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Re: additional transformers [rolled caps]
From: DR.RESONANCE[SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Saturday, August 02, 1997 9:59 AM
To: Tesla List
Subject: Re: additional transformers [rolled caps]
To: Peter Electric
You must "bake" the plastic first before use. A controlled temp furnace
simply made with a 75 watt light bulb in a box 4 foot square will do the
trick. Bake for 36 hours at 130 degrees F. prior to use. The problem is
that most plastics (including the construction grade) are slightly
hygroscopic and small amounts of H20 molecules will adhere to the plastic.
This produces surface "creepage" from high potentials which will actually
crawl across the surface of most plastics for several inches unless all
traces of moisture are removed from the plastic. The surface crud you
suspected is in fact usually atmospheric moisture that unless removed will
cause creepage even under oil.
DR.RESONANCE-at-next-wave-dot-net
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Re: additional transformers [rolled caps]
> Date: Thursday,July 31,1997 8:27 AM
>
>
> From: Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
> Reply To: elekessy-at-macquarie.matra-dot-com.au
> Sent: Thursday, July 31, 1997 6:15 AM
> To: Tesla List
> Subject: Re: additional transformers [rolled caps]
>
> Tesla List wrote:
> >
> > From: richard hull[SMTP:rhull-at-richmond.infi-dot-net]
> > Sent: Wednesday, July 30, 1997 1:27 PM
> > To: Tesla List
> > Subject: Re: additional transformers
> >
> > >Just though I'd throw in my two bobs worth after having blown up a few
> > >rolled poly caps!
> > >
> > >All of mine failed at the edges (even being under oil) so I reckon the
> > >secret is to put big overlaps between the plastic and the Al plates
i.e.
> > >at least an inch or more. Also here the thick poly sheet is bloody
> > >expensive! so use multiple sheets of 8 mil concreters plastic,
> > >preferably the clear stuff but if all else fails use black plastic
with
> > >engine oil! It ran ok on my coil for more than 3 months.
> > >
> > >Cheers,
> > >
> > >Peter E.
> > >
> > >Peter,
> >
> > I recommended leaving a full 2" edge separation metal to edge of
dielectric
> > in all rolled capacitors!
> >
> > Richard Hull, TCBOR
>
> Thanks for the info on that, I will go 2" on my future overlaps. It
> seems strange to me that sparks seem to travel much further along the
> surface of an insulator, no matter how clean it seems to be. Maybe this
> is due to microscopic impurities on the surface of the plastic?
>
> Another little trick that you probably have already figured out is to
> insulate the input connections to the plates by rolling a few layers of
> poly around them.
>
> Cheers, Peter E.
>
>
>