Shelf maintenance for VFDs ?

[Ken Roach]

This is a little OT, but I know there are some experts here on the forum with the relevant experience.

I have a project that expects a very long lifespan from PowerFlex 70 VFDs. To insure them against inevitable obsolescence, I would like to buy a few and have them available in our stock as replacements.

But I know that capacitors get cranky if left on the shelf for years. I don't do enough VFD repair to be capable of doing capacitor reformation on these little 1/2 HP drives.

I was thinking of basically automating my storage: I have a disused cabinet with an old MicroLogix and a 480V contactor. I could have the MicroLogix power those drives up once every few months, read their serial numbers and runtime hours, then send me an e-mail to remind me that they've done so.

If you did that, how often would you power up those drives ? Every 3 months ? 6 ? 12 ?