Ieee guide for safety in ac substation grounding ieee std 802000. The substation design manual is not intended to replace asset management standards, but rather to act as a reference document that crossreferences existing standards and process documentation and plugs any gaps where asset management documentation does not exist. The present day earthing system in a substation takes the form of a grid or mat comprising a number of square or rectangular meshes of earthing conductor buried horizontally and connected to several electrodes driven at interval as shown in figure. Scope this document states the functional requirements with regard to substation earthing and bonding, and integration into a substation, as well as items that. The substation earthing system comprises of a grid earth mat formed by a horizontal buried conductors. Stations with uniform resistivity throughout the entire area are rarely found. Ensure safety to personnel in substations against electrical shocks. Substation and transmission lines earthing system design. Since absence of safe and effective grounding system can result in maloperation or. Read about design of substation earthing system here. Before 1960s the design criterion of substation earthing system was low earth resistance. The fence is connected to a separate grounding conductor. All system earthing arrangements sea provide equivalent protection of life and property.
Earthing or grounding method for transformer substation lv switchgear is to have separate main earthing bar connected to framework or earth bar of each item by insulated conductor. Earthing or grounding method for transformer substation. Typically, for a distribution substation with multigrounded neutrals, the water system acts as an extended grounding system and can considerably reducetouch and step voltages within and outside the substation periphery. Components of earthing system an effective substation earthing system typically consists of earth rods, connecting cables from buried earthing grid to metallic parts of structures and equipments, connections to earthed system neutrals, and the earth surface insulating covering material briefly discussed in 1,3. The major components of an earthing system are as follows. Substation lightning protection and earthing standard. Individual electrodes should be designed in such a way that the earth resistance of each electrode is less than 3. This voltage rise could reach unacceptable and dangerous levels. Medium voltage products technical guide the mvlv transformer. Earthing practices electrical substation transformer.
Earthing system for large installation like power stations and coal processing plants require more sophisticated calculations to achieve safe costeffective designs. The functions of grounding systems or earth mat in include. The design of earthing system for 230 kv substation is challenging task. It is the part of which is always buried into the earth. There are two protected leads provided on two opposite sides of the bay marshalling kiosk. This paper presents the design of earthing system for 400 kv substation and calculation of its parameters. Successful operation of entire power system depends to a considerable extent on efficient and satisfactory performance of substations. The grounding system in substation is very important. Substation earthing is a highly specialist subject in its own right, and therefore this chapter will provide an overview of the basic. Main lv switchgear panel is connected to main lv earth bar in electrical room which in tum connected at two ends by 2 insulated earthing conductors through testing. Cable sheathsscreens in particular those that are bonded to the substation earthing grid and to a remote earth. Design of earthing grounding system in a substation grid.
Earthing system of a substation comprises, a number of earth electrodes and a mesh of earthing strips. Before the design of the grounding system begins, soil resistivity measurements need to be taken at the substation. System substations although the general methodology referred to in the document can also provide a general guidance to the design of earthing systems for system substations. Guidelines to properly designed substation grounding. The chapter on dc system earthing was contributed by messes m obrien transpower and rab logan designpower of new zealand. Substation earthing is critical both to the operational performance of the power system, and the provision of a safe working environment. Components of electrical earthing system earth continuity conductor or earth wire. The diameter of main earthmat conductor and risers for extended portion shall be identical to the existing one. We must know the suitable earthing types to ensure our system is fully protected and. Method of statement for installation of earthing, bonding. In this post, i will discuss the requirement of the electrical earthing system and methods of electrical earthing systems. Aug 17, 2017 this is my second post about the electrical earthing system. Important formulas for designing a substation grid earthing system.
For commercial and industrial systems, the types of power sources generally fall into four broad categories. Ena level 3, 40 blackall street barton act 2600 this is a free 9 page sample. Find, read and cite all the research you need on researchgate. The use of telecommunications structures as part of a lightning system is permitted where they are present. Technical specification for secondary substation earthing. It is a salient area of design when either constructing a new substation or extending or modifying an existing substation. Pdf grounding system design in electrical substation. 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. In any substation, a welldesigned grounding plays an important role.
