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Re: HomeMade Poly Cap...Tricks
The more sheets you try to roll up the harder it gets. If you can get 6
mil poly at the lumber yard it will be much easier to roll up than 4 mil
poly. Also the longer the sheet are the harder it is to roll up and keep
it all lined up straight.
I have made several rolled caps and have discovered a few tricks to make it
easier. I make a rolled cap rated .01 uf 40,000. volts. The caps actually
test .0106 uf. I use 18 sheets of 6 mil poly to get 108 mil thick for
40,000. volts. I cut the poly sheets 14" wide by 222" long. The aluminum
flashing is 10" wide and I cut it 108" long with a tab 1" wide by 12" long
for connection. The tab is folded out 90 degrees to the side. I lay the
aluminum flashing on top of 9 sheet of poly and fold the poly over the
aluminum so there is poly on both sides. Then I make another one and lay
them on top of each other so that one tab is on the left side and the other
tab is on the right side.. Once they are rolled up I get 18 sheets of
poly between the plates. It is hard to keep all 18 sheets of poly together
while rolling it up, that is why I fold the poly over on one end, it keeps
it all together and lined up on that end. Cut a piece of 1" diameter pvc
pipe 14" long and put it on the end that is folded over and start rolling.
Have a friend help you keep all 18 sheet of poly straight and lined up the
best you can. Roll it up slow and very tight then put a piece of tape
around the thing to hold it together. It will slide very nicely into a
piece of 6" pvc pipe 15" long. As you slide it into the pvc pipe remove
the tape if you want. I have tried it both ways removing the tape and
leaving the tape on and its works best to leave the tape on. Usually after
removing the tape the cap will unroll just enough that it won't fit into
the 6" pipe then I have to start over and roll it up again. Drill and tap
the pvc end caps for 1/4" bolts for electrical tab connections. Drill and
tap one pvc end cap 18" NPT pipe threads for a vacuum pump. Attach the
tabs to the end caps with the bolts and glue on the ends. Stand the cap up
on end and pump a vacuum then back fill it with oil and plug the hole. It
is now ready to use. It takes me 2 hours from start to finish to build one
of these caps and they cost me $47.00 each..
.005 uf capacitor. Aluminum flashing is 10" wide by 48" long with a tab of
1" wide by 10" long. The polyethylene is 16
sheets of .006 mil 14" wide by 112" long. The rolled capacitor is placed
inside of a 4" PVC pipe. I had no trouble keeping
things lined up while rolling this cap.
.0025" uf capacitor. Aluminum flashing is 10" wide by 27" long with a tab
of 1" wide by 9" long. The polyethylene is
16 sheets of .006 mil 14" wide by 58" long. The rolled capacitor is placed
inside of a 3" PVC pipe.
.0014" uf capacitor. Aluminum flashing is 5" wide by 27" long with a tab of
1" wide by 9" long. The polyethylene is
16 sheets of .006 mil 9" wide by 58" long. The rolled capacitor is placed
inside of a 3" PVC pipe.
By placing different values in parallel you can get any value you need for
your coils.
I have several photos I can email you if you want. weaver77-at-home-dot-com I
also have all the photos on my web page. I switcher internet services last
month and my web page has not been removed yet. I expect my web page to be
removed at any time. You can check my web page at
http://home.earthlink-dot-net/~gweaver I will have a new web on the new
service as soon as I get some free time.
Gary Weaver
Tesla List wrote:
> Original Poster: "Michael Novak" <acmnovak-at-execpc-dot-com>
>
> Hi All,
>
> In the coming weeks I plan to make a rolled poly cap for my medium
> power TC...
> Okay, here's the catch: The plastic I can get is approx. $6 per 250 sq
> ft roll which is 4 mil. In order to conservatively rate my cap I'll
> need at least 70 sheets per cap (I'm planning on making 3; then putting
> them in parallel... ) Does that sound like alot of cutting for one
> cap? The sheets must be 16" x 150" (40mm x 375mm for all you metric
> coilers) which must be as perfect as possible.
> Does 1/2 kV per mil sound okay as a voltage rating for LDPE (low
> density polyethylene) ? Also, does anyone know where to find some real
> bonafide High Voltage Oil like that found in pole pigs?
> This is my first rolled cap so I thought I would get some advice
> before spending all my time cutting out LDPE and ending up with a big,
> useless pile of it.
>
> Thanks
>
> -Michael