The Siemens 4EP3500-4US00 is a three-phase mains choke — Netzdrossel f. FU in the catalog — sized for the line side of a variable-frequency drive. It sits between the supply and the drive rectifier, smoothing current peaks and limiting harmonic distortion. Rated for 400/480 V AC at 50/60 Hz, it carries a maximum continuous current of 6.3 A and a nominal rating of 5.67 A. The 4.6 mH inductance and 4% relative voltage drop are matched to the drive's input stage; the 28 W copper loss plus 14 W iron loss give a total dissipation of 42 W at rated load.
This is an IP00 open-frame choke — no enclosure, so it mounts inside a panel or cabinet. The foot-print is 148 mm wide by 139 mm tall by 68 mm deep; plan for clearance around the screw/tab terminals on the main circuit. Thermal class B (130 °C rise) means it runs warm but stays within standard panel ventilation. Ambient rated at 40 °C; derate above that per the thermal curve. It's a line reactor for a 3-phase drive, not a filter for the DC bus or output.
The 6.3 A maximum is the thermal limit at 40 °C — the choke can run at that current continuously without exceeding the Class B temperature rise. The 5.67 A rated value is the nominal current at which the 4% voltage drop is measured; if your drive draws a steady 5.5 A, this choke is sized correctly. The 4.6 mH inductance is the key parameter for harmonic attenuation — don't substitute by current alone without matching inductance. The 3-phase, 480 V rating covers 400 V line-to-line as well; the 50/60 Hz range means it works on either supply frequency.