State Assessment for the Grounding Grid of an 110 kV Old Substation Before Reconstruction

In order to improve the reconstruction efficiency, the grounding grid of an 110 kV substation was evaluated by the electrical impedance tomography (EIT) technology. Results indicated that five breakpoints of the down lines were found underground, but the impedance increase of grid was in a reasonable scope, proving that the level ground grid had not suffered serious corrosion. According to the evaluation results, a reconstruction program of just replacing the grounding metal of down lines was proposed, which could reduce the reconstruction cost of grounding grid and the waste of grounding metal. EIT technology could be used to evaluate the corrosion of grounding grid rapidly and effectively, which could reduce the blindness of grounding grid corrosion detection and improve the fine management level of grounding apparatus.