Crosslinked Polyethylene Cable Sheath with Integrated Pulling Lubricant
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Solution Overview
Problem
The installation of electrical power cables with crosslinked insulation requires high pulling forces due to the coefficient of friction between the cable sheath and conduit surfaces, leading to potential cable degradation and increased installation costs, as existing lubrication methods are either inefficient or require significant changes to manufacturing processes.
Innovation Solution
Incorporating a pulling lubricant, such as high viscosity silicone or fatty acid amides, into the crosslinkable polyethylene resin during the cable manufacturing process, allowing it to migrate or permeate to the exterior surface, reducing the coefficient of friction and necessary pulling force during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a lubricant is applied to the exterior surface of the cable sheath at the job site, then the coefficient of friction is reduced and installation pulling force is decreased, but additional time, expense and manpower are required for lubrication and cleanup
Solution Approach 1:
The lubricant is incorporated into the polymeric material during the cable manufacturing process, before the cable is installed. This preliminary incorporation eliminates the need for job site application and cleanup, while ensuring the lubricant is available when needed during installation
Solution Approach 2:
The lubricant function is merged with the structural polymeric material of the cable sheath. Instead of being a separate application step, the lubricant becomes an integral component of the sheath material itself, combining structural and lubrication functions in one element
2Force
If a separate lubricant layer is applied after the polymeric sheath is formed, then the pulling force is reduced, but major alterations to the manufacturing line are required and manufacturing time increases
Solution Approach 1:
The lubricant function is integrated into the existing polymeric sheath material formulation, combining the structural and lubrication functions in a single manufacturing step. This eliminates the need for separate lubrication equipment and process steps
Solution Approach 2:
The polymeric sheath material serves dual functions: providing structural protection and electrical insulation, and providing lubrication during installation. This multi-functionality is achieved by incorporating the lubricant into the base polymer material
3Force
If granules of lubricant material are applied to the still-hot sheath during extrusion, then the pulling force is reduced, but the geometrical dimensions of the cable sheaths fluctuate and manufacturing precision decreases
Solution Approach 1:
The lubricant is uniformly distributed within the polymeric material at a molecular level during compounding, ensuring consistent lubrication properties throughout the sheath without creating surface irregularities or dimensional variations
Solution Approach 2:
The lubricant is incorporated into the polymer matrix during the compounding process, changing the material's internal composition rather than adding external granules. This maintains the sheath's geometric dimensions while providing lubrication through the material's inherent properties
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the installation pulling force and maintains the integrity of the cable sheath, eliminating the need for external lubrication and minimizing manufacturing disruptions while ensuring effective friction reduction.
Implementation Method 1
the pulling lubricant, either by migration through, or permeation throughout, the sheath becomes available at the exterior surface of the cable sheath
Implementation Method 2
the pulling lubricant, either by migration through, or permeation throughout, the sheath becomes available at the exterior surface of the cable sheath
Implementation Method 3
effective to reduce the amount of force required to install the cable
Data Source
AI summary
Electrical power cable having a reduced surface coefficient of friction and required installation pulling force, and the method of manufacture thereof, in which the central conductor core, with or without a separate insulating layer, is surrounded by a sheath of crosslinked polyethylene. A high viscosity, high molecular weight silicone based pulling lubricant or fatty acid amide pulling lubricant is incorporated by alternate methods with the polyethylene to form a composition from which the outer sheath is extruded, and is effective to reduce the required pulling force on the cable during installation.