Analytical methods for earth surface potential calculation. Advanced measurement methodologies and modern software packages were used to obtain and. Ground potential rise gpr with respect to a remote ground as a function of distance from the grid. Gpr studies use a series of calculations to determine step and touch voltages in accordance with specific standards. What is step and touch potential and reducing resistance. Design of earthing grounding system in a substation grid. This voltage, gpr, is equal to the maximum grid current times the grid resistance.
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. Safety criteria calculations for maximum permissible touch and step voltages. The maximum touch voltage within a mesh of a ground grid. Ground potential rise how is ground potential rise. I have talked with crews who just thought they were getting bit by rogue static electricity, so did not take necessary precautions. We use skms stateoftheart groundmat software module and accurately determine the touch and step potentials. The potential difference between the ground potential rise gpr and the surface potential at the point. 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. 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. Step and touch potential voltage earth potential rise risk. This paper will present ground potential rise gpr causes, effects, variations in the values gpr in high voltage substations. A potential reference point sufficiently distant from the fault to experience negligible potential rise. Soil measurement data based on wenner fourpin method. Awareness of step and touch potential, caused by ground potential rise, is important for anyone working on highvoltage power transmission systems.
Gpr is a concern in the design of electrical power systems because the high potential rise may be a hazard to people andor equipment. Pdf the analysis and mitigation of earth potential rise. Performance analysis of actual step and mesh voltage of. Ground potential rise characteristics of urban stepdown. This poses significant problems when attempting to validate a design based on raw test data that are interpreted using approximate methods to evaluate substation ground impedance, and determine ground potential rise gpr, touch and step voltages. Pdf the analysis and mitigation of earth potential rise in. I am trying to calculate ground potential rise to make sure it is not over 5000v. The ground potential at different outlets may differ by as much as 10 to 20 volts due to voltage drops from these currents. This earth fault current when returns to the substation ground grid causes huge ground potential rise which appears at the earthed structures. Actual touch and step voltage, current injection method, earth rod, earthling grid design, grid resistance, ground potential rise, multisim simulation software. 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. This paper shows some special ground potential rise characteristics of substations fed by power cables. Grounding design calculations part fifteen electrical. In addition, ground potential rise, maximum permissible step and touch potentials have also been estimated using the simulation software.
Earth potential rise in the underground power distribution cable. 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. Federal law mandates that all known hazards must be eliminated from the work place for the safety of workers. Evaluation of ground potential rises in a commercial. The difference between neutral and ground on the electric panel duration.
Ground grid systems software ground grid design ieee. First of all, ground potential rise is very important and very dangerous event. Ground potential rise influence near hv substations in. Ground potential rise how is ground potential rise abbreviated. For very low impedance grids, which can be quite inductive, it can be useful to measure the phase angle between the voltage and current to determine. What is step and touch potential and reducing resistance to. 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.
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. Finite element analysis of the ground grid conductors and rods. The analysis and mitigation of earth potential rise in.
Calculationofimportantdesignparametersforgroundingsystemsi. 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. Figure 3 illustrates the 3 dimensions 3d and contour profile for the case r014p16. The multifunction groundhound site safety warning system is an instrumentation system designed for the protection of linemen on a work site. 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 grounding engineer will be required to develop safety systems to protect any personnel working where ground potential rise hazards are known to exist. Ability to analyze the potential rise for each grounding system including. Ground potential article about ground potential by the. By using resap module of cdegs software optimizing the parameters. Ground potential rise influence near hv substations in urban areas l grcev, v filiposki, v arnautovski st. Skm groundmat is a program for substation ground grid design and analysis. Extra high voltage substation groundinggrounding calculation.
Surface potential, touch and step voltage analysis over the area of the grid and beyond in 2d and 3d colour perspectives. 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. The earthing system provides a low resistance return path for earth. The substation is in the basement of a high rise with concrete pad. Ground potential rise influence near hv substations in urban. The purpose of this paper is to analyse the impact of ground potential rise in the design of substation. 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.
