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Re: need capacitor information
Subject: Re: need capacitor information
Date: Thu, 29 May 1997 19:45:54 +0500
From: "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
In a message dated 97-05-26 00:07:31 EDT, MSM write:
> I recently found a 12kv 60ma sign transformer and I have been
> designing the tesla coil on paper.
>
> I have designed the primery and secondary but I need some information
> about the primary capacitor.
>
> I need to know the dielectric constants and voltage resistance per mil
> of polypropelene, polyethelyne, polystyrene. etc. so I can use the
> capacitance formula to design the cap.
>
> If someone has a table with this information of can help in any other
> way it would be much appreciated.
By voltage resistance per mil, I assume you mean dialectric strength
or puncture voltage. Below is a copy of a table produced by Richard
Quick some time ago.
=====================================================================
Dielectric strength Puncture Voltage
Material K per Mil(0.001 inch)
---------------------------------------------------------------------
Miscellaneous
-------------
Vacuum 1.0
Paper, bond 3.0 200
Paper, Royal Grey 3.0 200
* Paper, telephone, treated 2.5 - 4 200 - 250
Paper, Parafin Coated 2 -3.5
Paper, Kraft 2.2
Oil, Castor 4.67
Oil, Mineral, Squibb 2.7 200
Oil, Mineral 2.2
* Oil, Transformer 2.1 - 2.5 75
Rubber 3.0
* Rubber, Hard 3.0 160 - 500
1 Rubber, Vulcanized 3.2 - 3.9
Fibre 5.0 - 7.5 150 - 180
Fibre, Red 5.0
Mica 4.5 - 8.0 3800 - 5600
Mica, Ruby 5.4 3800 - 5600
Quartz 3.8 - 5.0 1000
* Quartz (Fused) 4.2 150 - 200
Shellac 2.5 - 4.0 200 - 400
Spar Varnish 4.8 - 5.5
Steatite, low loss 5.8 150 - 315
Steatites (Magnesium silicate,etc)5.5 - 7.5 200 - 300
2 Cambric (Varnished) 4.0
Alsimag 196 5.7
3 Gutta Percha 4.0
4 Amber 3.0 - 7.0
Resin 2.48 - 2.57
Enamel 5.1 450
Mycalex 7.4 250
Silicone RTV 3.6 550
Wood 2.0 - 5.2
* Wax (Parafin) 2.1 - 2.5 250 - 450
Beeswax 2.9 - 3.0
5 Slate 7.0
Barium titanate(25 C) 1200
Bariam titanate 6000
Titanium dioxide 125
Cellulose acetate 3.3 - 3.9 250 - 600
6 Casein, Moulded 6.4
A Polytetraflourethylene 2.0
Aluminum oxide 8.7
Tantalum pentoxide 22
Glass
-----
Glass 4.8 - 10 300
Plate Glass 6.8 - 8.4
Pyrex Glass 4.8 - 10 335
Window Glass 7.6 - 7.8 200 - 250
Ceramics
--------
Cordierite ceramics 5.0 - 5.5 100
Magnesium titanate ceramic 12 - 18 150
Porcelain 5.1 - 7.5 40 - 280
Titanium dioxide ceramic 70 - 90 100
Titanium-zirconium dioxide ceramic40 - 60 150
Plastics
--------
Bakelite 4.4 - 5.8 300
Bakelite, Mica filled 4.7 325 - 375
Epoxy Circuit Board 5.2 700
7 Formica 4.6 - 4.9 450
Nylon (lowest values of 3 types) 3.2 407
PVC (rigid type) 2.95 725
Plexiglass 2.8 450 - 990
Polyethylene 2.2 - 2.3 450 - 1200
Polycarbonate (Lexan) 2.96 400
Polyethylene Terphthalate (Mylar) 3.0 - 3.1 7500
Polystyrene 2.5 - 2.6 500 - 700
Teflon 2.1 1000 - 2000
Gases
--------
Air (dry air at 1 atm) 1.0006 30 - 70
* Air (20 atm, 19 deg. C) 1.0108 500
* Carbon dioxide ( 1 atm, 0 deg. C) 1.000985 36
Carbon dioxide (20 atm, 15 deg. C)1.020
* Hydrogen (1 atm,0 deg.C) 1.000264 26.1
Liquids
--------
Ammonia (liquid) 22
Benzene 2.28
8 Carbon tetrachloride 2.24
9 Chlorinated diphenyl 6.5
Ethyl Alcohol (O C) 28.4
Ethyl alchohol (20 deg.C) 25.8
Methyl alchohol 33.1
Water (distilled) 80 - 81
LEGEND:
* = Measured in Kilovolts per centimeter. All others are Volts
per mil (.001 inch) unless otherwise stated.
1 = Vulcanized means it has been melted, or heated in some
way.
2 = Cambric is a finely woven white linen or cotton fabric.
3 = Gutta Percha is a rubbery substance made from the latex of
tropical trees and is used in insulation, waterproofing,
and dentist use it in thin sheets sometimes when working
on teeth.
4 = Amber is a hard, translucent, yellow, orange, or brownish yellow
fossil resin, used in making ornamental objects like jewelry.
5 = Slate is a fine grained metamorphic rock that splits into
thin smooth faced layers. Black Boards for writting are
made of this. Also used as roofing material in some areas.
6 = Casein is a white, tasteless, oderless milk and cheese protein
used in the manufacture of plastics, glues, paints, and food. The
word 'moulded' means it has been shaped by a mold.
7 = Formica is a trademark for any of various high-pressure laminated
plastic sheets of melamine and phenolic materials used for
chemical and heat-resistant surfaces.
8 = Carbon tetrachloride is a very toxic substance. It has also been
shown to cause cancer in lab animals. It is banned in most labs.
It is a liquid that was used as a strong solvent.
9 = Chlorinated diphenyl is a liquid dielectric that is used to
impregnate Kraft paper in small A.C. capacitors. This is a PCB
and may cause cancer, handle carefully.
A = Polytetraflourethylene films retain good properties even at 200
degrees Celsius (200 C).
atm = atmospheres (pressure of air at sea level is 1 atm).
deg.C = degrees Celsius.
Warning - Some liquids and gases listed may be explosive under the
right conditions. Many solids can catch fire and burn. Use
CAUTION and GOOD COMMON SENSE.
Note: Some books gave very different values for each substance so I
have given you the highest and lowest values reported. The
values will depend on the purity of the substance your using.
If you know your substance is very pure then use the higher
value reported. If you know your substance is contaminated or
of poor quality then use the lower values reported. If you have
unknown purity then use the average of the values given.