Evaluating the impact of aging in field transformer oil using optical spectroscopy techniques

Recently, optical spectroscopy techniques have been proposed for condition assessment of transformer oil. They can be conducted online using less expensive equipment than other traditionally used techniques. In this paper, aged transformer oil samples were collected from different field transformers, and then evaluated by optical spectroscopy techniques. These techniques included UV-Vis, emission and FT-IR spectroscopy. Also, the dielectric properties of the oil samples were evaluated by breakdown voltage test and dielectric dissipation factor test. In addition, water content test was performed due to its influence on dielectric properties. The obtained optical spectra have shown remarkable results for different aged oil samples. We find that the level of decomposition by-products can be evaluated from the obtained UV-Vis spectra. The results authenticated the good correlation either between optical spectra features and aging period or between optical spectra features and dielectric losses.