Reverse short distance measurement method of grounding resistance of large grounding grid

Abstract

At present, there are some problems in the measurement method of grounding resistance of large grounding grid, such as lead length and result judgment depending on measurement experience, resulting in large resistance measurement error. A reverse short distance measurement method of grounding resistance of large grounding grid is proposed. The scattered current of the grounding grid and the return current of the current electrode will form a positive and a negative electric field between the grounding grid and the current electrode, so as to determine the ground potential distribution law and calculate the hemispherical grounding current electrode potential of the grounding grid. In order to eliminate the influence of shunt on grounding resistance measurement, the injected current of grounding grid is shunted. Through theoretical derivation, the analytical function of the ground potential measurement data in the very near area of the current is obtained, the undetermined parameters of the analytical function are solved by the least square principle, and the reverse short-distance measurement method of the grounding resistance of the grounding grid is deduced by the compensation principle. The test results show that the reverse short distance measurement method can effectively measure the grounding resistance. Compared with the traditional potential drop method and 0.618 method, the measurement result has less error and higher accuracy.