Insulation coordination and pollution measurements in the island of Crete

The performance and reliability of outdoor dielectrics used in power systems is strongly linked to local environmental conditions. A major factor affecting their performance is the pollution severity in the area along with local climatic conditions. Sea is considered a major pollution source and therefore coastal installations and islands usually face severe pollution problems. The Mediterranean island of Crete provides a rather interesting case study as the particular conditions met there have resulted to the island being a reference point on both national and global scale. The Greek utility has employed several different remedies to cope with the pollution problem over the years. Pollution measurements have been performed throughout the island in order to acquire a pollution map to assist in insulation coordination and maintenance. Measurements have been performed on un-energized insulators similar to the ones used in each area/tower at that time. However, as both material and profile play an important role on the actual pollution impact, comparative measurements have also been performed in a specially designed High Voltage Test Station in order to derive a suitable correlation factor between different insulators. The final version of the acquired pollution map is presented in this paper and is correlated to network experience regarding the maintenance and selection strategy of outdoor insulators.