Magnet Wire Break Down Voltage

We received this question at our offices and have paraphrased it below.

"We are in a tropical country and have a serious problem with enamel strip during rainy season because of the humidity. Due to the humidity the BDV (Break Down Voltage) is reduced and our customers face problems. We would like to know what are the procedures/ equipment necessary to permanently resolve this problem.

Thank you."

Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

Here are some words of advice that Spectre07 (A magnet wire specialist.) wrote in the Forums some time back:

"Some wire enamels or varnishes are hygroscopic meaning that they will adsorb moisture from the air. This moisture is in form of microscopic droplets of water. Since water does not mix with enamels that are not water based, these droplets are applied to the wire and since water evaporates at a higher temperature than most solvents used in enamel, they become trapped bubbles and, as the wire is heated, the bubbles burst leaving pin holes. Sometimes the next coat of enamel will cover the pin hole(s) and if you get lucky, the wire passes. You can also get pinholes if you get entrapped solvents in the enamel and same thing happens as mentioned with the moisture."

I believe you need to talk to your enamel suppliers so that a non-hygroscopic enamel is selected instead.

Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212

If you cannot get an enamel that is not hydroscopic, you should try to enclose your enamelling supply system. Never leave enaamel exposed to atmosphere, keep supply sealed. Put lids on supply tank. There are other things that you can try but without knowing what type system or wire you are using or making it would be hard to list all the things you might try.