Underwater Cable Termination Shielding Air Gaps
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Solution Overview
Problem
Existing underwater cable termination assemblies face issues with relative movements due to differing thermal expansion coefficients of materials, leading to air gaps that can cause arcing and reduce the lifespan of the termination when subjected to significant temperature changes.
Innovation Solution
The conductive crimp screen is designed to extend axially over and radially outwardly of the annular insulation portion, enveloping any potential air gaps and shielding them from electrical stresses, while a stress control sleeve with a conductive portion is used to manage relative movements between the insulating and conductive components, ensuring the conductive portion remains in contact with the screen layer even under temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the assembly uses materials with different thermal expansion coefficients, then the assembly can accommodate thermal stress, but relative movements between components occur causing air gaps that lead to arcing
Solution Approach 1:
A flexible conduit is introduced as an intermediary element between the cable insulation and the termination assembly. This conduit flexes and deforms to accommodate thermal expansion and contraction of different materials, maintaining continuous contact and preventing air gaps that would cause arcing. The flexible conduit acts as a mediator that absorbs dimensional changes without creating harmful voids.
Solution Approach 2:
The invention changes the physical state and properties of the conduit material to be flexible and deformable. By selecting a material with appropriate elasticity and flexibility, the system can dynamically adjust to thermal parameter changes (temperature variations) without creating air gaps. The conduit's flexibility parameter allows it to compensate for differential thermal expansion between rigid components.
2Reliability
If the crimp screen is positioned to extend over the insulation portion, then air gaps are shielded from electrical stresses, but the assembly complexity increases
Solution Approach 1:
The crimp screen is merged with the flexible conduit by positioning the screen to extend over both the cable insulation and the conduit. This combining of protective functions (electrical shielding and mechanical protection) into a single integrated arrangement simplifies the overall structure while maintaining reliability. The crimp screen serves dual purposes: preventing arcing and protecting the flexible conduit.
3Adaptability or versatility
If components are allowed to move relative to each other during thermal contraction, then thermal stress is accommodated, but air gaps form that reduce the lifetime of the termination
Solution Approach 1:
The flexible conduit serves as a mediator that allows controlled movement between components while preventing harmful air gaps. It flexes and deforms to accommodate thermal contraction of the cable and surrounding structures, maintaining continuous electrical and mechanical contact. This intermediary element absorbs the dimensional changes that would otherwise create voids and arcing paths.
Solution Approach 2:
The invention employs a flexible conduit (shell) that can deform and flex to accommodate thermal movements. This flexible shell structure maintains continuous contact between components during thermal contraction and expansion, preventing the formation of air gaps. The flexibility of the shell allows it to adapt to dimensional changes without creating harmful voids or disconnections.
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
This design effectively shields air gaps from electrical stresses, preventing arcing and ensuring reliable operation across varying temperatures, and reduces assembly time by pre-moulding insulating and conductive portions, enhancing the termination's durability and efficiency.
Implementation Method 1
injecting a curable insulating compound between the electrode and the sleeve under pressure and curing the insulating compound
Implementation Method 2
differences in the thermal coefficient of expansions of the different materials used in the assembly cause relative movements between components in the assembly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A cable termination apparatus for an underwater cable comprises a cable crimp for electrically connecting the underwater cable to a pin; a conductive crimp screen; and an insulating portion which is located radially outwardly of the conductive crimp screen. The insulating portion has been moulded on the conductive crimp screen prior to assembly of the termination.