The S201-D8 is a 1-pole miniature circuit breaker rated 8 A with a Trip Curve D characteristic, meaning it tolerates brief inrush currents up to 10–20× rated current before tripping — the right curve for motor loads, transformers, or solenoid valves where the starting surge exceeds what a Curve C or B would pass. Finger-safe terminals reduce arc-flash exposure during maintenance — a practical consideration when a line-down swap happens hot.
As a 1-pole DIN-rail breaker, it occupies a single module width. Used as a supplementary protector in control circuits feeding contactors, relays, or PLC power supplies — not as a main service disconnect. The 277 VAC rating covers line-to-neutral on a 480Y/277 V system; the 60/110 VDC rating extends its use to DC control buses.