The ABB S203P-Z3 is a 3-pole miniature circuit breaker rated at 3 A continuous, with a Trip Curve Z characteristic and a 10 kA interrupting capacity at 277 VAC. Curve Z is the most sensitive standard trip curve — it trips at 2 to 3 times rated current (6–9 A for this 3 A unit), making it the right choice for protecting semiconductor circuits, PLC power supplies, and sensitive electronic loads where standard B- or C-curve breakers would allow too much fault energy through before opening.
Three-pole width (3 modules, 17.5 mm per pole = 52.5 mm total) matches the S200 family footprint — no panel rework if swapping from another S200-series 3-pole breaker. Rated 277 VAC phase-to-neutral in a 480Y/277 V wye system; the 3-pole construction lets you protect all three phases with one device.