Phase Resolved Measurement and Simulation of Partial Discharges in Solid and Liquid Insulating Materials

Partial discharges (PD) may take place in solid and liquid insulating materials. This paper reports experimental results on partial discharges in low density polyethylene (LDPE) and transformer oil in divergent field under AC voltage. The applied voltage was adjusted from low voltage up to the partial discharge inception and was increased to higher voltage to get PD patterns. The measurement of the partial discharges was conducted using a PD measurement system which able to measure PD magnitude as well as phase of PD occurrence. The partial discharge pulses were recorded and presented in phase resolved patterns. The measurement results showed that the applied voltage significantly influenced the magnitude as well as the phase of PD occurrence. The PD patterns from solid material were different with those from liquid insulating materials. The characteristics of the PD in both materials were analyzed and modeled. In order to know better the characteristics of the PD, phase resolved simulation of PD were conducted and the role of applied voltage was investigated. The validity of the simulation was assessed based on the phase resolved PD distribution. It is shown that PD patterns from simulation are in good agreement with experimental results.