500 kV变电站接地网腐蚀分析及防护措施

Analysis on Corrosion Failure of 500 kV Substation Grounding Grid

采用现场照片、扫描电子显微镜(SEM)、电子能谱(EDS)和X射线衍射(XRD)分析了某500 kV变电站接地网腐蚀失效情况,探讨了腐蚀机理,结果表明地网腐蚀为局部腐蚀,主要原因为:降阻剂铺设不均匀,造成接地网局部盐浓差腐蚀;土壤中存在硫酸盐还原菌促进接地网腐蚀;石墨与扁钢之间存在电偶腐蚀,泄漏电流促进了接地网局部腐蚀。文中最后给出了接地网的防腐建议。

The corrosion condition of the 500 kV substation grounding grid was investigated by the analysis live photograph, scanning electron microscopy（ SEM）,electron diffraction spectra （EDS） and X-ray diffraction （XRD）. The result shows that the most severely corrosion is appeared on the local region. The local corrosion of the grounding grid is caused by these reasons ： the resistance reduces agent laid uniformly,which lead to the salt concentration cell corrosion of grounding grid; the existence of sulfate reduces bacteria in soil promoted the corrosion of grounding gr id; galvanic corrosion of carbon steel/graphite and leakage current facilitates the corrosion of grounding grid. The corresponding protection measures are suggested finally in the paper.