Research On The Corrosion Law Of New Grounding Materials

Grounding device is an indispensable part of the power system.The corrosion of grounding device is a problem that cannot be ignored.The corrosion of grounding material will not only shorten the service life of grounding material,but also cause the increase of grounding resistance of grounding grid and reduce the dissipation capacity of grounding body.When the transmission line or tower is struck by lightning,the lightning current cannot be discharged from the ground in time,which endangers the life safety of the construction and maintenance personnel around the tower and destroys the auxiliary equipment of the nearby substation.In order to ensure the stability and reliability of the grounding system,the corrosion of grounding materials must be effectively solved.Soil corrosion test methods mainly include field buried test and indoor simulation test,indoor simulation test includes simulation field test and accelerated corrosion test.Although the traditional field burial test can objectively reflect the corrosion of the soil at the burial site,the test cycle is long and the test time is long.In order to quickly obtain the corrosion law of the grounding material,the accelerated solution corrosion test is a test method for artificially controlling the test conditions.The purpose is to determine whether the metal material has a certain corrosion tendency in a short time,whether the material has a strong corrosion resistance or a strong medium corrosion ability.The corrosion law of grounding materials was explored through field buried test and indoor solution accelerated corrosion test,which provided a basis for the selection of grounding grid materials.The main work is as follows:（1）Field experiments were carried out in Huangpi District of Hubei Province and Dangyang of Yichang City.In this paper,eight kinds of materials,including carbon steel,stainless steel,galvanized steel,copper,copper clad steel,carbon nano,modified silicate and flexible graphite,were buried in soil.The weight loss method was used to calculate the corrosion rate and corrosion mass loss of different materials,and the corrosion environment of grounding materials was tested to obtain relatively real and reliable corrosion data.The experimental results show that stainless steel,carbon nano and flexible graphite not only have strong corrosion resistance,but also have good time tolerance when they are used as grounding materials in Huangpi District of Hubei Province and Dangyang District of Yichang City.The corrosion rates of stainless steel,galvanized steel,copper,carbon nano,modified silicate and flexible graphite decrease significantly with the increase of embedding time,indicating that when they are used as grounding materials,the corrosion rate gradually slows down with the increase of time,which is conducive to the increase of service life.The corrosion rate of carbon steel decreased first and then increased with the increase of buried time,and the corrosion rate of copper clad steel decreased and then stabilized with the increase of buried time.The corrosion law of carbon steel and copper clad steel in Wuhan Huangpi and Yichang Dangyang are quite different.The main factors affecting the corrosion law of the two grounding materials are the difference of Cl^-and SO4^2-content.（2）The accelerated corrosion test method of solution was used to simulate the corrosion of grounding materials under different soil environments,and the accelerated corrosion laws of grounding materials such as carbon steel,stainless steel,zinc clad steel,copper clad steel,high silicon,high silicon ferrochrome,graphene composite materials and carbon nanoparticles under different soil environments were compared.The effects of accelerated corrosion time,chloride ion content and temperature on the corrosion law of grounding materials were analyzed.The test results show that in acidic soil environment,stainless steel,high-silicon ferrochrome and carbon nano-modified materials have good corrosion resistance,which are suitable for grounding materials in this environment and have a long service life.Stainless steel and high silicon ferrochrome are suitable for the selection of grounding materials in areas with high chlorine content in this environment.High silicon ferrochrome shows good corrosion resistance in areas with large temperature difference in acidic soil environment.In neutral soil environment,the comprehensive corrosion resistance of high silicon and high silicon ferrochrome is the best,and it is recommended to be used as grounding material in this environment.The corrosion rate of high silicon and graphene composites has been low under neutral and high chlorine content conditions,which is recommended for grounding materials in such areas.High silicon,high silicon ferrochrome,graphene composite and carbon nano-modified materials are suitable for areas with large temperature difference between day and night in neutral environment,and graphene composite coating can be considered to enhance the corrosion resistance of grounding materials in such areas.