What the ratings mean for fit
The 5SY4220-7CV is a 2-pole miniature circuit breaker with a C-trip characteristic, rated 20 A at 35 °C and 15 kA breaking capacity per IEC/EN 60947-2. The C-curve trips between 5 and 10 times rated current, so it handles moderate inrush from motor starters or transformer banks without nuisance opening — typical for mixed industrial loads in mechanical engineering and industry applications. The 15 kA SCCR at 440 V AC means it safely interrupts faults up to that level without cascading upstream, which is the figure that governs selectivity coordination in a distribution panel. Rated current derates with ambient temperature: 18.54 A at 40 °C, 17.76 A at 45 °C, 16.9 A at 50 °C, and 16.08 A at 55 °C. If the panel ambient runs above 40 °C, size the upstream protection for the derated value, not the 35 °C mark.
Panel integration and mounting
Width is 36 mm (2 modular units), depth 76 mm, height 90 mm. Mounts in any position on a DIN rail via the quick assembly system; installation depth behind the panel is 70 mm. IP20 with conductors connected — suitable for enclosed distribution boards, not open washdown zones. The top and bottom terminals accept combined wiring, and the housing is halogen-free and silicon-free, which matters if the panel serves a clean room or food line where outgassing is restricted.