Magnet wire with a semi-conductive insulation layer

Abstract

Magnet wire improved partial discharge performance may include a conductor, a first layer of polymeric enamel insulation formed around the conductor, and a second layer of polymeric enamel insulation formed around the first layer. The second layer may be a semi-conductive layer that includes a base polymeric material and filler particles dispersed within the base polymeric material. Additionally, at least sixty percent by weight of the filler particles may be positioned in an outer half of a thickness of the second layer.

That which is claimed: 
     
         1 . A magnet wire comprising:
 a conductor;   a first layer of polymeric enamel insulation formed around the conductor;   a second layer of polymeric enamel insulation formed around the first layer, the second layer comprising a base polymeric material and filler particles dispersed within the base polymeric material,   wherein at least sixty percent by weight of the filler particles are positioned in an outer half of a thickness of the second layer.   
     
     
         2 . The magnet wire of  claim 1 , wherein the filler particles comprise one of a metal or a metal oxide. 
     
     
         3 . The magnet wire of  claim 1 , wherein the filler particles comprise at least one of tin oxide, indium oxide, silver, or gold. 
     
     
         4 . The magnet wire of  claim 1 , wherein the base polymeric material comprises one of polyimide or polyamideimide. 
     
     
         5 . The magnet wire of  claim 1 , wherein at least seventy-five percent by weight of the filler particles are positioned in the outer half of the second layer. 
     
     
         6 . The magnet wire of  claim 1 , wherein at least twenty percent by weight of the filler particles are positioned at an outer surface of the second layer. 
     
     
         7 . The magnet wire of  claim 1 , wherein the second layer comprises:
 a first surface adjacent to the first layer; and   a second surface opposite the first surface,   wherein a first surface resistivity of the second layer at the first surface is higher than a second surface resistivity of the second layer at the second surface.   
     
     
         8 . The magnet wire of  claim 7 , wherein:
 the first surface resistivity is greater than 10 12  S2/square, and   the second surface resistivity is less than 10 9  Ω/quare.   
     
     
         9 . The magnet wire of  claim 1 , wherein the filler particles comprise between five percent and twenty percent by weight of the second layer. 
     
     
         10 . The magnet wire of  claim 1 , wherein the second layer comprises an outermost layer of the magnet wire. 
     
     
         11 . A magnet wire comprising:
 a conductor;   a first layer of polymeric enamel insulation formed around the conductor;   a second layer of polymeric enamel insulation formed around the first layer, the second layer comprising a base polymeric material and filler particles dispersed within the base polymeric material,   wherein the filler particles are not uniformly dispersed within the second layer, and   wherein a first surface of the second layer adjacent to the first layer has a first surface resistivity and a second surface of the second layer opposite the first surface has a second surface resistivity that is less than the first surface resistivity.   
     
     
         12 . The magnet wire of  claim 11 , wherein:
 the first surface resistivity is greater than 10 12  Ω/quare, and   the second surface resistivity is less than 10 9  Ω/square.   
     
     
         13 . The magnet wire of  claim 11 , wherein the filler particles comprise one of a metal or a metal oxide. 
     
     
         14 . The magnet wire of  claim 11 , wherein the filler particles comprise at least one of tin oxide, indium oxide, silver, or gold. 
     
     
         15 . The magnet wire of  claim 11 , wherein the base polymeric material comprises one of polyimide or polyamideimide. 
     
     
         16 . The magnet wire of  claim 11 , wherein at least sixty percent by weight of the filler particles are positioned in an outer half of a thickness of the second layer. 
     
     
         17 . The magnet wire of  claim 11 , wherein at least twenty percent by weight of the filler particles are positioned at an outer surface of the second layer. 
     
     
         18 . The magnet wire of  claim 11 , wherein the filler particles comprise between five percent and twenty percent by weight of the second layer. 
     
     
         19 . The magnet wire of  claim 11 , wherein the second layer comprises an outermost layer of the magnet wire. 
     
     
         20 . A magnet wire comprising:
 a conductor;   a first layer of polymeric enamel insulation formed around the conductor, the first layer comprising one of polyimide or polyamideimide;   a second layer of polymeric enamel insulation formed around the first layer, the second layer comprising a base polymeric material comprising polyimide and tin oxide filler particles dispersed within the base polymeric material,   wherein at least sixty percent by weight of the tin oxide particles are positioned in an outer half of a thickness of the second layer.