Analysis of physical and electrical characteristics of transformer oil insulation during accelerated thermal aging experiment and its lifetime estimation using arrhenius law and breakdown voltage test

In this paper, the physical and electrical characteristics of accelerated thermal aged transformer oil insulation were investigated. The accelerated thermal aging of commercial transformer oil was conducted by increasing its temperature with different time. They were 100°C for 168 hours, 115°C for 96 hours, and 125°C for 48 hours. The lifetime of the tested oil was then estimated based on Arrhenius law and breakdown voltage test. The result showed that the physical characteristic of the tested oil during accelerated thermal aging could be analyzed based on its color changes, in which the higher level of thermal aging resulted in darker oil's color. The electrical characteristic was associated with significant decreasing of breakdown voltage. The lifetime estimation based on Arrhenius law for the tested oil with 100°C, 115°C, and 125°C were about 25663 hours, 4300 hours, and 1408 hours, respectively. The lifetime estimation based on breakdown voltage test for the tested oil with 100°C, 115°C, and 125°C were about 20064 hours, 1526 hours, and 1106 hours, respectively.