Continuous monitoring of eccentricity and coaxial capacitance variables during electrical insulation extrusion

Claim 2

Apparatus for monitoring the capacitance across an insulative layer extruded over an axially advancing metallic member comprising: a capacitive probe having plural mutually insulated segments, each said segment comprising an inner surface disposed along a locus of points substantially equidistant from said member axis and in noncontacting relation to said layer; guard means enveloping said advancing member adjacent the inlet and the outlet ends of said probe for establishing a reference electrical potential; means for maintaining said metallic member at ground potential; means for selectively connecting each said segment individually to said guard means thereby placing each segment so connected at said reference potential; and means for measuring the capacitance between each segment not so connected and said metallic member.

Claim 3

Apparatus pursuant to claim 1 wherein said guard means comprises first and second hollow metallic cylinders disposed coaxially with said probe segments and having their inner surfaces located along said locus of points.

Claim 4

Apparatus pursuant to claim 2, wherein the space between said layer, said cylinders and said inner surfaces of said segments constitutes a dielectric medium.

Claim 5

Apparatus for monitoring the capacitance across an insulative layer placed over an axially advancing metallic member, comprising: means, including two spaced-apart metallic guards each enveloping said advancing insulated metallic member, for electrically isolating a discrete portion of said member from the remainder of said member; four capacitive plates located between said guards spaced symmetrically about said insulative layer and at equal distances therefrom; a sinusoidally varying reference electrical signal; means for connecting said isolating means and ones of said plates to said signal; and means for measuring the capacitance between each of the remaining said plates and said metallic member.

Claim 6

Apparatus for monitoring the capacitance across an insulative layer placed over an axially advancing metallic member, comprising: means, including two spaced-apart metallic guards each enveloping said advancing insulated metallic member, for electrically isolating a discrete portion of said member from the remainder of said member; four capacitive plates located between said guards spaced symmetrically about said insulative layer and at equal distances therefrom; a sinusoidally varying reference electrical signal; means for connecting said isolating means and ones of said plates to said signal; and means for measuring the capacitance between each of the remaining said plates and said metallic member.

Claim 7

Apparatus pursuant to claim 4, further comprising means for maintaining said advancing metallic member at ground potential.

Claim 8

Apparatus pursuant to claim 5, further comprising means for utilizing said capacitance measurements of claim 2.

Claim 9

Apparatus for continuously deriving indicia of coaxial capacitance of an insulated conductor and also for deriving indicia of the extent of cross-sectional eccentricity of said insulation about said conductor, comprising: means for advancing said insulated conductor tautly through a measuring station; at least four capacitive plates comprising like cylindrical segments symmetrically disposed at said station along a locus of points substantially equidistant from said advancing conductor; a sinusoidally varying reference source of electrical potential; guard means disposed on either side of said station and connected to said source and comprising first and second hollow metallic cylinders disposed coaxially with said probe segments and having their inner surfaces located along said locus of points; means for maintaining said advancing metallic member at ground potential; capacitive bridge means; and means for selectively connecting each said segment individually either to said source or to said bridge means whereby, by connecting all said segments to said bridge and none to said source said coaxial capacitance is measured; and by connecting a first set of oppositely disposed said segments to said source and a second set of oppositely disposed said segments to said bridge, a measure of said eccentricity is achieved.

Claim 10

Apparatus for continuously deriving indicia of coaxial capacitance of an insulated conductor and also for deriving indicia of the extent of cross-sectional eccentricity of said insulation about said conductor, comprising: means for advancing said insulated conductor tautly through a measuring station; at least four capacitive plates comprising like cylindrical segments symmetrically disposed at said station along a locus of points substantially equidistant from said advancing conductor; a sinusoidally varying reference source of electrical potential; guard means disposed on either side of said station and connected to said source and comprising first and second hollow metallic cylinders disposed coaxially with said probe segments and having their inner surfaces located along said locus of points; means for maintaining said advancing metallic member at ground potential; capacitive bridge means; and means for selectively connecting each said segment individually either to said source or to said bridge means whereby, by connecting all said segments to said bridge and none to said source said coaxial capacitance is measured; and by connecting a first set of oppositely disposed said segments to said source and a second set of oppositely disposed said segments to said bridge, a measure of said eccentricity is achieved.