The ABB S201P-C1 is a 1-pole miniature circuit breaker rated 1 A with a Trip Curve C characteristic, 277 VAC, and a 10 kA interrupting rating. The 1 A rating means it protects a branch circuit or load drawing up to 1 A continuously — undersized for a motor or a power supply primary, but correct for a control transformer secondary, a PLC power supply input, or a small signal circuit. Trip Curve C means it holds 5–10× rated current (5–10 A) for a short period before tripping magnetically, so it tolerates moderate inrush from small transformers or capacitive loads without nuisance tripping.
Single-pole width (roughly 17.5 mm per module) means it occupies one position on the rail. The 10 kA SCCR at 277 VAC is sufficient for most commercial lighting and small power panels; verify it coordinates with the upstream overcurrent device if the available fault current exceeds that figure.