Flexible HVDC Cable Transition Joint for Diameter Changes
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Solution Overview
Problem
Current high voltage DC mass impregnated submarine cables face challenges when joining sections of different diameters or configurations, leading to stiff transition joints that complicate handling, installation, and increase damage susceptibility.
Innovation Solution
A flexible transition joint method is developed, involving the removal of protective and insulation layers, sequential unwinding and clamping of stranded wires, use of a conical connection piece for central wires, and thermal joining of strands with subsequent shaping to achieve a smooth conical transition, allowing for reapplication of insulation and protective layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conical connection piece is used to join conductors of different diameters, then the different diameters are accommodated, but the joint becomes stiff and requires additional equipment and handling procedures
Solution Approach 1:
The conductor is divided into separate components: a conical connection piece for diameter transition and stranded wires that are pulled back and clamped. This segmentation allows the joint to accommodate different diameters while maintaining flexibility through the stranded wire configuration that can bend and flex independently.
Solution Approach 2:
The joint design transitions from a static rigid connection to a dynamic flexible connection by using stranded wires that can be pulled back, clamped, and allowed to move. The stranded wire configuration enables the joint to adapt to bending and flexing during spooling and installation, maintaining handling capabilities similar to non-spliced cable sections.
2Adaptability or versatility
If a stiff transition joint is used, then cable sections of different diameters can be joined, but the cable is more susceptible to damage at the joint during transportation and installation
Solution Approach 1:
The conductor is segmented into a conical connection piece and separate stranded wire sections that are pulled back and clamped. This segmentation creates a flexible joint that can absorb mechanical stresses during transportation and installation, reducing susceptibility to damage compared to rigid stiff joints.
Solution Approach 2:
The stranded wire configuration acts as a flexible structure that can bend and flex without rigid constraints. This flexibility allows the joint to accommodate mechanical stresses and movements during handling, transportation, and installation, significantly reducing the risk of damage at the joint location.
3Adaptability or versatility
If a stiff transition joint is used, then different cable configurations can be joined, but additional equipment and handling procedures are required
Solution Approach 1:
The conductor is segmented into a conical connection piece and pulled-back stranded wire sections that are clamped. This segmentation provides adaptability to join cables of different configurations while maintaining a simple joint structure that requires no additional equipment or special handling procedures, as the flexible stranded wire configuration naturally accommodates various cable types.
Solution Approach 2:
The joint design using pulled-back stranded wires and clamps creates a universal connection method that can accommodate different cable configurations and diameters. This multi-functional approach allows the same joint technique to be applied across various cable types without requiring different equipment or procedures, simplifying the overall joining process.
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 method enables the creation of a flexible joint that matches handling capabilities of non-spliced sections, reducing equipment needs and installation difficulties, and minimizing damage during transportation and installation.
Implementation Method 1
The insulation and protective layers are removed, exposing the conductors and the ends of the conical connector are thermally joined/welded to the entire diameter of each conductor, i.e. welded to the center wire as well as the stranded wires of each cable.
Implementation Method 2
The conical connector accommodates the different diameters
Data Source
AI summary
A method for creating a flexible transition joint between HVDC-MI cables having different diameters. The central wires of the conductors are thermally joined by a conical connection piece. The strands of the layers of stranded wires surrounding the central wires are rewound, cut and thermally joined along their respective lay lengths. The stranded are sanded/ground along the lay length of the strands to form a smooth uniform transition having the same slope as the conical connection piece. A paper lapping machine is used to form an insulation patch over the transition joint.