Re: viynl instead poly
From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: bert.hickman-at-aquila-dot-com
Sent: Saturday, November 15, 1997 10:43 AM
To: Tesla List
Subject: Re: viynl instead poly
Tesla List wrote:
> From: Raymond C. Howes[SMTP:rchowes-at-email.msn-dot-com]
> Sent: Friday, November 14, 1997 8:37 PM
> To: Tesla List
> Subject: viynl instead poly
> Does any one know anything of viynl plastics?
> Here in Florida they use it to enclose screen porches. It's pretty thick at
> least 1/16 thick.Realy stretchable. I haven't been able to find anything
> about it from the manufacturer except the thickness and how long it stays
> flexible,years in the sun.
> Just wondering if it could be used in building caps?
> rchowes-at-msn-dot-com any thing on the subject
> would be appreciated.
Could be a variety of different formulations, but most likely polyvinyl
acetate (like heat sealing material) or polyvinylidene chloride (like
Saran wrap). In any event. while the vinyls have good DC voltage
breakdown strength, they tend to also have relatively high dielectric
loss. This means that a significant portion of energy will be expended
in heating the cap's dielectric rather than heating the air as
streamers. Caps made from lossy materials tend to perform poorly, and
heat up excesively. Once an internal "hot spot" forms, it rapidly leads
to flashover and failure of the dielectric. With some materials this is
like a "thermal runnaway" condition - the hotter the dielectric gets,
the more the losses, etc. This is why Mylar makes for great DC filter
caps but lousy Tesla Coil caps. Stick with polyethylene or polypropylene
for best results.
Safe cappin' to you!
-- Bert --