ZnO Surge Arresters Diagnosis Using Microcontroller

Surge arresters are equipments used for the power electrical systems protection. They limit the voltage level during the occurrence of switching and atmospheric surges. A surge arrester failure can cause the equipments insulation breakdown or flashover, or even the surge arrester explosion. To avoid this problem, the maintenance of these equipments is made by means of regular monitoring. Measurement of the resistive leakage current and analysis of its harmonic components is one of the most used techniques to evaluate the degradation level of metal oxide surge arresters. In this paper is presented a new measurement technique for the resistive component of leakage current based on the orthogonal position between this component and the capacitive component. The technique is accomplished by means of inductive current sensors based on nanocrystalline alloys and a PIC microcontroller to provide the measurement of the first, third and fifth harmonic components of the resistive leakage current in the arrester.