Abstract:

For overhead power transmission lines， the fittings' corrosion rate is fast and maintenance is inconvenient due to the high altitude. The fittings of overhead transmission lines in Hunan and Guangxi province were investigated by means of macro-morphology examinations， mechanical property tests， X-ray diffraction （XRD）， scanning electron microscope （SEM）， electrochemical tests and zinc coating thickness measurement. Then the mechanism and behavior of fittings corrosion were discussed and the protection measures were proposed. The results show that three failure forms of cross section size decreasing， tensile strength decreasing and material brittle are caused by fittings corrosion； sulfur is the critical factor of fitting corrosion； the fittings corrosion is increased by both tensile stress and fretting friction. Therefore， the anti-corrosion measures for fittings in heavycorrosion industrial areas should be strengthened and the zinc coating thickness should be increased to more than 192 μm， in order to ensure the safety operation of power grid.

Key words: power transmission line, fittings, corrosion, protection