Reforming capacitors (technical description, not politics)

Charles Dickman chd at
Wed Jul 29 19:43:31 CDT 2015

On Wed, Jul 29, 2015 at 3:34 AM, Eric Smith <spacewar at> wrote:
> Some people seem to think that "reforming" an aluminum electrolytic
> capacitor is some kind of cheat, akin to zapping NiCd cells or
> rejuvenating CRTs. Actually reforming is the same electrochemical
> ....

Reforming is standard practice with industrial motor drives.
Manufactures (ABB, Allen-Bradley, Siemens) will require that a drive
that is not powered for a year or more have the DC bus capacitors
reformed or any warrantees could be voided. The procedures they
recommend are very similar to those that have been discussed here. ABB
suggests a 3phase rectifier and current limitting power resistor or a
current limiting DC (1000V) power supply.


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