Electromagnetic emission based monitoring technique for polymer ZnO surge arresters

Electromagnetic emission at the very high frequency (VHF) range of 30 to 300 MHz is used to detect surface defects on outdoor polymer zinc oxide (ZnO) surge arresters. The partial discharge related signals are recorded and studied. Since the surge arresters are usually exposed to adverse weather conditions, the effect of moisture and pollution on the characteristics is also investigated. Samples subjected to surface pollution were created according to the IEC standard under both wet and dry conditions. The collected electromagnetic signals were sampled and analyzed using a joint time-frequency analysis tool called the Wigner-Ville distribution (WVD). The results of this work indicate that the WVD analysis can be used as a diagnostic tool for polymer ZnO surge arresters.