Re: insulation testing

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

Original poster: "Sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sundog-at-timeship-dot-net>

Hi All,

For basic insulation testing, I use a NST and a full-wave rectifier.  I 
submerge the part to be tested (say a loop of enameled magnet wire) in a SW 
bath and put the negative lead of the FWR in the bath, and the positive to 
the item to be tested.  Then I bring up the voltage with a variac and watch 
the amp-clamp on the NST primary.  When the current spikes, that usually 
means it's broken through the insulation.  This is a pretty basic and crude 
test, but it works for me.

Shad G2-1203

   At 12:11 PM 3/30/02 -0700, you wrote:
>Original poster: "PotLuck by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><potluck-at-xmission-dot-com>
>
>Hi List,
>Has anyone done home insulation testing? I'm primarily interested in whether a
>material will "hold off" a certain voltage or not. I see on the net in
>commercial testing such tests for power factor tests, power losses and
>monitoring of currents in the uA area. These of course are important 
>properties
>of a material but may be a little too in-depth for home testing and the
>properties I'm looking for.
>
>The voltages I'm interested in looking at are in the range of ~7.5Kv at 60Hz,
>not in the RF range inherent in normal tesla coil operations.
>
>Any suggestions as to an "apparatus" that can be made easily? I have various
>NSTs, variacs and transformer oil at hand along with a scope and several
>multimeters.
>
>Simply using a two electrodes with the material in question placed between 
>them
>(not under oil) sometimes produced a purple haze or what appears to be a
>corona. Allowing the test to run for several minutes with the corona didn't
>appear to form any holes in the material, not by the naked eye anyway, and
>there was no burning. I've looked at mylar, polypropylene and HDPE.
>
>Mylar film (adhesive backed) from McMaster-Carr has a dielectric strength 
>rated
>at 7500 V/mil. with 4mils placed between the electrodes "corona" developed at
>about 4000 volts but no damage to the mylar was apparent. Again this was not
>under oil.
>
>But what is it I'm looking for? Lack of corona? Corona can't be good.
>
>I'm relatively new to the high voltage arena so and advice in this area would
>be greatly appreciated since insulation is a big part of coiling.
>
>Thanks in advance! :)
>
>Rick W.
>SLC