The study of partial discharge characteristics of mineral oil using needle - plane electrode configuration base on partial discharge pulse current measurement

Abstract

The aim of this paper is to describe the Partial Discharge (PD) pulse current characteristics of the Partial Discharge Inception Voltage(PDIV) testing of mineral oil. This paper represents the experimental investigation of the PD characteristics of the mineral oil, Nynas 4000x, with the water content not more than 10 ppm, at the PDIV levels 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 connected to ground via the shunt resistor of 50 ohm. The gap distance of the electrode system was set up at 50 mm. The test experiment, conventional PD measurement, was set up according to IEC 60270. The test procedure was performed in accordance with IEC 61294 under room temperature. PDIV was examined. Then, PD activities at the PDIV and 1.1 PDIV test level were investigated. Furthermore, PD currents were also detected and recorded by a high quality oscilloscope. Phase- resolved PD characteristics of the mineral oil, PD magnitudes and PD pulse currents of the tested electrode systems are analyzed and presented in this paper. From the test results, we will gain the knowledge of PD characteristics of the mineral oil tested by needle - plane electrode systems and we also found that the PD pulse current measurement can be used as an alternative indicator of the mineral oil degradation. The PD pulse current patterns are useful for analysis the oil characteristics as well.