Siemens 4EU4521-4AA00 Commutating Choke, 1000A 750V 55µH

The Siemens 4EU4521-4AA00 is a commutating choke (line-reactor equivalent) designed for 3-phase AC converter drives. Its job is to limit di/dt and smooth the current waveform on the input side of a variable-frequency drive or DC-link converter, reducing harmonic distortion and protecting the converter diodes from peak currents. Rated for a continuous 1000 A at 750 V AC (50/60 Hz), it carries a DC-rated current of 1225.4 A — the higher DC figure reflects the lower ripple content in DC circuits. This is an open-frame (IP00) component, so it requires panel or cabinet mounting with no direct touch access. Thermal class H insulation (180 °C) allows sustained operation at the 40 °C ambient temperature rating without derating; above that, the iron-core and coil losses (404 W and 500 W respectively, total ~900 W) drive the internal temperature rise, so forced ventilation is recommended in a sealed enclosure. Connection is via flat-type terminals — expect bus-bar or heavy-gauge cable lugs, not spring-cage or screw-clamp. The footprint is 0.46 m wide × 0.435 m tall × 0.293 m deep, so it occupies a significant panel footprint; plan for a dedicated mounting plate section.