Electrical Power system Insulators Selection and Testing Criteria

Abstract

The performance of insulators used on overhead transmission lines and overhead distribution lines is a key factor in determining the reliability of power delivery systems. The insulators not only must withstand normal operating voltage, but also must withstand over voltages that may cause disturbances, flashovers and line outages. Some power system networks designed without consideration to insulators length and characteristics which should adjusted according to the relevant contamination conditions of the area crossed by the lines to eliminate under design or over design scenarios.By analysis of the current networks and compare the installed insulators characteristics with the requirement of the international and local standards the insulators length and characteristics will be adjust to eliminate the possibilities of frequent flashover voltages alongside analysis the benefits of using new polymer insulators. Insulator selection for overhead transmission lines and overhead distribution lines is an exercise which requires specific considerations given the particularity of the application. Insulators for AC lines are made with specific dielectric materials, and this project presents the key and fundamental attributes of these insulators. Additionally, the insulator length and characteristics, such as leakage distance, have to be adjusted according to the relevant contamination conditions of the area crossed by the line hence the reduction in the performance of outdoor insulators occurs mainly by the pollution of the insulating surfaces from air-borne deposits that may form a conducting or partially conducting surface layer especially when wet. Guidance is given in this project to help understand the process of definition of insulators for an AC application and its Electrical & Mechanical Ratings and testing. Using examples from Sudanese electricity Distribution Company and Sudanese transmission line company as case study.