When should I use an Input Choke with my VersiDrive i?

An Input Choke is not automatically required but is generally recommended and can be used with the VersiDrive i range to help prevent issues with the power supply causing a problem for the AC drive and to help reduce the effects of the AC drive in distorting the incoming power supply.

Supply Harmonics:

Input Chokes are designed to effectively reduce the input harmonic distortion caused to the incoming supply by non-linear loads. Most types of drive products create harmonic distortion on the supply owing to the configuration of the power input circuit and Input chokes are used to reduce the effects of the VersiDrive i upon supply harmonic distortion.

For smaller kW drives on larger supplies the distortion effects of the drive may be acceptable as the overall effect on the supply network is proportionally small. However for multiple small kW units on the same supply network or for larger kW drives Input chokes should be used.

For some of the higher power rated VersiDrive i models a 3 phase line choke is included as part of the products basic design to improve product robustness and to provide additional cost benefits.

Always check for any local regulations specifying limits for harmonic Distortion or for restrictions on supply quality. If in doubt fit a line choke.

Drive Protection:

Input chokes have the additional benefit of protecting the input of the drive from line surges, spikes and notches or where a line imbalance might exist (3 phase drives). These could be caused generally by the poor quality of the incoming supply or by other equipment (such as DC drives or welders) present on the same supply network.

Smaller kW drives can be particularly susceptible to supply variations and also to connection to supplies with low impedance / high short circuit current and line chokes are recommended in these cases.

Notes:

Fitting an Input line reactor will cause a drop in the incoming supply voltage level to the AC drive (generally between 2 and 5%). For low voltage supplies check that the resultant supply to the AC drive is within the specifications given in the user manual.

The Input line choke will also produce some additional heat that may need to be considered in enclosure design and component location.