变电站接地电极的腐蚀与防护研究

Corrosion and Protection of Earth Screen in Transformer Substation

为了研究变电站接地网在降阻剂中的腐蚀情况 ,用化学分析的方法测试了变电站的土壤和所用降阻剂的理化性质 ,用失重法分析了除去镀锌层后的A3钢电极在土壤和降阻剂中的腐蚀情况。试验结果表明 ,A3钢电极在弱碱性降阻剂中的腐蚀比在中性土壤中的腐蚀严重 ,主要原因是降阻剂中含有Cl-使降阻剂成为一种强腐蚀性介质 ,造成了电极的点蚀穿孔。通过动态恒电位扫描法测定A3钢在各种溶液中的极化曲线以获得各离子对电极的自腐蚀电位和孔蚀电位的影响 ,结果表明在降阻剂中加入缓蚀剂 ,如磷酸盐和硅酸盐 ,可以缓解降阻剂中Cl-对A3钢的点蚀影响 ,使降阻剂既能降低接地电阻又可缓解接地网的腐蚀。

To study the corrosion of grounding grids in transformer substation, the constitutes, pH and moisture of soil and reducing resistance reagent in transformer substation were measured by chemical analysis, and the pitting corrosion on A3 steel grounding electrodes scraped off zinc plating in reducing resistance reagent was observed in lab. Factors effecting corrosion behavior of grounding grids were investigated. Cl^- in the reducing resistance reagent is the key for the corrosion of earth screen. The pitting corrosion potential and corrosion potential of A3 steel electrode in soil containing of 4% NaCl move positively by adding some corrosion inhibitors such as NO^-_3, CO^(2-)_3, PO^(3-)_4, SiO^(2-)_3. Adding inhibitors as PO^(3-)_4 and SiO^(2-)_3 to the reducing resistance reagent can decrease the corrosion of earth screen.