Experimental Study On Deterioration Characteristics Of Disk Porcelain Insulators In Extremely Cold Region

The paper conducts an experimental study on the deterioration characteristics of disk porcelain insulators in extremely cold regions to explore the degradation mechanism led by disk porcelain insulator in extremely cold environment,adding certain theoretical support to degradation condition assessment for extremely cold areas.Porcelain insulators in the extremely cold area not only stay in the extremely low temperature environment for a long time,but also experience the influence caused by the sharp temperature change every year.In addition,When the disk porcelain insulator operates in an extremely low temperature environment and is affected by temperature changes,which leads to the contraction or expansion of its different components and crystals;Apart from those,the disk porcelain insulator subjected to mechanical,electrical and external forces gradually leads to the deterioration of the disk porcelain insulator.This deterioration fails to be detected by currently available methods of detecting zero values.Disk porcelain insulators are subjected to large changes in ambient temperature,the low temperature will cause shrinkage of iron cap and expansion of cement adhesive by freezing,resulting in a certain degree of internal stress.Under the simultaneous action of the above two kinds of stress,the so-called "hidden stress" is generated for disk porcelain insulators.Cement adhesive in such a rapid changing temperature of the environment generates moisture absorption,resulting in its loose structure.Such repeated circulation eventually increases stress applied to the porcelain.porcelain made of a variety of crystals is heterogeneous.In practice,many disk porcelain insulators have reached or exceeded their expected operating life of 30 years.Therefore,it is very important to check the disk porcelain insulators of transmission lines in extremely cold regions and replace the aging disk porcelain insulators to maintain the reliability of the transmission system.According to the deterioration mechanism of disk porcelain insulators,this paper conducted freeze-thaw cycle experiments on the cement used for insulators to verify the deterioration mechanism.The mechanical failure experiments of disk porcelain insulators under long-term low temperature and freeze-thaw cycles were carried out,and the experimental results under different environments were compared to further prove the deterioration effect of cement binder under freeze-thaw cycles.In order to further simulate the actual working environment of disk porcelain insulator and explore the deterioration law of disk porcelain insulator after freeze-thaw cycles,electromechanical joint experiments were carried out on disk porcelain insulator after freeze-thaw cycles,and the experimental results were analyzed.In order to explore the influence of extremely low temperature on the deterioration of disk porcelain insulator’electrical properties,two power-frequency breakdown experiments in oil were designed for disk porcelain insulator undergoing different low temperature durations.The influence of low temperature on the electrical properties of disk porcelain insulator was explored according to the breakdown voltage,and steep-wave impact experiments were carried out on the insulators after freeze-thaw cycles.To investigate whether the failure stress produced by cement adhesives can degrade the electrical properties of disk porcelain insulator.The research results have certain significance for analyzing the deterioration of disk porcelain insulator in the extremely cold area.From the perspective of manufacturing,as long as the stress generated by porcelain insulator components due to temperature changes is prevented from any of the links,the reliability of disk porcelain insulator used in extremely cold regions can be improved.From the perspective of operation,regular sampling testing should be adopted to detect the residual electromechanical load of disk porcelain insulator in the extremely cold region to evaluate the health status of the whole porcelain insulator on the transmission line,so as to provide a certain degree of theoretical reference for the operation,maintenance and status evaluation of disk porcelain insulator operating in the extremely cold region.