Fluorinated Insulation Layers for Partial Discharge Resistance

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Solution Overview

Problem

Electrical cables used in aeronautics face challenges with high voltage-induced partial discharges, which lead to degradation of insulating materials, especially under conditions of high temperature and low pressure, and existing insulation compositions do not adequately address resistance to these discharges at voltages of 230 V.

Innovation Solution

An electrical cable design featuring a conductive element surrounded by a polyimide layer, a fluorinated layer, and optionally a fluorinated semiconducting and adhesive layer, with a total thickness of fluorinated layers exceeding 0.4 mm, primarily utilizing materials like PTFE, FEP, and PFA, to enhance resistance to partial discharges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of fluorinated layers is increased to improve resistance to partial discharges, then the cable's reliability under high voltage conditions improves, but the cable's weight and diameter increase

Engineering Contradiction:

Improveresistance to partial dischargesVSAvoidcable weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent specifies precise thickness parameters for fluorinated layers (at least 0.4 mm total thickness) to achieve the necessary resistance to partial discharges while controlling weight increase. This parameter optimization resolves the contradiction by finding the minimum effective thickness that provides adequate protection without excessive weight gain.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite insulation structures combining polyimide layers and fluorinated layers (PTFE, FEP, or PFA) with specific thickness ratios. This composite approach provides enhanced partial discharge resistance compared to single-material solutions, achieving better reliability per unit weight by leveraging the complementary properties of different materials.

Inventive Principle:

Principle #40Composite materials

2Reliability

Engineering Contradiction:

Improveresistance to partial dischargesVSAvoidcable diameter

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent establishes specific thickness parameters for fluorinated layers (minimum 0.4 mm total) to achieve adequate partial discharge resistance while controlling diameter increase. This parameter optimization balances protection requirements with space constraints in aeronautical applications.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The insulation is divided into multiple functional layers (polyimide base layer and fluorinated protective layers) with optimized individual thicknesses. This segmentation allows each layer to perform its specific function efficiently, achieving the required overall protection with minimized total thickness compared to a single thick layer.

Inventive Principle:

Principle #1Segmentation

3Reliability

If existing insulation compositions are used, then the cable structure remains simple, but the resistance to partial discharges at high voltages is insufficient

Engineering Contradiction:

Improveresistance to partial dischargesVSAvoidinsulation composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs composite insulation structures combining polyimide and fluorinated polymers in specific configurations. This composite approach provides superior partial discharge resistance at high voltages (230 V and above) compared to single-material insulations, justifying the increased structural complexity through enhanced performance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different layers are assigned specific materials and thicknesses based on their local functional requirements: polyimide provides base insulation and thermal stability, while fluorinated layers provide enhanced resistance to partial discharges. This localized optimization of material properties achieves high voltage resistance without uniformly increasing complexity throughout the entire cable structure.

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 increased thickness of fluorinated layers significantly increases the cable's resistance to partial discharges, ensuring reliability under high temperatures and low pressures, with the solution effectively withstanding higher discharge inception voltages, even at 230 V.

Implementation Method 1

partial discharges (PD) on electronic equipment, such as electrical cables. Now, partial discharges, which are minute electric arcs in the material insulating the cable

Methodology Applied

Scientific EffectDielectric: Dielectric

Data Source

PatentUS10096398B2Electrical cable that is resistant to partial discharges

Publication Date: 2018.10.09 NEXANS SA

AI summary

An electrical cable (1) is provided having (1) a conductive element (2), a first layer (3) having polyimide (PI) surrounding said conductive element (2), a second fluorinated layer (4) having at least one fluorinated compound, surrounding the first layer, and optionally at least one fluorinated semiconductor layer having at least one fluorinated compound, where the total thickness of the assembly of fluorinated layers is at least 0.4 mm.