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Problems With DRY Caps (fwd)
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From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Monday, April 27, 1998 12:20 AM
To: Tesla List
Subject: Re: Problems With DRY Caps (fwd)
Hi Fr Tom, all,
> Date: Sun, 26 Apr 1998 12:49:40 -0400
> From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Cc: acmq-at-compuland-dot-com.br
> Subject: Problems With DRY Caps
<snip>
> Perhaps others who have built "dry" capacitors and used them for a reasonable
> time would be willing to chime in here and tell us what the end results
> were.
I use home rolled dry-fired caps in a coil running at about 1.5kW but
with a primary voltage of only 7.5 - 8kV peak. The caps are *doomed*
to fail, BUT, we can roll them easily and cheaply (about NZ$20/cap),
we KNOW that the 15kVDC test is unnecessary (but we still do it) and
we know that if they are run for no more than a minute per time
(perhaps two or three firings around this length per session (time
between sessions being defined as the time it takes for the cap to
cool (*completely*) internally, we can get at least half an hour's
runtime out of them and often more. I also know that the Lself is
*very* low due to extended foil construction and the Q is not too bad
despite the internal coronas. They stack up very well against the
HiVolt caps I have used as an alternative. We get a measureably
better output. The design would be excellent for lo-f apps and slow
repetitive apps such as Marx banks (I have used it in two).
Malcolm