The interrupting capacity is 15 kA at 230 VAC and 10 kA at 125 VDC.
This is the curve for loads with high inrush — motor starters, transformers, welding equipment, and capacitor banks. A standard Curve C (5–10× In) would nuisance-trip on the same start-up surge; Curve D holds through it. For DC circuits, the 10 kA rating at 125 VDC handles battery banks and DC bus faults common in UPS or solar combiner panels. Single-pole construction protects one phase or one DC leg. In a 230 VAC single-phase circuit, the breaker goes in the line conductor; the neutral is common. For 125 VDC, it protects the positive leg. The DIN rail footprint means it clips into any standard 35 mm rail in an enclosure — no special adapter or panel cutout needed.