What it is and what the ratings mean for fit
The ABB S201-K1.6 is a 1-pole miniature circuit breaker from the S200 series, rated 1.6 A with a K-curve trip characteristic. It's a supplemental protector per UL 1077, meaning it's intended for branch-circuit protection inside equipment — not as a service-entrance main breaker. The K-curve is the key spec here: it trips magnetically between 8× and 12× rated current, so it's designed to ride through the inrush of inductive loads like small motors, transformers, or solenoid valves without nuisance tripping, while still clearing a hard short. That 1.6 A rating makes it a fit for a fractional-horsepower motor or a control transformer secondary — think a 24 VDC power supply feed or a conveyor zone controller's input.
Where it goes in the panel
Snaps onto standard DIN rail — the S200 series uses the same 17.5 mm module width as any other MCB, so it drops into a populated panel without re-spacing. Rated 277 VAC line-to-neutral, which covers 277/480Y V wye systems common in North American commercial and light industrial panels. The 6 kA interrupting capacity at 277 V is adequate for most downstream supplemental protection applications; if the available fault current at the panel exceeds that, you'd need a current-limiting upstream breaker or fuse.
Compliance and approvals
Listed under UL 1077 and CSA 22.2 — the key standards for supplemental protectors in North American panels. The UL 1077 listing means it's recognized as a component-level overcurrent protective device, not a branch-circuit rated breaker per UL 489. That distinction matters for panel builders: the S201-K1.6 can be used where a UL 489 breaker isn't required, typically inside a piece of equipment or a control panel fed by a branch-circuit rated device upstream.