Electrical bushing having means for lowering the power factor

Claim 2

In a dry type bushing; an insulator having a first dielectric constant; an axially extending bore having a wall surface formed in said insulator; a conductor extending through said bore but not in contact with the wall thereof; an air gap defined by said conductor and the wall of said bore, the air in said air gap having a second dielectric constant which is lower than the first dielectric constant of said insulator; a semiconductive glaze on the wall of said bore with shunting means having a multitude of connections between the conductor and the semiconductive glaze distributed both axially along the length of the bore of said insulator and angularly about the circumference of the wall surface of the bore of said insulator to shunt out the air of said air gap to thereby remove the air from the insulation system of said bushing, whereby the electrical stress is uniformly distributed and a lower value for the voltage gradient is obtained to thereby control the corona discharge between said conductor and the wall of said bore.

Claim 3

In a dry type bushing: an insulator body having an axial bore; a coating of a semiconductive glaze on the wall of the bore of said insulator; a conductor extending through the bore of said insulator but not in contact with the wall of the bore; an air gap defined by the surface of said conductor and the wall of the bore of said insulator; a conductive shunt of a relatively thin, resilient metallic sheet disposed in coiled axially extending relationship in the bore of said insulator, said metallic sheet being constructed and arranged to present a multiplicity of outwardly extending contacts arranged in a plurality of annular rows distributed axially along the bore of said insulator to firmly engage the semiconductive glaze on the wall of the bore of said insulator; and means electrically connecting said metallic sheet to said conductor; whereby said metallic sheet shunts said air gap and the electrical field is thereby made more uniform to control the power factor and reduce the corona inception probability.

Claim 4

In a dry type bushing: an insulator body having an axial bore; a coating of a semiconductive glaze on the wall of the bore of said insulator; a conductor extending through the bore of said insulator but not in contact with the wall of the bore; an air gap defined by the surface of said conductor and the wall of the bore of said insulator; a conductive shunt of a relatively thin, resilient metallic sheet disposed in coiled axially extending relationship in the bore of said insulator, said metallic sheet being constructed and arranged to present a multiplicity of outwardly extending contacts arranged in a plurality of annular rows distributed axially along the bore of said insulator to firmly engage the semiconductive glaze on the wall of the bore of said insulator; and means electrically connecting said metallic sheet to said conductor; whereby said metallic sheet shunts said air gap and the electrical field is thereby made more uniform to control the power factor and reduce the corona inception probability.

Claim 5

A dry type bushing according to claim 2 wherein said sheet is manufactured of a spring phosphorus bronze alloy, and said contacts are formed as punched tongues having one end attached to said sheet, said tongues being arranged in rows and constructed and arranged to extend radially outwardly into engagement with said semiconductive glaze when said sheet is mounted in coiled relationship with the bore of said insulator around said conductor.

Claim 6

In a dry type bushing: an insulator body having an axial bore; a coating of a semiconductive glaze on the wall of the bore of said insulator; a conductor extending through the bore of said insulator but not in contact with the wall of the bore; an air gap defined by the surface of said conductor and the wall of the bore of said insulator; a conductive shunt of a relatively thin, resilient metallic sheet disposed and arranged in coiled axially extending relationship in the bore of said insulator, said metallic sheet being constructed and arranged to present a multiplicity of contacts which extend axially outwardly with respect to the axis of the bore of said insulator and in firm engagement with the semiconductive glaze on the wall of the bore of said insulator; means electrically connecting said metallic sheet to said conductor comprising a spring carried by said conductor and constructed and arranged to engage and bias said metallic sheet in a direction to effect positive engagement of said extending contacts with the wall of the bore of said insulator; and whereby said metallic sheet shunts said air gap and the electrIcal field is thereby made more uniform to control the power factor and reduce the corona inception probability.

Claim 7

In a dry type bushing: an insulator body having an axial bore; a coating of a semiconductive glaze on the wall of the bore of said insulator; a conductor extending through the bore of said insulator but not in contact with the wall of the bore; an air gap defined by the surface of said conductor and the wall of the bore of said insulator; a conductive shunt of a relatively thin, resilient metallic sheet disposed and arranged in coiled axially extending relationship in the bore of said insulator, said metallic sheet being constructed and arranged to present a multiplicity of contacts which extend axially outwardly with respect to the axis of the bore of said insulator and in firm engagement with the semiconductive glaze on the wall of the bore of said insulator; means electrically connecting said metallic sheet to said conductor comprising a spring carried by said conductor and constructed and arranged to engage and bias said metallic sheet in a direction to effect positive engagement of said extending contacts with the wall of the bore of said insulator; and whereby said metallic sheet shunts said air gap and the electrIcal field is thereby made more uniform to control the power factor and reduce the corona inception probability.

Claim 8

A dry type bushing according to claim 4 wherein said spring is a compression spring disposed in said conductor and extending radially outwardly therefrom into biasing engagement with said metallic sheet; an opening in said metallic sheet adjacent to said compression spring; and, an auxiliary contact having a head portion and an elongated body portion, said body portion extending through the opening in said metallic sheet into the interior of said compression spring, said head portion of said auxiliary contact being disposed between said metallic sheet and the wall of said bore, whereby said compression spring operates to bias said metallic sheet in a direction to effect positive engagement of said outwardly extending contacts with the wall of said bore and also bias the head portion of said auxiliary contact into positive engagement with the wall of said bore.

