The focus of this research is on the insulation structure where radial and axial spacers connect in a power transformer. The interaction between the occurrence of partial discharge (PD) and the generation of bubbles using a model that is very similar to the real structure in a transformer is studied. The inception voltage of the PD caused by the oil gap created by the axial and radial spacers might lower than that caused by a metallic impurity. However, PD caused by the metallic impurity was more likely to generate bubbles because of its higher discharge energy. It is also found that the residual space charge on the insulation surface prevents the occurrence of PD and also affects the generation of bubbles under repeated lightning impulse voltage. Moreover, it is found that generated bubbles do not affect the occurrence of PD. One reason for this is that the bubbles disappear during the interval time between repeated impulses. The effect of the residual space charge is considered to be another reason.

中文翻译：

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复杂结构模型在变压器反复雷电冲击下局部放电与产生气泡的相互作用

这项研究的重点是绝缘结构，其中在电源变压器中径向和轴向垫片相互连接。使用与变压器实际结构非常相似的模型，研究了局部放电（PD）的发生与气泡生成之间的相互作用。由轴向和径向垫片产生的油隙引起的PD的起始电压可能低于由金属杂质引起的起始电压。但是，由金属杂质引起的PD由于其较高的放电能量而更可能产生气泡。还发现绝缘表面上的残余空间电荷防止了PD的发生，并且还影响了在重复的雷电冲击电压下气泡的产生。此外，发现产生的气泡不影响PD的发生。其原因之一是气泡在重复脉冲之间的间隔时间内消失。剩余空间电荷的影响被认为是另一个原因。