Design of earthing grounding system in a substation grid. This paper will present ground potential rise gpr causes, effects, variations in the values gpr in high voltage substations. In addition, ground potential rise, maximum permissible step and touch potentials have also been estimated using the simulation software. Soil resistivity and ground resistance for dry and wet soil.
We use skms stateoftheart groundmat software module and accurately determine the touch and step potentials. Abstractthis paper utilizes cdegs software to calculate the transient ground potential rise gpr in a commercial building, with a base of 39 m. Extra high voltage substation groundinggrounding calculation. Ground potential article about ground potential by the. Ground potential rise, or gpr, is a phenomenon that occurs when large amounts of electricity enters the earth at a given point, such as in the case of a lightning strike andor a fault occurring at a substation or transmission tower. The groundhound site safety warning system ground potential. Obviously, the epr of a 3 ohm earth mat with 1732 a fault current is only 5196 volts compared to 30kv calculated by the earth mat analysis software. Introduction the design consideration of substation grounding is important for providing low resistance path to ground, to allow discharge path for lightning strike and protection of equipment and personnel against. Safety analysis including surface materials, based on body weight and exposure time. Ground potential rise how is ground potential rise. Ability to analyze the potential rise for each grounding system including. The cymgrd software is a substation grounding grid design and analysis program specially developed to help engineers optimize the design of new grids and reinforce existing grids, of any shape, by virtue of easy to use, builtin danger point evaluation facilities.
Computation of the station ground resistance rg and the ground potential rise gpr. Soil resistivity and ground resistance for dry and wet. The maximum electrical potential that a substation grounding grid may attain relative to a distant grounding point assumed to be at the potential of remote earth. Ground potential rise is a concern in the design of electrical substations because the high potential may be a hazard to people or equipment. Its not that ground has no voltage, or sea level has no elevation. The sensor unit, a selfcontained ruggedized case that is safety. Introduction the main objectives of a substation grounding system is to. An engineer with some knowledge of power system fault analysis would have quickly worked out that the maximum phase to earth fault current post transient steady state at the source substation could not be greater than 33,000 3 11 ohm or 1732 amperes. This earth fault current when returns to the substation ground grid causes huge ground potential rise which appears at the earthed structures. Evaluation of ground potential rises in a commercial. The potential difference between the ground potential rise gpr and the surface potential at the point. This voltage, gpr, is equal to the maximum grid current times the grid resistance. Step and touch potential voltage earth potential rise. Safety criteria calculations for maximum permissible touch and step voltages.
Pdf the analysis and mitigation of earth potential rise in. This can be caused, for example, in a signal circuit referenced to ground, if enough current is flowing in the ground to cause two points to be at. Ground potential rise influence near hv substations in urban. Fast analysis of irregular largescale renewable ground grid application. Optimization of multilayer earth structure by using. The maximum touch voltage within a mesh of a ground grid. Design and analysis of substation grounding grid with and.
Pdf reduction of ground potential rise of earthing grid for 230. Rise of earth potential from substation phase fault. Two other important design parameters, which depend upon the value of the ground potential rise and the ground resistance of the grounding grid are the mesh voltage and the step voltage. The purpose of this paper is to analyse the impact of ground potential rise in the design of substation. The durations and magnitudes of resulting gprs are unique for dl faults and tl faults because the corresponding fault currents are significantly. Federal law mandates that all known hazards must be eliminated from the work place for the safety of workers. The ground resistance, the ground potential rise, touches and step voltages are the basic design quantities of the grounding grids. Earth potential rise earth potential rise epr is caused by electrical faults that occur at electrical substations, power plants, or highvoltage transmission lines.
Skm groundmat is a program for substation ground grid design and analysis. I am trying to calculate ground potential rise to make sure it is not over 5000v. Awareness of step and touch potential, caused by ground potential rise, is important for anyone working on highvoltage power transmission systems. The grounding engineer will be required to develop safety systems to protect any personnel working where ground potential rise hazards are known to exist. Ground potential rise influence near hv substations in. Finite element analysis of the ground grid conductors and rods. Hi pryianga, thank you for your question regarding ground potential rise. In electrical engineering, earth potential rise epr also called ground potential rise gpr occurs when a large current flows to earth through an earth grid. Ground grid systems electrical power system analysis software. The multifunction groundhound site safety warning system is an instrumentation system designed for the protection of linemen on a work site. Cyril and methodius university, macedonia introduction the ground potential rise gpr in high voltage substations in case of ground faults 1 may cause dangerous voltages between telecommunication installations and local ground. Therefore the potential difference is the highest between a distant point and the point where the current enters the ground.
Fault current distribution between the grounding system and. Ground potential rise is a frequently misunderstood sitesafety issue in the distribution of power and telecommunications services. Ground potential rise on the high voltage substation, measurement point no. Step and touch potential voltage earth potential rise risk. Ground potential rise gpr with respect to a remote ground as a function of distance from the grid. The earthing system provides a low resistance return path for earth. The ground potential rise gpr for this transmission scheme is important as it is to be used to develop specifications for systems and component protection. Performance analysis of actual step and mesh voltage of.
Computation of the station ground resistance rg and the ground potential rise gpr touch and surface potential analysis, inside and outside the grid perimeter, with color display in 2d or 3d representation. Earth potential rise in the underground power distribution. The potential relative to a distant point on the earth is highest at the point where current enters the ground, and declines with distance from the source. What is step and touch potential and reducing resistance to.
