Influence of Circuit Capacitance on Intensity of Electromagnetic Wave from Circuit Current due to Partial Discharge

Abstract

Electric power equipment currently plays an important role in social infrastructures. Partial discharge (PD) may occur due to the electric field concentration in the electrical insulation parts of the electric power equipment, for example if metallic foreign matter deposited on the insulation parts. It is considered that continuous PD occurrence may lead to dielectric degradation and finally breakdown. Therefore, it is necessary to detect PD, which is precursor phenomenon of dielectric aging and breakdown. The PD detection by impedance method is often used but it is sometimes difficult to insert the detecting impedance into the actual electric circuit. In this case PD detection using an antenna method has more advantage than that using the impedance method. However, in antenna method the radiation of EM waves has been considered to be emitted directly from the PD source and the EM waves indirectly emitted from the circuit current around the PD source has been almost ignored. In this paper, it is investigated the intensities of EM waves emitted both directly from the PD source and indirectly from the circuit current around PD source.