Monitoring and Diagnosis of ZnO Arresters

Surge arresters are part of the protection system of electrical substations and transmission and distribution networks. They avoid damages in equipments of main importance for the electric system, such as power transformers, not allowing them to be reached by overvoltages. An arrester presenting any kind of failure may not actuate in a satisfactory way during the occurrence of an electric surge. As a consequence, it will present an overheating which can lead to its complete degradation and exposing the system that should be protected and bringing risk to those who are working nearby [1]. In order to avoid this kind of problem, several monitoring techniques are used. The measurement of leakage current and the thermal analysis are the most used of these techniques. A work being developed in the High Voltage Laboratory of the Universidade Federal de Campina Grande together with the Companhia Hidrelétrica do São Francisco has the main purpose of developing a technique to be used for arrester monitoring by means of continuous analysis of its leakage current and variations on its thermal patterns, resulting in a useful tool for the diagnosis and preview of failures in ZnO arresters.