I have recently aquired 3 very large transformers. At least one is useless and needs to be rebuilt. I have been to the library, on the net, everywhere, and I can find very little practical information on how to tear apart/rebuild a transformer, especially when it needs to be rewound for high voltage.
For those in the know, here are just a few questions:
1) The windings on there now are potted in what looks like formvar resin or similar compound. Is there any way to remove this stuff?
2) What kind of insulation requirements are encountered when winding a HV transformer? In theory, the insulation needs a rating of V/n/m + s, where V=volts, n=turns, m= layers, and s=safety factor. That is inferred from the info I DID find.
3) What are the advantages/disadvantages of winding on the outer legs vs. on the middle leg?
One place that has *some* good information is listed below. It is more for small, low voltage transformers though.