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LDPE Caps for 15kv Pulse

 * Carbons Sent to: usa-tesla-at-usa-dot-net
                    marcusy-at-ozemail-dot-com.au

Quoting Marcus Young <marcusy-at-ozemail-dot-com.au>:

> Anybody know if 120mills ( 3mm ) of low-density polyethelene 
> will be sufficient dielectric thickness for a 15kv system?

Should work just fine if the material is dye-free virgin plastic
(no recycled content) that is free from defects in the material
and everything is very clean during the construction.

> I'm using a hospital-grade material, as the stuff at the
> hardware seemed pretty poor quality.

There you go!

> It was speckled with little grains of 'crap' (????) embedded in
> it. (just asking for trouble! ) 

This particular grade of plastic sounds like it contained a
substantial precentage of recycled material.

> My new Magnifier system will employ the series 'equidrive' 
> system. The pair of series caps will use 60mills each. I can 
> increase the voltage on the transformer to around 17kv with the
> variacs'  overwind. Do you think they can handle it ? Should I
> change the variac tap to limit voltage to 15kv?

My experience shows that at 17kvac rms with pulse discharging
(i.e. Tesla tank circuit application) the dielectric should
survive, but this is running about the limit.

> I want these suckers to be 'bulletproof' !   :) 

Then place two caps (120 mil dielectric in each) in series.

> I was told that LDPE can take 500V per 1/1000 inch. Does that 
> sound right?  

This depends on the construction and application, whether they
are dry fired or submerged in oil. The 60 mil plastic will hold
up pretty well to 10kvac rms pulse application if it is submerged
in oil. That works out to about 167 volts per mil in this
application. Strangely enough, the 120 mil plastic will probably
come in around 140 volts per mil dielectric strength.

Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12