RE: [CAD_CAM_EDM_DRO] Re: CNC power supply question

> At 16:04 09/03/2004, you wrote:
> >On Tue, 09 Mar 2004 09:30:57 +0000, you wrote:
> >
> > >Ken -
> > >
> > >The following extract from a spec sheet chosen at random,
> for a range of
> > >"long life" screw terminal electrolytics:
> > >
> > > Shelf life 2000 h at 0V +85°C, or
> > > 4 years at 0V +40°C
> > > Operational life time 60000 h at +85°C
> > >
> > >Seems to indicate pretty clearly that the lifetime is
> severely shortened if
> > >stored at 0V.
> >
> >No, I'd think more like the 85 degrees C.
>
> I think you missed the point. Take a closer look at the
> numbers. Shelf
> life, at 0V, at +85 degrees C, is 2000 hours, versus
> operational lifetime
> (not at 0V), at +85 degrees C is 60,000 hours. Same
> temperature; factor of
> 30 difference in lifetime.

I think you misread/understood the numbers.

Shelf life from the capacitor manufacturers' point of view is the storage
time after which the capacitor still meets the performance specs (the exact
definition varies between manufacturers).

This means that (with the numbers above) the capacitor, after an accelerated
aging process of 2000 hours at +85 degrees C, should still have an
operational life of 60000 hours at +85 degrees C.

At 'normal' temperatures, shelf life is many years. Only if you store your
capacitors in an oven, you'll have to worry about a shortened lifespan. :-)

Sincerely
Eric