Mains choke for 2000 A frequency converter lines
The Siemens 4EU4521-0UB10-0B is a three-phase mains choke (Netzdrossel f. FU) rated for 2000 A continuous at 690 V AC, 50 Hz. It is designed to sit between the supply and a frequency converter drive, limiting harmonic distortion and reducing voltage notching on the line side.
The 2000 A rating (both maximum and rated value) sets the continuous current capacity — this choke is sized for large drives, typically 800 kW to 1 MW class on 690 V systems. The 690 V operating voltage covers 400 V and 690 V line supplies common in European industrial networks. Inductance is 13 µH (0.000013 H), which combined with the 2 % voltage drop gives the impedance needed to limit di/dt and reduce harmonic currents from the drive's rectifier stage. Total power loss is 980 W (680 W coil loss + 300 W iron core loss) at 40 °C ambient. This heat must be dissipated — the IP00 open-frame construction means no enclosure; the choke relies on the panel's forced ventilation or natural convection. Class H insulation (180 °C rated) per IEC 60085 gives thermal headroom for overloads and high ambient temperatures inside the cabinet.
Dimensions are 0.460 m wide × 0.435 m high × 0.293 m deep — a substantial footprint requiring a floor-mount or heavy-duty shelf inside the panel. Main circuit connections use flat-type terminals (busbar or large cable lug interface), not spring-cage or screw clamps. The IP00 rating means no ingress protection; install in a clean, dry cabinet with adequate clearance for airflow and arc-flash boundaries.