The Siemens 4EP4001-1US00 is a three-phase mains choke (Netzdrossel f. FU) designed for installation between the supply and a variable-frequency drive. It smooths line current, reduces harmonics, and limits inrush — the 0.63 mH inductance and 4 % relative inductive voltage drop at rated current are sized for a 40.5 A continuous load on a 400/480 VAC, 50/60 Hz system. The 45 A maximum rating gives a small headroom margin above the 40.5 A nominal.
IP00 open-frame construction means this choke is intended for enclosure mounting — no touch protection on the live terminals, so it goes inside a panel with a lockable door or interlocked guard. The 0.219 m width and 0.179 m height fit a standard backplate; depth is 0.143 m. Connection is via screw-type terminals, sized for the 40.5 A circuit. Thermal class B (130 °C rise) and 70 W coil loss plus 29 W iron loss mean the panel needs ventilation to keep ambient below the 40 °C rating.