Litz wire for use in Boost PFC inductor winding?....informative datasheets available?

[opampsmoker]

Hi,
Does Anybody know of any off-the-shelf vendors of Litz wire for winding of Boost PFC inductors? (We need Litz as the coil will be near a gap in the ferrite and exposed to the fringing field)

We know of Furukawa TEX-ELZ, but we don’t need the triple insulation, and would like more strands than the seven that TEX-ELZ gives….

TEX-ELW TIW Litz:
https://www.furukawa.co.jp/tex-e/en/product/texelz.html

Other than Furukawa, none of the Litz wire vendors offer a Litz wire datasheet with sufficient info on it for you to decide if the wires were suitable or not (eg, they don’t give the insulation rating, don’t say if its solderable, don’t give the overall max outer diameter, etc etc).

Power integrations recommend “served Litz Wire” (anything from 40 to 60 strands of AWG38) in all of their PFC Application notes eg DER-484. I contacted Power integrations for the part number, and they just gave me two company names, “mwswire.com” and “newenglandwire.com”. However, I contacted mwswire.com, and they just emailed me back and told me to ask Power integrations which Litz wire part number they were referring to.

Does anybody know of any Litz datasheets for offtheshelf Litz wire that we can look at?

We need an insulation test rating of 500VAC for 1 minute at <500uA.

 

[ronsimpson]

For a Boost PFC inductor, why do you need 500VAC insulation? The two ends of the inductor should never see each other. I often put tubing on the wire as it inters and exits the transformer. Inside the transformer wind in layers neatly. If you are worried, add one layer of tape between each layer of wire.

A PFC inductor will have 400 volts end to end worse case. (actually less than that) If you wind down and back, down and back so you have four layers then the worse case is 200V from one layer to the next. You can also wind Left to Right, + Left to Right+ Left to Right + Left to Right in 4 layers and have only 100V/layer.

Litz wire has "magnet insulation" that is not great, but that is what we wind with. Same as all their magnet/transformer wire. Now Furukawa wire is very different.

 

[opampsmoker]

why do you need 500VAC insulation?

Thanks, we have to have some level of insulation , and we figure that "500VAC, 1minute, 1mA" is easy to achieve and does the job.
As we've just found out, Litz wire is always a custom build, eg "60 strands of AWG#38, Max out diam of xxxx, solderable coating, and insulation to 500VAC, 1minute, 1mA".
There is so little inductor and transformer manufacture in the west now, that the only place you can get off the shelf litz for our use, is China...but the Chinese only sell it to their own manufacturers.
When we send the quote, we have to send a spec, so we picked "500VAC, 1 minute and 1mA.".....even standard enamelled copper wire would pass this so we guess its going to be ok for the quote...you have to give them something to go on