Silicone rubber composite insulators are widely used in the power system because of advantages such as excellent hydrophobicity, high mechanical strength and light weight. Currently the methods for accuracy and effective analysis of the aging status of the composite insulators are still lacking. Although previous studies have investigated the degradation of composite insulator shied, none of them focused on composite insulator rod sheath. To measure the aging status of rod sheath, a nuclear magnetic resonance (NMR) sensor was designed, which could be applied to arc-shaped samples. The magnet structure was optimized to have a main magnetic field distribution matching up with the curvature of the rod sheath. A flexional helical radio frequency transmission coil was designed and optimized. The sensor was applied to three kinds of rod sheath with different ages. A CPMG pulse sequence was used to acquire T2 relaxation curves of the samples, which were then subjected to an inverse Laplace transformation to obtain T2 spectrum. The result showed that the T2 of the rod sheath decreased with increasing operation time. It is concluded that the parameter T2, long mean calculated from the T2 spectrum can be used for measuring the aging status of rod sheath.
LI Jun-fang
,
WU Jia-min
,
XU Zheng
,
HUANG Qiao-lin
,
SHENG Cong-bing
,
LIU She-min
,
YE Qiang
,
FENG Pan-zeng
. An Arc-Shaped NMR Sensor:Design and Application in Measuring the Aging Status of Composite Insulator Rod Sheath[J]. Chinese Journal of Magnetic Resonance, 2017
, 34(2)
: 223
-230
.
DOI: 10.11938/cjmr20170212
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