A mini NMR sensor for assessing the aging level of the silicone rubber insulator

A novel portable NMR sensor with an adjustable `clamp´ structure has been designed and constructed for the purpose of noninvasively assessing the aging status of the silicone rubber insulator used in the high voltage power transmission. The silicone rubber insulators in different depth and serviced for different years were measured and the effective transverse relaxation time T2eff was recorded. The result shows that the effective transverse relaxation time T2eff decreases as the insulator´s service year increases and the depth decreases. The relative permittivity was meassured which shows a same changing trend as transverse relaxation time T2eff It indicates that the T2eff measured by the portable NMR sensor can be used as an index to reflect the degradation of the insulator´s insulation performance.