The lower the earth resistance, the smaller the voltage funnels. Built to withstand an entire spectrum of ground testing methods, flukes family of earth ground testers have been designed to be accurate, safe and easy to use. The standard used as a reference for fallofpotential testing is ieee standard 81. Voltage drop testing is important because high resistance can prevent proper circuit operation. 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. The most commonly used method of measuring the earth resistance of an earth electrode is the 3point measuring technique shown in figure 1. Earth electrode resistance the resistance of an earth electrode to earth. The earth termination system should be tested as a whole and individual earth electrodes where practical should be tested in isolation i. An approximate value of earth resistance can be obtained by the two wire system which utilizes existing earthed equipment as shown in fig. Gp2 ground resistance and resistivitytester data sheet.
Earth electrode conductive part, which may be embedded in the soil or in a specific conductive medium, e. This test requires a 3point ground resistance tester such as aemcs 4620 or 4630 ground resistance tester. Earth resistance is measured in two ways for two important fields of use. Measuring resistance of g r ound electrodes 62% method the 62% method has been adopted after graphical consideration and after actual test. Earth resistance measurements on installations with a single earth electrode it is important to point out that the earth resistance measurement of reference is the 2stake method. Ieee recommended guide for measuring ground resistance and.
It is the purpose of this guide to describe and discuss the present state of the technique of measuring ground resistance and impedance, earth resistivity, and potential gradients resulting from currents in the earth and the prediction of the magnitudes of ground resistance and potential gradients from scale model tests. The principles and methods of earth resistance testing covered in this section apply to lightning arrester installations as well as to other systems that require low resistance ground connections. These testers are the key tools in ground electrode tests, which are mandatory every three years, according to the international electrical testing association. Earth test and ground resistance testers for electricians ensuring an effective earth system is essential in a telecommunications system, and megger is expert in earth testing having been there right from the start. For ground resistance testing, the 1621 kit is the first line of defense in detecting reliable ground connections. Earth tester working principle construction the earth megger is essentially a direct reading ohmmeter and it has a hand driven generator which supplies the testing current. The simplest and somewhat misleading idea of a good ground for an electrical system is a section of iron pipe driven into the earth with a wire conductor connected from the pipe to the electrical circuit figure 1 a practical guide to earth resistance testing megger on photo. These days, megger offers topend systems for design and soil surveys as well as tough, easytouse testers for field engineers. The resistance offered by the earth electrode to the flow of current into the ground is known as the earth resistance or resistance to earth. This method is generally not suited to large earthing installations, as the stake separations needed to ensure an accurate measurement can be excessive, requiring the use of very long test leads refer to table 1. Megger det4t2 series 4terminal earth resistance and soil. Browse our top selling 16232 geo earth ground resistance meter, 16252 geo earth ground tester and the 1630 ground resistance meter today. Principles and testing methods of earth ground resistance. A the resistance of the metal and that of the connection to it.
Soil resistivity influences the plan of an earthing system absolutely and is the major factor that decides the resistance to earth of a grounding system. Earth and ground resistance testers for highvoltage. Fourterminal earth ground resistance and soil resistivity. The test probe is a tool to use measurement of earth resistance. Mar 01, 2020 earth resistance is the resistance of the ground electrode that is being measured, not that of the test probe. Mutual earth resistance mer and inductance can also significantly affect results if not considered effectively. Measuring earth resistance with fall of potential method photo credit. And that the ground electrode is in firm contact with the earth. Practical test methods and techniques are presented for measuring the electrical characteristics of grounding systems. Earth resistance measurements with 4, 3 and 2 wires earth.
The electrode b is moved from position b 1 and b 2 respectively so that the resistance area do not overlap. Discover our offering of earth ground resistance testers to help prevent electric shocks in your facility. Methods of earth resistance testing part2 electrical. Pdf analysis of methods for measuring earth resistance and soil. Seasonal variation of earth resistance with an electrode of 34inch pipe in rather stony clay soil. Earth resistance measurement earth resistance measurement with 4, 3 and 2 wires and six ranges covering measurements from 0. For these reasons, threepoint testing is usually only recommended for very simple, isolated earth grids. Bureau of standards now nist developed the theory behind this test in 1915 see reference pg. The earth resistivity test ert of soil was carried out at site for studies work for andhrapradesh medtech zone amtz, vishakhapatnam, andhrapradesh.
