50 A K-curve breaker for 480Y/277 V panels
The ABB S201-K50 is a single-pole 50 A miniature circuit breaker with a K-curve trip characteristic, rated at 277 VAC and a 6 kA interrupting capacity. It's a UL 1077 supplemental protector from the S200 series, designed for 480Y/277 V systems where you need branch-circuit overcurrent protection on a single leg to neutral. The K-curve means it tolerates the inrush of motor and transformer loads — typically 8-12x rated current for magnetic trip — without nuisance tripping, while still clearing a hard fault fast. That 50 A rating handles heavy individual loads like a large conveyor drive or a compressor bank.
Mounting and panel fit
Snaps onto standard 35 mm DIN rail. Single-pole footprint means it takes one module width (roughly 18 mm) in the enclosure. For a 50 A breaker at 277 V, expect 14 AWG to 6 AWG wire range on the terminals — torque to the values stamped on the side. Leave breathing space around it if the panel ambient runs hot; the thermal trip element in a 50 A K-curve needs free air convection to hold calibration.