Variation of soil resistivity and ground resistance during. Use the reference button in below of the calculation window for getting the following information. Soil resistivity is the key factor that determines what the resistance of a grounding electrode will be, and to what depth it must be driven to obtain low ground resistance. Ground grid systems software ground grid design ieee 80. Wenner spacing soil resistivity calculator, calculate. Where r is the resistance measured by the machine a is the spacing of the probe.
Soilresistivityre2cap re2cap is free software freeware that was designed and developed i for the area of electrical engi. In general, soil resistivity increases as temperature decreases. Soil resistivity is a measure of a soils ability to retard the conduction of an electric current. So we need a good understanding of both the deep earth resistivity, and the shallow earth resistivity. Soil resistivity and ground resistance for dry and wet soil. Resistivity and induced polarization data interpretation. Use the belowgiven wenner spacing soil resistivity calculator to calculate the soil resistivity, electrode spacing, voltage at inner electrodes, and current at outer electrodes. Soil resistivity tests measure the electrical conductivity of the soil to allow the creation of an electrical equivalent soil model that can be. Soil resistivity equations and formulas calculator geophysics geophysical measurement.
The measuring procedure described below uses the universally accepted wenner method developed by. Miller soil boxes can be used to satisfy either the 4electrode method astm g57 standard or the 2electrode methods astm g187 or aashto t288 standards. Resistance of 1 rod and arrays of 2, 3, 4 rods in parallel. Analysis techniques applied to investigate impacts. Multifunction ground resistance soil resistivity tester. If the soil resistivity gets worse with depth, deeper electrodes will be unlikely to lower the resistance.
The resap soil resistivity analysis computation module is used to determine. Terrapro is a pioneering ssaas scientific software as a service platform, designed to provide modern and reliable engineering tools for simulation of electrical grounding systems and electromagnetic interferences. Data set b represents lowresistivity soils in the first few feet. For the 2electrode method, the two interior pins are removed which changes the multiplication factor from 1 cm for the 4electrode method to either 0. Electrical tomography resistivity imaging is technique including both the method of field observations and technology of processing and field resistivity and ip data interpretation.
The measure of the resistance offered by the soil in the flow of electricity, is called the soil resistivity. Contains information and software to assist measurement of soil resistivity and calculation of earth electrode resistance. Determine the average earth resistivity to a specific depth 4electrode application. Electrical tomography resistivity imaging is technique including both the method of field observations and technology of processing and field resistivity and ip. The type of anode and number of anodes required peabody, 1959, the length and diameter of the backfill column, and the voltage rating of the rectifier and power cost are all influenced by the soil resistance van nouhuys, 1953. Resap soil resistivity analysis ses safe engineering. Soil resistivity testing is the process of measuring a volume of soil to determine the conductivity of the soil. The most widely used test for determining soil resistivity data was developed by wenner and is called either the wenner or fourpin method. High efficient multicore parallel calculation allows fast analysis of irregular. It is also part 3 in a series of short posts on soil resistivity testing methods. In this paper, soil resistivity and ground resistance at two different sites near an electrical substation are measured using a grounding system grid with and without rods.
Louie, applied geophysics class at the university of nevada, reno, lecture 19. Wenner soil resistivity testing with the aemc model 6472 in an electrical system, effective grounding ensures a safe working environment as well as proper equipment performance. Soil resistivity is a function of soil moisture and the concentrations of ionic soluble salts and is considered to be most comprehensive indicator of a soils corrosivity. Soil resistivity testing is the process of measuring a volume of soil to. The wenner 4 probe is one of the most common soil resistivity testing methods using a. Once all the soil resistivity data is collected, the following formula can be applied to calculate the apparent soil resistivity in ohmmeters. Soil that contains 10% moisture by weight will as much as five times lower soil resistivity than that which contains 2. Cymgrd simulation software is then used to determine the. Soil resistivity calculator given electrode spacing, inner electrodes voltage. Based on the resistance r, as determined by the voltage and current, the apparent resistivity can be calculated using the following equation, assuming bis small compared with a. Figure 11 shows the entire soil resistivity formula in detail.