Kc series test leads ground resistance testing covers the testing of earth electrodes and the measurement of soil resistivity. The earth resistivity test ert of soil was carried out at site for studies work for. Measurement of earth resistance by potential fall method. The most common methods of measuring the resistance of an. The objective of the test and analysis was to evaluate the plant grounding system with respect to safety. Resistance to earth tests for plumbers and heating engineers. The unit features basic ground testing methods including 3pole fallofpotential as well as 2pole ground resistance tests. Normally, the voltage drop on the power feed side and ground side wires, connectors, and connections should not exceed 0. The principles and methods of earth resistance testing covered in this section. Ok lamp lights up when the instrument is ready for. If connected at the test set, say with a jumper, the resistance of the wire from the test set to the earth electrode adds to the reading. The resistance area of the earth electrode is the area of the soil around which a voltage gradient is measured with a commercial instrument. When determining the earth resistance, the voltage drop is measured which has been generated by a known and constant current applied to the earth resistance to be measured.
Ground resistance depends on grounding electrode selection, soil resistivity, soil contact, and other factors. If the current and potential probes both are far enough away from the electrode, that is, outside the influence of the electrode, the reading corresponds to the resistance of the. Ieee guide for measuring earth resistivity, ground impedance. The earth electrode under test should be isolated from the circuit it is protecting before testing commences. The goal in ground resistance is to achieve the lowest ground resistance value possible that makes sense economically and physically. The information given uses simple language for easy understanding by the users and it is intended to be an educational tool. Nov 10, 2017 practical earth resistance testing of electrode earth pit. Det4td2, det4tr2, det4tc2 and det4tcr2 4terminal ground resistance and soil resistivity testers. Pdf soil resistivity and ground resistance for dry and.
The resistance of the surrounding body of earth the ground electrode is surrounded by earth which conceptually is made up of concentric shells all having the same thickness. Determining effectiveness of ground grids and connections that are used with. Figure 11 measurement of earth electrode resistance 34 figure 12 earth resistance curves 35 figure measurement of earth resistivity 36 figure 14 single low voltage standby generator without paralleling facility 39 figure 15 low voltage standby generators with neutrals connected 40 figure 16 low voltage standby. An earth electrode and earth electrode resistance are defined in bs 7671 as. The 2 ma measurement current allows floor resistivity to be tested. Numerically, it is equal to the ratio of the potential of the earth electrode to the current dissipated by it. Earth resistance tests in order to determine the d. Substation earth system injection testing swp page 3 of 14 standard work practice sp0510 ver 4 ergon energy corporation limited abn 50 087 646 062 sun protection to be used when working outdoors. Topics addressed include safety considerations, measuring earth resistivity, measuring the power system frequency resistance or impedance of the ground system to remote earth, measuring the transient or surge impedance of the ground system to remote earth, measuring step. Ieee guide for measuring earth resistivity, ground. The resistance of the earth can be measured with the help of megger earth tester or earth megger.
If this is not possible, art may be used to measure electrode resistance. The resistance indicated by the test set is the resistance between the earth electrode and the potential probe. Earth test and ground resistance testers for electricians. High voltage substation earth grid impedance testing. Megger offers top end systems for design and soil surveys as well as tough easy to use testers for field engineers. High voltage substation earth grid impedance testing dean sharafi ulrich klapper western power australia omicron electronics austria introduction the purpose of this paper is to report a new test method and make a recommendation to improve the procedures according to the findings. Fluke 1625 geo earth ground tester manual pdf instrumart. Some of the most important features of the the t3v are. Measurement of earth resistance the measurement of earth resistance is made by the potential fall method. Resistance of the earth termination system, earth resistance tests are conducted.
