What the ratings mean for your panel
The Siemens 5SY4301-8CC is a SENTRON miniature circuit breaker with a D tripping characteristic, rated 1 A at 230/400 V AC and 10 kA breaking capacity per EN 60898. The D curve means it tolerates high inrush currents — typically 10–20× the rated current — making it the right choice for motor, transformer, or welding-equipment branch circuits where a B or C curve would nuisance-trip on startup. At 40 °C ambient the continuous rating derates to 0.94 A, so if your enclosure runs warm, size the upstream protection accordingly. Three poles, 3 modular width units (54 mm wide), and a 76 mm depth. It snaps onto a standard DIN rail in any mounting position and accepts combined top/bottom terminals. The IP20 rating (with connected conductors) is standard for enclosed panel gear — no special washdown sealing needed inside a cabinet.
Where it fits
Rated for mechanical engineering and industrial environments per the manufacturer's suitability listing. The 3-pole format with no neutral switching suits three-phase motor or distribution subfeeds where the neutral is bonded elsewhere. Overvoltage category III and pollution degree 3 cover fixed-installation mains panels.