Re: Dielectric constant table

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader" <tesla-at-lists.symmetric-dot-net> 

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, September 19, 2003 1:31 PM
Subject: Re: Dielectric constant table


 > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
 >
 > Hi,
 >
 > At 10:25 AM 9/19/2003 -0600, you wrote:
 > >Terry F: I know you think you are correct, but just to keep the board
 > >correct. I use mmc capacitors and poly oil capacitors. Oil capacitors are
 > >messy and large but the deliver much more current per pulse than dose the
 > >mmc capacitors. Yes my commercial high power pulse capacitors do supply
even
 > >higher current but 250 pounds each  in a bank of 3 is not very
 > >transportable.
 >
 > Do your commercial pulsed caps perform better than an equal value MMC
 > cap?  Commercial pulse caps will have high peak current ability and

Assuming these are large can capacitors with embedded terminals, there is
nothing a MMC can do to touch their current rating. I doubt these these 250
pound cans are of tesla coil use either, they must be in the uF range at
10's of kV. I have some ~260 pound caps, they are 50kV at around 7uF, pulse
current rating is from 150 to 400kA depending on who I ask. The high voltage
terminal is a 1" diameter bolt. Aerovox no longer has datasheets on my part
number but says they are foil, kraft paper and oil with no plastic, reason
being you get a higher current rating with just impregnated paper vs.
plastic.

 > slightly lower ESR, but that should be far far below what can be detected
 > in a Tesla coil's performance.  If your commercial caps actually perform
 > better, we should find out what is causing the difference.
 >
 > >So please don't say no one makes their own oil filled
 > >capacitors.
 >
 > Ok, very few people still make oil filled caps ;-))  It would be very
 > surprising if the oil filled caps are performing better...

You have to define what you think performance is, and it will vary for
different applications. There is no universal fits all capacitor constructio
n.

I have a General Atomics tesla coil-ish capacitor. The SMALLEST internal
connection is 2" copper ribbon. No sprayed on tinned steel lead comes close
to that (dry rolled poly cap). It was designed for RF and high currents from
the bottom up, not to be sold for $2 from a omponents distributor. It is not
metallized with self healing abilities, nor was it made with a high
probability that it will even short out during notmal use requiring self
healing capabilities.

I don't have a way to measure corona yet, but I suspect this impregnated cap
has little to no corona compared to the little caps in AC usage.

KEN