The Siemens 4EP3801-1FK00 is a SIDAC output reactor (choke) for 3-phase AC motor drives, rated for a maximum continuous current of 10.2 A at 120 Hz and a switching frequency of 3 000 Hz (3 kHz). It handles the high-frequency pulse-width-modulated output from a VFD, smoothing the voltage spikes and limiting the rate of rise of current to the motor windings — critical for long cable runs or when the motor is far from the drive. The 0.0019 H inductance and 5.4 % voltage drop (UK) are sized for a typical motor load around 9.2 A (I LN).
The 10.2 A maximum at 120 Hz is the thermal current rating (Ithmax) — the continuous current the reactor can carry at its rated ambient of 40 °C without exceeding insulation class B (130 °C hot-spot). Below 40 °C you get some headroom; above it, derate. The 3 kHz switching frequency matches most IGBT-based VFDs on the market; if your drive switches at 4 kHz or higher, the core losses increase and you may need a larger reactor. The screw-type terminals accept standard power wiring; strip length and torque are per the manufacturer's recommendation on the nameplate.
Mounts inside the motor-drive cabinet, wired between the VFD output terminals and the motor cable. The 0.17 m width, 0.15 m height, and 0.12 m depth (170 × 150 × 120 mm) mean it occupies about the footprint of a small contactor — plan for clearance around the screw terminals for cable bending radius.