Substation a part of an electrical transmission system that transforms voltage from high to low, or the reverse. It is the intention of the working group to consider all existing regulations and wherever possible comply with same. For single phase and double phase earth faults, this is in systems with. The base of the cvt or capacitive voltage transformer is connected to the main earthing grid via a riser. Introduction the substations are important part of power system. The rus design manual of high voltage transmission. Part ianalytical study, ieee transactions on power apparatus and systems, vol. The armouring of such cables is usually earthed to the substation earthing grid at both. In poland the resistance of line tower earthing is commonly measured using the impulse method, with earthing measurements for power line towers.
Responsibilities the group manager works enablement is the process owner responsible for approving this reference. Increased earth lead size for indoor substations with remote earths to 120mm2. The continuity of supply depends to a considerable extent upon the successful operation of substations. This paper presents the design of earthing system for 2 kv substations and simulation for calculation of required parameters. The problem is formulated as a mixedinteger linear. Shield and ground wire wires used primarily for protection from lightning strikes and corresponding surges. The cross section of the buried cable should calculated in accordance with the value of the phasetoearth short. Under substation fault, both the substation earth grid and the pole grid resistance are exposed to voltage rise. The bottom portion of the support structure is also connected to the main earthing grid via riser. All rus borrowers rus electric staff effective date. Asnzs 4383 all partspreparation of documents used in electro technology. Grounding system plays crucial role in the performance of a substation as it provides place for connecting system neutral points, equipment body and support structures to the earth. National grid earthing technical specification ts 3. Under normal circumstances, it is the current constitutes the main threat to personal.
Earthing system design ensures safety compliance for both the substation and transmission lines under fault conditions. Substation types distribution substation located near to the endusers changes the transmission or sub transmission voltage to lower levels for endusers distribution voltages varies from 34,500y19,920 v to 4,160y2400 v blast and burn generally associated with fault current. Handbook on construction techniques asian development bank. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. Without a properly designed earthing system, large potential differences can exist between different points within the substation itself.
Request pdf substation and transmission lines earthing system design under substation fault highvoltage substations are fed by transmission lines with. Substation and transmission lines earthing system design under. Mukhedkar, optimum design of substation in a two layer earth structure. Design of earthing grounding system in a substation grid. 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. Grounding of a 230 kv transmission line over a limestone ridge. Preparatory survey on electricity sector reconstruction project ii in kurdistan.
Reduction of the impedance helps in reducing outages due to backflashes. 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. Under substation fault, both the substation earth grid and the pole grid. The substation earthing system comprises of a grid earth mat formed by a horizontal buried conductors. Highvoltage substations are fed by transmission lines with the. Substation earthinggrounding and lightning protection ground bars cadweld structure connections fence post clamp fc078 fence b162 2q ground plate connection to ground grid transformer hv control scada panel station control house 18 450 mm crushed rock ehv hv transmission line vs cadweld connection crushed rock substation vb vs 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. This manual does not cover transmission, subtransmission, zone and bulk supply. Chapter 6 substation and transmission line facilities. These rules relied on metallic sheathed cables providing a grading effect hence controlling. A substation is assembly of large no of electrical equipment. 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. Substation and transmission lines earthing system design under substation fault.
The design of this foundation factorsin soil condition among others. Lightning protection design, earthing system design lightning protection for buildings design duration. I used the cdegs software to create a uniform model of. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. The functions of grounding systems or earth mat in include.
If the live wire touches the grounded case then the circuit is effectively shorted. This diverts part of the earth fault current to the tower footing earthing. A cable fed substation will have a split factor somewhere between 5% and 40% depending on the cable sheaths and earthing configuration where a substation is fed via overhead line and has no metallic return path, all the earth fault current with flow through the. A substation standards switch operating platforms steel design and details 49.
Pdf grounding system design in electrical substation. Elevation layout, earthing grid, earthing grid design, dslp direct stroke lightning protection, dslp design, opgw cable, distribution substation and substation design 1. Power substation design calculations a checklist of 18. Optimized design of substation grounding system using. Read about design of substation earthing system here. Asnzs 3931risk analysis of technological systemapplication guide. Therefore, it is important to know what state the earthing system is in and that an adequate level of safety should be. Transmission tower lightning protection and grounding. The grounding system in substation is very important. This voltage rise could reach unacceptable and dangerous levels.
The main reason for doing earthing in electrical network is for the safety. Principal author of epri transmission line reference red book, 200 kv and above, chapter 6 lightning protection. Earth fault current distribution on transmission networks core. Double earthing of each tower is done using manual labor to ensure proper. Once again, however, it may be difficult andor prohibitively expensive to obtain better earthing at some tower sites. Important formulas for designing a substation grid earthing system. Earthing design of 11kv and 33kv rural substations in the uk. This guide is the first document to be produced by esaa on the subject of substation earthing. The earthing system of electricity substations and transmission lines is required to ensure i electrical safety for persons working within or near the substation or in. An introduction to electric power transmission presentation. Case 1 single potential control ring case 1 is an example from epri grounding system design guide 2.
This bulletin is an update and revision of previous rea bulletin 651, design guide for rural substations revised june 1978. It also ensures safety of working personnel within the substation and enables earth. Data needed for design of earthing substation grid area soil resistivity at the site fault clearing. This section defines the standard substation components. A substation is a part of an electrical generation, transmission, and distribution system. At the 220kv substation the fault current again takes two paths. Substation earthing system grounding system earthing mat. A high tower footing impedance increases the occurrence of backflashes and hence interruptions.
Grounding is used to get a reference point to measure voltage, to get a common return path for current and to physical connection of body. Design of grounding system for an electrical substation. Chapter 6 substation and transmission line facilities 6. Substation and transmission lines earthing system design. Syllabus of substation design course advance electrical. D transmission line standards special earthwork 92.
Earthing of electrical transmission tower electrical4u. Detailed syllabus for substation design course, our syllabus is comprehensive,structured and aim to build design career in epc companies,aedei syllabus bases on the epc industries, all the content and syllabus are realated to the industries, aedei is providing priactical projects on substration design. Scope this document states the functional requirements with regard to substation earthing and bonding, and integration into a substation, as well as items that. Earthing systems design steps part one electrical knowhow. The proposed site drawings should show the layout of the highvoltage tower or substation, and any additional construction for new equipment that may be occurring on the site, including fencing and gate radius. A transmission line standards lattice steel towers structure grounding 93. The special earthing point on the base of the cvt is connected to the pipe earth electrode with 50 mm. The property map and general location plan of the substation should provide good estimates of the area to be grounded. Here we connect the galvanized wire with the leg of the tower with the help of galvanized lug and the galvanized lug is fitted with a tower leg with the help of 16 mm dia nut and bolts. The main purpose of this work is the development of an optimization model for the design of the grounding grid in electrical substations. Grounding of overhead transmission lines william a. Ensure safety to personnel in substations against electrical shocks.
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