Anhydride-Free Epoxy Insulation for Vacuum Pressure Impregnation
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Solution Overview
Problem
Current epoxy resin-based insulation systems for vacuum pressure impregnation in electrical machines face challenges due to the expected restriction on anhydride hardeners, leading to high initial viscosity, reduced storage stability, and inadequate thermal class, especially with the need for cooling and higher dielectric dissipation factors.
Innovation Solution
An anhydride-free insulation system using thermally curable epoxy resin formulations with quarternary ammonium salts and diarylethane derivatives as curing initiators and co-initiators, integrated into mica paper or tape, to maintain low viscosity, enhance storage stability, and achieve higher thermal classes without the need for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If anhydride hardeners are used in epoxy resin formulations, then good impregnation effectiveness and low initial viscosity are achieved, but regulatory restrictions are expected and working hygiene deteriorates
Solution Approach 1:
The patent extracts and removes the problematic anhydride hardener component from the epoxy resin formulation, replacing it with alternative curing agents that do not trigger regulatory restrictions. This extraction eliminates the harmful factor while maintaining the essential impregnation functionality through the use of restricted epoxy resins and alternative hardeners.
Solution Approach 2:
The patent changes the chemical parameters of the formulation by switching from anhydride-based hardeners to alternative curing agents. This parameter change in the chemical composition allows the system to meet regulatory requirements while maintaining acceptable impregnation performance through adjusted formulation parameters.
2Object-affected harmful factors
If restricted epoxy resins are used to comply with regulations, then working hygiene improves, but initial viscosity increases and storage stability reduces
Solution Approach 1:
The patent introduces an intermediary substance - a reactive diluent or modifier - that mediates between the restricted epoxy resin and the final formulation properties. This intermediary component helps reduce the high initial viscosity and improve storage stability of the restricted resin system without compromising the regulatory compliance achieved by using restricted epoxy resins.
3Object-affected harmful factors
If restricted epoxy resin formulations are used, then regulatory compliance is achieved, but thermal class performance becomes inadequate
Solution Approach 1:
The patent creates a composite insulation system that combines restricted epoxy resins with alternative hardeners and additional functional components. This composite formulation achieves both regulatory compliance and adequate thermal class performance by leveraging the synergistic effects of multiple materials, where the combination compensates for the thermal limitations of the restricted resin alone.
4Object-affected harmful factors
If restricted epoxy resin formulations are used, then regulatory compliance is achieved, but dielectric dissipation factor increases
Solution Approach 1:
The patent adjusts the formulation parameters by selecting specific alternative hardeners and additives that minimize the dielectric dissipation factor. Through careful parameter optimization of the restricted resin system, the patent achieves regulatory compliance while controlling the harmful dielectric losses by modifying the chemical composition and curing characteristics of the formulation.
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 system achieves improved impregnation effectiveness, storage stability, and thermal performance, with a dielectric dissipation factor below 10% at elevated temperatures, addressing the limitations of existing systems while being compliant with regulatory requirements.
Implementation Method 1
a thermally curable epoxy resin formulation... thermally curable in order to mechanically fix the mica-wrapped current-carrying parts
Implementation Method 2
comprises a thermally activatable curing initiator for the epoxy resin formulation consisting of one or more quarternary ammonium salts of an aromatic-heterocyclic compound and a co-initiator
Implementation Method 3
the construction components of the engine, which shall be impregnated, are inserted into a container, which is then evacuated, so that humidity and air are removed from all gaps and voids
Implementation Method 4
an impregnation formulation is fed into the evacuated container followed by a period of applying an overpressure... the formulation penetrates the mica paper or tapes and the gaps and voids existing in the components forced by the pressure difference
Implementation Method 5
the formulation penetrates the mica paper or tapes and the gaps and voids existing in the components forced by the pressure difference between the vacuum and the high pressure applied to the components
Data Source
AI summary
Disclosed is a mica paper or mica tape for wrapping parts of an electric engine that are potentially current-carrying during operation of the engine, which mica paper or mica tape is impregnable via vacuum pressure impregnation with a thermally curable epoxy resin formulation and comprises a thermally activatable curing initiator for the epoxy resin formulation consisting of one or more quarternary ammonium salts of an aromatic-heterocyclic compound, which contains 1 or 2 nitrogen atoms, and a complex anion selected from the group consisting of BF4, PF6-, SbF6-, SbF 5 (OH) ", AsF6- and AI[OC(CF3)3]4 in an amount sufficient to cure the epoxy resin taken up by the mica paper or mica tape and the construction part of the engine during the vacuum pressure impregnation step. Also recites an anhydride-free insulation system therewith.