What this choke does in the drive line
The Siemens 4EP3801-1US00 is a three-phase mains choke (Netzdrossel f. FU) sized for variable-frequency drive inputs. It sits between the supply and the drive rectifier, limiting harmonic current and reducing the voltage-notch stress on the DC bus. Rated 40.5 A continuous (45 A max) at 400/480 V AC, 50-60 Hz, with a 2 % relative inductive voltage drop at rated current and an inductance of 0.31 mH. That 2 % drop is the design sweet spot — it knocks down the dominant harmonics without dragging the DC bus voltage down enough to trigger undervoltage on the drive. The 57 W copper loss plus 12 W core loss (69 W total at 40 °C ambient) means this choke needs free air around it; IP00 tells you it's an open-frame component for enclosure mounting, not a standalone box.
Footprint is 0.178 m wide × 0.153 m tall × 0.12 m deep. Thermal class B (130 °C) per IEC 60085, so the winding insulation holds up under the 69 W total loss at 40 °C ambient. In a typical panel, leave a few centimetres around the choke for convection; the iron core runs warm, not hot. UL/CSA recognized per EN 61558-2-20, which covers the safety isolation and thermal-rise testing for this class of choke.