الفهرس 
LITERATURE REVIEW ANDOnly 14 pages are availabe for public view
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Abstract
Insulators failures in high voltage transmission lines can lead to outages of transmission lines, thereby reducing system reliability. One common form of insulator failure is flashover voltage. Contamination of the surface of the insulators such as salts, fog, rain and dust enhances the chances of flashover.
High voltage insulators are the most vital components of the power transmission and distribution networks. They hold the transmission line carriers of the electrical energy and isolate them from the ground.
Since 1970’s, a composite insulator has been introduced internationally as the potential replacement of the conventional porcelain and glass insulators. This insulator introduces many advantages represented in light-weight, ease of handling, resistance to vandalism and relatively low-cost. In principle, composite insulators should provide the same service as conventional ceramic insulators; withstand electrical, mechanical and weather stresses. However, the composite insulator was faced to contaminated weather as coastal area which leads to change the electrical and physical properties.
This work presents a study of the flashover voltage for outdoor polyester insulators under different salinities conditions. Polyester composite samples have been prepared, loaded with different concentrations of inorganic filler Alumina Trihydrate [ATH] to improve the physical and electrical properties in addition to maximizing the surface flashover voltage as well as decreasing the tracking phenomena.
Test results showed that while the flashover voltage of the tested specimens reached 40 kV for samples without filler, it reached 51 kV for samples containing 50 wt % of ATH under dry atmospheric conditions (i.e. 27.2% increases in the flashover voltage).
In this study, the effects of salinity on the electrical surface resistance of polyester composite samples have been investigated in details and evaluated as function of the equivalent salt deposits density. Also the physical properties have been illustrated. The microstructure and the internal structure of molecules have been investigated. The marine test discussed the effect of salt deposits on the surfaces of the specimens. The contact angle indicated that the material was hydrophobicity.