First, it provides a means of dissipating electric current into the earth without exceeding the operating limits of the equipment. In many wind farms the substation transformer provides. Design of grounding system for an electrical substation. Td703 revision 6 temporary protective grounds for td.
Design and analysis of substation grounding grid with and. Large multiturbine wind farms provide an example of the use of grounding transformers for fault protection on ungrounded lines. P80 guide for safety in ac substation grounding this guide is primarily concerned with outdoor ac substations, either airinsulated or gasinsulated. Two day national conference rteece2014 17th,18th january 2014 88 optimized design of substation grounding system. These include distribution, transmission, and generating plant substations. This is a discussion of the basic principles behind grounding systems and how grounding is related to safety and the effective operation of circuit. The computation program modules resap, malt and fcdist are used for this study. Review of substation grounding practices, safety and. Some of the papers were only available as hardcopy. Features septemberoctober 2002 utility and power stations david young. Optimal design of substation grounding grid based on.
Pdf considerations about substation grounding system design. Pdf grounding system design in electrical substation. Over the years grounding design terms and definitionsprocedures have been developed as well as appropriate standards, most notable. Pdf ieee guide for safety in ac substation grounding. One paper, safety grounding a performance approach was provided only in pdf. The substation grounding system is an essential part of the every electrical system. Review of substation grounding practices, safety and constructability enhancements authors. Abstract the main purpose of this paper is to acquaint the reader with various types of grounding. Model circulating currents within the substation grounding grid and account for the voltage drop in grid conductors through which. Principles of electrical grounding john pfeiffer, p. Ieee guide for safety in ac substation grounding the institute of electrical and electronic engineers ieee std 80 ieee guide for measuring earth resistivity, ground impedance, and earth surface. D substation standards lighting fixture pole and bracket mounting 19. One paper, safety grounding a performance approach was provided only in pdf due to the complex nature of the document.
The proper grounding of a substation is essential and very important for the following two reasons. Power systems analysis and design br gupta power systems earthing. The design is based on the measured soil resistivity of the substation site and proposed methodology is found to be safe for operation. 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. Where specific grounding connection points are not available, grounding. The ground grid consists of horizontal interconnected bare conductors mat and ground rods. The substation earthing system comprises of a grid earth mat formed by a horizontal buried conductors. Distribution substations michigan technological university.
Before the design of the grounding system begins, soil resistivity measurements need to be taken at the substation. The grounding system in substation is very important. Substation steel structures, that have not been retrofitted, can be upgraded using commercially available threaded stud grounding sockets. Ensure safety to personnel in substations against electrical shocks. The grounding system includes all of the interconnected grounding facilities in the substation area, including the ground grid, overhead ground wires, neutral conductors, underground cables, foundations, deep well, etc. Guidelines to properly designed substation grounding system. Besides changing the voltage, the job of the distribution substation is to isolate faults in either the transmission or distribution systems. Review substation grounding practices with special reference to safety, and develop safety criteria for design. The use of a swage ground connection improves field safety, facilitates a better quality installation, improves constructability and project efficiency with time and labor savings in all weather site conditions. When the electrical contact is such that the circuit path through the body is across the heart, you have the greatest potential for death. Ieee std 4872007, recommended practice for the protection of wireline communication facilities serving electric supply locations. The grounding method shall be made in accordance with the grounding methods of section 9. Distribution substations may also be the points of voltage regulation, although on long distribution circuits several kmmiles, voltage regulation equipment may also be installed along the line. Substation earthing and bonding and their integration into a substation and the potential impacts on third party owned assets in the immediate vicinity of the substation.
The functions of grounding systems or earth mat in include. Substation grounding training the electricity forum. Provide a safe and costeffective conceptual grounding system design for the substation by means of. Index terms substation, grounding, grounding system. As the skin becomes moist, the contact resistance drops. Fence grounding n the national electrical safety code requires grounding metal fences used to enclose substations with energized electrical conductors or equipment. Outdoor ac substations, either conventional or gasinsulated, are covered in this guide. Distribution, transmission, and generating plant substations are also included.
