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We propose here a cost-effective, realistic method for testing the continuity of the grounding grid and for identifying its weak points or discontinuities. The proposed method involves injecting an ac current of ~200 A frequency not 60 Hz or 60 Hz harmonic into a grounding grid. The purpose of the frequency setting is to be able to distinguish the magnetic field produced by the injected current when...
In this paper, a new program solution is presented to analyze the electromagnetic field around the grounding grid. In contrast to recently existent procedure based on the “classical” finite element method (FEM), in this new methodology the soil and the air domain of the problem are discretized by the 3-D finite elements and the conductors of the grounding grid are discretized by 1-D finite line elements...
This paper proposes a hybrid Genetic Algorithm-Simulated Annealing technique for optimal design of grounding grids. The technique aims to minimize the installation cost while ensuring the safety of personnel. The safety indices are obtained; using an electromagnetic formulation based on the well-known quasistatic complex image method together with a closed form of Green's function. This method provides...
In this paper, a numerical model is presented to analyze the grounding grids. The effect of the mutual inductances among grounding system conductors on the performance of the grounding grid is investigated. It can be seen that although the effect of the mutual inductances is very small at power frequency, when a large grounding grid buried in soil with low resistivity is analyzed, the effect of the...
This study presents an advanced methodology and a computer model for analysis of grounding systems conforming to standards IEEE Std 80-2000, IEEE Std 81- 1983 and IEEE Std 837-2002. The methodology and computer program is validated with actual system measurements. The accuracy of computer algorithm is dependent on how well the soil model and physical layout reflect actual field conditions. The tolerable...
The information in this paper includes the basic corrosion theory and forms of substation grounding grid corrosion. In order to investigate the corrosion in substation grounding grid and acquire corrosion data to give a guide for steel grounding grid's design, 21 grounding grids of substations distributed in different areas of Foshan were excavated to test corrosion rates of grounding conductors....
A detailed analysis of potential profile at a surface above energized unequally spaced grounding grid has been carried out, for soils with multiple layers. Exact and approximated algorithms are used to obtain the voltage profile and then to calculate the step and touch voltages. The analysis shows that the voltage distribution is highly dependent on soil structure type and characteristics and also...
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