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RE: silicon oil in capacitors

Subject:  RE: (no subject) silicon oil in capacitors
  Date:   Sun, 20 Apr 97 15:57:31 UT
  From:   "William Noble" <William_B_Noble-at-msn-dot-com>
    To:   "Tesla List" <tesla-at-pupman-dot-com>


the post brought up something I had been wondering about - the use of
DOT5 
brake fluid, which is a light silocone oil (DOT-3 and 4 are glycol
based).  
The oil is non-combustible, stable at VERY high temperatures, and
hydrophobic, 
so it seems ideal.  I'ts also expensive, and typically a pretty color. 
The 
coloring may be a problem if the dye is conductive.  Some motorcycles
use 
DOT5, in general cars don't because of cost (there was a lengthy series
of 
articles a few years back in automotive restoration magazines about it
and 
it's advantages, but that's way off thread here).  If it is potentially 
suitable, it has the following advantages to us small scale guys:

1. fairly readily available in pints (and quarts)
2. not as sticky or messy as mineral oil
3. doesn't burn or eat paint.
4. if the coil doesn't work you can use it in your car (probably not
visa 
versa, unless you don't stop a lot when you drive)
5. less viscous, very low surface tension - (but famous for air bubbles)

So, if this is plausible, what would be a good way of testing it?? I can
put 
my 15KV transformer output leads into some and see how close they come
before 
an arc develops - would that be a good test???

[Bill]  snip
   From:   Kristian Ukkonen <kukkonen-at-cc.hut.fi>
    To:   Tesla List <tesla-at-pupman-dot-com>


On Thu, 17 Apr 1997, Tesla List wrote:

>    From:  Phil Chalk <philoc-at-ozemail-dot-com.au>
> 
> I've been thinking of making a stacked cap from fibreglass PCB.  I read
[Bill]  snip 
> Has anyone ever tried silicone oil in caps ?  Or know of its HV
> properties ?  It's used in
> e.g. high-quality brake-fluids, as I believe it has very good
> anti-hygroscopic properties.

They do use "silicone oils" in caps - but that term applies for
lots of grades, I'd guess.. I'm certain they don't use brake-
fluids for cap insulation commercially :)

> But mainly I'm wondering about PCB caps - any comments ?

It will work - but a LDPE/PP cap will work better.