The Siemens SIDAC 4EP3806-0BS01 is a 3-phase output reactor (choke) rated for 1 mH inductance with a 4000 Hz switching frequency, designed to sit between a variable-frequency drive and the motor leads.
The 4000 Hz rated switching frequency and 8000 Hz maximum tell you this reactor is wound for IGBT drives running PWM carrier frequencies in that range — common on modern VFDs for reduced motor audible noise. The 1 mH inductance and 4% short-circuit voltage (Uk) are sized to limit the rate of rise of current from the drive's output pulses, protecting the motor windings from reflected-wave voltage spikes on longer cable runs.
Dimensions are 0.17 m wide, 0.15 m tall, and 0.12 m deep — roughly 170 × 150 × 120 mm. At IP00, it requires a clean, dry enclosure; no dust or conductive debris should reach the windings. The 30.7 W coil loss plus 15 W iron core loss means about 46 W total heat to dissipate inside the panel — account for that in your thermal budget.