What it is and what the ratings mean for fit
The ABB S802S-D40 is a 2-pole miniature circuit breaker rated 40 A with a Trip Curve D characteristic, designed for DIN-rail mounting in distribution panels. The 40 A rating and Curve D mean it handles high inrush loads — motor starting, transformer energization, welding equipment — without nuisance tripping, while still clearing faults. The 50 kA interrupting rating at 230 VAC gives it enough breaking capacity to sit upstream of sub-panels or directly at the service entrance in most commercial and light industrial installations, without needing a current-limiting fuse ahead of it.