When measuring the resistance of earth electrode systems, c1 and p1 are connected together either at the test set or at the electrode. With the wenner fourpole equalmethod, the soil resistivity is measured at. B the contact resistance of the surrounding earth to the electrode. Auxiliary earth resistance and lead wire connection can be selfchecked by pressing batt. Getting down to earth 5 4 getting down to earth safety there is an inherent safety problem in earth resistance testing that requires care and planning by the user of the test set. Earth resistance test october 31, 20 tom bunworth latest news last time we did the physical check, this time we will look at the earth resistance test, which must be done under the standard asnzs37602010, it sounds complicated but it is dead easy and anyone can do it, you only need to know how and have the right portable appliance tester. Simplified earth resistance measurement method this method is recommended where an earth resistance higher than 10 ohms is measured or where it is not possible to drive auxiliary earth bars. Earth ground testers digital earth resistance testers. Such tests are made in powergenerating stations, electricaldistribution systems, industrial plants, and telecommunication systems. Microprocessor controlled universal earth resistance meter with fully auto mated measuring frequency selection process as well as automatic testing of probe and. Leon markwell, senior engineer at the iet, discusses the inspection and testing of earth electrodes. Guide for measuring earth resistivity, ground impedance, and earth surface potentials of a grounding system. Thus before designing and installing a new grounding system, the determined location should be tested to find out the soils resistivity.
To measure grounding accurately with this method, it is. If the test setup has adequate spacing, the probes will be far enough away outside of the electrical field of the test ground so that watering them has no influence on. The simplest and somewhat misleading idea of a good ground for an electrical system is a section of iron pipe driven into the earth with a wire. Influence on measurement accuracy the instrument amprobe earth test offers the option to set a maximum. Earth tester working principle your electrical guide. The most common method of earth ground resistance measurement is the fall of potential method. One of the basic prerequisites for guaranteeing safety on any residential or industrial electrical is to provide an earth. Topics addressed include safety considerations, measuring earth resistivity, measuring the power system frequency resistance or impedance of the ground system to remote earth, measuring the transient or surge impedance of the ground system to remote earth, measuring.
The threepoint method is the most thorough and reliable test method. This method is referenced in all the electrical installation testing standards and can be used to measure the earth resistance both accurately and safely. The earth resistance mainly implies the resistance between the electrode and the point of zero potential. Ensuring an effective earth system is essential in a telecommunications system, and megger is expert in earth testing having been there right from the start. Circuits with high current draw cannot tolerate high resistance. Insulation resistance test includes line and neutral together to earth and between live conductors duration.
It is essential that the probe be placed outside the sphere of influence of the ground electrode under test and the auxiliary earth to achieve the highest degree of accuracy when performing a 3pole ground resistance test or the effective areas of resistance will overlap and invalidate any measurements. This method is derived from the 4point method which is used for soil resistivity measurements the 3point method, called the fall of potential method, comprises the earth electrode to be measured and two other electrically independent test. Dec 30, 2016 simple earth pit resistance test how to test it duration. If the resistance values determined are of approximately the same in all three cases, the mean of the three readings can be taken as the earth. Earth ground testers digital earth resistance testers fluke. Pdf on sep 1, 2018, szczysny artur and others published analysis of methods for measuring earth resistance and soil resistivity find, read.
Earthground measurement guide chauvin arnoux metrix. Earth electrodes part 2 installing, loop impedance testing duration. The resistance of the electrode has the following components. Earth ground resistance testers electrical power testing. Earth resistance measurements with 4, 3 and 2 wires. A practical guide to earth resistance testing weschler instruments. Earth resistance value can be read directly from the scale. May 02, 2019 this practical guide to earth ground resistance testing contains procedures commonly practiced by electrical contractors, electricians and maintenance workers of power utilities. It is well known that the resistance of an earth electrode is heavily influenced. This test uses a modern clampon meter to test the impedance of a circuit through available earth.
Sample smart ground report lightning protection by. Three point test fall of potential measures earth ground resistance as required by equipment manufacturer specifications and as mandated by national code requirements for proper grounding two point test is used to test grounding wires resistance and resistance of connection points between ground system elements i. The fluke 1621 kit is an easytouse earth ground tester. Executive summary this report describes the ground tests and analysis of the springfield power station.
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