Re: [CAD_CAM_EDM_DRO] Bleed resistor question.

Just a thought here

I believe that if you bleed resistor is getting HOT that you have selected
too small a resistance / wattage.

There is an additional hazard in that a resistor running HOT has a higher
possibility of failing because of overload. If it fails open (most likely)
you are left with no bleeder and charged caps.

Large cap banks that I have worked with (1000 VDC 10,000 uf) made up of 10
1,000 uf caps in parallel had bleed resistors on each cap. Of course each
resistor was 10 times larger that that required for the whole bank. The
failure of any one or few of the resistors was not as critical as the
single failure of one resistor discharging the whole bank.

Also place the resistors right at the cap and do not put heat shrink over
them, makes it easier to tell at a glance if the resistor has blown or leads
are broken.

Then never trust the bleeders, measure the voltage first to be sure the
bleeders are working before you reach in to work.

Probably not encountered in machine shop cap banks but some cap banks come
with a Thunder Stick designed to safely discharge the cap bank when
required.

Hugh
There are old electricians and there are bold electrictians but there are
few old bold electrictians.

----- Original Message -----
From: Alan Marconett KM6VV <KM6VV@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, March 08, 2001 6:24 PM
Subject: Re: [CAD_CAM_EDM_DRO] Bleed resistor question.


> Hi Jason,
>
> If the two caps are in parallel, you can put the bleeder resistor across
> either cap. Just make sure it won't touch anything, as it will get HOT!
>
> Alan KM6VV
>
>
> andesign2@... wrote:
> >
> > In the power supply I am building I have used two capacitors in
> > parallel to get the rating I need. I have purchased a resistor to
> > use as a bleed, but I am not quite sure how to wire it up. Can I
> > simply wire it across one of the capacitors? Any information would be
> > appreciated.
> >
> > Thank You,
> >
> > Jason
>
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