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. This is a DC-specific MCB — the 440 V DC rating and 10 kA interrupting capacity mean it can safely clear a fault on a 440 V DC bus (common in solar string combiners, UPS battery banks, or industrial DC drives) without welding its contacts or cascading the arc upstream. The C-curve (5–10× In magnetic trip) suits it for loads with moderate inrush, like DC motor starters or capacitive filter banks.
What the ratings mean for fit
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 10 kA breaking capacity at 440 V DC tells you it can interrupt a fault current up to 10,000 A on a DC circuit without failing. The 2-pole configuration means both poles are switched simultaneously, which is required for DC circuits to ensure complete isolation. The C-curve (magnetic trip between 5 and 10 times the rated current) means it will hold through the inrush of a DC motor or a capacitor bank but trip quickly on a hard short.
Deployment context
This MCB snaps onto a standard DIN rail inside an enclosure. 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.