Swellable Yarn Water Blocking in Power Cable Conductors

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Solution Overview

Problem

Existing water blocking methods for medium voltage power cables, such as Strandblock and simple water swellable yarns, are costly, difficult to maintain, and do not adequately meet safety standards for longitudinal water penetration resistance.

Innovation Solution

A combination of helically wound and longitudinally arranged water blocking yarns is applied between conductor elements in a power cable, forming a robust water blocking layer that enhances water ingress protection while reducing cable diameter and production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If strand filling compound is used to block water penetration, then water blocking performance is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvewater blocking performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the water-blocking function from the complex strandblock process and implements it through simple water-swellable yarns that are easily inserted into conductor spaces, eliminating the need for specialized equipment and complex manufacturing procedures while maintaining effective water blocking performance

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses inexpensive water-swellable yarns as a disposable-like solution that provides effective water blocking without requiring costly specialized equipment or complex maintenance, replacing the expensive and complex strandfill compound system

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If strand filling compound is used to block water penetration, then water blocking performance is improved, but production cost increases

Engineering Contradiction:

Improvewater blocking performanceVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive water-swellable yarns that can be easily inserted into conductor spaces, providing effective water blocking at a fraction of the cost of strandfill compound while eliminating the need for specialized application equipment and reducing production costs

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If strand filling compound is used to block water penetration, then water blocking performance is improved, but maintenance difficulty increases

Engineering Contradiction:

Improvewater blocking performanceVSAvoidmaintenance difficulty

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent extracts the water-blocking function from the maintenance-intensive strandblock system and implements it through simple water-swellable yarns that require no specialized maintenance equipment or procedures, allowing for easy inspection and replacement if needed

Inventive Principle:

Principle #2Taking out (Extraction)

4Ease of operation

If water swellable yarns are applied to conductor core, then installation simplicity is improved, but water protection adequacy worsens

Engineering Contradiction:

Improveinstallation simplicityVSAvoidwater protection adequacy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent combines multiple water-swellable yarns in different orientations (longitudinal and helical) and positions within the conductor structure to create a comprehensive water blocking system that maintains both installation simplicity and adequate water protection by addressing multiple potential water ingress paths

Inventive Principle:

Principle #5Merging (Combining)

5Productivity

If cable diameter is reduced using water swellable yarns, then manufacturing efficiency is improved, but water blocking effectiveness may worsen

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidwater blocking effectiveness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent combines longitudinal and helical water-swellable yarns in a multi-layer arrangement within the conductor, creating a compact yet effective water blocking system that reduces cable diameter and improves manufacturing efficiency while maintaining comprehensive water blocking effectiveness through multiple protective layers

Inventive Principle:

Principle #5Merging (Combining)

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 water blocking yarn arrangement provides effective circumferential protection, reduces production costs, and is more environmentally friendly compared to traditional methods, with improved performance in meeting safety standards and ease of equipment maintenance.

Implementation Method 1

Water swellable powders are a form of polymers that, when brought into contact with water, expand, trapping the water within, forming a water locking gel-like substance

Methodology Applied

Scientific EffectWater swelling: Absorption (physical)

Data Source

PatentUS7884282B2Swellable tapes and yarns to replace strand filling compounds

Publication Date: 2011.02.08 NEXANS SA

AI summary

A cable has a conductor and an insulator over the conductor. The conductor includes a first layer of at least one conductor element, a second layer of conductor elements, disposed over the first layer, and an intermediate water blocking layer, between the first and second conductor layers. The intermediate water block layering has at least one longitudinally applied water swellable yarn and at least one helically applied water swellable yarn.