The Siemens SENTRON 5SY4220-6CC11 is a 2-pole miniature circuit breaker (MCB) with a B-tripping characteristic, rated 20 A at 400 V AC and 10 kA breaking capacity per EN 60898. It's designed for quick assembly on DIN rail, with a 36 mm width (2 width units) and a depth of 76 mm, fitting standard panel enclosures.
The 20 A rating at 400 V AC covers branch circuits feeding lighting, small heaters, or control transformers. For DC circuits, the maximum rated voltage is 72 V, so it's usable in 48 V or 60 V DC control loops but not for 110 V DC battery banks. The B-curve trips at 3–5× In (60–100 A instantaneous), which avoids nuisance trips on moderate inrush but still clears fast on hard shorts. Energy limiting class 3 means it restricts let-through energy well, protecting downstream wiring and loads. Ambient temperature range -40 to +70 °C covers most indoor and outdoor panel environments; derating applies above 40 °C per the thermal curve.
Snap-on DIN rail mounting, any position. Accepts solid or stranded copper from 0.75 to 35 mm² — covers everything from 1.5 mm² control wiring up to 10 mm² feeder tails. Combined terminals top and bottom simplify busbar or ring-tongue connections.