The Siemens 4EU4321-4CA00-0A is a commutating choke for converter applications — a 3-phase inductive component that limits rate-of-rise of current (di/dt) and smooths commutation notches in the DC link or AC input of a power converter. Rated for 500 V AC at 50 Hz, it handles a maximum continuous current of 910 A and a rated current of 819 A, with a peak current capability of 1 138 A.
The 910 A maximum (Ithmax) and 819 A rated current (ILN) are the numbers that decide whether this choke fits your converter's line current. The 1 138 A peak rating tells you the short-duration overload it can survive — useful for sizing against inrush or fault conditions. The 4 % relative inductive voltage drop (Uk) means the choke drops about 4 % of rated voltage at rated current; if your converter's DC-link voltage budget is tight, that drop matters. Thermal class H (180 °C insulation system) and 480 W coil power loss plus 300 W iron core loss mean the choke dissipates roughly 780 W total at full load — plan ventilation or forced cooling in the enclosure, especially since the IP00 rating offers no ingress protection.
Panel or cabinet mounting requires a 0.46 m by 0.435 m by 0.265 m bay. Flat-type terminals serve the main circuit. IP00 needs a clean, dry environment or an enclosure. The 40 °C ambient rating is the thermal reference.