UHF micro-strip antenna design for partial discharge detection of gas insulated switch

The study is focused on the partial discharge detection of the gas insulated switch using ultra-high frequency (UHF) method. The radiated electromagnetic wave generated due to internal defect was measured by the self-made ultra-high frequency micro-strip antenna, based on which so as to determine whether if partial discharge will occur. In this article, we make effort in analyzing the exciting, transmission, decaying, and leaking characteristics of electromagnetic wave as excited by the partial discharge inside the gas insulated switch. Based on the practical features and requirements, both an external UHF square micro-strip antenna with its central frequency of 400Hz and a broad band power amplifier whose gaining coefficient larger than 4dB are designed. In order to verify the measuring functionality of the self-made UHF micro-strip antenna, the partial discharge signals of the defected gas insulated switch are measured in practice. By means of the comparison with the commercial UHF sensor practically, the usability of the self-made micro-strip antenna and broad band power amplifier has been proven. Finally, the partial discharge signals of four typical types of defected gas insulated switches are measured to find the UHF features of the partial discharges signals. The measuring results show that the self-made micro-strip antenna is capable of measuring the partial discharges of various defected gas insulated switches as well as minimize the interference of noise.