The sizing of earthing conductors should always be performed, but touch and step potential calculations per ieee std 80 for earth faults with a return path through remote. As shown in the figure, the greatest rate of change in soil resistivity is at the point where moisture in the soil freezes. There may be a layer of somewhat less than ohmcm around the 1. Figure b2 shows soil resistivity changes as a function of soil temperature. The conversion between values measured using the schlumberger and wenner methods is possible only in an approximate way. Ohms law can then be applied to calculate the measured apparent. Calculate number of bags of gem required, yes, yes. Easypower is partnering with the industryleading grounding and emi analysis expert company, sint ingegneria, which offers a software package to analyze and design grounding, lightning and electromagnetic interference problems by focusing on its powerful and yet affordable grounding analysis software packages, xgslab easypower is the exclusive representative. The astm g57 standard also known as the fourpin wenner method is used to determine the properties of soil. Low soil resistivity is an indication of a potential corrosion hazard to buried metals such as copper used for earthing. The average of the readings shown 960 ohmcm represents the effective resistivity that may be used for design purposes for impressed current groundbeds or galvanic anodes.
Typically, the lower the resistivity, the higher will be the corrosivity as indicated in the following table. Soils made up of ashes, shale or loam tend to have the lowest soil resistivity. Nov 15, 2016 the astm g57 standard also known as the fourpin wenner method is used to determine the properties of soil. Resap soil resistivity analysis ses safe engineering service. Sep 27, 2017 wenner soil resistivity testing with the aemc model 6472 in an electrical system, effective grounding ensures a safe working environment as well as proper equipment performance. The resistivity of soil is also affected by its temperature. Soil resistance is one of the most important factors in selecting a groundbed location. The results obtained can be used as a basis for grounding mesh designs. Zondres2d software for 2d resistivity and ip imaging. The software was developed with microsoft visual basic and feature friendly gui. Soil made up of gravel, sand or stone have the highest soil resistivity. Soil resistivity measurements soil resistivity tests measure the electrical conductivity of the soil to allow the creation of an electrical equivalent soil model that can be used in earthing design software such as cdegs. In agricultural applications, a soil test may be useful for analyzing nutrients and moisture content. First, data is used to make subsurface geophysical surveys as an aid in identifying ore locations, depth to bedrock and other geological phenomena.
Input soil resistivity data for multiples traverses and obtained from wenner, schlumberger, dipoledipole or unipolar methods, or specify your own arbitrary arrangement general method. Measure the resistancetoearth of a buried electrode, such as a ground rod, or an anode, for example 3electrode application. Calculate soil resistivity when resistance of one rod is known. The model enters a processing queue and a robust calculation server performs. In environmental analysis, soil testing is used to detect hazardous material present in the ground. Generate the soil resistivity plot based on wenner fourpin method. Re2cap is a graphical tool for a twolayer soil electrical resistivity modeling by the inversion of parameters by numerical methods. Miller, soil resistivity meter, model 400a farwest. The deep layers of soil will impact the overall resistancetoearth of the large grid, while the shallow reading will impact our human safety step and touch voltages factors.
Marshy soils have low resistance, while rocky soils may have resistance of. Minimal third party impact during the soil resistivity measurements. Soil resistivity testing methods wenner 4 probe tester. The resistivity values of soil may be useful when designing earthelectrode systems. Soil resistivity is a key factor for determining what the resistance of a. Math geometry physics force fluid mechanics finance loan calculator. Soil is rarely homogenous and the resistivity of the soil will vary geographically and at different soil depths. Quick and accurate measurement of resistivity of a soil or water sample, field or laboratory. Data set b represents low resistivity soils in the first few feet. The electrical resistivity of soil can affect the rate of galvanic corrosion of metallic m. Use the belowgiven wenner spacing soil resistivity calculator to calculate the soil resistivity, electrode spacing, voltage at inner electrodes, and current at outer. Nov 02, 2018 download soilresistivityre2cap for free.
