The theory and implementation of corrosion diagnosis for grounding system

In China, the grounding system is made of steel. When the steel corrodes, it is a potential problem and very dangerous to the power system, since it is buried under ground. How to obtain the status of the corrosion easily is very important for the safety of the operation. A novel method is proposed, by which corrosion status of grounding system can be diagnosed from measured port resistances among the touchable down-lead conductors connected to the grounding grid. First, the mathematical relationship between the corrosion status of the grounding grid´s all grounding conductors and the measured port resistances is deduced in detail based on circuit model and theory. Then, an appropriate mathematical model is discussed for practicable computation. The completed corrosion diagnosis system, including hardware device of data measurement, diagnosis and analysis software, is also introduced concisely. Finally, the field test report is provided to validate the method.