Line-side filtering for converter harmonics
The Siemens 4EU4321-2BA00-0A is a 3-phase commutating choke (line reactor) sized for converter input circuits — it sits between the supply and the drive rectifier to limit current rise rates and reduce harmonic distortion. Rated at 504 A continuous with a maximum of 560 A, and wound for 750 V AC at 50 Hz, it delivers 98 µH inductance with a 4 % relative inductive voltage drop at rated conditions. Open-frame (IP00) construction means this choke is intended for enclosure mounting where the panel provides the environmental seal — not for standalone outdoor or washdown duty. Thermal class H insulation (180 °C rated) keeps the winding safe under full load, with a combined copper and iron loss of 787 W (474 W coil + 313 W core) that must be ventilated out of the cabinet.
The 504 A rated current (at 40 °C ambient) defines the continuous load capacity — match this to the drive's input current, not the motor FLA. The 560 A maximum is the thermal overload ceiling; sustained operation above 504 A requires derating or forced cooling. At 750 V AC line-to-line, the choke handles standard 400 V and 690 V drives with headroom. The 98 µH inductance and 4 % voltage drop are tuned for typical 6-pulse rectifier commutation — lower inductance would increase harmonic content, higher would drop more voltage across the choke under load. Power dissipation of 787 W means this is not a small component to ignore in thermal design — the panel must move that heat out.