The Siemens 5SP5280-7CC is a 2-pole miniature circuit-breaker rated for 440 V DC with a 10 kA breaking capacity, a C-trip curve, and an 80 A current rating.
The 440 V DC rating is the key selection parameter here — this is not a standard AC miniature breaker. Most MCBs are AC-rated (230/400 V AC); a DC-rated breaker must handle the lack of a natural zero-crossing to extinguish the arc. The 2-pole configuration means both poles are switched simultaneously, which is required for DC circuits to ensure complete isolation.
Deployment context
In a solar combiner box, it protects the string conductors from reverse-current faults. In a UPS or battery bank, it provides branch-circuit protection on the DC bus. The 80 A rating is sized for a high-current DC feeder — think a 40–50 kW solar inverter input or a large battery rack.