Injection Moulding Insulation System for Power Cable Joints

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Solution Overview

Problem

The existing methods for manufacturing high-voltage power cable joints are lengthy, vulnerable to contamination, and require extensive training, with manual processes that include multiple layers of tapes and lengthy heat treatment for crosslinking, leading to increased time and costs.

Innovation Solution

A method involving injection moulding to build an insulation system around a naked conductor section, using multiple mould inserts to form inner and outer semiconducting layers around an existing insulation layer, reducing the need for tape-based layers and eliminating heat treatment steps, thereby streamlining the manufacturing process and improving quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual tape-based layers are used for insulation system manufacturing, then the process allows flexibility in assembly, but the manufacturing time increases significantly and vulnerability to contamination rises

Engineering Contradiction:
Improveflexibility in assemblyVSAvoidmanufacturing time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces the manual mechanical process of winding and layering tapes with an automated injection moulding system. The injection moulding machine automatically forms the insulation layers by injecting compound material into a mould around the conductor, eliminating the need for manual tape assembly while maintaining precise layer formation and reducing manufacturing time significantly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If multiple separate curing steps are used for each insulation layer, then complete curing is achieved, but the manufacturing time and process complexity increase

Engineering Contradiction:
Improvecuring completenessVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple separate curing steps into a single integrated curing process. The injection moulding system cures all insulation layers simultaneously in one operation, eliminating the need for separate curing steps for each layer. This reduces process complexity while ensuring complete curing of all layers through the integrated moulding and curing cycle.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If extensive heat treatment is applied for degassing, then polar by-products are removed, but the manufacturing time extends by days or weeks

Engineering Contradiction:
Improveinsulation performanceVSAvoidheat treatment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent skips the traditional extensive heat treatment step for degassing. The injection moulding process is designed to minimize the formation of polar by-products during curing, eliminating or drastically reducing the need for prolonged heat treatment. This allows the manufacturing process to proceed without the days or weeks of additional heat treatment time while maintaining insulation performance.

Inventive Principle:
Principle #21Skipping (Rushing through)

4Manufacturing precision

If manual jointing procedures are used, then trained personnel can ensure quality assembly, but the process is vulnerable to contamination and requires extensive training

Engineering Contradiction:
Improveassembly qualityVSAvoidcontamination risk
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The injection moulding system performs the assembly function automatically without requiring manual intervention. The system self-regulates the injection process, curing cycle, and layer formation, eliminating the need for trained personnel to perform manual jointing. This automated approach reduces contamination risk by minimizing human contact with the insulation materials and assembly process.

Inventive Principle:
Principle #25Self-service

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

This approach reduces manufacturing time and costs by up to 40%, eliminates the need for tape production, and enhances the reliability and performance of the insulation system by minimizing voids and defects, while maintaining a cleaner and more consistent production process.

Implementation Method 1

moulding an insulation system around the naked conductor section, wherein the moulding of the insulation system involves injecting a first semiconducting compound into a first mould cavity to form an inner semiconducting layer around the naked conductor section, injecting an insulation compound into a second mould cavity to form an insulation layer around the inner semiconducting layer, and injecting a second semiconducting compound into a third mould cavity to form an outer semiconducting layer around the insulation layer

Methodology Applied
Scientific EffectInjection moulding:

Data Source

PatentEP3320588B1A method of building an insulation system around a naked conductor section of a power cable
Publication Date: 2022.02.23 NKT HV CABLES AB
  • EP3320588B1 patent drawingFigure 1~2
  • EP3320588B1 patent drawingFigure 3~4
  • EP3320588B1 patent drawingFigure 5a~5c

AI summary

The present disclosure relates to a method of building an insulation system around a naked conductor section of a power cable, which power cable has a conductor which includes the naked conductor section and which power cable comprises an insulation system already provided around a majority of the conductor. The insulation system comprises an inner semiconducting layer arranged around the conductor, an insulation layer arranged around the inner semiconducting layer, and an outer semiconducting layer arranged around the insulation layer, and which conductor has a naked conductor section. The method comprises: a) placing the naked conductor section in a mould, and b) moulding an insulation system around the naked conductor section, wherein the moulding of the insulation system involves injecting a first semiconducting compound into a first mould cavity to form an inner semiconducting layer around the naked conductor section, injecting an insulation compound into a second mould cavity to form an insulation layer around the inner semiconducting layer, and injecting a second semiconducting compound into a third mould cavity to form an outer semiconducting layer around the insulation layer.