Profile Wire Conductor Surface Geometry Against Cable Shrink Back
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Solution Overview
Problem
Power cables experience axial movement and exposure of conductors due to thermal shrinkage, leading to 'shrink back' issues, particularly in profile wire conductors with smooth surfaces, which can result in failures.
Innovation Solution
A profile wire conductor with concentric wire layers featuring an inner wire layer of one radial cross-sectional geometry and an outermost wire layer with a different geometry, including indentations or protrusions, to increase friction and grip the insulation system, thereby reducing shrink back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface conductor is used, then the manufacturing process is simple, but the insulation system experiences axial movement and shrink back
Solution Approach 1:
The patent applies local quality by providing indentations or protrusions only on the outer surface of the conductor where the insulation system contacts it, while the inner structure remains smooth for easy manufacturing. This localized modification increases friction at the contact interface without complicating the overall manufacturing process.
Solution Approach 2:
The patent uses curved or rounded indentations/protrusions on the conductor surface rather than sharp edges. This curvature design increases the contact area and friction with the insulation system, reducing axial movement while maintaining manufacturing feasibility through standard forming processes.
2Stability of the object's composition
If profile wires with high filling grade are used, then the conductor structure is compact, but the outer surface remains smooth causing shrink back
Solution Approach 1:
The patent maintains the compact profile wire structure throughout the conductor while applying surface modifications (indentations or protrusions) only at the outermost layer. This allows the high filling grade and compactness to be preserved internally while adding shrink back resistance only where needed at the insulation interface.
Solution Approach 2:
The patent transitions from a two-dimensional smooth surface to a three-dimensional surface with indentations or protrusions. This dimensional change adds vertical features to the outer surface that increase mechanical interlocking with the insulation system without disrupting the compact horizontal arrangement of the profile wires.
3Reliability
If the outer surface geometry is modified to increase friction, then shrink back is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent limits geometric modifications to only the outermost surface layer of the conductor, leaving the bulk structure simple and easy to manufacture. The indentations or protrusions are applied locally at the insulation interface, minimizing the increase in manufacturing complexity while maximizing the grip improvement.
Solution Approach 2:
The patent modifies surface parameters (adding indentations or protrusions with specific dimensions) rather than changing the fundamental conductor structure. By controlling the size, depth, and distribution of these surface features, the patent achieves improved grip while keeping manufacturing processes relatively simple and scalable.
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 unique geometry of the outer surface of the profile wire conductor effectively reduces the risk of insulation system failure by enhancing the grip and stability against axial shrinkage forces, minimizing shrink back and associated failures.
Implementation Method 1
the profile wire conductor will increase the friction forces and/or tortional forces to handle the axial shrinkage force of the insulation system arranged around the profile wire conductor
Data Source
AI summary
A profile wire conductor for an electric power cable, the profile wire conductor having a central longitudinal axis and including stranded individual profile wires arranged in concentric wire layers around the central longitudinal axis, the concentric wire layers including an inner wire layer of profile wires of a first type having a first radial cross sectional geometry, and an outermost wire layer of profile wires forming an outer surface of the profile wire conductor. At least one of the profile wires in the outermost wire layer being of a second type and having a second radial cross sectional geometry being different to the first radial cross sectional geometry, wherein the profile wires of the second type forms an indentation or protrusion in the outer surface of the profile wire conductor.