Shielded electrical conductor terminations and methods of making same

Claim 2

Method of preventing corona-induced failure at a terminal of a shielded electrical conductor, the conductor having an insulated surface, comprising the steps of winding a high voltage insulating tape member around said insulated surface of said shielded electrical conductor, said high voltage insulating tape member being capable of applying compressive force to said terminal, said high voltage insulating tape member having a corona-resistant electrical stress-relieving material bonded to a portion of the length of one side of said insulating tape member, said insulating tape member being wound such that said stress-relieving material is toward said insulated surface, said winding progressing in one direction along said insulated surface until said stress-relieving material is exhausted; reversing the direction of progression of the high voltage insulating tape member and wrapping said member back over itself and said insulated surface.

Claim 3

The method of claim 1, wherein the winding step is done by half-lapping.

Claim 4

The method of claim 1, wherein the stress-relieving material is a cold-flowable corona-resistant elastomer selected from the group consisting of ethylene-propylene copolymers, isobutylene-isoprene copolymers, polybutene, chlorosulfonated polyethylene, ethylene-propylene-diene terpolymers and mixtures thereof containing from about 350 to about 600 parts by weight per hundred of elastomer of a semiconductor material and up to about 10 parts per hundred of elastomer of processing aids.

Claim 5

The method of claim 3, wherein said corona-resistant electrical stress-relieving material contains up to about 10 parts by weight per hundred of elastomer of titanate stabilizer.

Claim 6

Method of preventing corona-induced failure at a terminal of a high voltage shielded electrical conductor, the conductor being covered on the exterior thereof by an insulator and said insulator being covered on the exterior by a conductive shield which terminates short of the end of said insulator with a length of the surface of said insulator being exposed beyond the end of the conductive shield, comprising the step of winding a high voltage insulating tape member around the end portion of said conductive shield and around said insulator surface proximate to the end of said conductive shield, said high voltage insulting tape member being capable of applying compressive force to said terminal, said high voltage insulating tape member having a corona-resistant electrical stress-relieving elastomeric material bonded to a portion of the length of one side of said insulating tape member, said insulating tape member being wound such that said stress-relieving elastomeric material underlies said tape member in contact with said end portion of the conductive shield and in contact with said insulator surface proximate to the end of said conductive shield, said winding progressing in one direction along said end portion of said conductive shield and said insulator surface unitl said stress-relieving material is exhausted.

Claim 7

Method of preventing corona-induced failure at a terminal of a high voltage shielded electrical conductor, the conductor being covered on the exterior thereof by an insulator and said insulator being covered on the exterior by a conductive shield which terminates short of the end of said insulator with a length of the surface of said insulator being exposed beyond the end of the conductive shield, comprising the step of winding a high voltage insulating tape member around the end portion of said conductive shield and around said insulator surface proximate to the end of said conductive shield, said high voltage insulting tape member being capable of applying compressive force to said terminal, said high voltage insulating tape member having a corona-resistant electrical stress-relieving elastomeric material bonded to a portion of the length of one side of said insulating tape member, said insulating tape member being wound such that said stress-relieving elastomeric material underlies said tape member in contact with said end portion of the conductive shield and in contact with said insulator surface proximate to the end of said conductive shield, said winding progressing in one direction along said end portion of said conductive shield and said insulator surface unitl said stress-relieving material is exhausted.

Claim 8

In a high voltage electrical terminal having an electrical conductor covered on the exterior thereof by an insulator and wherein said insulator is covered on the exterior by a conductive shield which ends short of the end of said insulator with a length of the surface of said insulator extending beyond the end of said conductive shield, a corona-resistant stress-relieving termination for said terminal comprising: a flexible high voltage insulating tape member, a layer of cold-flowable corona-resistant electrical stress-relieving elastomeric material bonded to at least a portion of one side of said tape member, said tape member being wrapped in overlapping relationship about the end portion of said conductive shield and also about the surface of said insulator beyond the end of said conductive shield with said layer of cold-flowable elastomeric material underlying said tape member in direct contact with the end portion of the conductive shield and in direct contact with the insulator surface beyond the end of said conductive shield, said tape member after being wrapped thereon applying continuing compressive force to the underlying stress-relieving material for cold-flowing said elastomeric material about the surface of said insulator and for providing self-mending capability, and said elastomeric material containing from about 350 to about 600 parts by weight per hundred parts of elastomeric material of a semi-conductor powder in which the voltage when measured at various currents in a cylindrical column of powder 1-inch in diameter packed at a pressure of 400 pounds per square inch is in accordance with the equation: I=kV n wherein the value of "n" exceeds about 2.

