The ABB S203-C20 is a 3-pole miniature circuit breaker (MCB) rated 20 A with a Trip Curve C characteristic, designed for DIN rail mounting in distribution panels and control cabinets.
Trip Curve C means it holds up to 5–10× rated current momentarily, so it won't nuisance-trip on motor inrush or capacitive loads but still clears fast on a hard short. The 6 kA interrupting rating at 277 VAC tells you it can safely quench a fault up to 6,000 A without welding contacts or venting gas into the panel — critical for SCCR compliance on the assembly.