Abstract: Arc-confining structure for an electric circuit interrupter has an arc-exposed portion constructed of an electrical insulating material that is the thermosetting reaction product of the constituents of a mixture consisting essentially of the following constituents in the following percentages by weight of the mixture:(a) 25 to 55 percent granular high-forsterite olivine,(b) 20 to 50 percent of a second granual constituent consisting essentially of silica sand, and(c) 15 to 28 percent phosphoric acid.The mixture is essentially free of asbestos.

Abstract: This surge suppressor comprises a tubular insulating housing having a metal end cap at one end and an integral end wall at its opposite end. A metal terminal extends through the end wall and has a portion within the housing. A stack of metal-oxide varistor blocks has one end bearing against said terminal portion and an external periphery spaced from the surrounding wall of the housing. A metal plate at the other end of the stack is urged against said other end of the stack by a spring between the end cap and the plate. A plurality of ceramic rods fixed to the end wall extend alongside said stack and through holes in the end plate and serve to limit such lateral motion of the stack as produced by vibrations and mechanical shocks.

Abstract: This current-limiting fuse comprises a fusible element having a predetermined location at which an arc will be initiated when prolonged overcurrents of relatively low value have persisted for a predetermined duration. For increasing the arc voltage developed by said arc, an electrical insulating member is disposed about the fusible element in a position where at least a portion of the arc will burn within the insulating member and cause vapors to be evolved from the material of the insulating member. The insulating member is of a material that evolves substantially no vapors or gases at the temperatures reached by the insulating material prior to arc-initiation during prolonged overcurrents of up to one hour in duration. This material is a baked material, a major portion of which is hydrated aluminum silicate including water of hydration that is released only at temperatures in excess of those attained by the insulating material during prolonged overcurrents as long as one hour.

Abstract: Discloses a method of applying an amorphous fused silica coating to a substance of refractory non-metallic material. High temperature arc plasma from an arc plasma spray gun is projected onto the substrate surface; and particles of a material consisting essentially of crystalline silica are fed into the plasma, where they are melted and entrained in the plasma. The gun is held close enough to the substrate to effect melting of the surface of the substrate, or the previously-applied material, in the region where the molten drops of silica entrained in the plasma are impinging against said surface.

Abstract: This arc chute comprises an arc-confining portion of an electric insulating material comprising the heat and pressure reacted thermoset product of a mixture of chrysotile asbestos, orthophosphoric acid, and silica sand. The silica sand is present in the mixture in an amount of between 23.5 and 30.5 percent by weight of the mixture. The insulating material prior to operation of the arc chute has a surface layer formed by subjecting the pre-existing surface of the material to arc-plasma flame treatment that converts the material at said surface to an amorphous fused material, the major proportion of which is silica.

Abstract: This method of making a ceramic insulator with a stress-grading coating comprises applying to a ceramic body a coating material comprising particles of silicon carbide and a binder comprising a high-silica glass or high-silica glass-forming material, said glass or glass-forming material having a fusion temperature in the range of 1850.degree. F to 2350.degree. F. The coated ceramic body is fired in an argon atmosphere at a temperature in the range of 1850.degree. F to 2350.degree. F to form on the ceramic body a glaze coating that has non-linear resistivity properties.