The Siemens 5SY6320-7CC is a SENTRON miniature circuit breaker rated 20 A with a C-curve trip characteristic, 3 poles, and a 6 kA breaking capacity per EN 60898 at 440 V AC. This is the part you spec into a 3-phase distribution board for general-purpose branch-circuit protection — lighting, small motor feeds, control transformers, that kind of load. The C-curve (5–10x In) handles moderate inrush without nuisance tripping, so it's a common choice for mixed resistive-inductive circuits in industrial panels.
The 20 A rating holds at 35 °C ambient; derate to 18.8 A at 40 °C, 18.18 A at 45 °C, 17.52 A at 50 °C, and 16.84 A at 55 °C — so if your enclosure runs hot, you need to account for that or step up one frame size. The 3-pole design switches all three phases together; there's no neutral pole (neutral conductor switching is not supported), so plan for a separate neutral bar or a 4-pole breaker if you need switched neutral. It snaps onto DIN rail (quick assembly system), mounts in any position, and takes up 3 modular width units — 54 mm wide, 90 mm tall, 76 mm deep plus 70 mm installation depth behind the panel. The terminals are combined top and bottom, which simplifies busbar routing.