Corrosion diagnosis for grounding grids by using electromagnetic induction method

The steel grounding grid buried in earth will corrode and become hidden danger to the safety of power system. It is difficult to get accurate status of corroded ground grid with traditional method. A novel method is presented in order to improve the efficiency and precision of diagnosis. A sine wave exciting current of different power frequency is injected directly into grounding grid by two ground lead wires. At the same time, the distributions of the surface magnetic induction intensities are measured based on the electromagnetic induction theory, then the faults of mesh conductors becoming thin or broken can be diagnosed. The feasibility of the method is demonstrated and the technical way of diagnosis is established by simulation computations using the grounding analysis software package. Combining with the practical EMI environments in substation, the diagnosis system has been designed. Experimental and practical results show that the functions of the system can satisfy the testing needs, this diagnosis method is simple and effective, and it can be used in engineering practice.