Why Does Partial Discharge Occur On The Surface Of Insulators? In-depth Analysis Of The Causes

Often, those subtle buzzing sounds during power grid operation foreshadow potential problems for the suspension insulator series electrical components. These seemingly insignificant electrical phenomena, if not handled properly, can escalate into serious power outages. A common concern is: how exactly does this partial discharge occur?

Synergistic effect of surface contamination and moisture

Dust, salt spray, or industrial exhaust gases in the environment will form a thin layer of contamination on the surface of suspension composite insulator over time. In foggy or drizzly weather, this contaminant dissolves in water, forming a highly conductive water film. Under these conditions, surface leakage current increases dramatically, and the electric field distribution becomes extremely uneven.

• Dry zone formation: Localized areas of high resistance are formed by the evaporation of moisture due to heat.

• Potential distortion: The voltage is almost entirely concentrated in a narrow dry area.

• Breakdown phenomenon: The air gap in the dry area cannot withstand the voltage stress, directly inducing a local electric arc.

Hidden defects left by the manufacturing process

Sometimes problems will appear before the composite suspension insulator product leaves the factory. If microbubbles are trapped inside during the molding process, or microcracks exist within the ceramic/composite material, the dielectric constant at these locations will be much lower than that of the solid insulating material. Under high voltage conditions, these defective areas will ionize prematurely.

Material Aging Due to Long-Term Operation

Under the long-term exposure to ultraviolet radiation and strong electric fields, the molecular chains of the material will gradually break down. This decline in physical properties makes the surface of polymer suspension insulator rough, and may even result in microscopic "dendritic" carbonization channels. This aged surface is like laying tracks for electric current, making discharge more frequent.

Misalignment in Structural Design and Installation Position

The electric field strength at the junction of metal fittings and insulating components is usually high. If there are burrs on the edges of the fittings, or mechanical scratches during installation, these can become breeding grounds for partial discharge. At high altitudes or in extreme weather conditions, these structural weaknesses will be magnified.