What the ratings mean for your panel
The 10 kA breaking capacity at 400 V means this breaker can safely interrupt a fault current up to that level without welding its contacts or venting arc gas into the enclosure — important for coordination with upstream devices on a DC bus or auxiliary transformer. The 2-pole form factor snaps onto standard DIN rail, so it fits alongside other Siemens 5SY series breakers in a mixed distribution board. The B-curve is faster than a C-curve on moderate overloads, which helps protect sensitive control circuits without nuisance tripping from inrush.