In electricity supply systems, an earthing grounding system defines the electrical potential of the conductors relative to that of the earths conductive surface. All of the following 7 electrodes that are present at a building shall be bonded together to form the entire grounding system. Distribution voltages are typically medium voltage, between 2. To connect the metallic conductive parts of an electric appliance or installations to. It also provides for a flow of current that will allow detection of an unwanted connection between system conductors and ground a ground fault. It has its roots in electrical systems of nearly a century ago. Its is a short, instructional video about electrical grounding, aimed at nabcep pv entry level students and technicians.
The equipment grounding system is the network of bare, uninsulated wires that runs through the home as part of residential branch circuit wiring installed since the 1960s. Electrical grounding or grounding originally began as a safety measure used to help prevent people from accidentally coming in contact with electrical hazards. This is a discussion of the basic principles behind grounding systems and how grounding is related to safety and the effective operation of circuit protection devices such as fuses and circuit breakers. Nec and the uks bs 7671 list systems that are required to be grounded. National fire protection association nfpa requires pipes. If your static grounding bonding system is bonded to the electrical service grounding electrode, by the nature of the code the lightning protection system and static grounding system will be one as electricity including lightning takes all paths to ground. Equipment grounding systems connect to the transformer on the street and protect homeowners against electrical shock from stray electricity in the home. The point of reference is the earths conductive surface. Article 250 grounding and bonding mike holt enterprises. A low voltage system usually 12 volts, but on large vessels can be 24, or 48 volts, to power basic equipment, using batteries. A fundamental aspect of electrical engineering, electrical grounding is the manner in which an electrical circuit is attached to the earth or the ground. The geography of the site is considered since the soil resistivity could alter the impedance of the grounding system. In an electrical installation, an earthing system uk or grounding system us connects specific. To prevent accumulation of static electricity in conductive equipment, the total resistance of the path to earth grounding path should be minimal to dissipate charges that are otherwise likely to be present.
Grounding metal parts helps drain off static electricity charges before flashover potential is reached. By using the earth as a conductor of electricity, grounding ensures that metal devices, other conducting substances or, more importantly, people, do not become the path for current to escape. Grounding system theory and practice ced engineering. The choice of earthing system has implications for the safety and electromagnetic compatibility of the power supply. Earthing is to be done with two separate connections. The function and importance of earth grounding systems part.
Solid grounding reduces overvoltages but has high groundfault currents. First, the system voltage with respect to ground is fixed by the phasetoneutral winding voltage. The substation site must be reasonably central to the distribution area to be served. When referring to grounding systems, the third definition applies. Here the focus is on classification of grounding systems with respect to the operating voltage of the system.
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. May 30, 2018 this is a brief walk through of a simple grounding and bonding system, and what happens with the flow of current in normal operation, and in a ground fault condition. At the end of the day, the type of grounding you use for your system will depend on which type of grounding best suits your needs and budget. Jun 19, 2016 this is a preliminary, rough cut, of a onetake training video. To connect the metallic conductive parts of an electric appliance or installations to the earth ground is called earthing or grounding. Static electricity is an accumulation of electric charge on an insulated body. The soil resistivity data at tls is collected and a new grounding system of low impedance 0.
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 is a preliminary, rough cut, of a onetake training video. The system grounding arrangement is determined by the grounding of the power source. Electrical grounding and bonding educational pdf document. What is grounding and why do we ground the system and. Dc is a two wire system, positive red and negative black or yellow, but there can be a third wire, a green grounding wire or a. In spite of their crucial role in safe, reliable, and economic operation of power supply systems, grounding systems do not receive the same level.
The national electrical code nec defines system ground as a connection to ground from one of the currentcarrying conductors of an electrical power system or. Design of earthing grounding system in a substation grid. How important is grounding on utility distribution systems. Ufc 357501 lightning and static electricity protection. However, many companies and industrial plants have used system grounding methods differently. When properly connected by grounding or bonding wires. Static electricity and grounding for dust collection. System earthing pdf, industrial electrical engineering and automation, lund university. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Classification of grounding systems fig 6 could be evasive.
