Computational Model And Application Of Electrically Conductive Concrete In Grounding Engineering

Electrically conductive concrete is a functional composite material which is madethrough mixing an appropriate amount of conductive components in ordinary concrete. Ithas the characteristics of structural material and conductive material. Currently, the metalmaterials such as galvanized angle iron, galvanized flat steel etc are used in most domesticgrounding engineering of electrical power system, but these earthing materials have moreserious corrosion problems which is a major risk for the safe operation of the power grid.In this papper, carbon fiber and carbon black were selected as conductive phases toprepare electrically conductive concrete and the basic grounding characteristics ofconductive concrete were researched. The grounding modules made of electricallyconductive concrete were grounded in parallel to build new type of the conductiveconcrete solid grounding.Carbon fiber and carbon black were selected as conductive phases to prepareelectrically conductive concrete. The amounts of carbon fiber and carbon black and theelectrode area, etc, were optimized through testing the resistivity of conductive concretesamples. The changes of resistivity along with the age growth and temperature growthwere studied and the basic grounding characteristics of conductive concrete were analyzed.The results showed that when the carbon fiber and carbon black contents were both0.1%and the electrode area was10%, the conductive concrete had good conductivity. Theresistivity of concrete tended to be stable along with the age growth and the stable valuewas530·cm. The range of resistivity between-40℃and50℃was less than5%. Theconductive performance was stable. The compressive strength of28d reached35MPa andthe bending strength of28d reached6MPa. The strength satisfied the requirement ofmechanical properties of the grounding materials.Using carbon fiber-carbon black composite electrically conductive concrete asgrounding material, grounding modules of electrically conductive concrete were laid inparallel on the bottom and side walls of the foundation ditch of transmission line tower tobuild new type of the conductive concrete solid grounding. Considering parallel grounding effect, the computational model of grounding resistance of conductive concrete solidgrounding was established based on the calculation of grounding resistance of the metalelectrodes. And experiments confirmed that grounding resistance amplification factor ψranged from2.5to3.5and utilization factor η ranged from0.6to0.8. The laying schemeof electrically conductive concrete rod grounding electrodes in different soil types couldbe designed according to the model. The validity of the model was verified through testingeffect of the grounding grid of practical grounding engineering of transmission line tower.And the solid grounding had good effect of reducing grounding resistance.