The objective of the test and analysis was to evaluate the plant grounding system with respect to safety. To perform the 62% method test, you position one of the electrodes that comes with the ground resistance tester in a straight line out from the grounding point that. The main purpose is to ensure that these components remain at the same potential, relative to earth or the ground reference. Record the results of the performance testing on the manufacturerprovided test form. A practical guide to earth resistance testing weschler instruments. Test boots or reducing tees may be used to pressure test the outer wall piping. The first is the threepoint grounding system test also referred to as the fall of potential grounding test and the second is the induced frequency test or clampon method of electrical ground test. Because of greater danger to personnel, code authorities frowned on ungrounded.
The boots must be pulled back from the secondary lines, and the reducing tee test port must be unplugged after lines have been tested unless the piping system is designed with a closed interstice and release detection is conducted within the closed interstice. Home technical articles inspection of groundfault protection systems. Earth test and ground resistance testers for electricians. The complete guide to electrical insulation testing. Ic 8767 1978 guide for the construction of drivenrod ground beds. Ground testing in electrical maintenance the what, why.
The fact that a solidlygrounded system will support a large ground fault current is an important characteristic of this type of system grounding and does affect the system design. Statistically, 9095% of all system shortcircuits are ground faults so this is an important topic. Checking ground electrode impedance for commercial. Perform any test where a client or third party require conformance to a. Upon completion of work, inspection and tests shall be made by the contractors representative and witnessed by an owners representative. Both test methods are applicable to groundfault relay systems, but only the highcurrent primary injection method can be used to test a system with integral groundfault trip circuit breakers. Before using this manual, the reader should refer to the chapter entitled ground anchor inspectors manual, in the task force 27 report entitled in situ soil improvement techniques, prepared by the subcommittee on new highway materials of the aashtoagcartba joint committee. Make tests at ground rods before any conductors are connected. Residual pressure with valve in test bar supp y test connection. Smart ground test report springfield energy springfield power. These tests are conducted to test and evaluate the capability of the ground system to meet the operational requirements. System tests and inspections type visible functional comments control unit interface eq. Measurement of lowimpedance grounding systems by power system staged faults 10. Permanent and continuous capacity to conduct fault current low impedance to limit voltage to ground.
One measure of the effectiveness of the system grounding is the ratio of the available groundfault current to the available threephase fault current. A leakage current testchecks that the current that flows between ac source and ground does not exceed a safe limit. Msha technical reports ground resistance testing in. Contractors material and test certificate for aboveground piping. Grounding system theory and practice ced engineering. Principles of electrical grounding john pfeiffer, p. In the real world, however, the ground system does have resistance. A total of 65 pointtopoint ground impedance measurements were performed. These include systems such as ring grounds, counterpoise, substation grounds, and various other multiple interconnected ground systems. This test also applies to moldedcase breakers utilizing anexternal neutral current transformer. What is grounding and why do we ground the system and.
Emergency system described in nfpa 70, article 700 legally required standby described in nfpa 70, article 701 optional standby system described in nfpa 70, article 702, which also meets the performance requirements of article 700 or 701. Apply a current to the ground point of a product or system. These tests are reported in section 5 and in appendix d. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Good low resistance grounding systems increases life safety. Test completed grounding system at each location where a maximum ground resistance level is specified, at service disconnect enclosure grounding terminal at individual ground rods. Bonding bonding ensures electrical continuity of all metallic parts in the circuit, from the service or source to the end utilization equipment. Pdf testing and evaluating grounding systems for substations. There are two methods for testing a grounding system. Top end systems that are tough and easy to use for engineers in the field.
Genuine ground testers are amenable to fielddeveloped standard procedures that have builtin crosschecks that expose insufficient test conditions. All defects shall be corrected and system left in service before contractors personnel finally leave. According to the information technology industry council, grounding is the most important factor in reliable network. This joke among electronic system engineers is worth keeping in mind. This compliance assistance guide for petroleum storage. Inspection of groundfault protection system consider visual and mechanical inspection, electrical tests and checking of tests values. Ground testing 1 protect your people and equipment from transient voltages stabilize system voltages your data centers grounding system is considered one of the most important systems for protecting your people and equipment. Measuring ground resistance with the 62% method ground resistance is a measurement of the conducting connection between a grounding system and earth. Ground resistance testers for ground resistance testing, including the testing of earth electrodes and the measurement of soil resistivity. Contractors material and test certificate for aboveground piping procedure upon completion of work, nspection and tests i be made by the contractors representative and w tnessed by an owners representat ve.
