Void-free electrical conductor for power cables and process for making same

• US 4,319,074 A
• Filed: 05/27/1979
• Issued: 03/09/1982
• Est. Priority Date: 08/15/1978
• Status: Expired due to Term

• Current Assignee: Camco International Inc. (SLB)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Budrow, Russell B., Yaste, Ruth E.
• Primary Examiner(s): Kucia, Richard R.
• Application Number:
  US06/079,280
• Time in Patent Office: 1,017 Days
• Field of Search: 174/DIG. 8, 174/116, 174/114 R, 174/23 C, 174/23 R
• US Class Current: 174/116
• CPC Class Codes: H01B 7/02 Disposition of insulation
• CPC Class Codes: H01B 7/285 by completely or partially filling interstices in the cable
• CPC Class Codes: Y02A 30/14 Extreme weather resilient electric power supply systems, e.g. strengthening power lines or underground power cables
• CPC Class Codes: Y10S 174/08 Shrinkable tubes

Abstract

A void-free electrical conductor for power cables including a stranded electrical conductor formed of a central member and a plurality of abutting peripheral conducting members, the stranded conductor having a primary layer of electrical insulation heat shrunk about the exterior thereof and having an insulation material completely filling the internal space of the conductor within the primary external electrical insulation layer, the filler insulation adapted to fill all interstices between individual conducting strands outward from the abutment points between peripheral conducting members and the area inside of the abutment points being insulated by the insulation around the central conducting member to thereby form a completely void-free filling of the space within the primary electrical insulation in order to prevent the axial flow of any liquid or gaseous substance therethrough, said primary electrical insulation layer being void-free to increase the dielectric strength of the final electrical conductor construction, the primary insulation and the filler insulation being applied simultaneously to the stranded electrical conductor from a laminated tape having an exterior layer formed of the primary electrical insulation material and an interior layer formed of the filler insulation material such that when this assembly is heat shrunk the primary electrical insulation material forms the external dielectric insulation and the filler insulation material flows inwardly to fill all the interstices between strands of electrical conductors and completely filling the interior of the primary electrical insulation with a void-free insulation.

Claims

1. A void-free electrical conductor for power cables comprising:

(a) a stranded electrical conducting means including a central conducting member and a plurality of peripheral conducting members located therearound and in abutment with adjacent peripheral conducting members, said central conducting member including a void-free central insulation filling the cross-sectional area around said central conducting member outwardly to the abutment points between adjacent peripheral conducting members;

(b) a first primary electrical insulation being a tape helically wound and heat shrunk about the exterior of said stranded electrical conductor means to form a void-free external layer of primary electrical insulation therearound, said first primary insulation being initially applied about said stranded electrical conductor means as a tape overwrap and heat shrunk to form a void-free insulating layer therearound, said first primary electrical insulation having a melting temperature and a heat shrink temperature both above the melting temperature of said central insulation; and

(c) a first filler insulation together with said central insulation filling all interstices between said peripheral conducting members, said first filler insulation providing a void-free insulation filling the interior space between said first primary electrical insulation and the points of abutment between adjacent peripheral conducting members, said first filler insulation having a melting temperature below the melting temperature of said first primary electrical insulation and below the heat shrink temperature of said first primary electrical insulation, said first filler insulation being initially applied about said stranded electrical conductor as a tape overwrap layer underneath the tape overwrap layer for said first primary insulation, said first filler insulation and said central insulation being bonded together at an interface at substantially the points of abutment between adjacent peripheral conducting members and being completely void-free to prevent any flow of fluids axially through the void-free electrical conductor, the tape overwrap layer of said first filler insulation and the central insulation both being responsive to heat that is sufficient to heat shrink said first primary insulation to flow into the interstices between said peripheral conducting members and central conducting member and be subjected to radial constriction to form a void-free insulation simultaneously with the heat shrinking of said first primary electrical insulation.

2. The conductor as defined in claim 1 further comprising a supplementary insulation means including a second primary insulation about the exterior of said first primary insulation and a second filling material positioned between said first primary insulation and said second primary insulation to form a void-free layer of filling insulation therebetween, said supplementary insulation means being formed by a second tape overwrapping being made about the first tape overwrapping.