It interrupts faults at 6 kA on AC circuits up to 277 V and 10 kA on DC circuits up to 500 V — the DC rating is notably higher than many comparable MCBs, making it a fit for DC bus or battery-string protection where the fault current can be stiffer.
Curve C and interrupting capacity
Trip Curve C means the magnetic trip operates at 5 to 10 times rated current (100–200 A for this 20 A unit). The 6 kA AC interrupting rating at 277 V is standard for branch-circuit protection in a distribution board; the 10 kA DC rating at 500 V is less common and tells you the arc-quenching chamber is designed for DC commutation, not just AC zero-crossing.
The S200MUC family shares the same footprint as the broader S200 series, so it swaps into an existing ABB distribution board or sub-panel without re-drilling the backplate. Spring-loaded terminal clamps accept 0.5–25 mm² conductors; torque to 2.5 Nm.