The Role of Harmonic Components on Partial Discharge Mechanism and Degradation Processes in Epoxy Resin Insulation

The paper describes problem related to measurements and interpretation of partial discharges in insulation systems in presence of voltage harmonics, with special focus on epoxy resin based insulation. Laboratory testing system with controlled generation of periodic sinusoidal and harmonically modified voltages was used. Several month investigations of partial discharges in specially prepared epoxy resin samples have been done. Results of measurements of partial discharges linked to high local electric field obtained in point-to-plane electrodes configuration are presented. Due to increasing number of non-linear high power loads harmonic disturbances of supplying voltages are more often present. The investigations of its influence on phase resolved images of partial discharges are the aim of this paper. It was found the influence of harmonics on partial discharge intensity, mainly increase, but also distinct changes in phase-resolved images.