High Magnetic Field Affecting Dielectric Polarization and Partial Discharge Behavior of Epoxy Resin

In this article, a joint measurement of dielectric polarization, depolarization, and potential recovery is carried out to investigate the instantaneous and relaxation polarization characteristics of epoxy resin in high magnetic field. The dielectric polarization of epoxy resin is converted to a combination of weakened instantaneous polarization and the relaxation polarization with reduced amplitude and increased speed. Changes in dielectric polarization processes leads to the decrease of relative permittivity. Furthermore, partial discharge (PD) of internal defects is harder to be initiated in high magnetic field. However, the discharge frequency is increased and the phase distribution becomes wider in the case of ac. In the case of dc, discharge lasts for longer time in high magnetic field. The experimental results are caused by the coupling effects of high-speed polarization and abnormal charge accumulation at the gas-solid interface due to the effects of Lorentz force on charges generated by PD.