Supplemental protector for 480Y/277 V branch circuits
The ABB S203-K8 is a 3-pole miniature circuit breaker from the S200 series, rated 8 A with a K-curve trip characteristic. It operates at 480Y/277 V AC and carries a 6 kA interrupting rating, listed as a UL 1077 supplemental protector. That UL 1077 classification means it protects downstream equipment in a branch circuit but is not a service-entrance or feeder breaker — it goes after the main overcurrent device, typically in a control panel or sub-distribution board.
K-curve means motor and transformer loads
The K-curve is the key selection parameter here. It allows higher inrush without nuisance tripping — typically 8–12× rated current for short magnetic trips — which suits inductive loads like small motors, transformers, and solenoid banks. A B-curve (3–5×) would trip on the same inrush; a C-curve (5–10×) sits in between. For a 8 A breaker on a 480 V control transformer or a fractional-horsepower motor, the K-curve is the right call.
DIN-rail integration for panel builds
Snap-on DIN rail mounting (standard 35 mm) means it clips directly into the panel enclosure alongside other S200 breakers, contactors, and terminal blocks. The 3-pole body occupies three modular 17.5 mm widths — 52.5 mm total rail space. No separate adapter or base required.