ZnO Microvaristor Tape for Nonlinear Field Control

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Solution Overview

Problem

Existing nonlinear electrical tapes for high and medium voltage applications face challenges in manufacturing complexity, material density, and reliability of nonlinear electrical properties, particularly with SiC and SnO2-based systems.

Innovation Solution

A nonlinear electrical tape using doped zinc oxide (ZnO) microvaristor particles with a binder, offering improved processability and robust nonlinearity, featuring reduced density and simpler production compared to conventional tapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SiC or SnO2 coated particles are used as filler, then nonlinear electrical properties are improved, but manufacturing complexity increases

Engineering Contradiction:
Improvenonlinear electrical propertiesVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the complex coating process from the manufacturing system by using pre-formed SiC and SnO2 particles directly, rather than coating them during production. This separates the particle preparation step from the tape manufacturing step, simplifying the overall process while maintaining the nonlinear electrical properties provided by these materials

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The binder serves multiple functions: it holds the filler particles together, provides adhesion to the substrate, and facilitates processing. By using a versatile binder system that can accommodate both SiC and SnO2 particles without requiring separate processing lines, the invention achieves manufacturing simplicity while maintaining reliable nonlinear electrical properties

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If SnO2 coated filler particles are used, then electrical nonlinearity is improved, but material density increases

Engineering Contradiction:
Improveelectrical nonlinearityVSAvoidmaterial density
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The invention applies local quality by using SnO2 coating only on the surface of filler particles rather than using bulk SnO2 material. This provides the electrical nonlinearity at the particle surface where it is most effective for field control, while the core particle material can be lighter, thus reducing overall material density while maintaining electrical performance

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention uses composite filler particles consisting of a core material coated with SnO2. This composite structure combines the electrical nonlinearity benefits of SnO2 with the lower density of the core material, achieving a balance between electrical performance and weight reduction

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If doped ZnO microvaristor particles are used, then processability is improved, but manufacturing precision requirements increase

Engineering Contradiction:
ImproveprocessabilityVSAvoidparticle size control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention changes the particle size parameters of the doped ZnO microvaristors to optimize both processability and performance. By selecting specific size ranges and using appropriate size distributions, the invention achieves easy processing while maintaining consistent electrical properties, reducing the stringency of precision requirements

Inventive Principle:
Principle #35Parameter changes

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 ZnO microvaristor tape provides enhanced nonlinear electrical properties, reduced dielectric losses, and increased impulse withstand voltages, while being easier to produce and less prone to processing and aging issues.

Implementation Method 1

the filler particles comprise microvaristor particles containing doped zinc oxide (ZnO)... providing robust nonlinearity... enhanced nonlinear electrical properties

Methodology Applied
Scientific EffectNonlinear electrical properties: Electrical Resistance

Implementation Method 2

a substrate that is impregnated with a binder containing inorganic filler particles

Methodology Applied
Scientific EffectImpregnation: Absorption (physical)

Data Source

PatentEP1894211B1Varistor-based field control tape
Publication Date: 2009.07.29 ABB RES LTD

AI summary

The invention relates to a nonlinear field control tape containing ZnO microvaristor particles. The doped ZnO particles are produced by crushing a sintered ZnO block, by desagglomeration or crushing of calcinated granulated particles, or by crushing of a calcined or sintered tape (tape casting). Embodiments, among other things, relate to: hollow ZnO microvaristor particles produced by granulation technique, having reduced average density and having diameters in a range well below 90 µm; and compounding the ZnO filler in binders that are used to impregnate tapes. Compared to nonlinear field control tapes with conventional embedded nonlinear filler particles, a stronger and more reliable nonlinear resistivity is achieved and the ZnO filler is simpler to produce and to compound in the binder. The resulting tapes are flexible, preferably self-adhesive and have a strong nonlinear electrical resistivity. The tapes are useful to protect high field-stress regions in electrical components.