The Siemens 4EU4321-0DA00-0A is a three-phase commutating choke (line reactor) designed for converter front-ends. It smooths the current ripple and limits di/dt on the line side of a variable-frequency drive or rectifier, protecting both the converter semiconductors and the upstream network from harmonic stress and switching transients. The peak current capability reaches 888 A, and at DC the rated value is 870 A — relevant if the choke is used in a DC-link application rather than the AC line input. Inductance is 53 µH (0.000053 H), with a relative inductive voltage drop of 4% at the rated current and frequency. That 4% figure is the design target for typical converter line reactors — high enough to limit harmonics effectively, low enough to avoid excessive voltage drop under load.
Thermal design and installation constraints
Total power loss splits between the coil (470 W) and the iron core (330 W), summing to 800 W of heat that must be dissipated. The thermal class is H (180 °C temperature index per IEC 60085), meaning the insulation system can handle sustained elevated temperatures — essential for a choke running near its full rating in a closed panel. Rated ambient temperature is 40 °C. IP00 protection class means the choke has no enclosure. Dimensions are 0.435 m high, 0.46 m wide, and 0.265 m deep. The main current circuit connects via flat-type terminals — busbar or flat-cable lugs, not screw-clamp wire terminals. Verify the busbar interface matches your panel layout before committing the footprint.