Variable Frequency Drive capacitor reforming. When VFD's are stored for extended periods of time (over 1 year) it is usually a good idea to "reform" the capacitors. This is done by controlling the amount of current, usually by controlling the voltage with a VARIAC. This is some video I made while I reformed some surplus VFD's I purchased. Two were on the shelf for almost 6 years, another almost 4 years.
For reasons why this is a good idea see the following manufacturer literature:
Yaskawa - http://tinyurl.com/lxom9k8
MICROMASTER 420 Manual - http://www.atopone.com/index_files/P/MICROMASTER%20420%20Operating%20Instructions.pdf
WEG Capacitor Reforming Guide - http://ecatalog.weg.net/files/wegnet/WEG-how-to-reform-weg-vfd-capacitors-usareform-brochure-english.pdf
