Re: Dielectric's

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Silicon, the element, isn't a particularly good insulator (it is, after
all, a "semi-conductor").

Silicone (with the "E") is actually a term for a whole raft of polymers,
which have widely different breakdown strengths.  In general, though, most
silicones have fairly high breakdown strength, and, furthermore, have good
high temperature characteristics (why they use it in spark plug wires, for
instance).

Most pure plastics/polymers have high breakdown strength (hundreds of
kV/cm).  The key is "pure".  Small particles, gas bubbles, imperfections,
etc. greatly reduce the dielectric strength.

The real choice among materials is usually made on the basis of things like
mechanical properties (important for structural applications) and
dielectric loss (important for RF applications, like tesla coils).

Some plastics are notoriously bad for HV electrical applications: those
loaded with carbon black (usually for UV resistance); nylon (it absorbs
water easily, reducing the breakdown strength). The disadvantag aren't
necessarily crippling, though, depending on how you use it; Lots and lots
of nylon cable ties have been used in tesla coils, but not in a place where
you depend on its electrical properties. 

Tesla list wrote:
> 
> Original poster: "Richard Raynault by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <raynault-at-home-dot-com>
> 
> Does any one know of a really good high dielectric material like Silicon for
> insulation?
> 
> Also do you know the dielectric strength of Enamal?
> 
> Thanks,
> 
> Richard
> raynault-at-home-dot-com