If the tension of the conductor is increased beyond the limit, it may get broken, and the power transmission of the system get erupt. The catenary equation is defined using hyperbolic sine or cosine functions. Design and optimization of overhead transmission lines using plscadd and tower software theoretical and practical training course dates plscadd training. During the time of installation, the conditions were t 15c and initial horizontal tension 25% of rated tensile strength rts. Sag depends on tower distance, wire weight and tension.
A novel affine arithmetic aa based transmission line sag, tension and conductor length calculation for parabolic curve is proposed and the proposed method is tested for different test cases. This paper is limited to the case where the supports of the transmission line are at equal elevations and all span lengths are equal. Sample calculation of sag and tension in transmission line uneven elevation posted by admin in the previous post, we calculated the sag and tension of a transmission line given that the conductors supports are at the same elevation. Pls caddultralite is a streamlined version of plscadd for quick modeling of a single span of conductor or wire. A transmission line conductor was strung between two towers, 300 meters apart and same elevation. Overhead transmission line sag estimation using a simple ncbi. Overhead power lines transmission and distribution lines are suspended on poletower supports.
Aaac all aluminum alloy conductor overhead transmission line for multiple spans with. It is because low sag means a tight wire and high tension, whereas a low tension means a loose wire and increased sag. Excessive sag, on the other hand, requires more raw material. August 1, 2018 electrical calculations overhead power lines sag and. The calculation of conductor at an equal level shown below. Sagsec is commonly used to determine the sags, tensions and support. Sagsec is a powerful and easy to use microsoft windows program for the exact. If the sag is too large, it may cause a short circuit between the line and objects below it or a short circuit between lines in extremely windy conditions. In this example we will calculate the sag and tension if the conductor supports are at different elevation. A method for the sagtension calculation in electrical.
Sag and tension of transmission and distribution lines. How to determine the sag in transmission lines sciencing. To ensure that no extreme mechanical tensions can occur, which could permanently damage or even brake them. Our goal in developing ultralite was to provide the simplest possible application for modeling a span of wire in either a level or inclined state. Also, perform sag and tension calculations overhead lines. What is the sag in transmission lines and how to calculate. Sgrc engineers are trained to use the latest design software for achieving the most economic and reliable design.
A new version of southwires sag10 software for calculating sag and tension in overhead conductors is now available with featured enhancements. Sag in overhead transmission line and its calculation. Utility line design has over twentyfive planned calculations that will be added to the website at no added charge in the coming months. Therefore, a conductor between two supports must not be fully stretched and allowed to have a dip or sag. Sagtension spreadsheet free calculator even elevation. Sample calculation of sag and tension of transmission line. Design and optimization of overhead transmission lines. Bulletin 1724e152 page 3 the mechanics of overhead distribution line conductors 1. Calculations of maximum sag of a transmission line with an. Transmission line design involves a lot of data manipulating and number of tedious calculations which take a major part of time required or devoted for planning and designing a new line. April 2016 this brochure identifies and describes the most essential elements of the sagtension calculation process and the various mathematical and experimental methods used to predict sag and tension of catenaries over the whole range of conductor temperatures and ice and wind loads. This substitution introduces unnecessary errors, inefficiencies, andor increased costs in the line design. Once initially set, the tension of the conductor is determined by creep and by line temperature.
Handle multiple overhead line spans between deadend structures. Also includes plscaddlite and plscaddultralite, but not any of the other items listed below. The starting point of the transmission line is bishop. It is critical that utility personnel apply the appropriate tension to overhead conductors. Sag10 software, a play on words for sagten tension, is widely recognized as the industry standard for overhead conductor sagtension calculations, utilizing the alcoa.
Conductor sag and tension calculator even elevation 10. The standard edition of plscadd is a line design program that includes all the terrain, sagtension, loads, clearances and drafting functions necessary for the design of an entire power line. A method of measuring the power line wire sag using. Sagtension calculation methods for overhead lines ecigre. The tension is generally decided by many factors like wind speed, ice loading, temperature variations etc. Southwires sag10 software combines more than 90 years of sagtension calculating experience with over 65 years of conductor design and modeling expertise to deliver an unequalled design tool. Sample calculation of sag and tension in transmission line. Catenary calculations and sagtension analysis tools enable users to design, edit and optimize transmission lines accordingly.
Fernandez 1 abstract the sag and tension values of overhead conductors are influenced by. This software approach will provide a handy means for new ones entering in this field. Review on design of overhead transmission line by matlab. You can use this spreadsheet to verify the results in my sample computation in the previous post. However, it can be reliably approximated by a parabola. Too much tension and the conductor can snap in cold weather. In acsraw conductors, the steel core is protected from corrosion by an aluminum coating. This report presents the results of the detail design of a crosscountry overhead 345 kv transmission line of approximately 168 miles in length in southern california. Too little tension and the sag of the line can be excessive.
