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RE: Cap Material
From: Rick Holland[SMTP:rickh-at-ghg-dot-net]
Reply To: rickh-at-ghg-dot-net
Sent: Thursday, November 27, 1997 1:20 AM
To: Tesla List
Subject: Re: Cap Material
>
> I'll run four rods thru all the sheets and bolt as a block. I'll use 3/8"
> rod and drill 1" holes for rods to slide thru. W1 will be an insulator
> washer to insulate rod from aluminum and center it in 1" holes. W2 will be
> 1 1/2" aluminum jumper washer to make circuit. 2 of the four rods will be
> totaly insulated and the other two rods will alternate insulator/jumper from
> plate to plate. This results in small gap between aluminum sheets.
>
> Is this at all right/possible??
>
> If so....
Hi!
I have a little experience with hommade HV caps (not much), and it
seems to me that you intend to cut this materiel to 11" squares and
apply voltage (simplified). The first and foremost problem I have is
that the dielectric material is the same width as the capacitor plate.
That means that all around the edges you'll have flash-over from one
plate to another. The only solution I see is to encapsulate the entire
thing in a potting compound of equal or greater dielectric quality as
the existing dielectric. If the potting compound bonds seamlessly with
the existing dielectric, it will effectively extend the dielectric
beyond the boundaries of the plates and allow plate charging/discharging
without flash-over.
>
> Can the plates be jumpered in this manner?
Plates can be alternated, and is the most commonly accepted way to add
capacitance without adding bulk.
>
> Can I then leave the paint/coating on and just sand where jumper washers
> make contact?
Any electrostatic protective/dissipative/conductive coating is a
conductor and changes the electrical properties of the capacitor. While
this can enhance the capacity of a plate, it generally decreases the
ability of the plate to work in a pulse discharge manner, dissipating
energy as heat and (usually) causing capacitor failure.
>
> 16 plates, in this configuration are only 4" high when stacked. Would I be
> better off splitting this into four caps hooked in series?
Series stacked caps can handle high voltage far better than a single
stack, since the voltage is divided over several units, but the
individual stacks must be very closly matched in order to distribute the
load evenly.
>
> Will I need to place all in oil bath or will the air in gaps between sheets
> just add to capacitance?
This is a matter for experimentation. Oil has a much higher dielectric
constant than air, so air will not add to your capacitance (as compared
to oil) but you may want to run without oil for several reasons, some of
which were posted on the list earlier today.
>
> What material should I seek for rods? Aluminum?
Aluminum will work fine, if it is heavy enough. Copper or Brass would
work better, but if you're talking about *bolts*, any heavy guage metal
will work fine.
>
> I have no idea what "MEGAFLON" is. How will this anti-static coating affect
> circuitry?
See above, about conductor material.
>
> A sheet of this stuff is basically a cap in and of itself is it not?
It is, indeed, but you have to remember that the distance from one sheet
of metal to another is very small, and if the insulator in between
doesn't stick out far enough, it's a very short trip for an arc of high
voltage.
>
> How in the hell do they then use this material as paneling in skyscraper
> construction? Suppose the janitor started hooking panels together and when
> no one was looking, wrapped a primary and secondary around the 'scraper next
> store? Anyone seen a deal on high voltage cable, say enough to run from
> Niagra to the Twin Towers? That might provide a display worthy of Tesla's
> dreams, heh?
>
> Gosh, must be way past my bed time......
>
> dj
I'll let that one ride...
--
Rick Holland
The Answer is 42.