Claim 9

In a high voltage electrical terminal having an electrical conductor covered on the exterior thereof by an insulator and wherein said insulator is covered on the exterior by a conductive shield which ends short of the end of said insulator with a length of the surface of said insulator extending beyond the end of said conductive shield, a corona-resistant stress-relieving termination for said terminal comprising: a flexible high voltage insulating tape member, a layer of cold-flowable corona-resistant electrical stress-relieving elastomeric material bonded to at least a portion of one side of said tape member, said tape member being wrapped in overlapping relationship about the end portion of said conductive shield and also about the surface of said insulator beyond the end of said conductive shield with said layer of cold-flowable elastomeric material underlying said tape member in direct contact with the end portion of the conductive shield and in direct contact with the insulator surface beyond the end of said conductive shield, said tape member after being wrapped thereon applying continuing compressive force to the underlying stress-relieving material for cold-flowing said elastomeric material about the surface of said insulator and for providing self-mending capability, and said elastomeric material containing from about 350 to about 600 parts by weight per hundred parts of elastomeric material of a semi-conductor powder in which the voltage when measured at various currents in a cylindrical column of powder 1-inch in diameter packed at a pressure of 400 pounds per square inch is in accordance with the equation: I=kV n wherein the value of "n" exceeds about 2.

Claim 10

In a high voltage electrical terminal having an electrical conductor covered on the exterior thereof by an insulator and wherein said insulator is covered on the exterior by a conductive shield which ends short of the end of said insulator with a length of the surface of said insulator extending beyond the end of said conductive shield, a corona-resistant stress-relieving termination for said terminal comprising: a flexible high voltage insulating tape member, a layer of cold-flowable corona-resistant electrical stress-relieving elastomeric material bonded to at least a portion of one side of said tape member, said tape member being wrapped in overlapping relationship about the end portion of said conductive shield and also about the surface of said insulator beyond the end of said conductive shield with said layer of cold-flowable elastomeric material underlying said tape member in direct contact with the end portion of the conductive shield and in direct contact with the insulator surface beyond the end of said conductive shield, said tape member after being wrapped thereon applying continuing compressive force to the underlying stress-relieving material for cold-flowing said elastomeric material about the surface of said insulator and for providing self-mending capability, said elastomeric material containing from about 350 to about 600 parts by weight per hundred parts of elastomeric material of a semi-conductor powder in which the voltage when measured at various currents in a cylindrical column of powder 1-inch in diameter packed at a pressure of 400 pounds per square inch is in accordance with the equation: I=kV n wherein the value of "n" exceeds about 2, and said elastomeric material being a mixture of isobutylene-isoprene copolymer and polybutene.

Claim 11

In a high voltage electrical terminal having an electrical conductor covered on the exterior thereof by an insulator and wherein said insulator is covered on the exterior by a conductive shield which ends short of the end of said insulator with a length of the surface of said insulator extending beyond the end of said conductive shield, a corona-resistant stress-relieving termination for said terminal comprising: a flexible high voltage insulating tape member, a layer of cold-flowable corona-resistant electrical stress-relieving elastomeric material bonded to at least a portion of one side of said tape member, said tape member being wrapped in overlapping relationship about the end portion of said conductive shield and also about the surface of said insulator beyond the end of said conductive shield with said layer of cold-flowable elastomeric material underlying said tape member in direct contact with the end portion of the conductive shield and in direct contact with the insulator surface beyond the end of said conductive shield, said tape member after being wrapped thereon applying continuing compressive force to the underlying stress-relieving material for cold-flowing said elastomeric material about the surface of said insulator and for providing self-mending capability, said elastomeric material containing from about 350 to about 600 parts by weight per hundred parts of elastomeric material of a semi-conductor powder in which the voltage when measured at various currents in a cylindrical column of powder 1-inch in diameter packed at a pressure of 400 pounds per square inch is in accordance with the equation: I=kV n wherein the value of "n" exceeds about 2, and said elastomeric material being a mixture of isobutylene-isoprene copolymer and polybutene.

Claim 12

An electrical stress-relieving termination as claimed in claim 7 wherein the weight ratio of said isobutylene to said polybutene is in the range of about 1:0.8 to about 1:1.