[Boatanchors] [BoatAnchors] Electrolytics- How Much is Too Much

[Dave Haupt]

When I was in the high power amplifier business, we tested all our caps for leakage and actually matched them, since we made series strings.  Our capacitor vendor said we were going overboard because we used equalizing resistors anyway, so mismatched leakage would be swamped by them.  But we went overboard in a lot of areas on our amplifier.

Our "failure criteria" was one of drift.  The leakage, one day after starting the test, had to be half or less of the starting value, and after one week, it must not rise - ever.  Ours were 650uF 450V "computer style" electrolytics, and it was unusual for us to see leakage above 250uA.  Older technology may leak more.

Dave W8NF

--- On Thu, 1/31/13, john <johnmb at nc.rr.com> wrote:

> From: john <johnmb at nc.rr.com>
> Subject: Re: [Boatanchors] [BoatAnchors] Electrolytics- How Much is Too Much
> To: "David Stinson" <arc5 at ix.netcom.com>, boatanchors at theporch.com, boatanchors at mailman.qth.net
> Date: Thursday, January 31, 2013, 2:14 PM
> I've always used the "old standards"
> (Radiotron Handbook), where there's a 
> formula I can't remember right now. What you observe doesn't
> look 
> excessive, though It probably would be more comforting to
> know if it's ONE 
> of those sections doing the leaking or is it ~ evenly
> balanced.
> 
> John
> 
> 
> 
> At 06:59 AM 1/30/2013, David Stinson wrote:
> >High Voltage electrolytics- how much current leakage
> >at rated voltage is "too much?"
> >
> >There are old standards published 70 years ago,
> >but I'm interested in your current insight.
> >Say- I have an original can capacitor, rated 40-40-40 at
> 450 volts.
> >After sitting with all three tied together and at
> >400 volts, total leakage was about 1.5. mA.
> >
> >I'm not interested in re-igniting the nasty
> name-calling
> >over whether or not "re-forming" caps is a good or bad
> idea- only in what 
> >level of leakage is, in your opinion,
> >acceptable in order to maintain a stock part in a set.
> >
> >73 DE Dave AB5S
> >
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