Comparative Analysis of Fresh and used Power Transformer Oils

Abstract

Uninterrupted electricity supply is a vital issue for Nigeria today. This is because the reliability for power transformer to generate electricity to be used for industrial activities, electric utility companies and our homes has become far more important to our present generation for financial reasons. This work presents experimental research on the variations of the physicochemical properties and composition of two transformer oils of different levels of degradation. The first one is a virgin/fresh new oil while the second was collected from an operating transformer after being used for five (5) years (used transformer oil). The physicochemical characteristics of both samples were studied using American Society for Testing Material (ASTM) standard test, and were found to be within the specified range by ASTM standard. Results for physicochemical characterization of both samples A and B gives acid value of 0.045 ± 0.089 & 0.12 ±0.07 (mg KOH-1), density of 0.75 ±0.01 & 0.99 ± 0.01 (g cm–1), and Flash Point of 143 and 152 (oC) values respectively. However, the used oil sample presents physicochemical properties of narrow value to standard specifications which indicated its high level of degradation in contrast to the fresh oil sample. The FTIR results of the two samples were compared and it revealed that they have similar compounds of paraffins, naphthene and aromatics present in them. Although the used oil indicated the presence of phenols, which is indicative of oxidation process occurring in the oil. Keywords: Fresh transformer oil, used transformer oil, insulation, FT-IR