Composite Power Cable Armoring With Protected Fiber Optics
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Solution Overview
Problem
Submarine HVDC power cables face challenges due to the low mechanical strength of optical fibers, which can lead to damage during handling and installation, and existing methods for incorporating fiber optics in cables are not robust enough, leading to issues with bending radius and handling requirements.
Innovation Solution
A method for manufacturing composite electric power cables that involves assembling inner layers with electric conductors and adding an armoring layer with fiber optic elements arranged within a tube, where the tube's outer diameter is between 40% to 95% of the armoring wires' outer diameter, allowing for improved mechanical protection and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fiber is provided as FIMT between lead layer and plastic sheath, then optical fiber is protected from damage, but minimum allowable bending radius becomes very high and large turntables are needed
Solution Approach 1:
The optical fiber is nested within a metallic tube (FIMT - Fiber in Metallic Tube), which is then integrated into the cable structure between the lead sheath and plastic sheath. This nesting approach provides mechanical protection to the fragile optical fiber while maintaining cable flexibility through proper layer integration
Solution Approach 2:
The patent transitions from placing optical fiber directly in the cable core to embedding it within a protective metallic tube dimension, and further integrating this FIMT structure into the intermediate layer between lead and plastic sheaths. This dimensional repositioning reduces bending radius constraints
2Reliability
If optical fiber is laid out in wave pattern to compensate for lengthening during bending, then fiber is protected from tension damage, but cable diameter increases and manufacturing complexity increases
Solution Approach 1:
The optical fiber is pre-installed within the metallic tube during the cable manufacturing process, before the final plastic sheath extrusion. This preliminary integration allows the fiber to be properly positioned and protected without requiring post-manufacturing adjustments or complex wave pattern arrangements
Solution Approach 2:
The patent merges the optical fiber, metallic tube, lead sheath, and plastic sheath into a single integrated cable structure. The FIMT is incorporated as an intermediate layer during extrusion, combining multiple protective functions into one unified manufacturing step rather than separate operations
3Length of moving object
If several lengths of optical fiber are joined to match cable length, then desired fiber length is achieved, but joints become weak points prone to damage and cable diameter increases
Solution Approach 1:
The metallic tube serves as an intermediary structure that encapsulates the optical fiber throughout its entire length. This continuous protective enclosure eliminates exposed joint areas where weaknesses would occur, as the tube provides uniform mechanical protection along the full fiber span without requiring external jointing cabinets or connectors
Data Source
AI summary
A method (30) for manufacturing a composite electric power cable (20) includes assembling (32) inner layers (21) of the composite electric power cable (20), where the inner layers include at least one electric conductor (27). The method further includes adding (34) an armoring layer (26) with at least one fiber optic element (23) by winding a plurality of armoring wires (22) helically around the inner layers (21), and winding the at least one fiber optic (23) element between at least two of the armoring wires (22).