Material Temperature Dependence on Behavior of Partial Discharge in Epoxy Resin

Abstract

For epoxy resin equipment, voids may exist owing to imperfection of insulation manufacturing. The electric field becomes high in the voids, and partial discharges (PDs) occur in such defects. Incidentally, the insulation material temperature varies with the status of load and the environmental condition. It is crucial to investigate PD activity at diffe re nt void te mpe rature and electric field. In this study, we carried out measurements of PDs in an artificial void of epoxy resin at various temperatures in the range of 30_50 degrees Celsius. The maximum electric fields in the void 1.5 mm in diameter were set at 4.6 kV/mm and 8.0 kV/mm. For a 4.6 kV/mm-void, the number of PDs was large at lower temperature at around 30 degrees Celsius. The number of PDs de cre ase d with the incre ase of the numbe r of te mpe rature-time cycles. The PD magnitude slightly incre ase d with the increase of temperature because the dielectric constant of epoxy resin might become high and the electric field in a void might become high. In contrast, the variation tendency of the number of PDs for an 8 kV/mm-void was much different from that for a 4.6 kV/mm-void. The number of PDs was large at around 50 degrees Celsius and in the middle of temperature rising from 40 to 50 degrees Celsius. Thus, we investigated that PD behavior during temperature-time cycles differs in electric field.