text: <s>[INST] Electrolytic Capacitors shelf life I have a panel with several PF40s and PF70s ( 30 hp) that has been in storage for several years. I was told that I need to re-form the capacitors and was referrenced TN 18015. Does this this mean I should not have spare inventory for drives? It seems to be a very complex procedure and not suitable for small plants? What is wrong with this picture? [/INST] This issue comes new to me, and it is an interesting thread. In effect this happens due to the *nature* of the Aluminium Electrolytic Capacitors, and thus it applies also to other Drives (I mean non-Rockwell... :smileytongue: )Some other infos in Wikipedia.... also there is explained the re-forming process... Then, it means you can have your spare for sure, but you have to be aware of this issue and prepare your drives before proceed to use them...that means that after several years you have not a quick direct replacement part in case of failure of original system... :smileysad: About the reforming procedure: yes, it seems quite complex... maybe the last explained could be the most suitable for simple reforming. The other option is to apply the input line voltage to the Drive, the current limited resistor should still be used in series with the input power. Then allow the drive to power-up, thus applying bus voltage across the capacitors and re-forming them. Allow the drive to sit in this state for at least an hour prior to operating the drive. - fuzzy logic \\n </s>