The ABB XT1NU3015AFF000XXX is a Tmax XT1N 125 frame molded case circuit breaker (MCCB), 3-pole, rated 15 A with a thermal-magnetic fixed trip mechanism and front flat terminals. Frame-mount design means it bolts into a panel or switchboard — not a DIN-rail snap-on — so plan for a dedicated mounting footprint and bus-bar connections. The 15 A rating covers branch-circuit protection for smaller three-phase loads like fractional-horsepower motors, lighting panels, or control transformers where you need a compact MCCB rather than a miniature breaker.
Frame mount — not DIN rail — so the breaker secures to a mounting plate or back panel with hardware. Front flat terminals accept bus-bar or cable lugs; the fixed thermal-magnetic trip means no interchangeable trip units to order separately. At 15 A on a 3-pole frame, it coordinates downstream with a 20 A or 25 A upstream feeder in a selective system, but verify the specific SCCR and let-through curves for your fault current. The Tmax XT1 frame size (125 A max) gives headroom if you ever up-rate the branch — same footprint, different trip rating.