Yes that is probably realistic from their point of view. They probably never dream that there are people trying to use the stuff for other than structural purposes.
Winding temperatures on many of these machines are exceeding 400F at the centre of the coils so it is way beyond anything the manufacturers would have in mind.
Realistically I would consider 120C a sensible limit but many are pushing things to 180C or more so it is just a case of how long will it last in normal wind conditions where the peak power is only seen for brief periods occasionally.
There are polyester class F insulating varnishes based on the styrene system used for fibreglass so I suppose you could expect operation in excess of 120C for a decent time.
Vinyl ester is better so it may stand true class F temperatures reasonably well. Epoxy varies dramatically, most structural epoxies are not a lot of good over 100C. There are special class H epoxies used in motor vpi windings that will run at 200C and still have strength but they are special and I doubt you will find a source that you can manage.
There seems to be little investigation done on true temperatures or what materials will reasonably stand. Many have found a working compromise that gives a balance between temperature rise, life and power out. Much could be done in this respect but it is not on my list of priorities I opted not to run machines in this stalled inefficient mode years ago for other reasons and I wouldn't expect any of my machines to reach 100C so this is not an issue.
Flux
