What the D-curve and 4 A rating mean for the panel
The 5SY7204-8CC: The D-characteristic trips magnetically at 10–20× In (40–80 A instantaneous), so it's sized for loads with high inrush — motor starters, small transformers, solenoid banks — where a B- or C-curve would nuisance-trip on startup. The 4 A thermal element holds continuously at nominal, but the spec table shows derating above 35 °C: 3.71 A at 40 °C, 3.55 A at 45 °C, 3.39 A at 50 °C, and 3.22 A at 55 °C.
Breaking capacity and approvals — IEC vs UL/CSA
The UL 1077 / CSA C22.2 No.235 listing at 5 kA is a supplementary-protector rating, not a branch-circuit rating — relevant for North American panels where this breaker protects individual loads, not feeders.
Two modular-width units (36 mm wide) on a DIN rail. Combined top and bottom terminals, touch-protected, sealable. Halogen-free and silicon-free construction.