Surface Contamination And Insulation Creepage Discharge Of Cable Terminals In Saline Environments

In near-shore, coastal, or heavily polluted industrial environments, airborne salt spray particles can deposit on the surface of cable lugs and its insulator, forming a salt-containing film. This type of contamination alters the surface state of the originally dry insulation material, reducing surface dielectric resistance and providing a path for current to propagate along the insulation surface. Upon contact with the insulation layer, this conductive thin layer can cause uneven electric field distribution, inducing leakage current and localized creepage discharge along the surface.

When the salt deposition is sufficiently high, the ion-carrying capacity of the water film increases, resulting in a significant increase in the surface leakage current observed along the interface between wire lugs and the insulation. The salt spray microenvironment reduces the dielectric strength of the insulation surface around electrical lugs, making it easier for additional voltage to form high-intensity electric field regions on the surface; these regions become discharge initiation points. The coexistence of wet contamination and air gaps enhances the electric field distortion within the insulation layer, leading to electrical breakdown and discharge phenomena under lower voltage conditions.

The creepage phenomenon caused by surface contamination not only affects the insulation performance of terminal lugs but also makes surface current paths more easily activated. Insulating materials may absorb more moisture under salt spray conditions, and their surface resistivity decreases with increasing humidity, promoting current diffusion along the surface and causing localized ion migration. This process differs significantly from the surface insulation behavior under traditional dry environments, leading to a faster rate of insulation performance degradation.