The ABB S802C-K20 is a 2-pole miniature circuit breaker from the S800C series, rated 20 A with a Trip Curve K characteristic.
At 20 A, that magnetic pickup sits between 200 A and 280 A, so it won't nuisance-trip on a motor start yet still clears a hard fault fast. The interrupting capacity is 15 kA at 230 V AC and 10 kA at 250 V DC. That 15 kA AC rating is enough for most commercial and light industrial panelboards where the prospective fault current stays under 10 kA; the 10 kA DC rating covers battery-backed or rectified DC bus circuits.