Claim 9

A dry type bushing according to claim 4 wherein said metallic sheet is formed into a symmetrical configuration having substantially equal sides and presenting external contact edges, the ends of said formed metallic sheet overlapping, with said overlapping ends having axially extending slots formed therein and disposed in coinciding overlapping relationship; a third slot formed in said metallic sheet in a position diametrically opposite to said overlapping end slots; a bore formed in said conductor having an axis in a plane transverse to the axis of said conductor; a compression spring disposed within said conductor bore and of a length so that its ends engage said metallic sheet, said metallic sheet being orientated in said insulator bore in a manner that said overlapping slots are adjacent to one end of said spring and said third slot is adjacent to the other end of said spring; a first auxiliary contact having a head portion and a body portion, said first auxiliary contact being disposed in a manner that the body portion thereof extends through said coinciding slots and into one end of the bore in said conductor, the head of said first auxiliary contact being disposed between said metallic sheet and the wall of said insulator bore; and, a second auxiliary contact having a head portion and a body portion, said second auxiliary contact being disposed in a manner that the body portion thereof extends through said third slot and into the other end of said bore in said conductor, the head of said second auxiliary contact being disposed between said metallic sheet and the wall of said insulator bore, whereby said compression spring operates to apply a force to said metallic sheet to thereby forcefully engage the head portions of said auxiliary contacts with the wall of said insulator bore and the force applied to said metallic sheet by said spring operates also to urge said metallic sheets to expand to firmly engage said contact edges with the wall of said insulator bore.

Claim 10

In a dry type bushing; an insulator; an axially extending bore formed in said insulator; a conductor disposed within said bore and having first and second threaded ends extending outwardly from said bore; a first end cap threadedly engaged on said first threaded end of said conductor and disposed in abutting securing engagement with an adjacent axial end of said insulator, the abutting surfaces of said insulator and said first end cap being constructed and arranged as complementary spherical surfaces which form a ball and socket joint the radii of which are substantially less than the length of said insulator to thereby effect positive radial positioning of the first end of said conductor with respect to the end opening of said bore through which said first end of said conductor extends; and, a second end cap threadedly engaged on said second threaded end of said conductor and disposed in abutting securing engagement with an adjacent axial end of said insulator, the Abutting surfaces of said insulator and said second end cap being constructed and arranged as complementary spherical surfaces which form a ball and socket joint the radii of which are substantially equal to the length of said insulator thereby operating to allow said second end of said conductor to assume any radial position with respect to the end opening of said bore through which said second end of said conductor extends.

Claim 11

In a dry type bushing; an insulator; an axially extending bore formed in said insulator; a conductor disposed within said bore and having first and second threaded ends extending outwardly from said bore; a first end cap threadedly engaged on said first threaded end of said conductor and disposed in abutting securing engagement with an adjacent axial end of said insulator, the abutting surfaces of said insulator and said first end cap being constructed and arranged as complementary spherical surfaces which form a ball and socket joint the radii of which are substantially less than the length of said insulator to thereby effect positive radial positioning of the first end of said conductor with respect to the end opening of said bore through which said first end of said conductor extends; and, a second end cap threadedly engaged on said second threaded end of said conductor and disposed in abutting securing engagement with an adjacent axial end of said insulator, the Abutting surfaces of said insulator and said second end cap being constructed and arranged as complementary spherical surfaces which form a ball and socket joint the radii of which are substantially equal to the length of said insulator thereby operating to allow said second end of said conductor to assume any radial position with respect to the end opening of said bore through which said second end of said conductor extends.

Claim 12

In a dry type bushing; an insulator; an axially extending bore formed in said insulator; a conductor disposed within said bore and having first and second threaded ends extending outwardly of said bore; a first end cap threadedly engaged on said first threaded end of said conductor and disposed in abutting engagement with the axial end of said insulator, the abutting surfaces of said axial end of said insulator and said first end cap being constructed and arranged as complementary conical surfaces having cone angles of substantially 12 degrees to thereby provide positive centering of said first threaded end of said conductor with respect to the end opening of said bore through which said first threaded end of said conductor extends; and, a second end cap threadedly engaged on said second threaded end of said conductor and disposed in abutting engagement with the axial end of said insulator, the abutting surfaces of said axial end of said insulator and said second end cap being constructed and arranged as complementary conical surfaces having cone angles of substantially 3 degrees which cooperate to permit said second threaded end of said conductor to assume a radial position with respect to the end opening of said bore through which said second threaded end of said conductor extends as dictated by the centering of said first threaded end of said conductor within the opening of the bore through which said first threaded end extends.

Claim 13

In a dry type bushing; an insulator; an axially extending bore formed in said insulator; a conductor disposed within said bore and having first and second threaded ends extending outwardly of said bore; a first end cap threadedly engaged on said first threaded end of said conductor and disposed in abutting engagement with the axial end of said insulator, the abutting surfaces of said axial end of said insulator and said first end cap being constructed and arranged as complementary conical surfaces having cone angles of substantially 12 degrees to thereby provide positive centering of said first threaded end of said conductor with respect to the end opening of said bore through which said first threaded end of said conductor extends; and, a second end cap threadedly engaged on said second threaded end of said conductor and disposed in abutting engagement with the axial end of said insulator, the abutting surfaces of said axial end of said insulator and said second end cap being constructed and arranged as complementary conical surfaces having cone angles of substantially 3 degrees which cooperate to permit said second threaded end of said conductor to assume a radial position with respect to the end opening of said bore through which said second threaded end of said conductor extends as dictated by the centering of said first threaded end of said conductor within the opening of the bore through which said first threaded end extends.