Re: [TCML] phillips question about wax and more

[Frank <fxrays@xxxxxxxxxx>]

Hi all,
Beeswax and rosin was found to be the "best" insulating medium for a 
Tesla coil, such as a pancake. Tesla himself found that to be most effective.
All insulating mediums have different characteristics at different 
frequencies, just like capacitors of different materials.
Tesla stated shellacs and varnish are not good insulators for Tesla 
coils but that is all we have today.
Trying to find beeswax or rosin in large quantities at reasonable 
prices is not easy.
The closest substitute are toilet rings for the beeswax. Of course 
that is new rings.

Now insulating medium for a HV transformer can be a variety of 
materials as discussed in this group.
Re-potting a NST without shunts is mainly for heat transfer as you 
are now operating a NST up to 10 times its original rating, you need 
to take the heat away.

Now, when you re-pot a transformer, or motor or even a capacitor, 
there will always be tiny air pockets in and around the windings due 
to surface tension of the insulating medium. Oil is better at filling 
those pockets and wax, varnish, tar, and etc is worse.
These pockets of air are a potential source for arcing due to reduced 
insulation resistance in those areas.

Vacuum impregnation is the only way to remove the air pockets and 
insure the system is at its best for insulation.

As stated, not all of us have means to draw a vacuum on our devices 
but most of us have simple wood working tools.
Pre heat the transformer before pouring the medium, this is very 
important for wax/ tar as the cold iron will cool the wax/ tar and 
form air pockets preventing the wax/tar from effectively insulating 
the windings
Take a vibrating sander and remove the paper, put the pad of the 
sander on the case of the transformer, coil, cap or etc when you are 
pouring the wax, tar, oil or etc. The vibrations will help "pop" the 
air bubbles and get the insulating medium more effectively 
distributed into the windings or plates.
Not as good as drawing a vacuum but works well and simple.

Now, using a ASRSG, there will be periods where the NST is "unloaded" 
and higher voltages will be across the windings. NST's do not like to 
run open circuited at all, they are not insulated to handle the open 
voltage for long periods of time.
As your transformer gets older, it is more susceptible  to shorting 
out as the insulation starts to break down.
This could be a possible reason for your NST dying with a ASRSG.

Frank

At 10:56 PM 6/10/2008 -0500, you wrote:
> While we're on the topic of NSTs, ASRGs are pretty bad for them right?
>  It seems that my NST keeps shorting, and I think it's due to the
> ASRG.
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> http://www.pupman.com/mailman/listinfo/tesla
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