Total Leakage Current Decomposition of Surge Arresters Using Discrete Fourier Transform

Overvoltage surge arresters (SAs) are subjected to degradation due to continuous operation, moisture ingress, and increasing heating conditions. Catastrophic failures of SAs can be avoided by assessing their performance using either online monitoring or offline testing techniques. This paper presents an efficient offline experimental technique for harmonic components extraction of leakage currents of SAs by decomposing the total leakage current (TLC) into its capacitive and resistive components. The technique aims to extract the third harmonic resistive current, which is considered an important indicator for assessing the degradation level of SAs, using discrete Fourier transform (DFT). In this work, diagnosis of three 33 kV, 10 kA SAs, namely polymer zinc oxide (ZnO), silicon rubber ZnO, and porcelain silicon carbide (SiC) distribution class SAs is presented. The experimental results show the capability of the proposed technique for diagnosing both ZnO and SiC arresters.