Reforming Capacitors on VFDs after Storage

[OldBroadcastTech]

How old are the caps in the first place? Rather than reforming, it might be easier (and give everyone some peace of mind) to just recap and be done with it.

Assuming, of course, that the replacements you get are new........

 

[ptonsparky]

I knew I kept this for some reason. Like if I need 0 - 580 volts to reform those capacitors.

I scavenged it from my father-in-law's shop.

 

[ptonsparky]

I knew I kept this for some reason. Like if I need 0 - 580 volts to reform those capacitors.

I scavenged it from my father-in-law's shop.

 

[garbo]

I wonder how much current the capacitors draw while reforming. The DC bus in those is about 600 volts?

For 480 volt three phase input the DC Buss equals 480 × 1.41 = 676.8 Volts DC. Usually around 665 volts. Have to be carefull whole troubleshooting larger drives. Some take over 15 minutes for capacitor bank to discharge. I measured the current for a 10 HP drive with no load. You get a spike in current for guessing a cycle or two until capacitor is charged. Did not pull any current that I could pick up with my Amprobe but should have used a VOM to get an accurate reading.