Electronics > Projects, Designs, and Technical Stuff
High temperature thin dielectric or insulating coatings for bare copper coils?
Conrad Hoffman:
BTW, can you vacuum impregnate? That helps fill everything for mechanical stability and eliminates air pockets that can encourage arcing.
duak:
Glyptal 1201 is the original product used in electrical equipment and engines but it's only good for 130 C.
Motors can be rated for class H which is 180 C winding temperature. Here's a description:
"Class H insulation consists of materials such as silicone elastomer and combinations of materials such as mica, glass fibre, asbestos etc., with suitable bonding, impregnating or coating substances such as appropriate silicone resins. Other materials or combinations of materials may be included in this class if by experience or tests they can be shown to be capable of operation at the Class H temperature."
Glyptal makes high temperaure silicone based products but it seems to have aluminum powder mixed in to give it a particular color. It probably does wonders for thermal conductivity but would also make it useless for electrical insulation. I'll bet someone does make a high temp insulating silicone - just a matter of finding it.
I wonder if the windings could be packed in silicone thermal grease and then cointained so that the ATF doesn't wash it away?
Best o' luck,
trobbins:
Are multiple coils (each of 4-5 turns) located in a slot?
Is the length of turn so long that you really do need thermal transfer in between turns to conduct heat from an enclosed turn? Due to the cross-sectional area of a turn, it appears most heat transfer would be occurring along each copper turn to where you are actively cooling the copper at the ends of the rotor, as compared to through the slot liner, or through presumably an air gap to the stator?
With that size of copper, it seems a bit strange from a packing efficiency perspective that you are then requiring such a thin insulation covering.
Are there AC losses in the coil due to some form of switchmode generation of currents? If so, then is that a significant loss contributor due to skin and proximity effects?
Conrad Hoffman:
There are ceramic coatings that can be painted on and fired, also plasma sprayed. I'd start here- https://www.aremco.com/
magicsmoke:
--- Quote from: Gyro on February 09, 2020, 05:58:12 pm ---Glass fibre sleeving?
If it's for motor use (a high vibration, high force application) then you need something to prevent winding 'shuffle'' - tight wedging, high temperature vacuum encapsulation or both. The porous glass fibre would help you there.
--- End quote ---
Unfortunately, glass fiber sleeving is too thick and won't easily go over some of the non-uniformities of the coil. I am trying to get a really high slot fill.
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