These tests are reported in section 5 and in appendix d. Ground faults are very unlikely to occur near the ground under test. 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. Upon completion of work, inspection and tests shall be made by the contractors representative and witnessed by an owners representative. The main purpose is to ensure that these components remain at the same potential, relative to earth or the ground reference. Metal frame of the building or structure where the following methods are used to make an earth connection. These include systems such as ring grounds, counterpoise, substation grounds, and various other multiple interconnected ground systems. Pdf this paper presents a method that enables elimination of the influence of metal installations. A i defects shall be corrected and system left n service befo e contractors personne final y leave the job.
Assured grounding equipment inspection form ardent services, llc assured grounding inspection form form no. Smart ground test report springfield energy springfield power. These include things such as problems in tripping tolerance too sensitive or too insensitive, polarity issues, and neutral connections to ground. A practical guide to earth resistance testing weschler instruments. Test boots or reducing tees may be used to pressure test the outer wall piping. One paper, safety grounding a performance approach was provided only in pdf due to the complex nature of the document. These tests are conducted to test and evaluate the capability of the ground system to meet the operational requirements. Perform any test where a client or third party require conformance to a. This report describes the ground tests and analysis of the springfield power station. 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. 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. Top end systems that are tough and easy to use for engineers in the field.
Msha technical reports ground resistance testing in. The grounding studies will detect any installation or calibration errors in your grounding system. System tests and inspections type visible functional comments control unit interface eq. 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. This joke among electronic system engineers is worth keeping in mind. For effectivelygrounded systems this ratio is usually at least 60% 2. Measure potential drop across the ground circuit and calculate the circuit resistance. Both systems have two separate electrical circuits. Addressing the testing challenges in large ground systems. Understanding the proper field application of this test is vital to obtaining accurate results. 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. This test also applies to moldedcase breakers utilizing anexternal neutral current transformer. Ground testing faqs transcat test, measurement, and. A leakage current testchecks that the current that flows between ac source and ground does not exceed a safe limit.
Over time, corrosive soils with high moisture content, high salt. Inspection of groundfault protection system consider visual and mechanical inspection, electrical tests and checking of tests values. Pdf testing and evaluating grounding systems for substations. Home technical articles inspection of groundfault protection systems. The following papers are being presented in either only pdf format or both html and pdf.
The objective of the test and analysis was to evaluate the plant grounding system with respect to safety. According to the information technology industry council, grounding is the most important factor in reliable network. Make tests at ground rods before any conductors are connected. Statistically, 9095% of all system shortcircuits are ground faults so this is an important topic. Contractors material and test certificate for aboveground piping. Lampsleds fuses primary power supply trouble signals disconnect switches groundfault monitoring secondary power type visible functional comments battery condition load voltage discharge test. Bonding bonding ensures electrical continuity of all metallic parts in the circuit, from the service or source to the end utilization equipment. 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. The first is the 3point or fallof potential and the second is the induced frequency test. Permanent and continuous capacity to conduct fault current low impedance to limit voltage to ground.
Ground testing in electrical maintenance the what, why. One measure of the effectiveness of the system grounding is the ratio of the available groundfault current to the available threephase fault current. Because of greater danger to personnel, code authorities frowned on ungrounded. This compliance assistance guide for petroleum storage. Record the results of the performance testing on the manufacturerprovided test form.
Checking ground electrode impedance for commercial. 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. A total of 65 pointtopoint ground impedance measurements were performed. Apply a current to the ground point of a product or system.
Earth test and ground resistance testers for electricians. Sample smart ground report lightning protection by. Measuring ground resistance with the 62% method ground resistance is a measurement of the conducting connection between a grounding system and earth. All defects shall be corrected and system left in service before contractors personnel finally leave. Each of these tests is described in detail later in this document. Figure 4typical record of insulation resistance of a mill motor. In the real world, however, the ground system does have resistance. There are two methods for testing a grounding system. All ground beds, even the very largest, have some measurable amount of resistance. Thank you for purchasing the megger earth ground tester. Hospital isolated power systems steven engineering. Test any complex ground system where a metallic loop exists. A ground continuity testchecks that a path exists between all exposed conductive metal surfaces and the power system ground. A ground electrode provides the contact between the electrical system and the earth.
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. 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. Current distribution in extended grounding systems 10. 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. The point of reference is the earths conductive surface. This can result in a continuity test being performed rather than a ground resistance test. 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. Toyota starting systems two different starting systems are used on toyota vehicles. 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. 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.
The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. 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. Good low resistance grounding systems increases life safety. Test support is provided by developers as designated in the statement of work sow. Reverse side of card at right is used to record the test data. To test soil resistivity, connect the ground tester as shown below. Measurement of lowimpedance grounding systems by power system staged faults 10. 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.
Figure 3typical scale on the megger insulation tester. Principles of electrical grounding john pfeiffer, p. Grounding systems allow a proper connection from your systems neutral to global earth potential. During a singlephase fault, the fault current flows back to the neutral via the grounding system which is ideally as low ohmic as possible.
The complete guide to electrical insulation testing. Genuine ground testers are amenable to fielddeveloped standard procedures that have builtin crosschecks that expose insufficient test conditions. It also provides for a flow of current that will allow detection of an unwanted connection between system conductors and ground a ground fault. 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. Residual pressure with valve in test bar supp y test connection. The induced frequency test can test grounding systems that are in use and does not require the interruption. The wire itself is usually copper or aluminum, which is known to be a good conductor of the electric current that powers your equipment. Ic 8835 1980 guide to substation grounding and bonding for mine power systems. Hospital isolated power systems class 4800 contents description page general information and application. 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. A solidlygrounded system is very effective at reducing the possibility of linetoground voltage transients. Some of the papers were only available as hardcopy. 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. Grounding electrode system and grounding electrode conductor part iii znec 250.
The voltage and current on the other two phases are not affected. Ic 8767 1978 guide for the construction of drivenrod ground beds. Grounding system theory and practice ced engineering. 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. However, to do this the system must be effectively grounded.
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