Study on the Effect of Transformer Oil Aging on Dielectric Loss

The open cup degradation method was used to age the transformer oil at a constant temperature of 115 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$^\circ \mathrm{C}$</tex>. The thermal aging degree of the transformer oil was analyzed by infrared spectroscopy. Based on the changes in peak position, peak intensity, and peak shape of the infrared spectrum, the changing trends of various functional groups in the preburning process of the transformer oil were determined. The preburning mechanism of the transformer oil was analyzed from a microscopic perspective. The constant voltage method was used to accelerate the insulation model of the electrically aged transformer oil. The inverse power function was used to fit the experimental data, and the voltage tolerance coefficient in the model was obtained to assess the electrical preburning of the transformer oil. The experimental results indicate that aldehydes and acid compounds are generated during the thermal preburning process of transformer oil, and the dielectric loss factor is logarithmically related to its acid value. As the transformer oil undergoes electrical preburning, the dielectric loss factor gradually raises.