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. Earthing system is made of a mesh of buried bare copper cable, with additional earth rods, and shall be calculated, being recommended to use ieee std. Provide the ground connection for connecting the neutrals. This voltage, gpr, is equal to the maximum grid current times the grid resistance. Read about design of substation earthing system here. This paper also details a ground grid integrity testing method that can be deployed to track the health of the ground grid. K substation standards switch operating and equipment platforms electrical design and details 20. This substation grounding course covers effective relaying and insulation of equipment. The design is based on the measured soil resistivity of the substation. Article 250 covers the grounding requirements for providing a path to the earth. Thus, measurements should be made at multiple locations within the site. Substation engineers must accurately assess the condition of grounding systems to ensure they are capable of dissipating additional fault current. With proper caution, the methods described herein are applicable to indoor portions of such substations, or to substations that are wholly indoors.
Large multiturbine wind farms provide an example of the use. General requirements a conceptual grounding design study is required that will satisfy the following requirements. Important formulas for designing a substation grid earthing system. Guidelines to properly designed substation grounding. I have written several times in theiaei newsabout the hazards associated.
Optimized design of earthing system for substations with high. In section 9, rule 096a, the nesc suggests that the grounding system of a supply station may be extensive, consisting of multiple buried conductors, grounding electrodes, or interconnected combinations of both. A grounding transformer provides a ground path to prevent this. The fence is connected to a separate grounding conductor. Stations with uniform resistivity throughout the entire area are rarely found.
Optimized design of earthing system for substations with. Optimal design of substation grounding grid based on genetic. Pdf the main purpose of this work is the development of an optimization model for the design of the grounding grid in electrical substations. Circulating currents and voltage drop in grid conductors. The maximum touch voltage within a mesh of a ground grid. As shown in figure 1, the human bodys resistance varies from as low as 500 ohms to as high as 600,000 ohms. Pdf ieee guide for safety in ac substation grounding ieee. This guide is primarily concerned with outdoor ac substations, either conventional or gasinsulated. Presentation outline electric power system grounding 3phase power systems reasons for grounding and bonding substation, transmission, and distribution grounding power faults and lightning strikes.
Before 1960s the design criterion of substation earthing system was low earth resistance. Substation earthing system grounding system earthing mat. Abstract the main purpose of this paper is to acquaint the reader with various types of grounding systems prevalent in an electrical substation and their importance. Replace previous bulletin 651 with this bulletin and file with 7 cfr part 1724.
In this paper design of the grounding grid for square and. These grounding connection points must be connected to the substation ground mat with 40 copper cable. These grounding connection points must be connected to the. Compliance with all technical requirements all energize elements comply with the required clearances clearances verify compliance with the last requirements of the national electrical safety code or prepa diseno subw\copy of svc subst profile 2. The cross section of the buried cable should calculated in accordance with the value of the phasetoearth short. This document and other three revisions on 1976, 1986, and 2000 are the main helping tools for engineers in designing a substation grounding mat systems 68. With proper caution, the methods described herein are also applicable to indoor. Article 250 grounding and bonding mike holt enterprises. These factors can have a considerable impact on the potential rise of the grounding grid and on the measured ground impedance.
Optimized design of substation grounding system using newly. The first guide for the substation grounding design was introduced on 1961. Design of earthing grounding system in a substation grid. Substation grounding grid design therefore requires calculating of parameters related to earth and grounding with a great concern for the safety of the persons who may come under the influence of the potential gradient due to severe earth fault. Ieee guide for safety in ac substation grounding the institute of electrical and electronic engineers ieee std 80 ieee guide for measuring earth resistivity, ground impedance, and earth surface potentials of a grounding system ieee std 81 ieee standard for qualifying permanent connections used in substation grounding ieee std 837.
The following papers are being presented in either only pdf format or both html and pdf. Optimized design of substation grounding system using newly developed ieee compliant software issn. The intent of this guide is to provide guidance and information pertinent to safe grounding practices in ac substation design. Mortezaeei 2 1 electrical engineering department, seraj higher education institute.
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