What it is and what it does
The ABB XT5HU450BBFF000XXX is a 4-pole molded case circuit breaker from the XT5H series, fitted with a TMA 500-5000 A thermal-magnetic adjustable trip unit. The 600 A frame carries the TMA trip, which means the breaker's continuous current rating is set by the trip unit — in this case adjustable from 500 A to 5000 A, covering a wide range of feeder and main breaker applications. The UL listing confirms it meets North American panelboard and switchboard standards.