vaccuum insulation?

[raburgeson]

for high voltage after liberally covering with slygaurd would it help to place
a part of a circuit in a vaccuum. Of course I can't afford a great vaccuum
but 15 inches of mercury worth, would that help retard arcing?

[Dinorben]

Well, as someone else mentioned in another thread (which I can't find now) vacuum is not a good insulator. Just as well, really, otherwise vacuum tubes would not work and we would never have gotten electronics.

But I can't see any reason why some sort of grease couldn't be used as an insulator. I don't know what slyguard is but a several millimetre thick plastering of some petroleum jelly might do the trick.

For finished EHT circuits, potting them in epoxy resin does the trick, but that's pretty irreversible 

Dinorben

[raburgeson]

They have come up with some sort of high voltage transformer gas insulation
and I haven't been able to id manufacturers yet but, believe one of them is
Westinghouse.Also I've been trying to redesign capacitors, basically I need
more space between the leads and to cut down the arcing at the edge of
the plates.So I did something stupid that seems to work.High voltage caps.
plates curve away from each other allowing more insulation between them
at the edges.50 cal shells are 2 1/4 inches long.We peened the points rounder
sanded them smooth and melted the lead out of them.Soldered leads to the
back ends of them. Glued them into 1/2 inch pcv pipe with trans former oil
in between them.They work but, pcv pipe conducts at high voltage so
will have to retry with ceramic.(The gas is supposed to be good up to
800KV)

[iceweller]

   "Hard" Vacuum has about the same K as dry air at 1 atm and so approximately the same breakdown curve (Paschen's curve). A rather easy way to insulate a transformer is to submerge it in baked oil, possibly heating it to remove all the air bubbles. This method was often used by Tesla for his HV induction coils. Regarding the pipe, try using a fiberglass one or wood if the operating temperature is not too high.
   Rounding the edges is a must in HV equipment to prevent the concentration of the field in the critical points so try to round off any sharp edges by curving the sharp parts so that it faces the back of the plate or any possible discharge point.

   Regards

[kenbo0422]

Ceramics are a good bet, but be careful which ones you use.  I work with transducer heads and they measure displacement by capacitance. The plates are separated by a ceramic which was recently upgraded because the old style didn't hold up under a megger test.  Caused us to have to recal the system in the field on many occasions.