Electrical tree degradation is one of the main causes of insulation failure in high-frequency transformers. Electrical tree degradation is studied on pure epoxy resin (EP) and MgO/EP composites at frequencies ranging from 50 Hz to 130 kHz. The results show that the tree initiation voltage of EP decreases, while the growth rate and the expansion coefficient increase with frequency. Moreover, the bubble phenomenon at high frequencies in EP composites is discussed. Combined with trap distribution characteristics within the material, the intrinsic mechanism of epoxy composites to inhibit the growth of the electrical tree at different frequencies is discussed. It can be concluded that more deep traps and blocking effect are introduced by doping nano-MgO into EP bulks, which can improve the electrical tree resistance performance of EP composites in a wide frequency range.

中文翻译：

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不同电压频率下MgO/环氧树脂复合材料的电树降解

电树退化是高频变压器绝缘失效的主要原因之一。研究了纯环氧树脂 (EP) 和 MgO/EP 复合材料在 50 Hz 至 130 kHz 频率范围内的电树降解。结果表明，随着频率的增加，EP树的起始电压降低，而生长速率和膨胀系数增加。此外，还讨论了 EP 复合材料中高频下的气泡现象。结合材料内部陷阱分布特征，讨论了环氧复合材料在不同频率下抑制电树生长的内在机制。由此可见，通过在EP块体中掺杂纳米MgO，引入了更深的陷阱和阻挡效应，可以提高EP复合材料在较宽频率范围内的电树电阻性能。