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High Voltage insulating resin

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xzswq21:
Hello
I want to use a high voltage insulating resin for several high voltage transformers (10kV and 20kV and above) but I don't how I should choose a proper resin:






Thanks

David Hess:
Wax may be an easier to use alternative.  There are specific was formulations intended for potting.

TimFox:
With any potting material, be careful to eliminate bubbles from the final state.  Normally, this is done by pumping a vacuum above the "pot" while the material is still liquid.
Wax is a traditional material:  note that it shrinks drastically at the phase transition between liquid and solid as it cools.

T3sl4co1l:
Beats me.  Have you checked mfg websites (e.g. 3M)?

As I recall, the stuff used in FBTs is extremely hard; probably mineral filled (silica or otherwise?).

And yeah, you definitely want a vacuum pot for that.  You can verify quality in a couple ways, like hi-pot for isolation barriers, but also partial discharge for breakdown around windings -- a pocket of air exhibiting breakdown, is detectable as high frequency (impulsive) emissions, when the part is excited (preferably by a nice smooth sine wave).

Tim

David Hess:
One reason I would avoid random epoxy potting compounds is that some have horrible dielectric loss even without leakage.  Tektronix had a horrible time with this when they initially changed from wax to epoxy.


--- Quote from: TimFox on August 04, 2021, 05:02:59 pm ---Wax is a traditional material:  note that it shrinks drastically at the phase transition between liquid and solid as it cools.
--- End quote ---

That is why I mentioned that there are specific wax mixtures used for potting.

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