CAP's (again) (was Re: another transformer question

Dave,

They still are aluminum electrolytics. Low ESR simply means
low "equivalent series resistance". The bigger the cap (uF), the
lower the ESR. One thing I forgot to ask; what is your power supply
voltage and what was the voltage rating of the cap that blew?

Mariss

--- In CAD_CAM_EDM_DRO@y..., "turbulatordude" <davemucha@j...> wrote:
> In reviewing the recent release of fluid from my cap, I am thinking
> that maybe the aluminum cap may not be the best choice.
>
> There was a post a month of so ago discussing the benefit of using
> low ESR and another saying that multiple caps. 100uf and one small
> unit.
>
> Is there any special style that is bad, or best ?
>
> Dave
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "JJ" <jj5412@e...> wrote:
> > For what it's worth, Jameco (www.jameco.com) has 470uf 100v caps
for
> > US$1.89.
> >
> > I know what I would do.
> >
> > Regards,
> > JJ
> >
> > Be Kind, Be Careful, Be Yourself
> >
> >
> >
> > > -----Original Message-----
> > > From: caudlet [mailto:tom@t...]
> > > Sent: Sunday, August 11, 2002 1:24 PM
> > > To: CAD_CAM_EDM_DRO@y...
> > > Subject: [CAD_CAM_EDM_DRO] Re: another transformer question
> > >
> > >
> > > <snip> for 48VDC so should just make it under 50V, but the
> > > measurement says
> > > > 60VDC, so should I risk it and go ahead to use the same
> capacitor,
> > > > even if only temporary? What happens when one exceed the
rated
> > > > voltage of a capacitor?
> > > >
> > > > Thanks
> > > >
> > > >
> > >
> > > In the short term normally nothing happens. If the overvoltage
> lasts
> > > too long or is way over the limit of the working voltage things
> can
> > > get interesting in a hurry. The insulation layer starts to
break
> > > down and the cap starts to draw excessive current which results
> in a
> > > rapid build up in internal heat and the electrolyte starts to
> turn to
> > > steam. Usually the result in larger caps is a hissing noise
with
> > > gook flowing out of the cap. The cap can explode (smaller ones
> go
> > > off like firecrackers) but the real danger is to down stream
> > > components. If you loose the filter cap the electronics running
> off
> > > of it are essentially running off half wave AC at 120HZ...not
> kind to
> > > components expecting nice smooth DC!
> > >
> > > A lot of transformers are designed and rated at close to full
> load to
> > > account for losses in the windings and other magnetive things,
so
> a
> > > 36VAC unit might go to 40VAC lightly loaded but 45Volts sounds
> > > excessive. Your two 12VDC fans in series should really be
> spinning
> > > at 60VDC! The resistor in series will reduce that some but you
> may
> > > have to increase the value to keep the voltage across the fans
> 24VDC.
> > >
> > >
> > >
> > >
> > > Addresses:
> > > FAQ: http://www.ktmarketing.com/faq.html
> > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > >
> > > OFF Topic POSTS: General Machining
> > > If you wish to post on unlimited OT subjects goto:
> > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > to reach it if you have trouble.
> > > http://www.metalworking.com/news_servers.html
> > >
> > http://groups.yahoo.com/group/jobshophomeshop I consider this
as a
> > sister site to the CCED group, as many of the same members are
> there,
> > for OT subjects, that are not allowed on the CCED list.
> >
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