PERFORMANCE OF HV TRANSMISSION-LINE INSULATORS IN DESERT CONDITIONS .3. POLLUTION MEASUREMENTS AT A COASTAL SITE IN THE EASTERN REGION OF SAUDI-ARABIA

Contamination flashover is the major cause of insulator failure in the eastern region of Saudi Arabia. Saudi Consolidated Electric Company in the eastern region (SCECO East) has adopted several countermeasures such as increasing the creepage distance and using insulators of different shapes and materials including resistive-glazed insulators. The utility, however, still relies primarily on an expensive, rigorous maintenance program. The insulator contamination problem is strongly environment-dependent and no generalized anti-pollution criteria can be offered. Optimization of insulators design and their subsequent maintenance requires information about the the performance of specific insulators under wet, contaminated, and energized conditions. The most reliable approach to acquiring this information would be long-term outdoor testing in areas of interest for existing and future transmission lines. As part of a national effort to study insulator contamination problems, ten field stations, five energized and five unenergized, have been constructed at representative locations throughout the country. The first dedicated energized insulator test station near the Ghazlan power plant has been operational since April 1985. The test site is about 500 m away from the coast. Insulator samples of different shapes and materials have been tested in different string configurations. Leakage current statistics in terms of surge counting and I-highest have been recorded simultaneously with meteorological parameters. Moreover, the number of flashovers experienced by different insulators were registered. All date were acquired and stored utilizing a digital automatic data acquisition system. In this paper, fundamental data of equivalent salt deposit density and the chemical composition of prevailing pollution are presented and a modified classification of pollution severity is proposed. Leakage current data and the flashover statistics are given. Based on various measured parameters, a comparison of performance among different insulators is discussed.