Determination of Epoxy Resin in Transformer Oils by FTIR Method and the Study of Its Damage

As the key equipment of power transmission and transformation system, the reliability of power transformer is directly related to the safe and stable operation of power system. In Guangdong power grid, a batch of epoxy resin insulating paint used in transformers is not compatible with transformer oil, which was dissolved in transformer oil gradually during operation, causing the damage of transformer medium loss and transformer insulation resistance dropping sharply. Therefore, the monitoring of epoxy resin content in transformer oil is an important index to evaluate the insulation performance of transformer oil. In this paper, method of the measurement of epoxy resin in transformer oil was developed by Fourier transform infrared spectroscopy (FTIR). The accuracy and precision of the method. Good linearity was obtained with correlation coefficient (R) equal to 0.9990. Satisfied reliability and reproducibility were achieved by evaluation of relative ranging from 88.7% to 110.2%, and relative standard deviations (RSD) less than 8.42%. The method was further applied to analyze the epoxy resin in 8 running transformer oils. Particularly, the method is suitable for fast determination of the epoxy resin in transformer oils owing to its ease to use in sample treatment and analysis. The relationship between epoxy resin concentration and dielectric loss in transformer oil was also studied, and the results show that the concentration of epoxy resin is positively proportional to the dielectric loss factor (tan$\delta$).