The study of partial discharge inception voltage of mineral oil using needle - Plane electrode configuration

The aim of this paper is to describe the feasibility study of using the needle - plane electrode system for Partial Discharge Inception Voltage (PDIV) measurement of mineral oil. This paper represents the experimental investigation of PDIV measurement of the mineral oil, Nynas 4000x, with the water content not more than 10 ppm under various tip radii of needle - plane electrode arrangements. The tungsten needle electrodes with the tip radius of 10μm, 20μm, and 40μm respectively were used as the high voltage electrode while the brass plane electrode with 75 mm diameter was used as the grounded electrode. The gap distance of the electrode system was set up at 50 mm. The electric field pattern of the electrode system was calculated using Finite Element program. The test experiment was set up according to IEC 60270. The test procedure was performed in accordance with IEC 61294 under room temperature. In addition, Scanning Electron Microscope (SEM) was employed to study the abrasion of the original and tested electrodes. Electric field distribution pattern and the average PDIV value of each electrode system including the SEM test results are analyzed and presented in this paper. From the test results, we found that the needle - plane electrode arrangements with the needle tip radius of 10μm, 20μm, and 40μm are highly possible alternative methods for the PDIV measurement of the mineral oil.