DC-rated miniature circuit breaker for 440 VDC rail protection
The Siemens 5SY5203-7CC12 is a 2-pole miniature circuit breaker from the 5SY5 series, rated for 440 V DC with a 10 kA breaking capacity and a C3 trip curve. This is a DC-specific breaker — the 440 V DC rating and 10 kA interrupting capacity are the headline numbers that govern fit for a DC distribution board or photovoltaic combiner box. The C3 curve (trips at 5–10× rated current) suits it for protecting motor circuits or transformer-fed loads where inrush is expected, rather than purely resistive DC loads where a C1 or B curve would be tighter.
The 2-pole construction means both poles are switched and protected — common in DC systems where the positive and negative rails each need overcurrent protection, or where a single-pole breaker cannot handle the DC voltage rating alone (series-connected poles increase the DC voltage withstand). Snap-on DIN rail mounting per EN 60715 fits standard 35 mm rail in enclosures or sub-distribution boards.