Aiming at the serious defects of wire-type free metal particles, which can cause severe partial discharge (PD) in Direct current (DC) gas-insulated equipment, the experiments on the influence of four lengths (3.0, 5.0, 7.0, and 9.0 mm) of wire-type free metal materials on SF6 decomposition under DC PD were conducted. The formation rules of four characteristic decomposition components, namely, CF4, SOF2, SO2F2 and SO2, under different lengths of wire-type free metal particles, were determined using gas chromatography. Results showed that the amounts of four kinds of SF6 DC PD characteristic decomposition components are proportional to the length of wire-type free metal particles. The long length of wire-type free metal particles increases the intensity of PD and the amount and effective generation rates of SF6 DC PD characteristic decomposition components. All these findings provide an experimental basis for the diagnosis of insulation defect types in SF6 DC gas insulated equipment.

中文翻译：

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直流气体绝缘设备中不同长度线状金属颗粒下SF6局部放电分解特性

针对直流（DC）气体绝缘设备中线型游离金属颗粒存在严重局部放电（PD）的严重缺陷，对四种长度（3.0、5.0、7.0、9.0）的影响进行了实验mm) 的线型游离金属材料在 DC PD 下对 SF6 分解进行了研究。采用气相色谱法测定了不同长度的线状游离金属颗粒下四种特征分解组分CF4、SOF2、SO2F2和SO2的形成规律。结果表明，四种SF6 DC PD特征分解成分的量与线型游离金属颗粒的长度成正比。线型游离金属颗粒的长长度增加了局部放电强度和SF6 DC局部放电特征分解成分的数量和有效发生率。这些发现为SF6直流气体绝缘设备绝缘缺陷类型的诊断提供了实验依据。