Insulation oil is an important dielectric in power devices, and many studies on mixed insulation oil have been conducted in recent years to improve the performance of insulation oils. To replace mineral oil directly, the authors previously developed a novel three-element mixed insulation oil successfully; the main parameters of which satisfy the IEC 60296-2012 standard for mineral oil. In the present study, the AC breakdown properties of insulation paper (pressboard) immersed by the new mixed oil and naphthenic mineral oil were compared. For both insulation oils, the increase in temperature cannot significantly reduce the breakdown strength of oil-immersed insulation paper (pressboard) at a low moisture content, and the increment of moisture content cannot reduce the breakdown voltage at a low temperature (25°C). The breakdown voltage decreases only when the two factors increase simultaneously. For the mixed and mineral oils, the AC breakdown voltage of oil-immersed paper (pressboard) with different thicknesses has significant difference. The mineral oil has a high breakdown voltage for the thin insulation paper, whereas the mixed oil has a high breakdown voltage when the thickness of the insulation paper (pressboard) exceeds 0.2 mm. This phenomenon is mainly caused by the breakdown field strength that varies with the increase of dielectric thickness and the different change trends of paper (pressboard) immersed with the mixed and the mineral oils. Moreover, the stack of thin multilayer insulation paper enables the mixed oil-immersed paper to have a higher breakdown strength than the mineral oil-immersed paper. For the AC breakdown voltage of oil-immersed pressboard with an oil-gap structure, the mixed oil is comprehensively superior to the mineral oil due to its larger relative permittivity.

中文翻译：

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三元素混合绝缘油和矿物油浸渍的绝缘纸（纸板）的交流击穿特性比较

绝缘油是电力设备中的重要电介质，近年来已经进行了许多关于混合绝缘油的研究，以提高绝缘油的性能。为了直接替代矿物油，作者先前已经成功开发了一种新型的三元素混合绝缘油。其主要参数满足IEC 60296-2012矿物油标准。在本研究中，比较了新混合油和环烷矿物油浸入的绝缘纸（压纸板）的交流击穿性能。对于两种绝缘油，温度升高都不会显着降低低水分含量的油浸绝缘纸（压纸板）的击穿强度，并且水分含量的增加不能降低低温（25°C）下的击穿电压。仅当两个因素同时增加时，击穿电压才降低。对于混合油和矿物油，不同厚度的油浸纸（压榨板）的交流击穿电压具有显着差异。矿物油对薄的绝缘纸具有较高的击穿电压，而当绝缘纸（压纸板）的厚度超过0.2 mm时，混合油具有较高的击穿电压。这种现象主要是由击穿场强引起的，击穿场强随介电层厚度的增加以及浸入混合油和矿物油的纸张（压纸板）的变化趋势的不同而变化。而且，薄的多层绝缘纸的堆叠使得混合油浸纸具有比矿物油浸纸更高的击穿强度。