某变电站接地网铜覆钢绞线防腐性能测试研究
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摘要
铜覆钢品质优劣直接决定着接地网系统的使用寿命及运行安全,加强铜覆钢材质的入网品质测试意义重大。对某变电站送检铜覆钢绞线样品目视检查、SEM扫描外观形貌,发现其表面存在大量腐蚀点。EDS分析发现腐蚀产物主要为Fe和Cu氧化物的混合物,表明腐蚀已局部深至基体钢材。对铜镀层厚度进行多点EDS元素mapping分析,发现镀铜层厚度仅为0.025 mm左右,远低于电力行业标准中关于铜镀层不小于0.25 mm的规定。采用四电极法测试其电阻,计算出电阻率及相对导电率,该铜覆钢绞线样品仅能符合行业标准中最低等级铜覆钢电阻率及相对导电率的要求,即相对导电率不小于15%(20℃)。综合评估,该铜覆钢样品防腐性能不合格,难以满足铜覆钢接地网免维护要求,甚至将发生严重电偶腐蚀,不应采用。
The service life and operation safety of earth mat depend on corrosion resistance performance of copper coated steel. Thus it is important to test the material quality of copper coated steel before it is used. It was found that there were a lot of corrosion sites on the surface of copper coated steel samples from a substation via visual inspection and SEM scanning. By EDS analysis, it was found that the corrosion products were Fe and Cu oxides, indicating that the corrosion is locally deep into the base steel. The thickness of the copper coating was analyzed using multi-point EDS element mapping analysis, and the coating was found merely0.025 mm thick, far lower than the power industry standard requirement that the copper coating should not be thinner than 0.25 mm. The resistivity and relative conductivity were measured by a four-electrode resistance measurement. The copper-coated steel strand sample can only meet the requirements of the lowest-class resistivity and relative conductivity, namely the relative conductivity is not smaller than 15%(20℃). The comprehensive assessment shows that the copper coated steel samples were not qualified in corrosion resistance performance and can not meet maintenance free requirement of copper-coated steel earth mat or even lead to severe galvanic corrosion, and it should not be used in substations.
The service life and operation safety of earth mat depend on corrosion resistance performance of copper coated steel. Thus it is important to test the material quality of copper coated steel before it is used. It was found that there were a lot of corrosion sites on the surface of copper coated steel samples from a substation via visual inspection and SEM scanning. By EDS analysis, it was found that the corrosion products were Fe and Cu oxides, indicating that the corrosion is locally deep into the base steel. The thickness of the copper coating was analyzed using multi-point EDS element mapping analysis, and the coating was found merely0.025 mm thick, far lower than the power industry standard requirement that the copper coating should not be thinner than 0.25 mm. The resistivity and relative conductivity were measured by a four-electrode resistance measurement. The copper-coated steel strand sample can only meet the requirements of the lowest-class resistivity and relative conductivity, namely the relative conductivity is not smaller than 15%(20℃). The comprehensive assessment shows that the copper coated steel samples were not qualified in corrosion resistance performance and can not meet maintenance free requirement of copper-coated steel earth mat or even lead to severe galvanic corrosion, and it should not be used in substations.
引文
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[2]DL/T 1342-2014电气接地工程用材料及连接件[S].北京:中国电力出版社,2014.
[3]GB/T 3048.2-2007电线电缆电性能试验方法第2部分金属导体材料电阻率试验[S].北京:中国标准出版社,2007.
[4]GB/T 3048.4-2007电线电缆电性能试验方法第4部分:导体直流电阻试验[S].北京:中国标准出版社,2007.
[5]Q/GDW 466-2010电气工程接地用铜敷钢技术条件[S].北京:中国电力出版社,2010.
[6]GB/T 50065-2011交流电气装置的接地设计规范[S].北京:中国计划出版社,2011.
[7]何莉,孙双魁.浅议铜覆钢接地材料在变电站的应用[J].青海电力,2014,33(2):35-38.
[8]沈晓明,钱洲亥,祝郦伟,等.浙江地区变电站土壤腐蚀性调查研究[J].浙江电力,2017,36(2):53-57.
[9]赵艳鹏.主接地网材料的选择及应用[J].机械管理开发,2017(8):95-96.
[10]文习山,宋周,谭波,等.铜覆钢接地导体的电气性能[J].高电压技术,2015(2):608-614.
[11]李文杰.变电站双层立体复合地网研究[J].低碳世界,2016(13):36-37.
[12]杨庆刚.江苏电网接地问题探讨[J].江苏电机工程,2015(2):82-84.
[13]王宏波.思居110 k V变电站的接地材料选型及降阻研究[J].电子世界,2014(13):49-51.
[14]赵立飞.镀铜钢材料在变电站地网中的应用[J].科技传播,2012(20):142-143.
[15]杨国雄,李文飞,邓庆祥.铜覆钢接地材料土壤腐蚀特性分析[J].广东气象,2015(5):76-77