Engineering experience shows that for transformers with long service life and serious moisture exposure, the inter-turn paper insulation inside the winding will precipitate bubbles under the condition of electric field and conductor heating, which will endanger the equipment insulation. In order to explore the influence factors of bubbles formation in the moist insulating paper of transformers, based on the existing research on the influence of moisture content and gas dissolution in transformer oil, this study further considers the influence of air pressure (AP) and electric field and establishes an experimental platform to change the air pressure and electric field, thereby studying the formation characteristics of bubbles in oil-paper insulation. The results show that air pressure and electric field can affect the initial temperature, volume, and shape of bubble formation. From 0 to −0.05 MPa for air pressure, the initial temperature of bubble generation decreased by 41°C, its maximum two-dimensional projected area increased by 418.4% with more severe distortion, and the breakdown voltage decreased. When the AC voltage applied on the needle plate electrode increased from 0 to 10 kV, the initial temperature of bubble formation increased by 29°C, and the maximum two-dimensional projection area increased by 336.6%.

中文翻译：

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油纸绝缘的气泡形成特性及其对绝缘性能的影响

工程经验表明，对于使用寿命长、受潮严重的变压器，绕组内部匝间纸绝缘在电场和导体发热的情况下会析出气泡，危及设备绝缘。为了探究变压器潮湿绝缘纸中气泡形成的影响因素，在现有变压器油中水分含量和气体溶解影响的研究基础上，本研究进一步考虑了气压（AP）和电势的影响。建立了改变气压和电场的实验平台，从而研究油纸绝缘中气泡的形成特性。结果表明，气压和电场会影响气泡形成的初始温度、体积和形状。气压从0到-0.05 MPa，气泡产生起始温度降低了41℃，最大二维投影面积增加了418.4%，变形更加严重，击穿电压降低。当针板电极上施加的交流电压从0 kV增加到10 kV时，气泡形成的初始温度增加了29℃，最大二维投影面积增加了336.6%。