This engineer used a 10ka fault current to simulate the substation earth potential rise and associated voltage contours. Therefore the potential difference is the highest between a distant point and the point where the current enters the ground. This effect is called earth potential rise epr or ground potential rise grp. 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. 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. Fast analysis of irregular largescale renewable ground grid application. Soil resistivity and ground resistance for dry and wet. 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. The system consists of a sensor unit and a handheld unit communicating via wireless protocol.
The cymgrd software is a substation grounding grid design and analysis program. Ground potential rise gpr is a concern in the design of substation grounding grid. 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. Computation of grid resistance and ground potential rise gpr. Even ieee std 80 recommends the use of computer software to. 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. 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 of multigrounded neutral and shield. Design of earth grid for a 3311kv gis substation at a high. 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. Soil resistivity and ground resistance for dry and wet soil.
Earth potential rise earth potential rise epr is caused by electrical faults that occur at electrical substations, power plants, or highvoltage transmission lines. The ground resistance, the ground potential rise, touches and step voltages are the basic design quantities of the grounding grids. Simulation numerical simulations were performed by multifields software package, which is a part of cdegs package 4. The maximum test gpr divided by the test current yields the impedance of the grounding system. The maximum touch voltage within a mesh of a ground. Computation of the station ground resistance rg and the ground potential rise gpr.
The sensor unit, a selfcontained ruggedized case that is safety. It is clear that the ground potential rise gpr as well as distribution of the earth surface potential esp during the. Oct 26, 2015 awareness of step and touch potential, caused by ground potential rise, is important for anyone working on highvoltage power transmission systems. 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. 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. Fault current distribution between the grounding system and. Its not that ground has no voltage, or sea level has no elevation. Ground potential rise is a concern in the design of electrical substations because the high potential may be a hazard to people or equipment.
The durations and magnitudes of resulting gprs are unique for dl faults and tl faults because the corresponding fault currents are significantly. 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. Design of earth grid for a 3311kv gis substation at a. Ability to analyze the potential rise for each grounding system including neighboring passive grids or rods. Investigation of soil structure in the substation site is the prerequirement to design the substation. Rise of earth potential from substation phase fault. 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. Pdf reduction of ground potential rise of earthing grid for 230.
The groundhound site safety warning system ground potential. Calculationofimportantdesignparametersforgroundingsystemsinsu. The purpose of this paper is provide knowledge about the gpr, substation grounding grid and step and touch potentials. Hello all, i created a ground grid for a multipeaker unit site with soil resistivity in the neibhborhood of 10. 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. Ground potential rise is a frequently misunderstood sitesafety issue in the distribution of power and telecommunications services. Abstractthis paper utilizes cdegs software to calculate the transient ground potential rise gpr in a commercial building, with a base of 39 m. The voltage between a grounding system and remote earth during a ground fault. Safety analysis including surface materials, based on body weight and exposure time. Step and touch potentials, ground potential rise, absolute potential, ieee std. To consider substation expansions, the ground grid is examined using software and, if required, extended to meet the ground potential rise gpr, touch and step potential criteria imposed by the. Step and touch potential voltage earth potential rise. Design and analysis of substation grounding grid with and. 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.
Number of layers, resistivity of each layer and thickness are the parameters to be estimated with the measured site data. 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 grid systems electrical power system analysis software. Hi pryianga, thank you for your question regarding ground potential rise.
Optimization of multilayer earth structure by using. 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. Feb 09, 2014 rise of earth potential from substation phase fault. Introduction the main objectives of a substation grounding system is to. Ground potential rise on the high voltage substation, measurement point no. Ground potential article about ground potential by the free. 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. 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.
Factors affecting ground potential rise and fault currents. There is approximately 7000 meters of 40 copper with some 500 kcmil in the heavy fault 60ka area. Safety criteria calculations for maximum permissible touch and step voltages based on either ieee std. Maximum limit of allowable ground potential rise of.
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