Line chokes are used to provide improved protection against over voltages on the line supply and to reduce harmonic distortion of the current produced by the drive.

The use of line chokes is recommended in particular under the following Circumstances:

• Close connection of several drives in parallel.
• Line supply with significant disturbance from other equipment (interference, overvoltages).
• Line supply with voltage imbalance between phases that is more than 1.8% of the nominal voltage.
• Installation of a large number of frequency inverters on the same line.
• Reduction of overloads on the cos ϕ correction capacitors, if the installation includes a power factor correction unit.