Self-supporting Figure-8 Telecommunication Cable Design
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Solution Overview
Problem
Self-supporting overhead telecommunication cables face challenges in maintaining structural strength and flexibility while minimizing size and weight, as traditional strength and protective elements increase cable resistance to environmental loads and reduce flexibility.
Innovation Solution
The cable design positions optical fibers at the center with electrical conductors grouped into sub-units around them, acting as both strength and protective elements, eliminating the need for additional members and maintaining flexibility by using a polymeric buffer tube and SZ stranding configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional strength and protective elements are added to the cable, then structural strength against external loads is improved, but cable size and weight increase
Solution Approach 1:
The patent combines the optical fibre conductor and electrical conductors into a single figure-8 configuration where both components serve dual purposes: transmission functions and structural strength functions. The electrical conductors are positioned to act as protective elements around the optical fibre, eliminating the need for separate strength members.
Solution Approach 2:
The electrical conductors in the transmission portion serve multiple functions: they carry electrical signals/power and simultaneously provide structural strength and protection to the optical fibre conductor. This multi-functionality reduces the need for additional dedicated strength elements, thereby reducing cable weight.
2Strength
If traditional strength and protective elements are added to the cable, then structural strength against external loads is improved, but cable flexibility is reduced
Solution Approach 1:
The patent merges the strength-providing function into the existing electrical conductors and the figure-8 configuration itself, avoiding the addition of rigid protective elements like metal armor or heavy strength members that would reduce flexibility.
Solution Approach 2:
The patent uses a polymeric outer sheath that provides protection while maintaining flexibility. The figure-8 configuration itself acts as a flexible structural element that can bend and adapt during installation without requiring rigid protective layers.
3Strength
If additional strength members are provided in the transmission portion, then protection against external loads is improved, but cable size increases
Solution Approach 1:
The patent combines the optical fibre conductor and electrical conductors in a figure-8 configuration where the electrical conductors are positioned to surround and protect the optical fibre. This integration provides protection without requiring additional separate strength members that would increase cable size.
Solution Approach 2:
The optical fibre conductor is positioned at the center of the transmission portion, with electrical conductors nested around it in the figure-8 configuration. This nested arrangement provides structural protection while maintaining a compact cable size.
Data Source
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AI summary
A self-supporting overhead telecommunication/power cable (100) comprises a supporting portion (20) and a transmission portion (30) mutually arranged according to a figure-8 configuration. The transmission portion (30) comprises at a central position thereof, an optical fibre conductor (31) and, at a radially outer position with respect to the optical fibre conductor (31), electrical conductors (36) stranded around the optical fibre conductor (31). Preferably, the electrical conductor (36) are grouped into sub-units (35a, 35b, 35c) which are stranded around the optical fibre conductor (31) to provide a mechanical protection thereto.