The Siemens 4EU3951-3UB00-0A is a three-phase mains choke (Netzdrossel f. FU) designed for the input side of a frequency converter. It smooths line current, reduces harmonic distortion, and limits inrush current peaks that would otherwise stress the drive's DC bus capacitors. Rated for 504 A continuous with a 560 A maximum, it handles the full-load current of a large drive without saturating. The 500 V AC operating voltage and 50 Hz line frequency match standard European industrial mains. The 65 µH inductance and 4 % relative inductive voltage drop are the key sizing parameters — they determine how much line impedance the choke adds, which governs the harmonic attenuation and the voltage sag the drive sees under load.
Thermal and construction details
Total power loss is 730 W — 540 W in the coil and 190 W in the iron core — all dissipated as heat. Class H insulation (180 °C thermal class per IEC 60085) means the winding can run hot without degrading; still, the panel builder needs to account for that heat load in the enclosure ventilation. IP00 protection class means it is an open-frame component — no housing, no splash protection. Main circuit connections are flat-type terminals (bus-bar style), not screw clamps. That means the installer needs a bus-bar or a flat-cable lug kit — standard ring terminals won't fit.
Because it is a mature, high-current line reactor with UL/CSA recognition per EN 61558-2-20, it is still widely specified for drive panels that need a listed input choke.
Physical footprint
Dimensions are 0.229 m deep, 0.41 m wide, and 0.385 m tall — roughly 9 by 16 by 15 inches. That is a substantial block; verify the cabinet depth and backplate space before committing the panel layout.