Evaluation of Soil Corrosivity for Ground Grid of Substations in an Area by Factor Analysis

Abstract

Soils in a depth corresponding to half length of the buried grouding grids are sampled from sites of 123 substations of a 110 kV transmission network in an area. Their physical and chemical properties(11 indexes) are measured, which then are analyzed and processed by using the method of factor analysis. The results show that soil corrosivity for substation ground grid in this area is mainly influenced by calcium and magnesium ions, pH value, chloride ion and water content. A comprehensive evaluation is made based on these five key corrosive factors. It follows that the soil corrosivity for substation ground grids in this area may be divided into four levels as: exceptionally strong(11 substations), strong(86 substations), relatively strong(14 substations) and middle(12 substations). Meanwhile, the corrosivity of all the soil samples are evaluated according to German Beckman standard method. The results of the two methods are in accord with each other, which indicates that factor analysis can be applied to evaluate the soil corrosivity for substation ground grid with a good reliablility.