What it is and what it does
The Siemens 4EU4321-5AA00-0A is a 3-phase commutating choke (line reactor) for converter applications, rated 500 V AC with a continuous current of 900 A and a maximum of 1 000 A. Its 35 µH inductance limits di/dt and smooths commutation notches on the line side of a drive or inverter, reducing harmonic distortion and protecting the converter's input rectifier.
Key ratings and what they mean for your panel
The 4EU4321-5AA00-0A carries a rated voltage of 500 V AC and a rated current of 900 A, with a maximum of 1 000 A. That 900 A figure is the thermal continuous rating at 40 °C ambient, thermal class H (insulation system rated for 180 °C hot-spot per IEC 60085). The 4 % relative inductive voltage drop at rated current is the impedance you need for coordination studies — it tells you the choke will drop about 20 V at 500 V line, which is typical for a 4 % impedance line reactor used to limit fault current and meet harmonic mitigation targets. Power loss splits into 480 W in the coil and 365 W in the iron core, for a total of 845 W at full load. That heat has to leave the enclosure — at IP00, this choke is an open-frame component meant for a ventilated cabinet or a dedicated cubicle. No washdown rating here; keep it dry and allow free airflow around the 0.265 m depth, 0.46 m width, 0.435 m height body.
Where it goes and how it connects
This choke sits on the AC line side of a converter — typically between the mains supply and the drive input. The flat-type terminals for the main current circuit accept busbar or large cable lugs, not spring-cage or screw-clamp connectors. No DIN-rail mounting; it bolts into the panel or chassis via its own mounting feet. At 0.46 m wide and 0.435 m tall, plan for a full-width sub-panel or a dedicated cubicle section.