Variable Frequency Drive (VFD) Reforming

Many companies keeps spare parts on hand to help reduce down time.  Some of those spare parts include VFD's.  After 6 months of not being powered the capacitors inside the VFD start to breakdown and in 2 years they are no longer usable.

We recommend applying line voltage to any VFD's you have in storage and keep detailed records of when that was last done.  This needs to be done every 6 months.  If it has been sitting unpowered for longer than 6 months you should consider having the VFD reformed. Most VFD manufacturers say that they must be reformed if left unpowered for 12 months.

If proper maintenance has not been performed and the reforming has not been done, than the VFD will likely let out some magic smoke when power is applied; at which time the drive is not functional.

VFD reforming is actually just reforming the DC bus capacitors, bringing Tham back to their original factory state.  We do this with an automatic DC reforming tool.  The tool starts by applying a very low DC voltage and  slowly increases this voltage up to the rated DC bus voltage of the VFD, it than holds that voltage for an extended period of time as it tests the capacitors.

After the reforming process has been completed we apply a label to the VFD showing when the reforming process was last completed and the test results.   Now your maintenance personal will know that the VFD should be safe to install and it should work as expected when installed as long as it has been done with the last 12 months.

The actual reforming process varies slightly based on how long it has been since the drive was last powered or the last time it was reformed.  If the date of the last time is not known it will take upwards of 6 hours for the reforming to be completed.

We can either come to your site for the reforming or you can ship to us.  Because of the time it takes to do the reforming it is best to ship the VFD to us if possible.  We do understand that emergencies can come up though and we can do the process on-site if needed or if it is a very large VFD that wouldn't make sense to ship.