What this breaker is and what it protects
The ABB S201-K30 is a single-pole, 30 A miniature circuit breaker with a K trip curve, rated for 277 V AC and a 6 kA interrupting capacity. It's listed as a supplemental protector under UL 1077 and CSA 22.2, meaning it's intended for branch-circuit protection inside equipment — not as a service entrance or feeder breaker. The K-curve trips between 10x and 14x rated current, designed to handle the high inrush of motor and transformer loads without nuisance tripping, while still clearing a hard fault.
DIN rail integration and panel fit
Mounts on standard 35 mm DIN rail per EN 60715. Single-pole width (17.5 mm) means it occupies one module position in a distribution board or control panel. The S200 series uses a captive screw terminal accepting up to 25 mm² conductor — strip length 12 mm, torque 2.0 Nm. No busbar bridging issues with adjacent S200 poles; the pin-and-fork busbar system is shared across the family.
What the K-curve means for your load
The K-curve is the deciding spec for this breaker. It's optimized for inductive loads — motors, transformers, solenoids, and power supplies — where the inrush current can briefly hit 8x to 12x the full-load rating. A standard C-curve (5x to 10x) might trip on the magnetizing inrush of a 30 A transformer; the K-curve's 10x to 14x magnetic trip window gives the headroom to pass that transient. The thermal element handles the 30 A continuous rating. If your load is purely resistive (heaters, incandescent lighting), a B or C curve would be a better fit and cheaper.
Approvals and compliance documentation
Listed under UL 1077 (Supplemental Protector) and CSA 22.2 No. 235. The UL 1077 listing means it's recognized for overcurrent protection within equipment — it's not a UL 489 branch-circuit breaker for service entrance use. CE marked for the European low-voltage directive. RoHS and REACH compliant per ABB's standard declaration, available on request with the order documentation package.