The Siemens 4EU3021-0AA20-0AA0 is a three-phase commutating choke (line reactor) designed for converter input circuits. It limits current rise and harmonics on the AC side of a drive or rectifier, reducing stress on the converter's semiconductors and improving power quality. Rated for 470 V AC at 50 Hz, it carries a continuous rated current of 555.3 A and a maximum current of 617 A, which means it can handle short-duration overloads typical during motor acceleration or line transients without saturating. The rated inductance is 0.000016 H per phase, with a relative inductive voltage drop of 1.21% at rated current and frequency.
Construction and environment
Thermal class H (180 °C insulation system) per IEC 60085, with a rated ambient temperature of 40 °C. Total power loss is 285 W — 245 W in the coil plus 40 W in the iron core — so forced-air ventilation or adequate natural convection within the panel is necessary. Dimensions are 0.3 m wide × 0.269 m high × 0.211 m deep. Terminals are flat-type connectors for the main current circuit, typical for high-current bolted busbar or cable-lug connections.