The study of the arcing phenomena of the mineral oil using the rod — Plane electrode configuration

The aim of this paper is to describe the study of the arcing phenomena of mineral oil using a rod - plane electrode configuration. This paper represents the experimental investigation of the arcing phenomena of the mineral oil, Nynas 4000x, with the water content not more than 10 ppm under various tip diameters of the rod - plane electrode arrangements. The tungsten rod electrodes with the tip diameter of 1mm, and 2mm with the curvature of 0.2 mm respectively were used as the high voltage electrode, while the brass plane electrode of 75 mm diameter was used as the grounded electrode. The gap distance of the electrode system was set up at 0.3 mm and 0.8 mm respectively. The electric field pattern of these electrode systems was calculated using Finite Element Program. The test experiment was modified from IEC 60156 and performed under room temperature. The arcing current, the arcing voltage and the partial discharge pulse current before the arc occurred including the arcing current pulse signal were investigated. The test results show that the 1 mm diameter rod - plane electrode yielded the highest electric field and the lowest arcing voltage at 9.9 kV including the maximum arcing current density of 54.24 A/cm². This electrode configuration gave higher a bit the arcing voltage than that of the 2 mm diameter rod - plane electrode. In addition, the PD pulse signals before arcing occurrence and the arcing pulse current signals were relatively similar in shape. Furthermore, the significant degradation of the mineral oil was clearly observed after testing.