Study and Analysis of Transformer Oil Characteristics with Variation of Load: A Case of 220 kV Substation

In electrical power systems, transformers are considered the most expensive and important components. During the service period, the transformer oil insulation is exposed to a number of stresses and, hence, is subject to aging. The continuous monitoring of transformer oil helps in understanding the behavior of insulation over time, along with improving the reliability of the power system. In this current study, three on-field power transformers installed at a 220 kV substation in Dera Ismail Khan, Pakistan, were studied. Dielectric dissipation factor and water content measurement techniques were used to analyze the condition of the oil insulation. whereas the impact of load variation during the service period on the dielectric dissipation factor and water content values was also analyzed. During the study, the correlation between the dielectric dissipation factor and water content was also investigated. It was found that the dielectric dissipation factor and water content had a close relationship with each other, whereas a significant behavior of load variation, dielectric dissipation factor, and water content was also observed.