基于频域反射法的受潮10 kV冷缩电缆中间接头阻抗特性研究

冷缩电缆中间接头受潮是造成其故障的重要原因之一。现有研究已表明,存在受潮缺陷的冷缩电缆中间接头阻抗特性会发生变化,通过频域反射法对整根电缆的阻抗不连续点进行检测,分析其阻抗特性可实现缺陷的定位与类型的判断。因此,开展受潮冷缩电缆中间接头阻抗特性的研究,可为电缆中间接头的受潮诊断提供理论依据与数据支撑。为此,对一根10 kV冷缩电缆中间接头样本开展加速受潮实验,采用反射系数谱测试仪定期检测其阻抗特性并进行研究。实验结果表明：随着受潮程度的增加,冷缩电缆中间接头阻抗不匹配峰幅值呈先减小后增大的趋势;对其时域反射波形进行恢复后发现,其时域波形的极性特征呈从“左正右负”到“左右持平”再到“左负右正”的变化情况。

Research on Impedance Characteristics of Moistened 10 kV Cold-shrinkable Cable Intermediate Joints Based on Frequency Domain Reflection

Damping of intermediate joints of cold-shrinkable cable is one of the important reasons for its failures. The existing researches have shown that the impedance characteristics of intermediate joints of cold-shrinkable cable with damp defects will change. The impedance of whole cable can be detected by frequency domain reflection method, and after the analysis of its impedance characteristics, the defect can be located and the defect type can be determined. Therefore, conduct-ing the research on impedance characteristics of intermediate joints of moistened cold-shrinkable cable can provide theoretical and data support for the diagnosis of moisture in cable intermediate joint. The accelerated moisture experiments on intermediate joint sample of a 10 kV cold-shrinkable cable is carried out, and then a reflection coefficient spectrum detection device is used to regularly detect and research its impedance characteristics. The experiment results show that as the degree of moisture increases, the reflection coefficient of cable intermediate joint shows a trend of first decreasing and then increasing. After restoring its time-domain waveform, it is found that its characteristics develop and change from "left positive and right negative" to "left and right balance" and then to "left negative and right positive".