The Effect of Electrothermal Aging on the Properties of Epoxy Resin in Dry-Type Transformer
Wang Youyuan1, Liu Yu1, Wang Shiyou2, Xu Haiying3
1. State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing 400044 China; 2. Chongqing ABB Transformer Limited Company Chongqing 400000 China; 3. Shiqu Power Supply Branch of Chongqing Electric Power Company Chongqing 400015 China
Abstract：In order to study the influence of electrothermal aging on the epoxy resin in dry-type transformers, the epoxy resin samples were subjected to electrothermal aging test. The mass loss rates, ac breakdown voltages, dielectric properties, and infrared spectrum of the aged samples were tested periodically. The results show that with the increase of electrothermal aging time, the mass and breakdown voltage decrease, while the dielectric loss increases. Compared with electrical/ thermal single factor effect, the effects of electrothermal aging on weight loss rate, dielectric loss and breakdown voltage change are greater. Using the Debye equation to fit the dielectric constant imaginary part, it is found that increasing the temperature or electric field of the electrothermal aging leads to the rise of electrical conductivity and polarization loss. Via infrared spectroscopy, it is observed that there are no new groups produced in samples after electrical aging. After thermal aging, hydroxyls are oxidized and hydrocarbon bonds are decomposed inside epoxy resin, which indicates the mechanism of thermal aging is significantly different from that of electrical aging. In addition, more hydroxyls are oxidized and hydrocarbon bonds are decomposed after electrothermal aging. The electricity and heat mutually reinforce aging effect and have a synergistic effect.
王有元, 刘玉, 王施又, 徐海鹰. 电热老化对干式变压器中环氧树脂特性的影响[J]. 电工技术学报, 2018, 33(16): 3906-3916.
Wang Youyuan, Liu Yu, Wang Shiyou, Xu Haiying. The Effect of Electrothermal Aging on the Properties of Epoxy Resin in Dry-Type Transformer. Transactions of China Electrotechnical Society, 2018, 33(16): 3906-3916.
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