Method of delivering geometric stress relief element to high voltage cable terminations Publication number US20060080831A1US20060080831A1 US10/964,956 US96495604A US2006080831A1 US 20060080831 A1 US20060080831 A1 US 20060080831A1 US 96495604 A US96495604 A US 96495604A US 2006080831 A1 US2006080831 A1 US 2006080831A1 Authority US United States Prior art keywords cable stress relief semiconductor shrink tube rubber Prior art date 2004-10-14 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)Granted 2004-10-14Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co 2005-01-18Assigned to 3M INNOVATIVE PROPERTIES COMPANY reassignment 3M INNOVATIVE PROPERTIES COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NGUYEN, NGA K., RICHARDSON, TODD H., TAYLOR, WILLIAM L., ZHANG, MING 2006-04-20Publication of US20060080831A1 publication Critical patent/US20060080831A1/en 2007-08-07Publication of US7251881B2 publication Critical patent/US7251881B2/en
A method for delivering a geometric type stress relief element to a terminated electrical cable is provided. The cable contains a conductor surrounded by at least one coaxial layer of insulator, semiconductor, grounded wires and cable jacket. First, the terminated cable is tapered to expose a portion of the conductor so as to protrude beyond the insulation, which protrudes beyond semiconductor, which protrudes beyond the conductive wires. A geometric stress cone is preloaded onto a cold shrink tube. The terminated, tapered cable is inserted into the cold shrink tube. The cold shrink tube is removed and the geometric stress cone collapses onto the tapered cable. The cable is rated for supplying high voltage.
1. A method of delivering a geometric type stress relief element to an electrical cable comprising conductor surrounded by at least one coaxial layer of cable insulation, cable semiconductor, grounded conductive wires, and cable jacket, the method comprising the steps of: terminating the electrical cable; tapering the terminated electrical cable, the tapering step comprising removing a portion of the cable jacket, collecting the grounded conductive wires, and removing a portion of the cable semiconductor so that a portion of the cable insulation is exposed and protrudes from the semiconductor and a portion of the cable semiconductor is exposed and protrudes from the cable jacket; providing the geometric type stress relief element preloaded on a cold shrink tube having a bore, the stress relief element comprising a semiconductor electrode embedded in an insulator; placing the tapered end of the terminated electrical cable into the bore of the cold shrink tube; and removing the cold shrink tube so that the stress relief element is disposed over a portion of the cable semiconductor and a portion of the cable insulation; wherein the electrical cable is rated for supplying high voltage.
2. The method of claim 1, wherein after the removing the cold shrink tube step, the semiconductor electrode of the stress relief element contacts the cable semiconductor.
3. The method of claim 1, wherein after the tapering the terminated electrical cable step, the method further comprises a step of applying a coating of semi-conductive material on a portion of the exposed cable insulation proximate to the cable semiconductor.
4. The method of claim 3, wherein the coating of semi-conductive material is applied via spray painting.
5. The method of claim 4, wherein the semi-conductive material comprises graphite.
6. The method of claim 1, wherein after the terminating the electrical cable step, the method further comprises the step of installing at least one skirt onto the cable insulation.
7. The method of claim 6, wherein at least one of the skirt and pre-stretched tube is made from a polymeric material selected from the group consisting of silicone rubber, ethylene-propylene terpolymer, polyurethane rubber, styrene-butadiene copolymer, polychloroprene, nitrile rubber, butyl rubber, polysulfide rubber, and combinations thereof.
8. The method of claim 1, wherein before the placing the tapered end of the terminated electrical cable into the bore of the cold shrink tube step, the method further comprises a step of applying a lubricant to at least a portion of the cable semiconductor and at least a portion of the cable insulation.
9. The method of claim 8, wherein the lubricant is substantially not absorbed by the cable insulation, the cable semiconductor, or the geometric stress relief element.
10. The method of claim 1, wherein the insulator of the geometric stress relief element is made from a polymeric material selected from the group consisting of silicone rubber, ethylene-propylene terpolymer, polyurethane rubber, styrene-butadiene copolymer, polychloroprene, nitrile rubber, butyl rubber, polysulfide rubber, and combinations thereof.
11. The method of claim 1, wherein the semiconductor electrode of the geometric stress relief element is made from a polymeric material comprising carbon black, the polymeric material selected from the group consisting of silicone rubber, ethylene-propylene terpolymer, polyurethane rubber, styrene-butadiene copolymer, polychloroprene, nitrile rubber, butyl rubber, polysulfide rubber, and combinations thereof.
12. The method of claim 1, wherein the insulator of the stress relief element has a dielectric constant of greater than about 2.
13. The method of claim 1, wherein the insulator of the stress relief element has a dielectric constant of less than about 6.
14. The method of claim 1, wherein the semiconductor electrode of the stress relief element has a minimum volume resistivity of greater than about 50 ohm-cm.
15. The method of claim 1, wherein the semiconductor electrode of the stress relief element has a maximum volume resistivity of less than about 10,000 ohm-cm.
16. The method of claim 1, wherein the cold shrink tube comprises a support member that extends longitudinally along its length.
17. The method of claim 16, wherein the support member is coextruded with the cold shrink tube.
18. The method of claim 17, wherein the support member is a polymer made of acrylonitrile-butadeine-styrene monomer.
19. The method of claim 1 for use in a wet type or a dry type termination. |