The ABB XT4NU3175AFJ000XXX is a 3-pole molded case circuit breaker from the XT4N series, built on a 250 A frame and fitted with a TMF 175-1750 A thermal-magnetic trip unit. The TMF designation means it combines a thermal element for overload protection with a magnetic element for short-circuit response, adjustable across the 175–1750 A range. That wide adjustment band lets you set the instantaneous pickup to coordinate with downstream branch breakers or motor starters without swapping the trip unit.
The 250 A frame and TMF 175-1750 A trip cover a broad motor and feeder range. The thermal element tracks RMS heating, so it handles sustained overloads on pump or conveyor loads without nuisance tripping. The magnetic pickup, adjustable from 175 A to 1750 A, lets you set short-circuit protection above the motor inrush — typically 8–12× FLA for a standard squirrel-cage start — while still clearing a bolted fault fast enough to keep downstream contactors from welding.
The UL/CSA listing means it is accepted for service-entrance and branch-circuit protection in the US and Canada without additional agency review. Line and load lugs are standard; the F F suffix indicates front-connection terminals both sides, which keeps wiring accessible in a tight enclosure.