The Schneider Electric A9F03663 is an Acti9 iC60N miniature circuit breaker rated at 63 A with a B-curve, 1P+N configuration. It carries a 36 kA breaking capacity at 12–60 V AC per EN/IEC 60947-2, stepping down to 10 kA at 220–240 V AC, and 6000 A Icn at 230 V AC per EN/IEC 60898-1. That dual-standard rating means it's certified for both industrial (60947-2) and residential/commercial (60898-1) installations — so it fits a panel destined for a factory floor or a building distribution board without swapping breakers.
The 63 A B-curve trips magnetically at 4 x In (252 A) plus or minus 20 %, so it's sized for resistive and general-purpose loads — lighting, small heaters, control transformers — where inrush isn't extreme. The 1P+N layout switches the line and breaks the neutral, with the neutral on the left side of the DIN-rail footprint. At 36 mm wide and 4 module pitches, it occupies standard DIN-rail space; the double terminals accept up to 35 mm² rigid or 25 mm² flexible, with a torque spec of 3.5 N·m. That's enough for a 63 A feed conductor without needing a reducer. The IP20 finger-safe terminals and tropicalisation class 2 (IEC 60068-1) cover humid storage and installation conditions up to 95 % RH at 55 °C.