Powder Coating Insulation with Spherical SiO2 for Low Viscosity
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Solution Overview
Problem
Existing insulation systems for electrical machines, particularly those with rated voltages above 1000 V, suffer from high viscosity formulations that lead to air-filled pores, poor degassability, and deficient surface quality, which can result in partial discharges due to the low dielectric strength of air inclusions.
Innovation Solution
A powder coating formulation comprising spherical SiO2 filler particles with specific properties, such as a maximum particle diameter of 100 μm, is used to create an insulation system with improved insulating properties, reducing viscosity and enhancing degassing properties, thereby minimizing air inclusions and improving surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fillers with high specific surface area (e.g., mica) are used in the formulation, then the insulating properties and electrical erosion resistance are improved, but the viscosity of the formulation increases significantly
Solution Approach 1:
The patent changes the particle shape parameter of the filler from platelet-shaped (mica) to spherical, and adjusts the particle size distribution (D50 between 3-7 μm, maximum 100 μm). This parameter change reduces the specific surface area while maintaining insulating properties, thereby reducing formulation viscosity and improving degassability.
2Reliability
If the formulation has high viscosity, then more filler can be incorporated for better insulating properties, but poor degassability occurs leading to air-filled pores in the cured insulation system
Solution Approach 1:
By changing the filler particle shape to spherical and optimizing the particle size distribution (D50: 3-7 μm, maximum: 100 μm), the formulation viscosity is reduced. This enables effective degassing during the curing process, preventing air-filled pores while maintaining high filler content for superior insulating properties.
3Reliability
If high filler content is used to enhance insulating properties, then the electrical erosion resistance improves, but the surface quality becomes deficient due to poor pore leveling
Solution Approach 1:
The use of spherical filler particles with controlled size distribution (D50: 3-7 μm, maximum: 100 μm) improves the flow and packing characteristics of the formulation. This enables better pore leveling and surface quality even with high filler content, while maintaining electrical erosion resistance.
4Reliability
If air inclusions are present in the insulation system, then the dielectric strength decreases leading to partial discharges, but removing air requires lower viscosity formulations
Solution Approach 1:
By optimizing the filler particle characteristics (spherical shape, D50: 3-7 μm, maximum: 100 μm), the formulation achieves reduced viscosity that facilitates complete degassing. This eliminates air inclusions that would compromise dielectric strength, while the high filler content maintains excellent electrical erosion resistance.
Data Source
AI summary
Various applications of the teachings of the present disclosure include a powder coating formulation suitable for producing an insulation system of an electrical machine. The formulation may include: a curable resin mixture; and spherical SiO2 filler particles having a maximum particle diameter of 100 μm.