How to protect the VFD if it is not used for a long time?

VFD in reserved storage
Many applications using variable frequency drives (VFDs) are critical and cannot afford extended downtime. Many people choose to keep a spare VFD on the shelf so that it can be switched when needed. However, if you're not careful, the VFD may not work when you need it. Here are a few things to look out for to ensure your spare VFD is ready to be taken out of long-term storage and put into service.

Environmental conditions
One of the easiest problems to solve is where and how to store the VFD. Make sure it's cool, clean and dry. A common problem we see is excess moisture, dust, and even animal problems in warehouses that store spare VFDs. VFDs will always be affected by moisture and dust.

Another issue to monitor is temperature. Most inverters are rated to operate close to 0-40°C. VFDs can be stored at slightly higher extreme temperatures than they can operate at, but be sure to consult your VFD manual for recommended conditions.

Maintenance of capacitors
Almost all low voltage VFDs use electrolytic capacitors, and some medium voltage VFDs also use electrolytic capacitors. These capacitors are filled with electrolytic gel, but when the capacitors are not being used, the gel starts to dry out and cause problems. Some medium voltage VFDs use dry film capacitors that do not experience these problems, so a key aspect of servicing the drive is determining the type of internal components.

The best thing to do is to charge the VFD at least once a year. If an electrolytic capacitor has not been energized for more than a year, you need to make sure that the capacitor is retrofitted before putting it into service, which can cost valuable time when your process stops. Most electrolytic capacitors have a shelf life of only 5-7 years.

One problem with only reforming the capacitors on the VFD is that you can only reform the DC bus capacitors, not the capacitors on the printed circuit board. That's why the best advice is to actually go beyond powering the stored VFDs on an annual basis and actually rotate the equipment during each annual preventative maintenance service to keep all VFDs operating optimally.
 
Services we can provide
Whether you're looking for variable frequency drives service, procuring a spare VFD, or exploring services for storage equipment, we're here to help.