A grounding electrode conductor gec is used to connect the system grounded neutral conductor, or the equipment to a grounding electrode, or a point on the grounding electrode system. This is a discussion of the basic principles behind grounding systems and how grounding is. System grounding has been used since electrical power systems began. Static protection through bonding and grounding iaei magazine. Studies show that good grounding, arbitrarily taken to be 25 ohms, rarely adds to good system performance. As stated earlier, earthing provides a simple path for the leakage current i. How the electric utility industry generates and delivers power to its customers covering basics, delivery, safety and generation. A utility service the system grounding is usually determined by the secondary winding configuration of the upstream utility substation transformer. Charged substances cause various problems such as the destruction of devices by electrical discharge, dust adhesion, and the like. Because parts of the power system, such as equipment frames, are. Grounding electrode system and grounding electrode conductor part iii znec 250. Grounding is a principle of electricity that sometimes puzzles homeowners. This ufc supersedes milhdbk 10046, lightning protection, and army tm 581 air force afm 889 chapter 3, electrical design, lightning and static electricity protection.
Principles of electrical grounding pfeiffer engineering. Drum containers with oilbased products in a storage room with a static grounding and bonding system employed at that location. Definitions and guidelines conference paper pdf available june 2015 with 1,812 reads. All electrical earth wells in a specific residential, commercial and industrial installation should essentially be interconnected to plant earthing systems form the main. The increased use of electrical and electronic equipment aboard naval ships introduces risk of electromagnetic interference emi problems to ship operation and performance. The fulllength brass flame arrester minimizes splashing, friction, and the buildup of static in the fluid.
Usually, that difference is measured relative to the earth, which is where the term grounding comes from. Simply put, grounding is the way that parts of an electrical circuit or system are connected to the earth. Electrical earthing, grounding, methods of earthing, types of earthing, components of earthing and its specifications in respect to electrical earthing for electrical installations. Even though it has very little application in modern electrical systems, the term persists, and continues to baffle and confuse.
Grounding conductors are sized according to the equation a kivs, where a is the cable size, commonly in circular mils, k is the connector factor, i is the maximum fault current and s is the maximum fault time, in seconds. The earth is so comparatively large, any excess current traveling through a circuit is absorbed by dirt, water, rocks, and everything else that comprises it. Ic 8835 1980 guide to substation grounding and bonding for mine power systems. The proper bonding and grounding of the system is often enough to control this static buildup. Hence, smc has a lineup of products to which conductive resin and rubber are applied in order to remove static electricity.
Grounding includes any grounding conductors, grounding electrodes, and the connections used to securely fasten these parts together. The code does require bonding and grounding as discussed above, however, when diesel fuel is pumped into a container that has previously held a higher grade product. Pdf grounding systems for power supply facilities researchgate. Ufc 357501 lightning and static electricity protection systems. Pdf this study aims to define some recommendations for choice of grounding system type for power supply facility. However, if rapid flow rates are used to transfer the liquid into a storage tank or container, high electrical potentials can occur on the surface of the liquid in the tank.
The function and importance of earth grounding systems. In order to minimize to acceptable values of the currents through the human body, to ensure electrical safety for people working within or near the installation, and also to limit any eventual electrical interference with thirdparty equipment, ais must be provided with an earthing or grounding system, to which all metallic nonlive parts of the installation must be connected, such as. Steel framing members of the building and metal siding that are electrically bonded together and not used for lightning protection. What is grounding and why do we ground the system and equipment. A grounding system protects electrical systems from the effects of faults and failures by channeling the excess current into the earth where it is safely dispersed. In essence, the grounding system in a residential wiring system serves a backup pathway that provides an alternate route for electrical current to follow back to ground in the case of a problem in the wiring system. C transformer the system grounding on the system fed by the transformer is determined by the transformer secondary winding configuration. Grounding grounding is one of the most abused and misunderstood electrical system terms in use today. Ic 8767 1978 guide for the construction of drivenrod ground beds. Grounding system theory and practice cedengineering. To manage static electricity when dispensing flammable liquids into plastic drums, use justrites large steel drum funnel with a 32inch flame arrester. The connection made with the earth is vital, for it uses the ground as a conductor. Static electricity requires grounding a dust collection system which is why air handling systems provides galvanized metal spiral pipe and fittings and flexible hose with wire helix. Distribution substations michigan technological university.