In an electrical system, a ground loop or earth loop occurs when two points of a circuit are intended to have the same ground reference potential but instead have a different potential between them. First of all, ground potential rise is very important and very dangerous event. Simulation numerical simulations were performed by multifields software package, which is a part of cdegs package 4. Cyril and methodius university, macedonia the ground potential rise gpr in high voltage substations in case of ground faults may cause dangerous voltages between telecommunication installations and local ground. Figure 3 illustrates the 3 dimensions 3d and contour profile for the case r014p16. Ground potential rise how is ground potential rise abbreviated. Soil measurement data based on wenner fourpin method. Gpr studies use a series of calculations to determine step and touch voltages in accordance with specific standards. Maximum limit of allowable ground potential rise of. Advanced measurement methodologies and modern software packages were used to obtain and effectively analyze fall of potential test data, compute fault current distribution, and evaluate touch and step voltages for this large substation. Pdf the analysis and mitigation of earth potential rise. Step and touch potentials, ground potential rise, absolute potential, ieee std.
The voltage between a grounding system and remote earth during a ground fault. Beginning with a discussion of electrical power system fundamentals, the work covers topics such as ground potential rise and zone of influence, critical telecommunications circuits in high voltage locations, high voltage protection equipment, level iii equipment installation and testing, and personnel safety with high voltage protection equipment. Calculationofimportantdesignparametersforgroundingsystemsinsu. Actual touch and step voltage, current injection method, earth rod, earthling grid design, grid resistance, ground potential rise, multisim simulation software. Number of layers, resistivity of each layer and thickness are the parameters to be estimated with the measured site data. The analysis and mitigation of earth potential rise in.
Ground potential rise gpr is a concern in the design of substation grounding grid. A ground grid mat study will determine if your substation grounding grid design is safe and will limit the touch and step potential to values below the ieee 80 standard ieee guide for safety in ac substation grounding limits. Even ieee std 80 recommends the use of computer software to. Ground potential rise of multigrounded neutral and shield. This effect is called earth potential rise epr or ground potential rise grp. Safety criteria calculations for maximum permissible touch and step voltages based on either ieee std. Hello all, i created a ground grid for a multipeaker unit site with soil resistivity in the neibhborhood of 10. Ground potential rise characteristics of urban stepdown. The diagram shows leakage current from an appliance such as an electric motor a flowing through the buildings ground system g to the neutral wire at the utility ground bonding point at the service panel. Then as a matter of theory, ground potential is whatever you decide to call zero, keeping in mind that only the difference between two potentials is physically significant, and gives the energy per uni. Introduction a grounding system with high ground resistance provides unsafe path for the fault current, which increases the risk of equipment failure as well as the likelihood of severe injury to human being. Gpr is a concern in the design of electrical power systems because the high potential rise may be a hazard to people andor equipment. This engineer used a 10ka fault current to simulate the substation earth potential rise and associated voltage contours.
Touch voltage is the potential difference between the ground potential rise on a structure and the surface potential at the point where a person is standing while touching the structure. Advanced measurement methodologies and modern software packages were used to obtain and. It is clear that the ground potential rise gpr as well as distribution of the earth surface potential esp during the. No hand calculation methods for gpr for highvoltage transmission line faults exist due to the complexity of the problem itself and vast amount of data input required.
Ground potential rise gpr is the maximum voltage that the earthing system may achieve relative to a remote point assumed to be at the potential of earth 2. Analytical methods for earth surface potential calculation. Grounding design calculations part fifteen electrical. Factors affecting ground potential rise and fault currents. Safegrid earthing electrotechnik pty ltdelectrical. Computation of grid resistance and ground potential rise gpr. Ability to analyze the potential rise for each grounding system including neighboring passive grids or rods. The substation is in the basement of a high rise with concrete pad. This paper shows some special ground potential rise characteristics of substations fed by power cables. By using resap module of cdegs software optimizing the parameters. The magnitude of the ground potential rise gpr and the associated voltage hazards are directly linked to the layout, fault currents and impedance of an overall grounding system. Earth potential rise in the underground power distribution cable.
The ground potential at different outlets may differ by as much as 10 to 20 volts due to voltage drops from these currents. Ground grid systems software ground grid design ieee. Investigation of soil structure in the substation site is the prerequirement to design the substation. Awareness of step and touch potential, caused by earth potential rise, is important for anyone working on highvoltage power transmission and distribution systems above 1 kv. There is approximately 7000 meters of 40 copper with some 500 kcmil in the heavy fault 60ka area. Design of earth grid for a 3311kv gis substation at a. Ground potential rise ground potential rise as defined in ieee std 367 is the product of a ground electrode impedance, referenced to remote earth, and the current that flows through that electrode impedance. Feb 09, 2014 rise of earth potential from substation phase fault. I have talked with crews who just thought they were getting bit by rogue static electricity, so did not take necessary precautions. The system consists of a sensor unit and a handheld unit communicating via wireless protocol. Ground potential article about ground potential by the free. The cymgrd software is a substation grounding grid design and analysis program. Power line faults create the ground potential rise gpr on both the neutral and shield conductors when the transmission lines tl and distribution lines dl are built on the same structures. Thus, reducing the ground potential rise will reduce the ground potential rise to the degree that the fault current flowing into the grounding system does increase in response to the reduced ground potential rise.
Ground potential rise influence near hv substations in urban areas l grcev, v filiposki, v arnautovski st. Calculationofimportantdesignparametersforgroundingsystemsi. For example, if the fault current for a highvoltage tower is 5,000 amps and the resistance to ground of the grounding system is 10. Oct 26, 2015 awareness of step and touch potential, caused by ground potential rise, is important for anyone working on highvoltage power transmission systems. Design of earth grid for a 3311kv gis substation at a high. What is step and touch potential and reducing resistance. The maximum test gpr divided by the test current yields the impedance of the grounding system. The purpose of this paper is provide knowledge about the gpr, substation grounding grid and step and touch potentials. The difference between neutral and ground on the electric panel duration.
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