Application of Circular Patch Microstrip Antenna (CPMA) for Partial Discharge Detector in oil insulation

Partial discharge (PD) is a localized dielectric breakdown (which does not completely bridge the space between the two conductors) of a small portion of a solid or fluid electrical insulation system under high voltage stress. While a corona discharge is usually revealed by a relatively steady glow or brush discharge in air, partial discharges within solid insulation system are not visible. PD can occur in a gaseous, liquid or solid insulating medium. It often starts within gas voids, such as voids in solid epoxy insulation or bubbles in transformer oil. Protracted partial discharge can erode solid insulation and eventually lead to breakdown of insulation. One of the PD measurements in oil insulation is using UHF method, by measuring the waves generated by PD using antenna. One of antenna having good characteristics is UWB double layer printed antenna. In this paper the application of circular patch microstrip antenna for partial discharge detection is reported. The application of antenna on PD measurement in oil insulation, shows that the antenna is able to detect PD. The characteristics of PD: PDIV, PD waveform, PD phase pattern are measured using this antenna. The VNA testing of the antenna shows that the antenna bandwidth is 3.39 GHz.