They are required to constrain earth potential gradients to safe voltage and current levels, for both system normal. Introduction to substation earthing grid important formulas for designing a substation grid earthing system maximum tolerable step potential maximum tolerable touch potential maximum tolerable current through the human body resistance of the earth grid substation earthing. Methods of electrical earthing systems an electrical engineer. Before 1960s the design criterion of substation earthing system was low earth resistance. Grounding or earthing is also done to protect against overvoltage, prevent stray charges accumulation, provide path for lightning currents. Earthing system design ensures safety compliance for both the substation and. Principles of electrical grounding john pfeiffer, p. Start the tool using the substation earthing design tool icon.
Power system earthing guide electrical engineering portal. We have already given an introduction to substation earthing system in an article published earlier. The earthing design tool will start and connect to the backend database as shown below. Substation and transmission lines earthing system design. Earthing ofsurge arresters is through the earthing system. Earthing or grounding method for transformer substation.
User guide secondary substation earthing design tool icp. Scope this document states the functional requirements with regard to substation earthing and bonding, and integration into a substation, as well as items that. In such cases it becomes necessary to increase the area of earthing grid. Today we are going to discuss the design of substation earthing system. All content in this area was uploaded by paneendra kumar bl on jul 10, 2017. Individual electrodes should be designed in such a way that the earth resistance of each electrode is less than 3. This paper presents the design of earthing system for 400 kv substation and calculation of its parameters. Proper earthing is a basic protection against ac line disturbances. If the live wire touches the grounded case then the circuit is effectively shorted. Introduction to substation earthing grid in high and medium voltage 1 air insulated substations ais the electromagnetic field, which causes are the static charges of bare cable and conductors and by the atmospheric conditions surges, induce voltages at nolive parts of the installation that create potential differences between metallic parts and ground and also between different points of the ground. All substation earthing systems must be designed to ensure the following functional requirements are met. Substation earthing system grounding system earthing mat.
Power systems analysis and design br gupta power systems earthing. Ena eg1 2006 substation earthing guide iec 619361 ed 2. A case study is done at 400 kv substation at aurangabad in. Earthing, earth electrodes, ground grid, hvehv substations. Earth resistance earthing system is connected to a zone or transmission substation earthing system. Mere increase in the quantity of earthing strip may not help much to reduce the resistance of the earthing system and the. Design and analysis of substation grounding grid with and. This voltage rise could reach unacceptable and dangerous levels. Scope this guide addresses the high level aspects of policy associated with power system earthing.
These rules relied on metallic sheathed cables providing a grading effect hence controlling. Guideline for application of ieee 80 for earthing of ac. This course is based on terms used in ieee and iec regulations. In this post, i will discuss the requirement of the electrical earthing system and methods of electrical earthing systems electrical earthing system. Railcorp engineering standard electrical distribution substation earthing ep. This is my second post about the electrical earthing system. Design and analysis of substation grounding grid with and without considering seasonal factors using edsa software mithun mondal, dr r.
Gis there are two terms presented in iec gas insulated switchgear and ieee gas insulated substations. This applies whether the source of the disturbance is lightning, powersystem switching activities, or faults in the. Home download center electrical engineering books and technical guides power substation guides power system earthing guide hazard scenarios consideration of appropriate safety criteria usually an allowable shock voltage is required for all electrical assets that form part of the network. Successful operation of entire power system depends to a considerable extent on efficient and satisfactory performance of substations. Z0g is the zero sequence self impedance for the 115 kv ground wire in. The substation design manual is not intended to replace asset management standards, but rather. Nov 27, 2011 what is the minimum frequency of earthpit maintenence as per indian standards in a lv installation like for example in petrol pumps etc. It is a salient area of design when either constructing a new substation or extending or modifying an existing substation. The main reason for doing earthing in electrical network is for the safety. In any substation, a well designed grounding plays an important role. The manual is applicable for all substation projects regardless of internalexternal construction delivery mode. Earth electrode is the last part of an earthing system.
The input for a distribution substation is typically at least two transmission or subtransmission lines. General method of electrical earthing installation step by step. This intensive threeday course will give you an insight into all aspects of substation earthing for low, medium and high voltage systems distribution and transmission, to ensure safety, protection and regulatory compliance. Earth mat design for 233kv substation in rivers state using etap. Therefore, it is important to know what state the earthing system is in and that an adequate level of safety should be. The process of transferring the immediate discharge of the electrical energy directly to the earth by the help of the low resistance wire is known as the electrical earthing. The substation grounding system comprises of a grid earth mat formed by a horizontal buried conductors. Mv switchgear and mv cables are to have separate main earthing bar connected to framework or earth bar of each item by insulated conductor and the earthelectrode by 2 insulated earthing conductors, one at each end of bar, via testing joints. Guidelines to properly designed substation grounding. Earthing of generator, earthing in industries, earthing of dc substation etc is not dealt in this guideline.
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. Aug 17, 2017 this is my second post about the electrical earthing system. Conductor, earthing, grid, impedance, thermal capacity i. Substation lightning protection and earthing standard 1 general lightning protection and earthing systems are an essential part of the transmission system. Ep 12 10 00 11 sp distribution substation earthing. The substation earthing system comprises of a grid earth mat formed by a horizontal buried conductors. Earthing switch is the protective equipment used after circuit breaker and isolators.
