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RE- Dielectric Constants and Breakdown Voltages (fwd)
From: Robert Michaels [SMTP:robert.michaels-at-online.sme-dot-org]
Sent: Thursday, November 13, 1997 12:07 PM
To: tesla-at-pupman-dot-com
Subject: RE- Dielectric Constants and Breakdown Voltages (fwd)
Ach du Liebe! Gott im Himmel!
Are you interested in Tesla-coiling, or in making fruit
salad -- I mean you've got a really good mixture going
there: grapes & grapefruit; apples, oranges & an orangutan.
- - - - - - -
The puncture voltages given in published tables are for
dc -- as in =direct current=. Men and women do not
behave alike, and dc and ac do not behave alike. Trust
me on both accounts. A 250,000-v. Van DeGraaff generator
does not perform like a 250,000-v. Tesla coil. Really.
Nor either is Tesla's polyphase ac system of
power generation and distribution like Edison's
dc system. Dc and ac are different -- as
different as male and female (even if it isn't
politically-correct to say that anymore).
So, =lose= the -at-$%#-at-^-at-!!&^&%$ puncture voltage tables
unless you have one assuredly made with Tesla currents
(and then I'll want to know the frequency of those
Tesla currents)!
If you're overtaken some dark night with
an irresistible urge to post a puncture-
voltage table to a mail list -- post it
to the High-Voltage List. That is where
dc calls home.
This in the interest of logic, staying on
topic, and not misguiding the uninformed
(a multitude, as it would seem).
- - - - - - - -
You write "I recall some comment that Mylar is not good
for caps ..."
That's like "recalling" some "comment" that Thou Shalt
Not Kill.
This is not a "comment". It's a Commandment --
11. Whomsover shall employ any polyester capacitor
in any Tesla coil, so also shall remorse be
visited upon him and upon his circuits, forever,
and forever, and forever (or, at least until
he gets rid of the damn polyester) - Amen.
It has thus been written:
--------------------------------------------------
If anyone offers you a polyester capacitor
(or leisure suit) -- run a mile.
(Gospel according to Michaels)
--------------------------------------------------
Keeping the faith
(and the physics),
-- in Detroit, USA
Robert Michaels
TL>From: DamDeName-at-aol-dot-com [SMTP:DamDeName-at-aol-dot-com]
TL>Subject: Re: Dielectric Constants and Breakdown Voltages (fwd)
TL>Hello all,
TL> With regard to the puncture voltage an dielectric
TL>constant of mylar -- 7500 v ? (not 750 v ? )
TL> In either respect --- I recall some comment
TL>that mylar was not good for caps for T.C. service --
TL>if this is so (meaning my memory is not failing me) :>)
TL>howcome ??? --- It seems worthwhile esp.if the 7500
TL>V/mil is accurate ---
TL>regards,
TL> Sandy
TL> ---------- Forwarded message ----------
TL> Date: Fri, 7 Nov 1997 19:32:37 -0700
TL> From: Ken & Pat Prentice <prentice-at-sympatico.ca>
TL> To: tesla-at-pupman-dot-com
TL> Subject: Dielectric Constants and Breakdown Voltages
TL> Good day Ladies and Gentlemen
TL> I'm new and have been lurking for some time.. and thought that this
TL>might help as a quick reference... I found this in one of the old electronic
TL>mags. (set your font Courier to see this properly)
TL> INSULATOR DIE..CONST. PUNCTURE VOLTS/0.001 inch
TL> ==================================================================
TL> Air.................................1.0......... 30
TL> Window Glass........................7.8......... 200
TL> Polyethylene........................2.3......... 450
TL> Paper (bond)........................3.0......... 200
TL> Polycarbonate (Lexan)...............2.9......... 400
TL> Teflon..............................2.1.........1000
TL> Polystyrene.........................2.6......... 500
TL> Epoxy Circuit board.................5.2......... 700
TL> Pyrex................................4.8......... 335
TL> Plexiglas...........................2.8......... 450
TL> PVC (rigid type)....................2.9......... 725
TL> Silicone RTV........................3.6......... 550
TL> Polyethylene Terphthalate (Mylar)...3.0.........7500
TL> Nylon...............................3.2......... 407
TL> Mineral Oil, Squibb.................2.7......... 200
TL> Shellac.............................3.3......... 200
TL> All measured at 1 MHz