Step and touch potential voltage earth potential rise. Ground potential rise or earth potential rise as defined in ieee standard 367 is the product of a ground electrode impedance, referenced to remote earth, and the current that flows through that electrode impedance. 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. Ena engineering recommendation erec s34 issue 2 july 2017 page 8 introduction this engineering recommendation erec is the technical supplement to ena ts 4124 2017, providing formulae, guidelines and examples of the calculations necessary to estimate the technical parameters associated with earth potential rise epr.
Methods of analysing epr in cable earthing systems, and several. This paper discusses the maximum ground potential rise gpr of substation grounding systems resulting from shortcircuit ground faults, the potential difference on the insulations of secondary cables and devices, and the relationship between the potential difference on the insulation. Ground potential rise how is ground potential rise. Analytical methods for earth surface potential calculation. This paper discusses the maximum ground potential rise gpr of substation grounding systems resulting from shortcircuit ground faults, the potential difference on the insulations of secondary cables and devices, and the relationship between the potential difference on the insulation of. The difference in surface potential experienced by a person bridging a distance if 1m with the feet without contacting. 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. Rise of earth potential from substation phase fault. This paper presents a construction procedure for a new.
First of all, ground potential rise is very important and very dangerous event. High voltage interfaces for telecommunications entering. Pdf analysis and mitigation of ground grid lightning. The grounding engineer will be required to develop safety systems to protect any personnel working where ground potential rise hazards are.
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. In order to mitigate the risk, horizontal grounding grid. This engineer used a 10ka fault current to simulate the substation earth potential rise and associated voltage contours. Touch potential nchrista electrical op 19 jul 07 19. Imagine lightning striking the center of an open field where cows are standing. Ieee 3672012 ieee recommended practice for determining. The potential difference between the ground potential rise gpr and the surface potential at the point. Analysis of transferred earth potentials in grounding systems core. 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. The current injected into the earth flows radially away from the strike. Presentation outline electric power system grounding 3phase power systems reasons for grounding and bonding substation, transmission, and distribution grounding power faults and lightning strikes fault current distribution ground potential rise gpr touch and step potentials safety 2 d ng. 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.
Grounding design calculations part fifteen electrical. Pdf reduction of ground potential rise of earthing grid for 230. Lightninga major source of ground potential rise there is a 50% probability that a lightning strike will be approximately 30ka. Maximum limit of allowable ground potential rise of. Perle launches industrial iec 618503 and hazloc media converters. 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 impedance. The potential relative to a distant point on the earth is highest at the point where current enters the. Ideally, the ground conductor would have no resistance, yielding no voltage drop across it, keeping the connection point between the circuits at a constant ground potential. A second auxiliary test probe, s, is driven into the ground between e and h to measure electrical potential voltage. The system consists of a sensor unit and a handheld unit communicating via wireless protocol. The difference between the ground potential rise and the surface potential at the point where the person is standing while at the same time having a hand in contact with a grounded structure.
The circuit diagram illustrates a simple ground loop. Ground potential rise, step and touch voltages during lightning. Step and touch voltages and grounding potential rise ieee. Ground potential rise influence near hv substations in. Ground potential rise gpr, grounding, resistivity, step.
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. The safe parameters of grounding systems should include touch voltage, step voltage and. Ultimate fault level the highest fault level expected in the future after all planned network augmentations have taken place. What is step and touch potential and reducing resistance.
Ground potential rise gpr is a concern in the design of substation grounding grid. 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. This paper will present ground potential rise gpr causes, effects, variations in the values gpr in high voltage substations. Ground impedance of a grounding system earth potential gradients to estimate step and touch voltages earth resistance data provides a quick estimate of the potential rise of the ground electrode at the time of a fault ground grids are designed to limit the surface voltage gradient. Ground potential rise gpr and zone of influence high. Engineering recommendation erec s34 issue 2 2017 a. Pdf the analysis and mitigation of earth potential rise in the. This voltage varies along the path between e and h.
