study, the short-time delay band lets you set intentional delay so the feeder holds in for a downstream fault — provided the upstream breaker's instantaneous threshold is set above the feeder's let-through. The 400–4000 A range on the long-time dial gives enough headroom to match transformer or generator ratings without swapping the breaker frame.