Partial Discharge Behavior of Epoxy/paper Insulated Tubular Busbars with Artificial Defects

Epoxy/paper insulated materials, with the merits of great insulation performance, excellent mechanical strength, are widely used in tubular busbars playing an important role in safe and steady operation of national grid. In this work, the partial discharge (PD) in epoxy/paper insulated tubular busbars with two types of artificial defects and different aging time were measured. The aging voltage imposed on the samples was 18 kV, and the aging temperature was 428 K. PD of samples at varied aging stage were measured. Sample with defect of cavity and metallic impurity (sample B) showed larger apparent charge magnitude, compared with the sample with defect of cavity (sample A). For example, the measured largest apparent charges of sample B was 8337 pC, much larger than the value of 2266 pC measured in sample A when aged for 700h. In addition, the value of PD inception voltage of sample A was fluctuated around the 16 kV, while PD inception voltage of sample B varied from 10 kV to 8.4 kV. And we analyzed the results in the article. To figure out the influence of defects on the PD activity, MATLAB Simulink tools were used to simulate the PD of samples with different defects. The results showed that the defect of cavity and metallic impurity discharged more severely than the defect of cavity. Moreover, finite element analysis (FEA) method was applied to obtain the electrical field distribution, which revealed that the defect of cavity and metallic impurity caused local electrical field distortion whose maximal value was 1.8 times of the defect of cavity.