Composite pin type insulators, including 11KV pin insulator, are widely used on HV distribution lines and have better hydrophobicity and anti-ageing properties for the silicone rubber material applications.

The service experience of composite pin insulators has shown that the property “hydrophobicity” is vital for a reliable operation under polluted conditions without precautionary maintenance measures such as cleaning or greasing. Typically, 11KV pin insulator for lines in silicone rubber has smaller average diameters than porcelain or glass insulators. As a result, an improved flashover performance is achieved by the shape and by the non-wettability of the composite pin type insulators surface.

If the hydrophobicity of composite pin type insulators is lost, the second “defence mechanism” of the material against intensive ageing (bulk erosion, tracking) must protect the 11KV pin insulator. This is preferably evaluated by tests investigating tracking and erosion performance of the 11kv pin insulator.

Regarding the insulating behaviour of composite pin type insulators or 11KV pin insulator, the property of hydrophobicity is considered to be the most important factor. The dynamic processes of the 11KV pin insulator hydrophobicity loss and recovery and their strong dependence on material (including basic formulation, filler, and additives) and on processing technology are fields of continuous optimization.