Failure Analysis in ZnO Arresters Using Thermal Images

ZnO arresters are protective devices of electrical power systems. An arrester with some kind of failure is not able to operate properly during an electrical surge. As a consequence it will present an excessive heating which can lead to a thermal runaway [1,2,3]. Thermographic inspection is a widely used method to monitor surge arresters preventing their failure. When an arrester is substituted due to some abnormality detected by means of thermal inspection, no further analysis is done, so that the causes of the problem cannot be evaluated. In addition, there is no study indicating which are the main causes of failures in ZnO arresters or if there is another alternative to the substitution of them. This work presents a study done with 96 kV ZnO arresters presenting the most common failures detected in substations and their effects on the thermal image.