The Siemens 4EU4521-1AA00 is a three-phase commutating choke (also called a line reactor or converter choke) rated for 1000 A continuous at 690 V AC, 50/60 Hz. It sits between the AC supply and a converter's input to limit current rise during commutation, reduce harmonic distortion, and protect the DC-link capacitors from voltage notching. The 0.048 mH inductance at 4 % relative inductive voltage drop (on the measurement-level current, voltage, and frequency) is sized for high-current drives and rectifier front-ends where a low-impedance grid can cause excessive di/dt.
Rated 1000 A at 690 V AC, three-phase — this choke handles the full line current of a large converter or drive input without saturating. The DC-rated value of 1225.4 A gives headroom for the DC-link side if used in that leg. Power loss splits into 500 W in the coil and 350 W in the iron core, so the total 850 W must be vented from the enclosure; an IP00 open-frame design means it mounts in a clean, dry cabinet with forced airflow — not in a washdown or dusty environment. Thermal class H (180 °C insulation) per IEC 60085 allows high internal temperatures, but the 40 °C ambient rating sets the cooling baseline: derate above that.
The footprint measures 0.46 m wide by 0.435 m tall by 0.293 m deep, so plan for a sub-panel or chassis mount, not a DIN rail. IP00 means no integral enclosure; the installer provides the cabinet and cooling.