A neutral earthing system is a system in which the neutral is connected to earth, either solidly, or through a resistance or reactance of value sufficient to materially reduce transients, and to give sufficient current for selective earth fault protection devices to operate. Pdf design of earthing system for 230 kv high voltage. We have already given an introduction to substation earthing system in an article published earlier. Thus, measurements should be made at multiple locations within the site. Methods of electrical earthing systems an electrical engineer. The interaction between the substation or powerline earthing systems and secondary systems for example, scada needs also to be considered as those systems can adversely affect each other. In this post, i will discuss the requirement of the electrical earthing system and methods of electrical earthing systems electrical earthing system. 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. A good grounding system is one that provides low resistance to earth which in turn minimizes the ground potential rise.
Hence substations in general can be considered as heart of overall power system. Substation earthing system grounding system earthing mat. The cross section of the buried cable should calculated in accordance with the value of the phasetoearth short. Substation earthing system design optimisation through the. Types of earthing systems electrical engineering centre. These rules relied on metallic sheathed cables providing a grading effect hence controlling. Design of earthing system for new substation project citeseerx. This technical specification describes spens requirements for earthing and bonding systems at secondary substations. However each has certain advantages and inconveniences in other terms that may be important for a given installation. Provide the ground connection for connecting the neutrals.
Earthing system is designed followed by electrical system required and the application. The earthing design practices for small dimension sites like small substation have been quite well established. This paper is to provide information pertinent to safe earthing practice in substation. Methods of electrical earthing systems an electrical.
Standard equations are used in the design of earthing system to get desired parameters such as touch and step voltage criteria for safety, earth resistance, grid. Major substation earthing design, construct and commissioning. Substation lightning protection and earthing standard documents should be brought to the immediate attention of tasnetworks for resolution and no action must be taken that might result in a breach of law or mandatory requirement. The system grounding arrangement is determined by the grounding of the power source. The reactance of the earthing system is the reactance of the earthing conductor and of metal parts of the earth electrode. Power system earthing guide electrical engineering portal.
For transmission substations that are isolated from the water system, earth potential gradients. Verification of earthing design through measurement experienced team of engineers with full understanding of electrode testing 2. Pdf earth protection system, also known as grounding system, is to protect the equipment in the substation by providing low impedance path. Pdf this is a guideline to design the earthing system of ac substation based on ieee 80 standard. Electrical earthing system is composed of, earth electrode.
Substation earthing system design underground horizontal earth mesh matgrid the mesh is formed by placing mild steel bars placed in x and y directions in mesh formation in the soil at a depth of about 0. In any substation, a well designed grounding plays an important role. Under substation fault, both the substation earth grid and the pole grid resistance are exposed to voltage rise. Earthing systems design steps part one electrical knowhow. Please forward any comments or requests for interpretations to. The main purpose of this work is the development of an optimization model for the design of the grounding grid in electrical substations. The problem is formulated as a mixedinteger linear. Today, the three system earthing arrangements, defined by standards iec 60364 and nf c 15. Today we are going to discuss the design of substation earthing system. That part of the earthing system which interconnects the overall metallic parts of electrical installation e. Soil resistivity surveys experienced surveyors key to creating effective earthing system multiple readings taken to ensure safe and accurate designs 3.
A safety is one major concern in the operation and design of an electrical power system. Pdf electric substation design implementations through cymgrd. The supporting structure of a cable sealing system should be connected to the main earthing grid via two risers. This is my second post about the electrical earthing system. Earth electrode is the last part of an earthing system. Guidelines to properly designed substation grounding system eep. With tt, the consumer must provide their own connection to earth, i. Management principles ena eg1 2006 substation earthing guide iec 619361 ed 2. Individual electrodes should be designed in such a way that the earth resistance of. Substation project basic concepts process starts with a need system deficiency is identified system deficiencies. Principles of electrical grounding john pfeiffer, p. Sizing and choice of the switchgear and components.