10 kV电缆中间接头绝缘用硅橡胶内部典型缺陷的超声信号表征方法

Ultrasonic signal characterization of typical defects in silicone rubber for 10 kV cable intermediate joint insulation

电缆中间接头的绝缘状态对电缆安全稳定运行起重要作用。针对太赫兹成像技术的不成熟和有限元分析法的局限性,本文提出一种电缆附件硅橡胶内部典型缺陷的超声信号表征方法。首先通过仿真设计硅橡胶中不同类型的典型缺陷,然后对超声检测仿真中接收的反射回波进行时域特征量和相关性分析,得到时域波形特征量与缺陷尺寸、角度的相关系数。最后基于脉冲回波法搭建超声试验平台,对含缺陷的平板硅橡胶样品进行超声检测试验。结果表明:硅橡胶内部缺陷的尺寸、角度与一次回波的振幅峰值具有良好的相关性,且相较于气泡类缺陷,裂纹类缺陷检测结果受缺陷角度的影响更大,不同角度缺陷的振幅峰值差异较大。说明超声信号可以有效表征电缆附件硅橡胶内部典型缺陷。

The insulation status of the cable intermediate joint plays an important role in the safe and stable operation of cable.In view of the immaturity of terahertz imaging technology and the limitation of finite element analysis method,an ultrasonic signal characterization method for typical internal defects of silicone rubber in cable accessories was proposed in this paper.At first,different types of typical defect in silicone rubber were designed by simulation.Then the time-domain characteristic quantity and correlation analysis were carried out on the reflected echoes received in the ultrasonic detection simulation,and the correlation coefficient between the time-domain waveform characteristic quantity and the size and angle of defects was obtained.Finally,an ultrasonic test platform was built on the basis of pulse echo method to carry out ultrasonic test on the flat silicone rubber samples with defects.The results show that the size and angle of the internal defects of silicone rubber have a good correlation with the amplitude peak of the first echo,and the detection results of crack defects are more affected by the angle than that of bubble defects,and the amplitude peaks of defects at different angles are significantly different.It is concluded that the ultrasonic signal can effectively characterize the typical internal defects of silicone rubber in cable accessories.