The evaluation of the failure probability is essential in the reliability-centered and risk-based maintenance of power transformers. The breakage of the pressboard in disc-type transformers is one of the critical factors determining the lifetimes of power transformers. In this paper, a hierarchical method for evaluating the probability of pressboard failure, which is the breakage of the pressboard, in power transformers that considers the axial displacement of the winding is introduced. In the method, the diagnosis of the axial displacement is classified into three distinct classes. In class 1, no diagnosis is implemented, and the probability of failure is evaluated with the maximum possible axial displacement. In class 2, the diagnosis determines whether the winding is axially displaced. When the winding is diagnosed to be displaced, the probability of failure is evaluated with the maximum possible axial displacement. In class 3, the axial displacement is diagnosed quantitatively, and the probability of failure is then evaluated using the diagnosis result. Examples of the evaluated probabilities of pressboard failure are introduced, and the extension of the evaluated lifetimes of power transformers via the diagnosis of winding axial displacement is demonstrated. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

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盘式绕组电力变压器外部短路电磁力引起压板失效概率的评估方法

故障概率的评估对于以可靠性为中心和基于风险的电力变压器维护至关重要。盘式变压器中纸板的破损是决定电力变压器寿命的关键因素之一。本文介绍了一种考虑绕组轴向位移的电力变压器压板断裂概率分级方法。在该方法中，轴向位移的诊断分为三个不同的类别。在第 1 类中，不进行诊断，并以最大可能的轴向位移来评估失效概率。在第 2 类中，诊断确定绕组是否发生轴向位移。当绕组被诊断为移位时，用最大可能的轴向位移来评估失效概率。在第 3 类中，对轴向位移进行定量诊断，然后使用诊断结果评估故障概率。介绍了纸板故障概率评估的例子，并证明了通过绕组轴向位移诊断延长电力变压器评估寿命的方法。© 2021 日本电气工程师学会。由 Wiley Periodicals LLC 出版。证明了通过诊断绕组轴向位移来延长电力变压器的评估寿命。© 2021 日本电气工程师学会。由 Wiley Periodicals LLC 出版。证明了通过诊断绕组轴向位移来延长电力变压器的评估寿命。© 2021 日本电气工程师学会。由 Wiley Periodicals LLC 出版。