The ABB S202-Z40 is a 2-pole miniature circuit breaker rated 40 A with a Trip Curve Z characteristic, for 277 VAC circuits. The Z curve trips between 2.5x and 5x rated current, designed to protect semiconductor loads and sensitive electronic equipment where standard B or C curves would allow too much through-fault energy before clearing.
Interrupting rating and deployment
Rated 6 kA interrupting capacity at 277 VAC — sufficient for most commercial and light industrial panelboards where the available fault current stays under that threshold. Snaps onto standard DIN rail; occupies two pole spaces in the enclosure. The 40 A rating and Z-curve make this a candidate for UPS output branches, rectifier feeds, or control transformer primaries where the inrush is low but the short-circuit protection needs to be fast.