Re: Large GE Caps (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 16 May 2007 11:52:52 -0500
From: Bert Hickman <bert.hickman@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Large GE Caps (fwd)

Tesla list wrote:
> Original poster: List moderator <mod1@xxxxxxxxxx>
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Tue, 15 May 2007 19:45:59 -0400
> From: Chip Ford <chipford@xxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Large GE Caps
> 
> Check out these large GE caps on ebay. They look simular to the ones used on the Green Monster Coil.
> 
> 
> Green Monster--->   http://dawntreader.net/hvgroup/david/gm.html
> 
> 
> 
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=016&sspagename=STRK%3AMESE%3AIT&viewitem=&item=260118573481&rd=1&rd=1
> 

Hi Chip,

These caps (GE 17L480PH) were originally made especially for Varian, and 
were used in HV pulse forming networks (PFN's) in 1970's vintage 
electron beam accelerators. These systems accelerated electrons up to 16 
MeV, then smashed them into targets (usually copper) in order to 
generate high energy X-rays for various medical applications.

In 2003, I pulled out a batch of these from some Varian equipment, and I 
asked GE for any specs on them at the time. The applications engineer in 
the Capacitor & Power Quality Products area indicated that these were 
paper/foil/oil pulse capacitors, and they had been (at that time) 
obsolete for over 20 years.

Although they are pulse caps, they do NOT use a  polypropylene 
dielectric system. Because of the paper-oil dielectric system, they are 
ideal for DC, PFN, and light oscillatory duty. However, they will be 
lossy and will heat up under extended TC use, but they should work OK in 
a TC if properly derated or if pairs are connected in series. Because 
they are so large (14" x 12" x 4"), they have significant thermal mass, 
so it should take a while to heat them up. And they sure have nice 
"Frankenstein-looking" insulators...  :^)

Bert
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