The 20 kA breaking capacity under IEC 60947-2 means it can safely interrupt a short-circuit fault up to 20,000 A at the supply side — adequate for most industrial panelboards fed from a transformer of 630 kVA or less. Under UL 1077 and CSA C22.2 No. 235 the interrupting rating is 5 kA, so verify the available fault current at the point of installation if the panel carries a North American listing.
Thermal derating — the real-world current limit
The 63 A rating holds only at 35 °C ambient. At 40 °C the breaker must be derated to 59.54 A; at 45 °C to 57.71 A; at 50 °C to 55.82 A; at 55 °C to 53.86 A.
The quick-assembly fastening system clips onto the rail without tools. Both top and bottom terminals accept combined (screw + clamp) conductors. The breaker is sealable, halogen-free, and silicon-free, which keeps it compliant for clean-room or food-grade panels where outgassing matters.