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Network operation and maintenance
Published in Nemanja Trifunović, Introduction to Urban Water Distribution, 2020
Soil resistivity is the measure of its conductivity i.e. the capacity to resist the flow of electricity, which is mostly influenced by the moisture and presence of different salts. More corrosive soils will have a lower resistivity, which is illustrated in Table 6.12 (Robinson, 1993).
Feasibility study on reducing the grounding resistance of a transmission tower with conductive concrete
Published in Rodolfo Dufo-López, Jaroslaw Krzywanski, Jai Singh, Emerging Developments in the Power and Energy Industry, 2019
Xu Tian, Feng Pei, Xin Liu, Lulu Jia, Chenxing Deng, Xin Wang, Pinghao Yang, Hongbo Cheng
Accurate calculation of the transmission tower grounding resistance is very complicated when factors such as soil quality and moisture are taken into account. But essentially, soil resistivity is the the most obvious factor that directly influences the grounding resistance of an electrical grounding system. Similarly, although conductive concrete is a synthesis of different kinds of characteristics, when taken into the application simulation model, its resistivity is the one that we should put more focus on. We therefore choose the function “Arbitrary Heterogeneities Soil” in module MALZ to simulate conductive concrete. By modifying the size and the resistivity of the arbitrary heterogeneities of soil, any types of conductive concrete can be simulated. The electrical resistivity of the simulated conductive concrete is set to 25 Ω • m (Xin. 2012), and both the thickness and its horizontal size are set to 10 cm. The simulation models are shown in Figure 3.
Grounding Systems
Published in Mazen Abdel-Salam, Hussein Anis, Ahdab El-Morshedy, Roshdy Radwan, High-Voltage Engineering, 2018
The most common method of measuring soil resistivity employs four electrodes driven into the soil. The theoretical basis of this method has been derived. Small electrodes are inserted into four small holes in the earth all to a depth of b meters and spaced along a straight line at intervals of a meters, and making electrical contact with the earth only at the bottom. A test current I is injected through the earth between the two outer electrodes and the potential E between the two inner electrodes is measured with a potentiometer or high-impedance voltmeter. The ratio between the observed potential and the injected current is referred to as the apparent resistance, which is a function of soil resistivity and the electrode geometry. The apparent soil resistivity is computed by multiplying the apparent resistance by a geometric multiplier. The apparent soil resistivity down to a depth equal to a is () ρ=4πaR1+2aa2+4b2−aa2+b2
FEM simulation of a grounded carbon steel pipe under impressed current cathodic protection
Published in Corrosion Engineering, Science and Technology, 2022
M. Attarchi, A. Brenna, M. Ormellese
In CP, soil resistivity is one of the most critical factors as it strongly affects the current distribution and potential variation. Soil resistivity could change in a wide range of values, from soil saturated with saline water to rocky and frozen soil and the same soil may experience different resistivities due to seasonal variations. For water-saturated soil, the resistivity could be around 10–30 Ω m. In many reasonable conditions it is around 100–300 Ω m and it is possible to have higher values, even 1000 Ω m is drylands and frozen or rocky soil [16–18].
Research on earth surface potential distribution and amendment for soil resistivity horizontal hierarchical model in current inflow test
Published in Australian Journal of Electrical and Electronics Engineering, 2018
Li Qiu, Liyang Huang, Yao Xiao, Pan Su, Jie Yang, Bin Peng, Qi Xiong, Xiwu Zhao, Changzheng Deng
Therefore, some domestic researchers verify the SRHHM using the current inflow test, and the main way of which is to amend the model based on the ESP distribution. Currently, literature that uses the current inflow test to detect the SRHHM is rare. However, the effect of soil resistivity on ESP distribution in the single pole operation of HVDC is similar to this work. Ji-ming Lu, etc. from Huazhong University of Science and Technology have analysed the effects of soil resistivity on ESP with multi-layer soil models. The results show that the ESP decreases rapidly near the ground electrode and the downward trend of which decreases with the increasing distance. The resistivity of the surface layer and high resistivity layer in the underground has a great influence on the ESP distribution (Zou, Yao, and He 2016). Zhiguo Hao, etc. from Xi’an Jiaotong University have established the two-layer and four-layer soil resistivity models through the ANSYS software. Their results show that the layered structure of soil resistivity do have a lot of impacts on the ESP distribution, and a more accurate calculation value can be obtained by using a multi-layer soil resistivity model (Zhang, Cai, and Wen 2014). Ling Ruan, etc. from Hubei State Grid Electric Power Research Institute have adopted the magnetotelluric method to measure the deep-layer soil resistivity and have got the DC grounding electrode resistance by comparing the 5-layer horizontal soil resistivity model to the 15-layer one. It turns out that only by taking the shallow soil resistivity instead of the actual one will cause obvious deviation of the ESP (Zhang, Xiang, and Chen 2014). In addition, Lianguang Liu etc. from North China Electric Power University also have established a multi-layer soil resistivity model. Their study findings show that the soil resistivity near the pole site has a great influence on the grounding electrode resistance and step voltage (Zhang, Zhou, and Zhong 2011).