A line choke is used to provide better protection against overvoltages on the line supply and to reduce the harmonic distortion of the current produced by the drive.

The recommended chokes limit the drive line current and they have been developed in line with standard EN 50178 (VDE 0160 level 1 high-energy overvoltages on the line supply).

These chokes should be installed upstream of 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 above 1.8% of the nominal voltage
• Drive power supplied by a line with very low impedance (in the vicinity of power transformers 10 times more powerful than the drive rating)
• Installation of a large number of frequency inverters on the same line
• Reduction of overloads on the "cos phi" correction capacitors, if the installation includes a power factor correction unit.

Released for:Schneider Electric Ireland