Polymeric pin insulator can be divided into common insulator and anti-pollution insulator or anti-fog insulator. Anti-pollution insulator can be used heavily pollution areas.

What do cause the polymeric pin insulator flashover phenomenon?
Dirt, pollution, salt, and particularly water on the surface of a high voltage polymeric pin insulators can create a conductive path across it, causing leakage currents and flashovers.

How to reduce polymeric pin insulator flashover phenomenon
◆The flashover voltage can be reduced by more than 50% when the polymeric pin insulator is wet.
◆High voltage composite pin type insulators for outdoor use are shaped to maximize the length of the leakage path along the surface from one end to the other, called the creepage length, to minimize these leakage currents.
◆To accomplish the surface for polymeric pin insulator is moulded into a series of corrugations or concentric disc shapes. These usually include one or more sheds; downward facing cup-shaped surfaces that act as umbrellas to ensure that the part of the surface leakage path under the 'cup' stays dry in wet weather.
◆Minimum creepage distances for polymeric pin insulator or composite pin insulators are 20–25 mm/kV, but must be increased in high pollution or airborne sea-salt areas.

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