Insulated wire, electrical equipment, and method of producing an insulated wire
View Patent ↗An insulated wire, containing: a conductor; a foamed insulating layer; and an unfoamed filled layer on the outer circumference of the foamed insulating layer, in which the filled layer contains a partial discharge resistant material, which insulated wire has all of high partial discharge inception voltage, resistance to partial discharge, heat resistance, and abrasion resistance (scratch resistance).
1. An insulated wire, comprising:
a conductor;
a foamed insulating layer obtained by foaming a thermosetting resin; and
a non-foamed layer on an outer circumference of the foamed insulating layer,
wherein the non-foamed layer contains microparticles of a partial discharge resistant material in an amount of 30% by mass or less relative to a resin, and
wherein the foamed insulating layer has a thickness of 30% or more of the sum of a thickness of the foamed insulating layer and a thickness of the non-foamed layer.
2. The insulated wire according to claim 1 , comprising a second non-foamed layer on an inner circumference of the foamed insulating layer.
3. The insulated wire according to claim 1 ,
wherein the foamed insulating layer is a layer obtained by laminating plural foamed layers having the non-foamed layer on both or one of an inner circumference and the outer circumference thereof.
4. The insulated wire according to claim 2 ,
wherein the foamed insulating layer and/or the second non-foamed layer on the inner circumference thereof contain the microparticles of a partial discharge resistant material.
5. The insulated wire according to claim 1 ,
wherein the partial discharge resistant material is titanium dioxide or silica.
6. The insulated wire according to claim 1 ,
wherein the foamed insulating layer and the non-foamed layer are composed of polyimide or polyamideimide.
7. The insulated wire according to claim 1 ,
wherein a layer composed of the foamed insulating layer and the non-foamed layer has a relative dielectric constant of 4 or less.
8. The insulated wire according to claim 1 ,
wherein the foamed insulating layer has an average bubble size of 5 μm or less.
9. A method of producing the insulated wire according to claim 1 , comprising the steps of:
applying a thermosetting resin varnish on the conductor directly or via the non-foamed layer; and
baking the thermosetting resin varnish thereby to foam the same during the baking step and form the foamed insulating layer.
10. An electronic/electrical equipment, comprising the insulated wire according to claim 1 in a motor or a transformer.