Analysis Of Pollution Accumulation In Transmission Line Insulators And Evolution Of Flashover Risk

The natural contamination layer formed by industrial dust, salt spray, and atmospheric particulate matter deposited on the surface of insulation material dead end insulators is a potential source of power system operational accidents. This physical deposition process is directly affected by environmental humidity, wind speed, and the structure of the insulation skirt, leading to fundamental changes in the electrical properties of the insulation surface.

Evolution Mechanism of the Physicochemical Properties of the Contamination Layer

The process of contamination accumulation on the surface of insulation material dead end suspension insulators exhibits distinct stages. Initially, the attached dry dust maintains a high surface resistivity. When the ambient humidity exceeds a critical value, the soluble salts in the contamination layer rapidly ionize, forming a conductive electrolyte film.

• Moisture Dissolution Stage: Water mist, dew, and drizzle transform the dry contamination into a highly conductive slurry.

• Local Dry Zone Formation: Joule heating generated by leakage current causes moisture evaporation, forming a high-resistivity annular dry zone.

• Arc-Induced Flashover: Voltage concentration on both sides of the dry zone induces localized sparks, ultimately leading to insulation strength collapse.

Analysis of Comprehensive Influencing Factors of Pollution Flashover Faults

Insulators made of different materials exhibit significant differences in their sensitivity to pollution. Porcelain surfaces, due to their strong hydrophilicity, easily form continuous water films; while composite materials, with their hydrophobic migration properties, can disrupt the continuity of conductive paths.

Geographical location plays a decisive role in the rate of pollution accumulation. The equivalent salt density (ESDD) formed on the polymer deadend insulator surface by salt particles in coastal areas and sulfur dioxide emissions from industrial areas differs greatly. Regular monitoring of equivalent salt density and assessment of ash density (NSDD) helps to understand the true insulation status of transmission equipment. For highly polluted areas, adjusting creepage distances or adopting anti-pollution structures can significantly improve the pollution resistance of lines.