Comparison and recommendations on earthing system measurement and simulation techniques including staged fault method

The article introduces the results of thorough measurement of an earthing system in 22 kV compensated network in comparison to the staged fault. A variety of measurements have been carried out including the staged fault, Wenner soil resistivity measurement, 62 % earth resistance measurement with low and high injecting current, touch voltages and potential distribution. A mathematical model of the earthing system was modelled to obtain the theoretical results and compare them with measurements. The aim of measurements was to investigate the impact of high injecting current on the earth resistance measurement. However, a discrepancy was found out leading to possible cause being the discontinuity of the earthing system or uncertainty of actual earthing system design as well as other possible causes. The helpfulness and complementation of each different method is demonstrated while the root cause of the observed discrepancy is investigated. Unfortunately, based on the results it cannot be ruled out whether it can be beneficial to carry out the measurement with high injecting current. However, the results seem to be on a safe side, meaning that conducting the measurement of earth resistance with low current leads to safer designs.