Studies On Corrosion And Protection Of Transmission Lines In Atmospheric Environment

Transmission line is the foundation of grid operation, and overhead wire is themain material of transmission lines. Serving as the longest and most widelyapplication scope of conductor currently, the dominant position of Steel corealuminum stranded wires（ACSR）will not change for a long period in the future. Thesafety and reliability have a great influence upon the protection of the powertransmission. Otherwise, the serving environment of ACSR has become more andmore complex; there are many factors in the atmosphere which may cause thecorrosion and fracture of the wire.In this paper, we choose LGJ240/30transmission lines as the research object,using the Tafel straight-line extrapolation,loss of qualitative method and periodic wet/dry cycling accelerated corrosion method to simulate the seaside salt sprayenvironment, studied the corrosion behavior of ACSR at50g/L NaCl solution. Theresults showed that under the condition of neutral NaCl, with the increase of NaClconcentration, the corrosion potential of the aluminum wire (open circuit voltage)occurs negative offsets,and the aluminum etching rate becomes larger; salt spray testresults show that in the initial corrosion, a lot of Cl-destroyed the Al2O3passivation ofaluminum surface, making aluminum substrate bared in a wet environment, formedoriginal battery with galvanized layer and accelerated corrosion. After consumptionof the zinc layer completely, the steel core formed primary cells with aluminum, thenthe corrosion rate of aluminum becomes faster, however, with the increase of thecorrosion product, the etching rate of aluminum becomes slowerHave an analysis of the fracture wire in the serving process, we can found thatwire before fracture has suffered serious corrosion, then studied the dirty content adhered on the surface of the conductor, the result showed that the composition iscomplicated, which is a mixture of oil, atmospheric dust, acid corrosion products,andthe main components are CaSO42H2O and CaSO4, CaCO3, SiO2and CaCl2.Analysis results shows that the Cl-and SO2in harsh atmosphere environment is themain cause of ACSR corrosion.