A Study on The Effect of Gap Distance and Brass Electrode Shape to Breakdown Voltage on Transformer Oil

DOI: 10.14416/j.ind.tech.2022.02.002


  • Anyarat Sonsanam Division of Industrial Engineering, Faculty of Technical Education, Rajamangala University of Technology Thanyaburi
  • Tawatchai Sonsanam Division of Electrical Engineering, Faculty of Science and Technology, Dhonburi Rajabhat University


Breakdown Voltage, Electrode, Electric Field


This research uses transformer oil insulation as an intermediary for testing the electric field pattern of the brass electrode. By supplying high voltage refer to IEC 60156, which divides the test into three forms based on the electrode shape: (1) the plane-plane shape, (2) spherical - plane shape and (3) the rod – plane shape. The gap spacing is 0.5, 1.0, 1.5, 2.0 and 2.5 mm. The ambient temperature of the test chamber is 30-33 °C, the atmospheric pressure is 755-760 mmHg and the relative humidity is 60-65 %. From the test, it is found that the breakdown voltage of the plane-plane shape is highest at 2.5 mm, 18.780 kV, and the second is the spherical-plane shape and the tipped-plane shape at 14.082 kV and 11.095 kV respectively, and the gap spacing is 2.5 mm. The reduction breakdown voltage is approximately 26% of each electrode. The damage condition on the brass surface of the electrode is analyzed by SEM. It showed that the plane-plane shape is the most arc damage surface with a diameter of 50 µm, the spherical-plane shape has a diameter of 27 µm and 10 µm on rod-plane electrode shape. After the test, the hardness is varied with the size of the arc damage and the breakdown voltage.


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บทความวิจัย (Research article)