VFD Capacitor Reforming Service
Do you have VFDs that have been in storage for greater than two years? If so, the capacitors in those units may have degraded and need to be reformed.
VFD capacitors are comprised of two charging plates, an anode, and a cathode, with an insulator/oxide layer between them. Over time and without power, the oxide layer degrades and becomes uneven, which can crack and allow leakage current to flow between the anode and cathode.
To avoid this, ES&E now offers a capacitor reforming service for any drive, regardless of the manufacturer. Reforming is the process that allows the oxide layer to reform and fill in the unevenness and cracks. Your drive may power up without issues after prolonged storage, but the capacitors will have weakened. Extended storage can significantly increase the chances of premature failure of a VFD capacitor.
The recommendations and process to reform the capacitors vary slightly from manufacturer to manufacturer. For example, Rockwell Automation's recommendations are the same for 750 drive up to frame seven, but frame eight and larger are very different.