What this MCB delivers
The Siemens 5SY7220-7CC is a 2-pole miniature circuit breaker from the SENTRON family, rated 20 A at 35 °C with a C-curve tripping characteristic. The C-curve means it trips between 5 and 10 times rated current — standard for motor and lighting circuits where moderate inrush is expected. Its 25 kA breaking capacity per IEC 60947-2 at 440 V AC gives enough fault-interrupting headroom for most industrial panel feeders; the standard certifies it can clear faults up to that level without welding contacts or cascading upstream. Rated current derates with ambient temperature: 18.54 A at 40 °C, 16.08 A at 55 °C. If the panel runs hot, size up accordingly — the 20 A rating at 35 °C is the reference, not the limit.
Panel fit and mounting
Occupies 2 modular width units (36 mm) on a DIN rail, with a quick-assembly fastening system and any mounting position allowed. Depth is 76 mm, installation depth 70 mm — verify gland-plate clearance if the enclosure is shallow. Combined terminals top and bottom accept the same conductor range; supply can come from either end. Pollution degree 3 and overvoltage category III suit it for fixed industrial installations where conductive pollution or transient overvoltages are expected. IP20 with connected conductors — fine inside a closed panel, not for wet or dusty environments.