Dissolved Gas Analysis of Palm Oil Compared with Mineral Oil from Different Types of Breakdown Voltage

Abstract

Natural products are required instead of chemical materials for saving the environment. Nowadays, the palm oil is a new alternative liquid insulation that may be used in a transformer. Normally, the characteristics of liquid insulation can be investigated and analyzed by various methods. One of the diagnosis methods widely used is a dissolved gas analysis technique (DGA). The propose of this paper is to study the interpretation of dissolved gases in the palm oil compared with that of in the mineral oil which is caused by different kinds of breakdown phenomena, i.e. AC breakdown, positive lightning impulse breakdown, and negative lightning impulse breakdown. An AC breakdown voltage test according to IEC 60156 was performed by using 3 difference gap spacing which were 1.0, 1.5, and 2.0 mm. For lightning impulse tests, the test cell was contained needle-sphere electrodes with 10, 15, and 20 mm gap different spacing. The lightning impulse tests were performed in accordance with IEC 60897. Each experiment was performed for 5, 10, and 15 times. For a material preparation, the mineral oil and the palm oil was heated at 80oC for 12 hours. Then, it was naturally cooled before filling into the test cell to perform AC and lightning impulse breakdown tests. After that, the mineral oil and the palm oil was sampled out of the test cell to perform the DGA experiment. The dissolved gases from the mineral oil and the palm oil were interpreted by applying IEC and IEEE gas interpretation techniques. It was found that the breakdown voltages of the palm oil were less than the mineral oil but the palm oil generates more dissolved gases than the mineral oil. Moreover, Duval pentagon for natural ester fluid seemed to be the most suitable method to interpret dissolved gases in the palm oil compared with the IEC ratio, Doernenburg ratio, Roger ratio, and Duval triangle.