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RE: [TCML] Capacitor encapsulent
Gary,
Thanks for the tip about corona inception, I had never read about this...but it makes sense I'm sure it will save some time and money.
John K.
--- On Mon, 5/25/09, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> From: Lau, Gary <Gary.Lau@xxxxxx>
> Subject: RE: [TCML] Capacitor encapsulent
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Monday, May 25, 2009, 11:57 AM
> No, I don't know what it is for
> HDPE. But it's important to understand that when
> building a reliable cap, it's incorrect to think that
> choosing a dielectric thickness based on X kv/mil and Y peak
> voltage required means you need Z thickness. I think
> there is a non-linear breakdown voltage vs thickness
> relationship. But more importantly is something called
> the corona inception voltage, which means that corona will
> occur if the applied voltage is more than something like
> 650V, regardless of dielectric thickness. As soon as
> corona forms with a plastic dielectric, the dielectric
> degrades rapidly. The CDE caps we use in MMC's are
> actually constructed as two seriesed caps, with a "floating
> plate" between the two terminals, to effectively double the
> corona inception point.
>
> So, unless you build your DIY cap as several seriesed
> units, you will get corona and a compromised life
> expectancy, regardless of dielectric thickness.
>
> Regards, Gary Lau
> MA, USA
>
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx
> [mailto:tesla-bounces@xxxxxxxxxx]
> On
> > Behalf Of John Kirby
> > Sent: Sunday, May 24, 2009 11:50 PM
> > To: Tesla Coil Mailing List
> > Subject: RE: [TCML] Capacitor encapsulent
> >
> >
> > Gary,
> >
> > I think I have seen a table like this before, and the
> dielectric strength was also
> > missing for HDPE. Do you (or anyone) know what
> it is?
> >
> > Regards,
> > John K.
> >
> > --- On Sun, 5/24/09, Lau, Gary <Gary.Lau@xxxxxx>
> wrote:
> >
> > > From: Lau, Gary <Gary.Lau@xxxxxx>
> > > Subject: RE: [TCML] Capacitor encapsulent
> > > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> > > Date: Sunday, May 24, 2009, 9:25 PM
> > > Hi James,
> > >
> > > I've not been able to locate the dissipation
> factor for
> > > common types of bottle and pane glass, but
> realize that all
> > > plastics are not suitable. Here's a list of
> common
> > > plastics with their dielectric constants and
> dissipation
> > > factors. Plexiglas is PMMA, and its dissipation
> factor
> > > is rather poor relative to PE and PP.
> > >
> > > polymer
> > > dielectric
> > > dielectric dissipation
> > >
> > > constant strength
> > > factor
> > >
> > > 50Hz / 1Mhz (Kv/cm)
> > > 50Hz / 1Mhz (x10^-3)
> > > -------- -----------
> > > -----------
> > > -----------
> > > LDPE 2.29 /
> > > 2.28 370
> > > .15 / .08
> > > HDPE 2.35 /
> > > 2.34 --
> > > .24 / .20
> > > PP 2.27 /
> > > 2.25 240
> > > .40 / .50
> > > PVC-plasticized 4-8 / 4-5
> > > 270
> > > 80 / 120
> > > PS
> > > 2.5 / 2.5 200-300
> > > .1-.4/.05-.4
> > > ABS
> > > 2.4-5/2.4-3.8 ~400
> > > 3-8 / 2-15
> > > PMMA
> > > 3.3-3.9/2.2-3.2 140
> > > 40-60/4-40
> > > POM 3.7
> > > / 3.7 400
> > > 5 / 5
> > > PTFE 2.1 /
> > > 2.1 480
> > > .2 / .2
> > > PCTFE
> > > 2.3-2.8/2.3-2.5 550
> > > 1 / 20
> > > PA-6 3.8 /
> > > 3.4 400
> > > 10 / 30
> > > PA-66 8 /
> > > 4 600
> > > 140 / 80
> > > PC 3.0 /
> > > 2.9 380
> > > .7 / 10
> > > PET 4.0
> > > / 4.0 420
> > > 2 / 20
> > > PI 3.5 /
> > > 3.4 560
> > > 2 / 5
> > > PUR-linear 5.8 / 4.0
> > > >300
> > > 120 / 70
> > > PUR-thermoset 3.6 / 3.4
> > > 240
> > > 50 / 50
> > > PUR-thermoplas 6.6 / 5.6
> > > 300
> > > 30 / 60
> > > CAB 3.7
> > > / 3.5 400
> > > 6 / 21
> > > Silicone 3.6
> > > 200
> > > 5-13 / 7
> > >
> > > Regards, Gary Lau
> > > MA, USA
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: tesla-bounces@xxxxxxxxxx
> > > [mailto:tesla-bounces@xxxxxxxxxx]
> > > On
> > > > Behalf Of James
> > > > Sent: Saturday, May 23, 2009 4:28 PM
> > > > To: 'Tesla Coil Mailing List'
> > > > Subject: RE: [TCML] Capacitor encapsulent
> > > >
> > > > Hi Ray, The problem with window glass is the
> iron in
> > > it. The dielectric
> > > > factor of window glass is POOR. Used as a
> Tesla coil
> > > capacitor, it will
> > > > crack and short your cap out. Use some form
> of
> > > plastic. Polystyrene,
> > > > polypropylene, Plexiglas, etc will be much
> better.
> > > Now, you might wonder
> > > > how I know this. It's a secret. James
> > > >
> > > > -----Original Message-----
> > > > From: tesla-bounces@xxxxxxxxxx
> > > [mailto:tesla-bounces@xxxxxxxxxx]
> > > On
> > > > Behalf Of Raymond Magdziarz
> > > > Sent: Friday, May 22, 2009 6:38 PM
> > > > To: tesla@xxxxxxxxxx
> > > > Subject: [TCML] Capacitor encapsulent
> > > >
> > > > I'm building my capacitor using window glass
> and brass
> > > sheets. I plan on
> > > > using paraffin instead of transformer oil. I
> would
> > > draw a vacuum on the
> > > > container while the paraffin is liquid to
> get the
> > > bubbles out and then
> > > > let
> > > > it solidify. Will this work, or what
> problems will I
> > > have.
> > > >
> > > > Ray M.
> > >
> > > _______________________________________________
> > > Tesla mailing list
> > > Tesla@xxxxxxxxxxxxxx
> > > http://www.pupman.com/mailman/listinfo/tesla
> > >
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