In an overhead line, the sag should be so adjusted that tension in the conductors is within safe limits. Therefore, in actual practice, a compromise is made between the two. Electra includes build in cables library and load parameters which can be user defined and customized. A method for the sagtension calculation in electrical overhead lines i. The ruling span concept is widely used to calculate sags and tensions for new overhead transmission lines and for upgrading existing lines. In this process, substations and transmission lines perform a fundamental role. The sag of a transmission line will increase by increasing conductor temperature caused by the electrical load and spec ific environmental conditions or additional rope forces e. Pdf sagtension calculation program for wood pole overhead lines.
Calculate the sag of conductors using matlab file exchange. Software to calculate southwire sag10 sag and tension software for transmission line design assists engineers calculate sag and tension of overhead. As promised, you can download for free my sag tension spreadsheet calculator. It can calculate the section static equilibrium configuration for arbitrary. The tension is governed by conductor weight, effects of the wind, ice loading and temperature variations.
Sag calculation in overhead line sag in overhead line. The overhead transmission line conductors sagtension calculations are. Analysis of the sag and tension is important in the transmission line for the continuity and quality of electrical services. Take note that because of the complexity of the creep in a conductor, it is not a factor in these calculations. This paper presents a method for the sagtension calculation of. Overhead transmission line sag estimation using a simple. The design of a substation is divided into two major categories. It develops a sagtension report as well as stringing charts for a user definable range of span lengths and stringing temperatures. It explains the guidelines used for preparing or selecting sagtension tables. The task of designing a hvac transmission line has a number of factors to consider such as planning, survey and design. Electra complies with en 50423321 and en 504231 standards. Sag and tension calculation software a new version of southwires sag10 software for calculating sag and tension in overhead conductors is now available with featured enhancements. March 30 to april 2, 2019 towerplspole training april 34, 2019 the courses daily schedule is from 8h30 to h00 and from 14h00 to 16h30 location. Normally the tension in conductor is kept one half of the ultimate tensile strength of the conductor and therefore safety factor for the conductor is 2.
Calculate self and mutual impedances, derated ampacity of overhead lines under various operating conditions. Sag10 software, a play on words for sagten tension, is widely recognized as the industry standard for overhead conductor sag. The sag in overhead line is a length in between support point of conductor and the lowest point on the conductor of transmission and distribution overhead line. Works with any of the over 5,000 predefined cables in our. Suspended conductors are subjected to mechanical tension which must be under safe value. This bulletin presents the methodology and equations required to calculate distribution line ruling spans and conductor sags and tensions.
Overhead conductors, however, elongate with time, temperature, and tension, thereby changing their original positions after installation. Sag and tension calculations for overhead transmission lines at high. A play on words for sagten tension, it is widely recognized as the industry standard for overhead conductor sagtension calculations, utilizing the alcoa graphic method. The simulations were carried out in etap software and the results showed. Fernandez1 abstract the sag and tension values of overhead conductors are influenced by the creep developed during the line lifetime. Usually, instead of making the necessary calculations for the actual span, transmission line designers have simply substituted the ruling span sag and tension data for the actual span sag and tension data. Sag10 is attractive to engineers due to its ease of use, the speed with which sag and tension calculations can be rendered, and the tremendous value the software brings to. The overhead transmission line conductors sagtension calculations are typically based on the catenary equation, which describes an entirely. Calculations of maximum sag of a transmission line with an ice load on one span rodney a. In addition, the permanent mechanical forces everyday stress elongate. Sagsec is a powerful and easy to use microsoft windows program for the.
Realtime ampacity and ground clearance software for integration. Catenary curve, calculation of sag tension, effect of. The overhead transmission line conductors sag tension calculations are typically based on the catenary equation, which describes an entirely flexible rope rigidly fixed at both ends. The energized conductors of transmission and distribution lines must be placed to totally eliminate the possibility of injury to people. Span having equal level supports is called level span, whereas when the level of the supports is not at an equal level is known as unequal level span. As discussed earlier in this post, enough sag shall be provided in overhead transmission line to keep the tension within the safe limit. Plscadd and saps also build upon the fe sagtension capability offered in. During the erection of overhead transmission line, the conductors are connected between two tower structures. Sagtension calculation program for wood pole overhead lines.900 1036 815 1013 64 593 550 15 1307 727 811 715 1119 565 1116 323 746 1426 1378 326 844 824 580 36 1360 859 170 1185 329 295 229 70 1082 1391