Siemens SENTRON 5SL4320-6CC — 3-pole B-curve MCB, 20 A, 10 kA
The Siemens SENTRON 5SL4320-6CC is a 3-pole miniature circuit breaker with a B tripping characteristic, rated 20 A at 400 V AC and a breaking capacity of 10 kA per EN 60898.
Derating and ambient performance
At 40 °C the continuous current derates to 18.94 A, at 45 °C to 18.39 A, at 50 °C to 17.82 A, and at 55 °C to 17.24 A. For a panel builder stuffing a crowded enclosure, that derating curve means the breaker's full 20 A is only available below 30 °C — above that, the load must be trimmed or the next size up selected.
The 3-pole design occupies 54 mm of rail width (3 modular units). Touch protection is integrated on the terminals. IP20 with connected conductors, so it belongs inside a panel, not exposed to washdown.