气固复合绝缘变压器聚酯材料老化特性研究

In order to study the aging state of SF₆ gas-solid composite insulated transformer under long-term operation, an aging evaluation model of polyester insulation material inside the transformer was established. Firstly, the accelerated thermal aging experiment of 6020 PET films was carried out, and then the aging characteristics of PET materials were detected by frequency domain dielectric spectroscopy, differential scanning calorimetry, tensile and near infrared spectroscopy. The experimental results show that the dielectric loss of PET films decreases first and then increases with aging. The typical characteristic parameters τ₁ and τ₂ were selected by using the Havriliak-Negami dielectric relaxation model, and the empirical formulas of aging time and τ₁ and τ₂ are obtained. The crystallinity and elongation at break of PET films firstly increase and then decrease with aging, while the tensile strength decreases. The near infrared absorbance of PET films decreases with aging, and the linear discriminant analysis algorithm was used to reduce the dimension of PET films, and good classification results were obtained. The results show that the dielectric relaxation time constants τ₁ and τ₂, the tensile strength and the absorbance characteristic parameters of near infrared spectrum can better characterize the aging degree of polyester materials.