The Siemens 5SY4205-8CV is a 2-pole miniature circuit breaker (MCB) with a D-trip characteristic and a 0.5 A rated current. Its listed breaking capacity is 15 kA at 400 V AC, which means it can safely interrupt fault currents up to that level on a 400 V line without upstream devices needing to clear the fault first — a useful selectivity margin for sub-distribution boards feeding short, high-fault-current circuits.
At 0.5 A, this is a low-current D-curve MCB, so it is sized for a control transformer or a small DC supply primary, not a branch motor circuit.
Panel Integration
The 2-pole width occupies two modular spaces (36 mm).