The shape of the earthing grid depends on the shape of substation. The company uses the cmen terminology for a zone substation bonded to the distribution earthing and potentially lv men system either directly or through hv cable. The fence is connected to a separate grounding conductor. Substation earthing system design optimisation through the. Pdf guideline for earthing of substation researchgate. Before the design of the grounding system begins, soil resistivity measurements need to be taken at the substation. Earthing practices electrical substation transformer. Pdf electric substation design implementations through cymgrd this book is to discuss developmental procedure of an effective. Substation lightning protection and earthing standard. Design of earthing grounding system in a substation grid. Introduction an electrical substation is a serioussource in a power system.
Major substation earthing design, construct and commissioning. Distribution substation earthing ep 12 10 00 11 sp issued may 2010 uncontrolled when printed version 3. Substation earthing is a highly specialist subject in its own right, and therefore this chapter will provide an overview of the basic. Our office has incomer feeder of 11 kv with sanctioned load of 600 kw in delhi. Stations with uniform resistivity throughout the entire area are rarely found. This fault current induces a fault voltage in the load earthing resistances. Specialist advice from our fully qualified technical team, which focuses on. Guidelines to properly designed substation grounding system.
Substation earthing is critical both to the operational performance of the power system, and the provision of a safe working environment. Collector substations also exist where multiple thermal or hydroelectric power plants of comparable output power are in proximity. Presented to the faculty of the department of electrical and electronic engineering. The collector substation can also provide power factor correction if it is needed, metering and control of the wind farm. Earth resistance pdf created with pdffactory pro trial version. Earth matearthing system in a substation earthing system of a substation comprises, a number of earth electrodes and a mesh of earthing strips. Earth mat earthing system in a substation earthing system of a substation comprises, a number of earth electrodes and a mesh of earthing strips. The neutral point of different voltage levels the metallic enclosure of all current carrying equipment the framework of all current carrying equipment all the metallic structure even not associated with current carrying equipment method of earthing we connect all the. The earthing systems for substations supplied directly from an overhead line network may require additional precautions e. Earthing system design ensures safety compliance for both the substation and transmission lines under fault conditions. Timely determination of the nature of soil resistivity within the vicinity of a proposed electrical substation is necessary for proper design of reliable earthing grounding systems and therefore. In this post, i will discuss the requirement of the electrical earthing system and methods of electrical earthing systems. After the circuit breaker and isolators are open their are some charges stuck in power lines due to their capacitance.
Pdf this is a guideline to design the earthing system of ac substation based on ieee 80 standard. Pdf electrical earthing grounding systems a technical. When all metallic parts in electrical equipments are grounded then if the insulation inside the equipments fails there are no dangerous voltages present in the equipment case. Electrical earthing system is composed of, earth electrode. In substation, earthing system is essential not only to provide the protection of people. Earthing system components earthing system in an installation is normally comprised of these components. The points we must earth in an electrical substation include. Ieee guide for safety in ac substation grounding ieee std 802000.
Difference between earthing, grounding and bonding. Earthing conductors earthing conductors which are defined in bs 7671 as a protective conductor connecting the main earthing terminal of an installation to an earth electrode or other means of earthing must be adequately sized. Oct 10, 2018 earthing switch is the protective equipment used after circuit breaker and isolators. The earthing systems for a substation must have a minimum design life of 50 years. Read about design of substation earthing system here. Oct 11, 2012 earthing ofsurge arresters is through the earthing system. This functional requirements document is in line with the organisations. Distribution voltages are typically medium voltage, between 2. Design of earthing system for new substation project citeseerx.
The manual is applicable for all substation projects regardless of internalexternal design delivery mode. Introduction to substation earthing grid important formulas for designing a substation grid earthing system maximum tolerable step potential maximum tolerable touch potential maximum tolerable current through the human body resistance of the earth grid substation earthing grid exothermic welding c connector. Jul 26, 2017 the substation grounding system comprises of a grid earth mat formed by a horizontal buried conductors. Earth continuity conductor or earth wire size of earth continuity conductor earthing lead or earthing joint size of the earthing lead earthing.
Hence substations in general can be considered as heart of overall power system. Pdf earth mat design for 233kv substation in rivers. It is the part of which is always buried into the earth. The use of telecommunications structures as part of a lightning system is permitted where they are present. Methods of electrical earthing systems an electrical.
The function of substation earthing system is to provide a grounding mat below the earth surface in and around the substation which will have uniformly zero potential with respect to ground and lower earth resistance to ensure that. It provides a framework for managing earthing related risk associated with electrical power systems to meet societally acceptable levels. Requirements for the installation, inspection, testing and maintenance of distribution earthing systems are. The electrical earthing is done by connecting the noncurrent carrying part of the equipment or neutral of supply system to the ground. Under substation fault, both the substation earth grid and the pole grid resistance are exposed to voltage rise. Lightning arresters, as part of the earthing system in an installation, are the protective devices, which avert the risks of lightnings. Thus, measurements should be made at multiple locations within the site. Distribution substation a distribution substation transfers power from the transmission system to the distribution system of an area. Several crucial terms are for better understanding of the presented material. 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 substation construction manual is not intended to replace asset management standards, but. Substation grounding a project presented to the faculty. The legacy approach to secondary substation earthing design was based on one or two earth rods and combining hv and lv earths if the measured earth resistance was less than 1 ohm.
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