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Study on the Influence of slight looseness of steel foot on performance of suspended porcelain insulators

Porcelain insulators not only bear the mechanical stress and electric field, but also suffer from environmental changes such as sunlight and rain. Because of the harsh operating environment, higher requirements for the quality of the insulator was put forward. The author found out that the slight looseness of the steel foot was found in the sampling inspection test of insulators. In order to investigate the effect of this phenomenon on the performance of insulator, the mechanical and electrical properties tests and high and low temperature alternating test were carried out on these porcelain insulators which steel foots were slightly loose or fixed. The research showed that no obvious difference of mechanical failed load and puncture voltage property between the insulators which steel foots were slightly loose and fixed; because there is an obvious gap between the steel foot and cement of the insulator which steel foots were slightly loose, the water molecules was more easily penetrated into the gap, and after repeated freeze-thaw cycles tests on the insulator, the mechanical property of cement decreased obviously, which leading to the mechanical failed load of insulator decreased significantly. Therefore, it is not suitable to use insulators with steel foots looseness in the operating environment with great temperature difference and humidity.