30 Jul
2015
30 Jul
'15
6:42 a.m.
On Wed, 29 Jul 2015, Charles Dickman wrote:
On Wed, Jul 29, 2015 at 3:34 AM, Eric Smith
<spacewar at gmail.com> wrote:
VFD manufacturers are also very specific about the lifetime ratings of the
large capacitors used in these units, and often specify that they are to
be replaced after X number of power on hours. VFD's also aren't /just/
used for process machinery...they are also used for air handling
equipment, and with a large facility, you /really/ do not want that sort
of critical equipment to spontaneously fail.
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.