Principles of electrical grounding john pfeiffer, p. As systems are added, they all contribute and could become susceptible to an intense electromagnetic environment eme. Jul 06, 2016 resistance grounding offers the advantages of ungrounded systems without the risk of large overvoltages. Electrical grounding electrode system grounding theory parameters, measurements and calculations electrical grounding and corrosion installation and protection sizing the grounding electrode conductor general requirements for. Although electrical grounding involves knowledge of circuitry, its basic definition is just what its name implies. Electrical earthing grounding systems a technical report and a short course technical report pdf available february 2018 with 15,508 reads how we measure reads. Anything over 50 volts, ac or dc, is considered high voltage. The electrical earthing is carried out by connecting the noncurrentcarrying part of the equipment or the neutral part of the supply system to the ground. Put simply, conductor size depends on magnitude and duration of fault current and on the type of connections used in the. The input for a distribution substation is typically at least two transmission or subtransmission lines. This is called system grounding and most electrical systems are required to be grounded. Electrical power and grounding systems study and improvement at. Download fulltext pdf download fulltext pdf download fulltext pdf the global grounding system.
Distribution substation a distribution substation transfers power from the transmission system to the distribution system of an area. Understanding electrical grounding and how it works. Grounding must be taking into account to protect passersby during a shortcircuit in the transmission system 7. Shipboard electrical grounding the electricity forum. Shipboard electrical grounding training electricity forum.
Justrites guide to safe grounding and bonding practices. Grounding of industrial and commercial power systems green book 4. A plastic or pvc pipe system cannot be adequately grounded. The problem of whether a system neutral should be grounded, and how it should be grounded, has many times been misunderstood completely. Three different types of grounding jmk engineering inc. This course provides insight into the workings of the grounding system from the end user back to the substation. Although good grounding is important when considering the effectiveness of shield wire protection, its far less important for determining fault levels and arrester protection. Attendees learn the causes of high ground currents, how they can be minimized, and the techniques to mitigating stray voltage. Oct 26, 2018 the electrical earthing is carried out by connecting the noncurrentcarrying part of the equipment or the neutral part of the supply system to the ground. Static grounding is often used in areas where the discharge arcing of the voltage buildup static can cause dangerous or undesirable conditions 500. In india as per central electricity authority regulations, cear, 2010, rule 41, there is provision of earthing, neutral wire of a 3phase, 4wire system and the additional third wire of a 2 phase, 3wire system. It is a metal box standing on rubber feet with electricity running in and out of it.
Metal frame of the building or structure where the following methods are used to make an earth connection. Pdf electrical earthing grounding systems a technical. It also provides for a flow of current that will allow detection of an unwanted connection between. Grounding systems are a crucially important component of any power supply system, because they directly impact public and employee safety, supply system reliability, power quality and life expectancy of power equipment. For commercial and industrial systems, the types of power sources generally fall into four broad categories. This is a brief walk through of a simple grounding and bonding system, and what happens with the flow of current in normal operation, and in a ground fault condition. Bond other interior grounding system conductors separately to static electricity bonding jumpers or other bonded metals, and connect at or below finished grade to an appropriate grounding electrode or grounding system.
951 185 1408 1454 886 1676 664 1094 1196 65 843 110 1617 735 566 1004 225 1314 130 832 734 547 1471 1290 59 124 223 1418 1335 110