What it is and what it does
The Siemens SENTRON 5SL4620-8CC is a 4-pole (3P+N) miniature circuit breaker with a D tripping characteristic, rated 20 A at 400 V AC. The D curve means it tolerates high inrush currents — think motor starts, transformer energization, or welding equipment — without nuisance tripping, while still clearing a fault at its 10 kA breaking capacity per EN 60898. That 10 kA rating is the maximum prospective short-circuit current it can safely interrupt at 400 V; if your panel's available fault current exceeds that, you need an upstream current-limiting device or a higher-rated breaker.
Where it fits and how it mounts
This MCB snaps onto a standard 35 mm DIN rail and occupies 4 modular width units (72 mm wide). Depth is 76 mm, installation depth 70 mm — typical for a SENTRON 5SL series breaker, so it clears most standard enclosure backplates. Mounting position is any, which helps when you're cramming gear into a tight panel. IP20 with connected conductors, so it's for indoor use inside a distribution board or final enclosure, not exposed to washdown.
Thermal derating and real-world current
The 20 A rating is at 30 °C ambient. At 40 °C it's 18.48 A; at 50 °C it's 16.82 A; at 55 °C it's 15.92 A. If your panel runs hot — say, a packed enclosure near a furnace line — you need to account for that derating. The breaker itself is rated for ambient from -40 °C to 75 °C, so the environment won't damage it, but the load current must stay under the derated curve to avoid thermal tripping.