Cable Semi-Conductive Layer Carbon Nanotube Integrity Testing

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Solution Overview

Problem

Existing electrical and optical cables face challenges in jacket integrity testing due to the use of graphite-based semi-conductive layers, which are messy and difficult to maintain, and electrically conductive polymers that are costly and incompatible with common cable materials, making it hard to perform integrity tests, especially on colored cables.

Innovation Solution

A cable with an external semi-conductive layer made of a composition comprising a base polymer material and carbon nanotubes as the electrically conductive filler, which provides the required conductivity for integrity tests without altering the natural color or compatibility, allowing for visually distinguishable layers and reduced costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If graphite-based semi-conductive layers are used for jacket integrity testing, then the required electrical conductivity for testing is achieved, but the cable becomes messy and difficult to maintain

Engineering Contradiction:

Improvejacket integrity testing capabilityVSAvoidmaintenance difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the material composition of the semi-conductive layer from graphite-based to carbon black-filled polymeric material. This parameter change maintains the required electrical conductivity for jacket integrity testing while eliminating the messiness and maintenance difficulties associated with graphite-based materials. The carbon black-filled polymer provides equivalent electrical properties for DC withstand testing without the operational drawbacks.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite material consisting of a polymeric base material filled with carbon black particles. This composite structure combines the electrical conductivity of carbon black with the mechanical properties and processability of polymeric materials, creating a semi-conductive layer that is both functionally effective for integrity testing and easy to handle and maintain during cable operations.

Inventive Principle:

Principle #40Composite materials

2Reliability

If electrically conductive polymers are used for semi-conductive layers, then jacket integrity testing is enabled, but the cost increases and compatibility with common cable materials decreases

Engineering Contradiction:

Improvejacket integrity testing capabilityVSAvoidmanufacturing cost and material compatibility

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive electrically conductive polymers with a cost-effective alternative: a polymeric material filled with carbon black. This substitution uses readily available, inexpensive materials that can be easily processed and applied during cable manufacturing, significantly reducing production costs while maintaining the necessary electrical conductivity for integrity testing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses a polymeric base material for the semi-conductive layer that is homogeneous with or compatible with the cable jacket material. This ensures consistent processing conditions, proper adhesion between layers, and uniform electrical properties throughout the semi-conductive layer, eliminating compatibility issues that arise with heterogeneous material combinations.

Inventive Principle:

Principle #33Homogeneity

3Reliability

If black semi-conductive layers are applied on colored cables, then integrity testing is possible, but the visual appearance and color identification are lost

Engineering Contradiction:

Improvejacket integrity testing capabilityVSAvoidvisual color identification

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies the semi-conductive layer with carbon black filler in a controlled manner where the concentration and distribution of carbon black provide the necessary electrical conductivity without completely obscuring the underlying cable color. This local quality approach allows the semi-conductive function to be achieved while preserving sufficient visual identification of the cable's color code for safety and routing purposes.

Inventive Principle:

Principle #3Local quality

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 solution enables cost-effective and compatible semi-conductive layers that maintain the natural appearance and color of the cable, facilitating easier integrity testing and visual differentiation of cable elements, thus improving maintenance and compliance with customer and regulatory requirements.

Implementation Method 1

an external semi-conductive layer around and in direct contact with the outermost polymeric layer of the jacket, made of a composition comprising a base polymer material and carbon nanotubes as the electrically conductive filler

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11651870B2Cable with semi-conducting outermost layer

Publication Date: 2023.05.16 PRYSMIAN SPA

AI summary

A cable includes a transmissive core; a jacket surrounding the transmissive core, which has at least an outermost polymeric layer; and an external semi-conductive layer around and in direct contact with the outermost polymeric layer of the jacket. The external semi-conductive layer is made of a composition comprising a base polymer material and an electrically conductive filler. The electrically conductive filler includes carbon nanotubes.