Composite Power Cable Fiber Layer for Smaller Bending Radius
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Solution Overview
Problem
Submarine HVDC cables face challenges due to the low mechanical strength of optical fibers, which are prone to damage during installation and repair, and require large turntables for handling, making existing methods costly and inefficient.
Innovation Solution
A composite electric power cable manufacturing method involving a data transmission layer with polypropylene bolts and fiber optic elements wound helically around inner layers, with the fiber optic elements arranged within a metallic tube to enhance mechanical strength and facilitate easier installation and repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fiber is provided as FIMT (fiber in metallic tube) between lead layer and plastic sheath, then optical fiber is protected during installation, but minimum allowable bending radius becomes very high requiring large turntables
Solution Approach 1:
A gel substance is introduced as an intermediary material between the optical fiber and the metallic tube (FIMT). This gel acts as a cushioning layer that allows the optical fiber to bend more easily while still providing protection, thereby reducing the minimum allowable bending radius without compromising fiber protection
Solution Approach 2:
The invention changes the physical state and properties of the protective layer by using a gel substance instead of a rigid or semi-rigid material. This parameter change in material flexibility allows for smaller bending radii while maintaining optical fiber protection during installation and operation
2Length of moving object
If optical fiber is joined in multiple lengths to match cable length, then desired length is achieved, but joints become weak points prone to damage and increase cable diameter
Solution Approach 1:
The optical fiber is provided with excessive length during manufacturing, allowing it to be laid out in a wave pattern on the bedding tape before cable assembly. This preliminary arrangement prevents the need for joints by ensuring the fiber is long enough to span the entire cable length, eliminating weak points while maintaining appropriate cable diameter
3Ease of manufacture
If FIMT is placed longitudinally on lead sheath layer after extrusion, then optical fiber element is integrated in cable, but large turntables are required for production and installation
Solution Approach 1:
The invention changes the flexibility parameter of the cable assembly by introducing gel substance that reduces the minimum allowable bending radius. This allows the cable to be handled on smaller turntables during both production and installation, reducing equipment requirements while maintaining proper optical fiber integration
4Reliability
If optical fiber damage occurs after production, then repair is needed, but repair processes are complicated and expensive
Solution Approach 1:
The gel substance serves as a mediator that facilitates easier repair by allowing the optical fiber to be accessed and replaced without complex disassembly. The gel's flexible nature enables simpler repair procedures compared to rigid protective structures, reducing repair complexity and cost while maintaining fiber integrity
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 (21) have at least one electric conductor (29). The method includes adding (34) a data transmission layer (24) with a plurality of polypropylene bolts (22) and at least one fiber optic element (23), by winding the plurality of polypropylene bolts (22) helically around the inner layers (21) and winding the at least one fiber optic element (23) between at least two of the polypropylene bolts.