This recognition is seen in the increasing use of cables within utilities. The material used in the manufacture of cable should be such that there is complete chemical and physical stability throughout. As these cables are not exposed to the air atmosphere, this makes the ug cabling system less susceptible to outages. Undergrounding high voltage electricity transmission lines. Construction of underground cables studyelectrical. Although several types of underground cables are available, the type of cable to be used will depend upon the working voltage and service requirements in general, an underground cable must fulfill the following necessary requirements. If the municipality passes ordinances making underground. An introduction to high voltage direct current hvdc. Specification for installation of underground conduit systems. This is known as direct burial, and if you do this, the uf cable must be at least 24 inches below the surface of the ground, to minimize the chance.
Understanding underground electric transmission cables. Cable riser insulators cable support blocks 2212 cable support blocks cable support blocks support underground cables in manholes, vaults, and conduit. Construction details of single core xlpe insulated armoured pvc sheath underground cable the figure shows a circular compacted stranded copper or aluminium conductor, xlpe insulated, with copper tape screened and covered with extruded pvc bedding, aluminium wire armored and pvc outer sheath. In overhead power lines, a structure based network is used to transmit. Vaults vaults are large concrete boxes buried at regular intervals along the underground construction route. Ppt underground cables powerpoint presentation free to. This chapter deals with many special features of underground power cables.
It helps to predict when and what kind of repairs might be needed in the future, or if faulty sections need immediate replacement. However, the latter method of classification of underground cables is generally preferred, according to which cables can be divided into the following groups. Maryland task force to study moving overhead utility lines underground md 2003 the maryland. The discussion is focused on transmission cables but also has relevance for distribution cable applications. Underground commercial distribution ucd installation and. Power grids underground medium voltage prysmian group. This article is about construction of underground cables. Used only in particular applications with specialised construction, these underground cables can be further divided as htype and s. Due to their different physical, environmental, and construction needs, underground transmission generally costs more and may be more complicated to construct than overhead lines.
Construction 4 general 61 additional cable variations 63 i additional electrical data 64 ii tests on power and control cables iii general information datasheets pvc insulated low voltage cables 70. Commission, which found that the cost to underground the entire distribution system to be prohibitive. For underground cables less than 345 kv, the connection from overhead to underground lines require the construction of a transition structure, also known as a. Beyond that, insulation required for the cable is too much. Technical specification for underground power cables and. Technical specification for underground power cables and accessories for nominal system. It has been in service for more than 40 years, has proven highly reliable and can be provided by european. The world leader in the energy and telecom cables and systems industry product finder discover products and solutions. For higher voltages, 3 cored constructions become too bulky, and hence, even with some limitations we employ single cored cables. Laying uf underground feeder cable directly into the ground. Although several types of underground cables are available, the. Maryland task force to study moving overhead utility lines underground md 2003 the maryland task force was created by law in 2002 and charged with facilitating converting the overhead lines to underground lines. Underground cables are usually employed to deliver 3 phase power.
Further, the vertical runs where the cable descends into the ground at the house side. An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by some protective layer. It may be increased at certain points, for example road, rail, river and canal crossings, to accommodate the more complex construction processes at these locations. See here for the magnetic fields produced by underground cables and. The structure of medium voltage cables with extruded insulation will always involve the following items. The focus is on thermoplastic and thermosetting insulated cables, however the construction of other cables are similar. Underground power cables high voltage underground cables 2 2 circuits 3000m 3x1x2000mm2 e. Underground power cable, distribution cable, overhead. High voltage direct current hvdc underground cables have been in commercial use since the 1950s.
Underground cable and ducts are part of the underground conduit system. Telecommunication conduits are made from various materials and buried directly into the soil or encased in concrete. Underground cables april 2018ver2mh the width of the working strip is dependent upon the the voltage of the underground cable, the number of cables and how many trenches are required. Transmission cables are often 35in 75125mm in diameter and may be installed directly buried or in, typically, 68in 152203mm plastic conduits with commercial installations up to 500kv. As these cables are not exposed to the air atmosphere, this makes the ug cabling system less susceptible to outages due to various atmospheric conditions like high wind, storm, thunder storms, heavy snow or ice storms etc. Underground power cables and accessories for nominal system voltages of 66kv and 2 kv jts040110. Under ground cables presention linkedin slideshare. Code of practice for avoiding danger from underground. Threeconductor cables are available up to 8kv, but the vast majority of underground extruded circuits use singleconductor cables. Underground technology development and engineering advances are spurred by underground construction requirements throughout the world parriaux et al.