The first is the 3point or fallof potential and the second is the induced frequency test. The objective is that in the event of a fault to ground, sufficient current will flow through the ground path to allow the protective equipment to operate and isolate the circuit. Sample smart ground report lightning protection by. A ground continuity testchecks that a path exists between all exposed conductive metal surfaces and the power system ground. It also provides for a flow of current that will allow detection of an unwanted connection between system conductors and ground a ground fault. Ground faults are very unlikely to occur near the ground under test. Toyota starting systems two different starting systems are used on toyota vehicles. These include things such as problems in tripping tolerance too sensitive or too insensitive, polarity issues, and neutral connections to ground. Each of these tests is described in detail later in this document.
Thank you for purchasing the megger earth ground tester. Grounding systems allow a proper connection from your systems neutral to global earth potential. Understanding the proper field application of this test is vital to obtaining accurate results. Over time, corrosive soils with high moisture content, high salt. Current distribution in extended grounding systems 10. Checking ground electrode impedance for commercial, industrial and residential buildings most facilities have grounded electrical systems, so that in the event of a lightning strike or utility overvoltage, current will find a safe path to earth. Reverse side of card at right is used to record the test data. The wire itself is usually copper or aluminum, which is known to be a good conductor of the electric current that powers your equipment. Pdf this paper presents a method that enables elimination of the influence of metal installations. Hospital isolated power systems class 4800 contents description page general information and application. The following papers are being presented in either only pdf format or both html and pdf. Ic 8835 1980 guide to substation grounding and bonding for mine power systems.
Contractors material and test certificate for aboveground. Test support is provided by developers as designated in the statement of work sow. A solidlygrounded system is very effective at reducing the possibility of linetoground voltage transients. The grounding studies will detect any installation or calibration errors in your grounding system. A ground electrode provides the contact between the electrical system and the earth. All ground beds, even the very largest, have some measurable amount of resistance. The point of reference is the earths conductive surface.
A i defects shall be corrected and system left n service befo e contractors personne final y leave the job. During a singlephase fault, the fault current flows back to the neutral via the grounding system which is ideally as low ohmic as possible. This report describes the ground tests and analysis of the springfield power station. Assured grounding equipment inspection form ardent services, llc assured grounding inspection form form no. Ground check monitors for underground power systems. In an electrical installation, an earthing system uk or grounding system us connects specific parts of that installation with the earths conductive surface for safety and functional purposes. Some of the papers were only available as hardcopy. Test the ground fault protection system using either a simulated or actual controlled ground fault to determine that the system settings are correct and that the system is operating as intended. But sometimes a single rod will not provide sufficient low resistance, and several ground electrodes will be driven and connected in parallel by a cable. Hospital isolated power systems steven engineering. Ground testing faqs transcat test, measurement, and. Measure potential drop across the ground circuit and calculate the circuit resistance. Both systems have two separate electrical circuits. To test soil resistivity, connect the ground tester as shown below.
Metal frame of the building or structure where the following methods are used to make an earth connection. Point to point measurements were taken to determine the status of the plant grounding system. One paper, safety grounding a performance approach was provided only in pdf due to the complex nature of the document. Addressing the testing challenges in large ground systems. System grounding, or the intentional connection of a phase or neutral conductor to earth, is for the purpose of controlling the voltage to earth, or ground, within predictable limits. For effectivelygrounded systems this ratio is usually at least 60% 2. Test any complex ground system where a metallic loop exists. Figure 3typical scale on the megger insulation tester. Install and calibrate the ground wire monitor system in accordance with the manufacturers specifications and instructions in a test circuit that is electrically equivalent to the test circuit shown in figure 1. This can result in a continuity test being performed rather than a ground resistance test. Ground testing in electrical maintenance the what, why and how previous next electrical circuits have a separate ground, or earth, circuit that provides an alternate lowimpedance path for electricity to safely reach the ground, in case of accidental physical contact. Grounding electrode system and grounding electrode conductor part iii znec 250. Lampsleds fuses primary power supply trouble signals disconnect switches groundfault monitoring secondary power type visible functional comments battery condition load voltage discharge test.
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