What this part is and what the ratings mean for fit
The ABB S201-K1 is a 1-pole miniature circuit breaker from the S200 series, rated 1 A at 277 VAC with a K-curve trip characteristic and a 6 kA interrupting capacity. The K-curve means it trips between 10 and 14 times rated current — designed for inductive loads like motors, solenoids, and transformers where inrush is higher than resistive loads but lower than what a D-curve would tolerate. The 6 kA SCCR at 277 VAC is the maximum fault current it can safely interrupt without welding or exploding; for a supplemental protector per UL 1077, that's the branch-circuit rating the part can handle when coordinated with an upstream overcurrent device. DIN-rail mounting means it clips directly into a standard 35 mm rail inside a panel — no additional bracket or screw-down required.
Deployment context — where this breaker lives in a panel
This is a supplemental protector, not a branch-circuit-rated main breaker. It goes downstream of a UL 489 main breaker or fuse, protecting a specific load — a small motor starter, a control transformer, or a solenoid valve bank. The DIN-rail footprint matches the S200 family, so it occupies the same 17.5 mm per pole as the rest of the series. If you're replacing an S201M-C3 in an existing panel, the S201-K1 shares the same physical envelope and wiring terminals; no rewiring or rail repositioning needed. The difference is the trip curve — K vs C — so verify the load's inrush profile before swapping.
Compliance and approvals
Listed under UL 1077 as a supplemental protector and CSA 22.2. The S200 series carries CE marking for the European market. RoHS and REACH compliance documentation is available from the manufacturer for this order code.