Breaking capacity and the standard that governs your panel
The 5SY4213-8 carries a 10 kA breaking capacity under EN 60898-1 and 20 kA under IEC 60947-2 — the higher figure applies when the MCB is installed in an industrial distribution board where the prospective fault current exceeds the residential limit.
D-curve trip — what it catches and what it lets through
That is deliberately high — it avoids nuisance tripping on transformer inrush, motor starting, or welding loads where the surge lasts a few cycles. For a general lighting or resistive heater circuit, a B- or C-curve would trip faster and give better conductor protection; the D-curve is right-sized for inductive and high-inrush loads.