The Siemens SENTRON 5SY8425-8BB08 is a 4-pole miniature circuit breaker rated 25 A at 400 V AC, with a D tripping characteristic and a breaking capacity of 30 kA per IEC 60947-2. It uses only magnetic tripping — no thermal bimetal — so it's built for short-circuit protection of circuits with high inrush loads like motor starters or transformers, where a standard thermal-magnetic breaker might nuisance-trip on startup.
The 30 kA breaking capacity at 400 V AC (IEC 60947-2) tells you this breaker can safely interrupt a fault current up to 30 kA without welding or exploding — that's the SCCR the panel needs to coordinate with upstream gear. The D curve means the magnetic trip threshold is 10 to 20 times rated current (250 to 500 A), which avoids nuisance trips on motor inrush or transformer magnetizing current.