Profile Wire Conductor Surface Geometry for Shrink-Back Resistance
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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 tortional forces, thereby enhancing the grip of the insulation system and reducing shrink back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface conductor is used, then manufacturing is easier and surface quality is better, but shrink back resistance is reduced
Solution Approach 1:
The conductor surface is made non-uniform by providing profile wires with different radial cross-sectional geometries in the outermost layer compared to inner layers. This creates local geometric variations (indentations or protrusions) that increase friction and tortional forces, improving shrink back resistance while maintaining overall manufacturing simplicity through standardized wire drawing processes
Solution Approach 2:
The invention introduces asymmetric geometric features on the conductor surface by using profile wires where at least one wire in the outermost layer has a different radial cross-sectional geometry than the inner layer wires. This asymmetry creates indentations or protrusions that mechanically interlock with the insulation system, preventing axial movement and reducing shrink back
2Reliability
If profile wires with different radial cross-sectional geometries are used in outermost layer, then shrink back is reduced, but manufacturing complexity increases
Solution Approach 1:
Instead of making all wires complex, only the outermost layer wires are given different geometries while inner layer wires remain uniform. This localized differentiation achieves the shrink back reduction effect at the critical interface with insulation, while minimizing manufacturing complexity by keeping the bulk of the conductor structure simple and standardized
Solution Approach 2:
The invention changes the geometric parameters (radial cross-sectional geometry) of specific profile wires in the outermost layer compared to inner layers. This parameter variation creates the necessary surface profile for improved grip, while the changes are implemented through standard wire drawing and stranding processes, keeping overall manufacturing complexity manageable
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 radial cross-sectional geometry of the outermost wire layer improves the grip of the insulation system, reducing the risk of failures caused by shrink back and maintaining the integrity of the power cable.
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
Figure 1~2
Figure 3~4C
Figure 5~6
AI summary
A profile wire conductor (201, 201') for an electric power cable (1), the profile wire conductor (201, 201') having a central longitudinal axis (200) and comprising stranded individual profile wires (210, 212, 212'a, 212'b, 214) arranged in concentric wire layers (220, 222, 222', 224) around the central longitudinal axis (200), the concentric wire layers (222, 222', 224) comprising an inner wire layer (224) of profile wires (214) of a first type having a first radial cross sectional geometry (301), and an outermost wire layer (222, 222') of profile wires (212, 212'a, 212'b) forming an outer surface of the profile wire conductor (201, 201'). At least one of the profile wires (212, 212'a) in the outermost wire layer (222, 222') being of a second type and having a second radial cross sectional geometry (302, 303) being different to the first radial cross sectional geometry, wherein the profile wires of the second type (302, 303) forms an indentation (240, 240') or protrusion (250) in the outer surface of the profile wire conductor (201, 201').