Power Cable Accessory Assembly for Insulation Shrinkback Prevention
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Solution Overview
Problem
The existing power cable accessories, such as joints and terminations, face issues with shrinkback due to the mechanical stresses in polymeric insulation, leading to increased risk of electrical breakdown.
Innovation Solution
A power cable accessory assembly is designed with a connector that is mechanically connected to the conductor and engages with the electrical insulation layer through a fastening device, preventing shrinkback by maintaining an axially fixed position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the insulation layer is stripped close to the conductor joint, then the connector can be mechanically connected to the conductor, but shrinkback occurs when the cable heats up due to built-in mechanical stresses in the polymeric insulation
Solution Approach 1:
The insulation layer is divided into two sections: a main section with larger diameter and an end section with smaller diameter. The fastening device is positioned in the end section, creating a segmented structure that allows the connector to be mechanically connected to the conductor while the fastening device prevents shrinkback by anchoring to the main section of the insulation layer.
Solution Approach 2:
The fastening device acts as an intermediary element between the connector and the insulation layer. It is mechanically connected to the connector and engages with the insulation layer, transferring and distributing the mechanical stresses to prevent shrinkback while allowing the connector to maintain its mechanical connection to the conductor.
2Reliability
If anchor elements are used to mechanically connect the tube sleeve to the XLPE insulation, then shrinkback is reduced, but the flanges may disengage at elevated temperatures due to low bending stiffness of XLPE
Solution Approach 1:
The insulation layer has different diameters in different sections: the main section has a larger diameter providing structural support and higher effective stiffness, while the end section has a smaller diameter allowing the fastening device to engage. This local quality differentiation allows the fastening device to anchor securely to the stiffer main section while accommodating the connector in the more flexible end section.
3Reliability
If the connector engages with the insulation layer to prevent shrinkback, then reliability is improved, but the structure becomes more complex
Solution Approach 1:
The fastening device and connector are merged into a single integrated component. The fastening device is positioned on the outer surface of the connector, combining the functions of mechanical connection to the conductor and prevention of shrinkback into one element, thereby reducing overall device complexity while maintaining reliability.
Data Source
Figure 1~2
Figure 3~4
AI summary
Power cable accessory assembly (1.1) comprising: a power cable (3) comprising: a conductor (5), and an electrical insulation layer (7.1) arranged around the conductor (5), wherein the electrical insulation layer (7.1) has a main section (7a) and an end section (7b), the end section (7b) having a smaller diameter than the main section (7a); a fastening device (11.1) engaging with the electrical insulation layer (7.1) in the end section (7b), and a connector (9.1) extending around the end section (7b) of the electrical insulation layer (7.1), the connector (9.1) being mechanically connected to the conductor (5), wherein the connector (9.1) has an inner surface provided with a structure that engages with the fastening device (11.1) to maintain an axially fixed position between the connector (9.1) and the electrical insulation layer (7.1).