用于复合绝缘子伞裙老化状态检测的单边核磁共振传感器

A Portable Unilateral Nuclear Magnetic Resonance Sensor Used for Detecting the Aging Status of Composite Insulator

为了实现对复合绝缘子老化状态的定量无损检测,设计出一种新型便携式单边核磁共振传感器,并对传感器的永磁体结构和射频线圈结构进行了优化设计。使用该传感器对三种不同使用时间的复合绝缘子进行了测量,并对核磁共振的回波衰减信号进行指数拟合,获得样品的等效横向弛豫时间,结果表明:随着使用年数的增长,复合绝缘子表面的等效横向弛豫时间呈减小趋势。同时利用静态接触角法测量了复合绝缘子的静态接触角,并将两种方法测得的结果进行比较。结果表明:两者变化趋势相同,但等效横向弛豫时间的变化更明显。

In order to quantitatively measure the aging status of the composite insulator with non-destructive method, a new portable unilateral nuclear magnetic resonance（NMR） sensor was designed. The structures of its magnet and radio-frequency coil were optimized. Three composite insulators with different years were tested. The NMR echo signals of the samples were obtained by the nuclear magnetic resonance spectrometer. These NMR echo signals were processed with the mono-exponential fitting method to obtain the equivalent transverse relaxation time T2. The result demonstrates that, as the service year of the insulator increases, the equivalent transverse relaxation time T2 decreases. At the same time, the contact angle method was employed to compare with the NMR method. It shows that T2 and static contact angle have the same changing trend along with the service time, but the T2 parameter changes more obviously than the static contact angle.