The ABB S202P-K40 is a 2-pole miniature circuit breaker rated 40 A with Trip Curve K, designed for 277 VAC (480Y/277 V systems) and a 10 kA interrupting rating. The K curve provides magnetic trip between 8x and 12x In, making it suited for motor branch circuits and transformer primary protection where high inrush currents are expected — the breaker holds through the start surge but clears a hard fault fast.
40 A continuous rating on a 2-pole breaker means it handles up to 40 A per pole in a 277 V line-to-neutral or 480 V line-to-line circuit. Trip Curve K is the deciding factor for motor loads: magnetic trip starts at 8x rated current (320 A) and is guaranteed by 12x (480 A). This means a 40 A motor drawing 6x locked-rotor current (240 A) during start will not nuisance-trip, but a dead short exceeding 480 A clears in under 10 ms. For resistive or general-purpose loads, Curve C or B would trip faster — K is specifically for inductive inrush.
DIN rail mount (per EN 60715) clips into any standard 35 mm rail in a distribution board or control panel. The 2-pole width is 36 mm (2 modules of 18 mm). For a panel OEM, the fill factor is one slot per pole; derating per IEC 60898 applies when ambient exceeds 30 °C or when multiple breakers are ganged without spacing.