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

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:

> 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

I threw a cheap multi meter over the lines to see what it is doing
right now.

I am getting 109 VAC from the wall as of now. Seems the well pump
starts and the light dim occasionally. So I would expect an
occasional drop.

21.9V out of the secondary. ( um... NOT 5 x the motor voltage, I
expected to connect to the 34 V lines.) that puts the DC at just
over 30 volts. (OK, the 6 V stepper just makes it on 5X)
The caps are Jameco, 470uF, 65 Volt. Once the bugs are out, I'll
move up to the NEME34's at 1.5Volt 4.2 amps. The low voltage of the
larger steppers is what I was using to set up.

The transformer has 8 secondary lines so I can go from 7 volts up to
45 volts by picking which two lines I need. I'm not sure of the
secondary windings to feed them in series for even more choices, but
with what I have now, I'm more than happy.

Dave

>
> --- 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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> POSTING
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