Breaking capacity and curve — what the ratings mean for fit
The C60HD120 carries a 30 kA Icu at 130 V AC and 15 kA Icu at 230–240 V AC, both per EN/IEC 60947-2. That 30 kA figure is the ultimate breaking capacity at the lower voltage — it tells you the breaker can safely interrupt a fault up to that level without failing, which matters for high-fault-capacity panels fed by large transformers. The 20 A D curve is designed for loads with high inrush current: motor starters, small transformers, or lighting ballasts where a B or C curve would nuisance-trip on startup. Thermal-magnetic trip unit handles overload and short-circuit protection. Single-pole construction limits it to line-side protection in a 1P circuit.
Where this class of breaker is used
Multi9 C60H breakers are panel-mount devices for distribution boards. The D curve and 20 A rating suit it for motor feeder circuits or loads with high starting current.