The Siemens 5SY5104-7CC12 is a 1-pole miniature circuit breaker from the 5SY5 CRH series, rated for 220V DC with a 10kA breaking capacity and a C4 tripping curve. This is a DC-rated MCB, meaning it's built to protect DC circuits — think solar arrays, DC bus bars, battery banks, or control power supplies — where a standard AC breaker might not clear a fault. The C4 curve (4x to 10x rated current magnetic trip) handles moderate inrush from loads like contactor coils or small DC motors without nuisance tripping.
Single-pole format saves rail space when you only need to break the positive leg of a DC circuit. The 10kA interrupting rating at 220V DC is the key spec for coordination — make sure the upstream device (fuse or breaker) can handle the let-through energy if this one clears a bolted fault. In a typical telecom or industrial DC distribution panel, this sits downstream of a higher-rated DC disconnect.