The eco-friendly insulating gas perfluoroisobutyronitrile (C₄F₇N) is potentially used in gas-insulated transformers (GIT) to replace sulphur hexafluoride (SF₆). However, evaluation of the long-term insulation reliability and gas–solid interface discharge decomposition characteristics of the gas–solid film insulation structure in GIT is indispensable. The authors simulated the gas–solid film insulation structure in GIT and explored the interface partial discharge (PD) characteristics of C₄F₇N/CO₂ gas mixture with polyethylene terephthalate (PET). The effect of gas pressure, mixing ratio on gas–solid interface gas decomposition, PET degradation was investigated, and the interaction mechanism was analysed. It is found that the interface PD generated three degradation regions on a PET film. The gas–solid interface reaction in the electrode contact region and the discharge development trace was significantly higher than that of halation region. The content of gas decomposition products decreases with the increase of gas pressure and the PD intensity of SF₆-PET is inferior to that of C₄F₇N/CO₂ under the same condition. Relevant results provide reference for the development and application of C₄F₇N/CO₂ based GIT.

中文翻译：

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环保气体绝缘变压器C4F7N/CO2气体混合物气体-聚对苯二甲酸乙二醇酯固体界面局部放电特性评估

环保绝缘气体全氟异丁腈（C ₄ F ₇ N）有望替代六氟化硫（SF ₆ ）用于气体绝缘变压器（GIT ）。然而，GIT气固膜绝缘结构的长期绝缘可靠性和气固界面放电分解特性的评估是必不可少的。作者模拟了GIT中的气固膜绝缘结构，并探讨了C ₄ F ₇ N/CO ₂气体混合物与聚对苯二甲酸乙二醇酯（PET）的界面局部放电（PD）特性。研究了气体压力、混合比对气固界面气体分解、PET降解的影响，并分析了相互作用机理。研究发现界面PD在PET薄膜上产生了三个降解区域。电极接触区域和放电发展痕迹的气固界面反应明显高于光晕区域。气体分解产物含量随着气体压力的增加而降低，相同条件下SF ₆ -PET的PD强度低于C ₄ F ₇ N/CO _{2 。相关结果为C 4} F ₇ N/CO ₂基GIT的开发和应用提供参考。