Abstract: To diagnose the corrosion fault of grounding grids，according to the topology structure of grounding grids，a topology dividing approach based on the accessible nodes is presented.A grounding grid is decomposed to circuit-blocks grid，accessible grounding grid and intrinsic grounding grid.The grounding grids topology is divided automatically，which make sure the conjunction character of branch in different layer.The testability of grounding grids is researched through the estimate of topology structure and estimate after diagnosis according the date structures of topology，the clear-branches are identified automatically，it is of great significance to scientifically utilize the diagnosis results.An experimental grounding grid with sixty branches is used as an example.The results of topology dividing show that the proposed algorithm and date structures are correct and feasible.

摘要： 为了对接地网进行故障诊断，通过对接地网支路拓扑结构进行分析，提出了一种以可及节点为裂点的分层拓扑分解方法，将接地网分解为元版块网、可及接地网和本征接地网。根据不同的数据结构，实现了接地网网络拓扑自动分解，明确了由拓扑结构决定的各层支路的关联性，采用结构判断和诊断后判断结合的方法对接地网支路的可测性进行了研究，可以自动识别诊断结果唯一确定的明晰支路，为科学利用诊断结果具有指导意义。对一个60支路的实验接地网采用所提出的算法进行分解和可测性判断，验证了提出的方法的正确性和实用性。