Earth potential rise events are a concern wherever electrical currents of large magnitude flow into the earth. Ground potential rise influence near hv substations in urban areas l grcev, v filiposki, v arnautovski st. The maximum touch voltage within a mesh of a ground grid. 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. Probably the most commonly noted ground potential rise or earth potential rise event involves the death of cows in a field during a lightning strike.
Keywords ground potential rise, safety criteria, step voltage, touch 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. This will make the touch voltage higher due to the steepness of gpr, which increases the risk of hazard. The difference between neutral and ground on the electric panel duration. Design of earthing grounding system in a substation grid. Ground potential rise influence near hv substations in urban areas. 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. Earth potential rise earth potential rise epr is caused by electrical faults that occur at electrical substations, power plants, or highvoltage transmission lines. Gpr studies use a series of calculations to determine step and touch voltages in accordance with specific standards. A committee ground water estimation committee was constituted in 1982 to improve the existing methodologies for estimation of the ground water resource potential.
The multifunction groundhound site safety warning system is an instrumentation system designed for the protection of linemen on a work site. This chapter contains safety criteria according to ieee standards, step and touch voltage criteria, reduction factor, simplified equations for mesh and step. Hello all, i created a ground grid for a multipeaker unit site with soil resistivity in the neibhborhood of 10. Ground potential rise of multigrounded neutral and shield. For access to this article, please select a purchase option. This can be at a substation, highvoltage tower or pole, or a large transformer. Touch potential the potential difference between the ground potential rise and the surface potential at the point where a person is standing while at the same time having a hand in contact with an earthed structure. Awareness of step and touch potential, caused by ground potential rise, is important for anyone working on highvoltage power transmission systems. 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.
Special electrical protection lightningprotectioninstitute. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Keywords ground potential rise, safety criteria, step. The ground potential rise gpr in high voltage substations in case of ground faults may cause dangerous voltages between telecommunication installations. This voltage, gpr, is equal to the maximum grid current times the grid resistance. Ieee std 812012 guide for measuring earth resistivity, ground impedance, and earth surface potentials of a ground system ieee std 3672012 recommended practice for determining the electric power substation ground potential rise and induced voltage from a power fault. As the lightning rods of the large substation are in multipoint connection with the grounding grid through the frame, the distribution of ground potential along the. 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. Substation grounding systems should guarantee the safety of equipment and human beings.
Step and touch voltages and grounding potential rise ieee and iec. The purpose of this paper is provide knowledge about the gpr, substation grounding grid and step and touch potentials. During a power line fault, a phase wire shorts to ground or another phase wire, which can cause a. In cases where an earth potential rise event may be of special concern, earthing precautions are required to ensure personnel and equipment safety. If the selfinductance of the earth is estimated very conservatively at. Using cdegs software, a 500kv substation grounding grid and its framework model are developed for the transient analysis of ground potential rise gpr, touch voltage and the step voltage when. Pdf ground potential rise gpr is the most important factor for the safety of substation earthing system. Step and touch potential resulting from ground potential rise gpr is well understood as a safety hazard in many situations involving energized power sources. There is approximately 7000 meters of 40 copper with some 500 kcmil in the heavy fault 60ka area. Federal law mandates that all known hazards must be eliminated from the work place for the safety of workers. Line to ground fault creates ground potential rise at a substation.
What is not as well understood is that gpr and the associated step and touch potential can arise from deenergized lines due to electromagnetic coupling from parallel live lines. 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. Scalar potential at the earth surface as well as step and touch voltage distributions were computed based on field theory approach. Ground potential rise gpr caused by lightning strike is a potential hazard for electrical equipment inside an oil and gas refinery plant. Earth potential rise in the underground power distribution. Case study of ground potential rise on two neighboring substations. The durations and magnitudes of resulting gprs are unique for dl faults and tl faults because the corresponding fault currents are significantly. Pdf this paper discusses earth potential rise epr in underground cable systems. It was recommended that the ground water recharge should be estimated based on ground water level fluctuation method.
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