The Siemens 4EU4521-0BM10 is a commutating choke (line reactor) designed for the DC link or AC input of a three-phase converter drive. It smooths current ripple and limits di/dt during commutation, protecting the converter's semiconductor switches. Rated 804 A continuous at 830 V AC, 50 Hz, with an inductance of 0.061 mH and a relative inductive voltage drop of 4 % at rated current — sized for a heavy-duty drive line. The 804 A rating is the continuous thermal current (Ith) at 40 °C ambient; derate for higher ambient or non-sinusoidal waveforms. The 4 % voltage drop means the choke is a standard impedance match for most 400–690 V class drives — it won't starve the DC bus of voltage under load.
IP00 open-frame construction — no enclosure, no touch protection. Must be mounted inside a cabinet with appropriate clearance to grounded metal and live parts. Footprint 0.46 m wide × 0.435 m tall × 0.293 m deep; flat-type terminals for the main circuit accept busbar or large cable lugs. Plan for bottom-entry cabling or busbar drop from the converter output. Class H insulation (180 °C thermal class per IEC 60085) means the choke can run hot without degrading the winding — typical for high-current line reactors in continuous-duty drives. Still, keep the ambient below 40 °C for full 804 A rating.