The information from this project contributes to energy research and development divisions energy systems integration program. So, this paper shows the details of different kind of cables and one is suitable for the long transmission line and. In terms of reliability, capability, cost, construction impacts and land use, overhead lines do have advantages when compared to underground cables. Any underground cables which are damaged during installation should be immediately repaired with equal quality material. This paper analyzes the application of directional comparison schemes to protect two 34. Vaults vaults are large concrete boxes buried at regular intervals. Underground circuits get rid of all that mess, with no visual impacts in the air. If it is done in coordination with other projects like road repair. Underground cable distribution up to and including 33kv infrastructure technical standards page b05. Construction 4 general 61 additional cable variations 63 i additional electrical data 64 ii tests on power and control cables iii general information datasheets pvc insulated low voltage cables 70 c 7 yyfl, unarmoured 2, 3, 4 and 5cores 8 multicores 12 yyryfl, armoured 2, 3, 4 and 5cores 14 multicores 18. The highvoltage underground cables used on the national grid system can be one of three types. An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by a protecting cover. However, a significant benefit of undergrounding cables is the reduction in visual impact.
Classification of underground cables construction of cables. Pdf design and implementation of underground cable fault. If it is done in conjunction with retiring old overhead lines. Mafijur rahman electrical and electronic engineer professional associates limited. Overhead or underground a comparison legislative services.
Introduction increasingly, utilities, developers and power producers seeking to build new power transmission systems are required to at least consider underground cables as an alternative to overhead lines. Underground electric transmission lines wisconsin psc. Commscope cables meet or exceed all telcordia gr409core and ansiicea 696 requirements, as well as gr20core requirements for crush resistance, impact resistance, flexing and twistbend. Conditionbased maintenance this checks underground power transmission cables and aboveground grid fixtures like joints and terminations that have already experienced partial damage. Fortisbc specification for installation of underground conduit systems revision date. Undergroundsubmarine cable protection using a negativesequence directional comparison scheme free download abstract protective relaying requirements for underground and submarine cables are.
Premise cables these cables are designed to handle the stresses of indoor applications. This is known as direct burial, and if you do this, the uf cable must be at least 24 inches below the surface of the ground, to minimize the chance of the cable being pierced by routine shoveling. Trees replace wires, and trees dont have to be trimmed. Read underground engineering for sustainable urban. Standard for distribution line design underground check this is the latest version before use page 2 standard stnw3369 ver 2 ergon energy corporation limited abn 50 087 646 062 2 references 2. Construction of underground cables electrical edition. Underground installation of optic fiber cable placing. A cable may have one or more conductor depending upon the type of service. Code of practice for avoiding danger from underground services 2 9.
Fiber optic cables have provided a more optimal use of available underground conduit space because of its small cable diameter and the much higher. Underground cable introduction and construction electrical. These are used when the voltage requirement exceeds 66kv and solid cables cant be used. Figure below shows the construction of 3 core cable.
Cable construction introduction this article gives a brief exposition on the construction of typical low voltage, medium high voltage and instrumentation cables. At ground level, instead of poles every 150 ft many having one or more guy wires urban construction has no obstacles, and urdstyle construction has just padmounted transformers spaced much less frequently. At ground level, instead of poles every 150 ft many having one or more. The primary function of the vault is for splicing the cables during construction and for permanent. Jun 02, 2018 classification of underground cables may be in two ways according to. Introduction since the loads having the trends towards growing density. See here for the magnetic fields produced by underground cables and specifically the fields produced by these three different types. In practice, underground cables are generally required to deliver 3phase power. G eotechnologies and related science and engineering fields make it possible to use underground space to support. Underground cables have different technical requirements than overhead lines and have different environmental impacts. The challenge with the existing methods used for locating faults in underground cables is the inaccuracy in calculating the distance where the fault is located and the low durability of such. Classification of underground cables may be in two ways according to. The other utilities must maintain clearances as outlined in the nesc or by mutual agreement. Innovative underground technology and engineering for sustainable development.1043 1311 1141 799 1105 56 868 1636 159 927 1355 1401 1423 952 313 1246 113 1641 1520 298 655 1317 829 661 1598 1051 99 83 1052 109 313 756 449 737 1131 833 741 1190 392 63