The resistivity of the soil depends on the various factors likes soil composition, moisture, temperature, etc. Calculation of multiple bespoke, representative soil models to best fit the customer requirements. Even in areas of low soil resistivity it would be difficult, if not impossible, to design an electrode adequate for such a duty. Ideally, soil resistivity test results from the site will be available for use in touch and step potential calculations if necessary. Current distribution, electromagnetic interference. This raw data is usually processed with computer software to determine the actual resistivity of the soil. Determining the soil resistivity to design a good substation. Performing a wenner soil resistivity test with the aemc model. Soil resistivity change in voltage change in current x pin spacing in feet x 191. Pdf soil resistivity and ground resistance for dry and. Soil resistivity dial reading x multiplier range x pin spacing in feet x 191. Aemc wenner soil resistivity testing explained using. The soil composition, moisture content, and temperature all impact the soil resistivity. Use the locking feature to have the program calculate a soil model.
Electrical resistivity of different soil and rock types 325 c1. The resulting soil resistivity is expressed in ohmmeter or ohmcentimeter. If the soil resistivity is better with depth, the ground system resistance can be improved by installing deeper electrodes. It is a critical factor in design of systems that rely on passing current through the earths surface. When designing grounding systems, soil resistivity testing is a necessity. The soil structure has been computed using soil resistivity measurements and specialized genetic algorithm software, which has been developed in our lab. Grounding design calculations part nine electrical knowhow. Continuously vary the ratio of current probe spacing to potential probe spacing e. Soil resistivity dial reading x multiplier range x pin spacing in feet x. Soil resistivity equations formulas calculator aj design software. Multifunction ground resistance soil resistivity tester model 6470b ground resistivity resistance instrument. Nassereddine is with the university of western sydney, locked bag 1797 penrith south dc 1797, nsw australia email.
An understanding of the soil resistivity and how it varies with depth in the soil is necessary to design the grounding system in an electrical substation, or for lightning conductors. Pdf soil resistivity and ground resistance for dry and wet soil. Re2cap is free software freeware that was designed and developed i for the area of electrical engineering. Zondres2d program is designed for twodimensional interpretation of electrical tomography data by resistivity and induced polarization method in land, crossborehole and water cases. Determine the resistivity of a soil sample, or of a liquid, via an electrolyte soil liquid box 4electrode application. Re2cap is free software freeware that was designed and developed in principle for the area of electrical engineering so that it is a soil modeling tool in two layers from the inversion of parameters by numerical methods using for the effect a graphical interface. The soil resistivity test kit is designed to conveniently store and carry all that is necessary to perform at test. Second, resistivity has a direct impact on the degree of corrosion in underground pipelines. Soil resistivity and ground resistance for dry and wet. Timely delivery of the report to the client outlining the findings of the study.
As shown in the figure, the greatest rate of change in soil resistivity is at. Electrical resistivity of different soil and rock types. Soil resistivity calculator given electrode spacing, inner electrodes voltage, outer electrodes applied current and wenner spacing. Originally published in 20 and now updated in 2020. Gsa is an engineering software for earth grid calculations and design including soil resistivity analysis. Moisture content, temperature and salts also affect soil resistivity. With the wenner fourpole equalmethod, the soil resistivity is measured at both selected sites, one of which contains wet soil while the other contains dry soil. It is therefore necessary to determine the maximum current, and its duration of flow 1 second given by design, which the electrode must safely transmit to or from the body of earth. Gsa is highly appreciated for its ease of use, user. In any cases, for both wenner and schlumberger methods the electrode spacing between the currents probe corresponds to the depth of soil investigation and the measured apparent soil resistivity is referred to a soil volume as in the figure.
Using four pins or electrodes driven into the earth along a straight line at equal distances of a, to a depth of b, current is passed through the outer pins while a voltage reading is taken with the two inside pins. Understanding soil resistivity testing soil resistivity measurements have a threefold purpose. The first set of data, set a, represents a uniform soil conditions. The 4rod wenner method of measuring soil resistivity. Measurement of soil resistivity and calculation of earth. Schlumberger array or schlumberger method soil resistivity. Our inhouse 1d interpretation of electrical resistivity sounding specially developed for noisy soil data with diffuse boundaries between soil horizons is still available for free. Soil resistivity vs resistance in this article, we refer to both soil resistivity and soil resistance. Geophysical and geostatistical software landviser, llc. Soil resistivity equations formulas calculator wenner. Sorry to see that you are blocking ads on the engineering toolbox. Soil resistivity testing is the single most critical factor in electrical grounding design. Wenner 4 probe test is one of the most common soil resistivity testing methods. The parameters to determine the safety voltage limits are.
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