Power Cable Accessory Assembly with Axial Locking Against Shrinkback
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Solution Overview
Problem
Existing power cable accessories face issues with shrinkback, where the insulation pulls back from the conductor joint due to mechanical stresses, increasing the risk of electrical breakdown.
Innovation Solution
A power cable accessory assembly that includes a connector mechanically connected to the conductor, with a fastening device engaging the electrical insulation layer to prevent shrinkback, using a structure on the connector's inner surface to maintain axial fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the insulation layer is stripped close to the conductor joint, then the connector can be mechanically connected to the conductor, but the insulation pulls back from the conductor joint due to built-in mechanical stresses (shrinkback)
Solution Approach 1:
The patent applies preliminary action by creating a groove in the insulation layer before connector installation, and by designing the connector with an expansion mechanism that creates axial tension on the insulation. This pre-established mechanical interlock prevents shrinkback when the connector is installed and the insulation is heated, maintaining the insulation edge at the intended position.
Solution Approach 2:
The patent applies local quality by creating a groove only in the end section of the insulation layer where the connector will be installed, rather than modifying the entire insulation. The groove is positioned locally to engage with the connector's expansion mechanism, providing targeted anchoring exactly where needed to prevent shrinkback while leaving the rest of the insulation intact.
2Ease of manufacture
If the insulation comprises polymeric material, then the insulation can be easily manufactured and installed, but the insulation pulls back from the conductor joint when heated due to built-in mechanical stresses
Solution Approach 1:
The patent applies preliminary action by creating a groove in the polymeric insulation before installation and designing the connector to expand and create axial tension. This pre-established mechanical interlock counteracts the shrinkback tendency of polymeric materials when heated, maintaining the insulation edge position without changing the material composition or manufacturing process of the insulation itself.
Solution Approach 2:
The patent applies preliminary anti-action by creating a mechanical interlock through the groove and connector expansion mechanism that opposes the shrinkback force before it can occur. The connector's expansion creates axial tension that actively counteracts the built-in mechanical stresses in the polymeric insulation, preventing the harmful shrinkback effect from manifesting.
3Strength
If the connector engages with the electrical insulation layer by means of a fastening device, then the connection is more durable, but the flanges in the XLPE insulation may disengage from the anchor elements due to low bending stiffness at elevated temperatures
Solution Approach 1:
The patent applies segmentation by dividing the connection mechanism into distinct functional elements: the groove in the insulation, the anchor elements in the connector, and the expansion mechanism. This segmentation allows each element to perform its specific function - the groove provides anchoring, the anchor elements provide mechanical engagement, and the expansion mechanism creates axial tension - creating a more reliable connection than a single integrated fastening device.
Solution Approach 2:
The patent applies dimensionality change by transitioning from a two-dimensional surface engagement (flange against insulation surface) to a three-dimensional volumetric interlock (anchor elements within the groove). The connector expands radially to engage the anchor elements within the groove volume, creating axial tension that prevents disengagement, rather than relying solely on surface friction or bending stiffness.
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 or prevents shrinkback, enhancing the reliability of power cable accessories by maintaining the insulation edge in its intended position, thus reducing the risk of electrical breakdown.
Implementation Method 1
shrinkback occurs when the insulation pulls back from the conductor joint because of built-in mechanical stresses in the insulation from the manufacturing process
Data Source
AI summary
Power cable accessory assembly having: a power cable including: a conductor, and an electrical insulation layer arranged around the conductor, wherein the electrical insulation layer has a main section and an end section, the end section having a smaller diameter than the main section; a fastening device engaging with the electrical insulation layer in the end section, and a connector extending around the end section of the electrical insulation layer, the connector being mechanically connected to the conductor, wherein the connector has an inner surface provided with a structure that engages with the fastening device to maintain an axially fixed position between the connector and the electrical insulation layer.