The S203-B63 is a 3-pole miniature circuit breaker rated 63 A with a Trip Curve B characteristic, interrupting 10 kA at 277 VAC. Mounts on standard DIN rail for panel integration.
What the ratings mean for fit
63 A is the continuous current rating — sized for a 63 A branch circuit. Trip Curve B means the magnetic trip operates at 3–5× rated current, so it clears short-circuit faults fast but tolerates moderate inrush from resistive loads. At 10 kA SCCR it safely interrupts faults up to that level without cascading upstream — sufficient for most distribution panels fed by a transformer larger than 10 kA prospective.