The Siemens 5SY5250-7CC12 is a 2-pole miniature circuit breaker from the 5SY5 series, rated C50 characteristic with a 440V DC breaking capacity of 10kA.
The 440V DC rating is the key spec here — most miniature circuit breakers are AC-only; this one is built for DC circuits where arc extinction is harder. The 10kA breaking capacity at that voltage means it can safely interrupt a fault current up to 10,000 amps without welding contacts or cascading failure. The C50 curve (50 amp nominal, magnetic trip between 5 and 10 times rated current) suits motor starters, lighting banks, or transformer primaries where a short inrush won't nuisance-trip a B-curve breaker.