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