The Siemens 5SY5250-6CC12 is a 2-pole miniature circuit breaker from the 5SY5 series, rated B50 curve with a 440V DC breaking capacity of 10kA. This is the DC-rated variant (CRH) of the 5SY platform, built for photovoltaic strings, DC distribution, or any 440V DC bus where a 10kA SCCR is required. The B50 curve means it trips magnetically at 5× to 10× rated current (250–500 A), so it handles moderate inrush from DC loads like inverters or contactor coils without nuisance trips.
The 440V DC rating is the key differentiator here. Standard AC MCBs often derate significantly on DC — this one holds its full 10kA breaking capacity at 440V DC, which is the typical string voltage for commercial solar arrays. The 2-pole configuration breaks both poles in series, doubling the arc-gap for DC interruption. The B50 curve (50 A rated continuous, magnetic trip at 5–10× In) suits resistive or moderate inductive DC loads; for highly capacitive DC bus banks, a C-curve would be preferred, but B50 works for most inverter-fed circuits.
Panel Integration
Snap-on DIN rail mounting, standard 2-pole width (36 mm). The 5SY5 family shares the same footprint as the 5SY4, so panel layouts already using Siemens MCBs can swap in this DC-rated variant without re-drilling or re-wiring.