复合绝缘子伞裙老化状态检测的单边核磁共振传感器

对复合绝缘子伞裙老化状态的评估,关系到电力系统的安全稳定运行。为了实现在工程现场对复合绝缘子伞裙的无损检测,提出了一种便携式单边核磁共振传感器的设计方案。对静态磁场的均匀度和射频线圈进行了优化,以获得较高的信噪比。以110kV等级下不同运行年份的绝缘子为样品进行测量,使用CPMG序列对样品进行激励;采用单指数拟合和反拉普拉斯变换对核磁共振横向弛豫回波信号进行处理。结果表明,随着复合绝缘子运行时间的增加,其等效横向弛豫时间减小。因此,这种便携式单边核磁共振传感器有望用于复合绝缘子伞裙老化程度的定量分析。

Unilateral NMR sensor for assessing the aging status of composite insulator sheds

Assessing the aging status of composite insulator sheds concerns the security and stability of power system. In order to realize nondestructive examination of the sheds of composite insulators at project site, the design of a portable unilateral NMR(nuclear magnetic resonance) sensor was proposed. We optimized the homogeneity of the static magnetic field and the RF(radio-frequency) coil to obtain high SNR(signal to noise ratio). The tested samples were the sheds of three composite insulators from 110 kV lines serviced for different years in the same area, and the standard CPMG sequence was employed. The measurement data was processed by both single exponential fitting and inverse Laplace transform. It shows that an increase of the service time of the composite insulators resulte in a decrease of the equivalent transverse relaxation time. Therefore, the portable unilateral NMR sensor has the potential to assess the aging status of composite insulator sheds.