The aim of this study is to propose simple and reliable techniques to assess the condition of metal oxide arrester based on the dielectric response techniques. A number of modern electrical diagnostics for Metal Oxide Surge Arrester (MOSA) are discussed in this paper. The techniques included return voltage, decay voltage and polarisation/depolarisation current measurement. The single and multipulse current (8/20micros) was used to artificially degrade the MOSA. The before and after diagnostic results of the new techniques are presented and interpreted. Finally, the correlation of different diagnostic results are discussed and compared to the existing techniques.
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