Self-supporting Cables Research Articles

СОВРЕМЕННЫЕ МЕТОДЫ ПРОЕКТИРОВАНИЯ И СТРОИТЕЛЬСТВА ВОЛОКОННО-ОПТИЧЕСКИХ ЛИНИЙ СВЯЗИ НА ПРИМЕРЕ ГОРОДА АЛМАТЫ

The article provides a brief analysis of the condition of the National transport network NISM (national information superhighway) based on fiber-optic communication lines, where work is being carried out on the construction of the DWDM backbone network (Dense Wavelength Division Multiplexing), increasing the power of external Internet channels, expanding the installed capacity of the DWDM backbone network equipment, ensuring traffic protection, and building a fiber-optic network to connect new corporate clients. The article also provides information about the state Program "Digital Kazakhstan", which aims to accelerate economic development and improve the quality of life of the population through the use of modern digital technologies in the future and create a digital economy of the future in the long term. Brief information on the draft program for the introduction of broadband Internet access for SNP was provided (Rural localities), where the basis for the implementation of this program is the FOCL. The features of the fiber-optic cable where the main element is the optical fiber (OF), are reflected. OF is currently considered the most advanced medium for transmitting information, which allows you to transfer large flows of information over long distances without additional costs. Attention is paid to the issues of designing the FOL, which consists of several stages and documents. Also, attention is paid to the problems in the design of the FOCL. In order to reduce the time of development of projects on FOCL, it is recommended to use electronic tools, among which we can highlight the program "Calculation of self-supporting cables" of Incab. At the end of the article, information about the methods of construction of the FOCL is briefly given, as well as a description of the experiment, the results of the study and the conclusion. Subject of research. The subject of the article is modern methods of design and construction of fiber optic systems. Purpose of work. To consider modern methods of design and construction of FOCL on the example of the city of Almaty (a suburban area with a complex mountain terrain). Methodology and methods. The research is based on the analysis of the National superhighway, the "Digital Kazakhstan" Program, as well as the program for the introduction of broadband Internet access for rural localities, which is based on the FOCL. A brief analysis of the transport network of communication (telecommunications) in the territory of Almaty with different types of technologies such as PDH, SDH and gradually introduced new technology DWDM.

Calculation of the ampacity of medium voltage self-supporting cable bunch

The paper presents various approaches for determining the current rating of the bunch of self-supporting insulated 10kV cables including the developed finite element method. The calculation results are compared to the experimental data obtained in laboratory tests. It has been shown that all available approaches have provided results that match with the experiments with a reasonable accuracy. However, the results obtained by the finite element approach have been found to be in the closest agreement with the measurements. This can be explained by the fact that this model makes it possible to consider all circumstances affecting the ampacity of cables including the heat transfer to the surrounding ambient by radiation and convection, as well as the effect of solar heating.

Aging of Polyethylene ADSS Sheath by Low Currents

The electrical environment of all-dielectric self-supporting cables on overhead power lines presents a challenge to cable materials. It is widely acknowledged that the application on lines of system voltages above 150 kV requires specialist sheath materials to prevent damage as a result of discharges on the cables' surfaces. It is widely held that below this system voltage, polyethylene sheaths are adequate. This is not always the case. However, one such cable which successfully served for 15 years on a 132-kV twin circuit has had its sheath examined. In particular, contact-angle measurements have been made along two span lengths. Even though predicted currents on the sheath are lower than those expected to cause damage, a reduction in contact angle is shown to be closely correlated to predicted current magnitude along the cable spans. An aging process is therefore illustrated, creating changes below levels which would normally be called damage. A 0.5-mA current limit is appropriate for the polyethylene material considered.

Modeling of Currents on Long Span, Dielectric Cables on HV Overhead Lines

It is well established that all-dielectric self-supporting cables on high-voltage overhead power lines can suffer from damage through the mechanism of dry-band arcing. A number of heuristics have evolved over the past 20 years and these are used to determine whether such cables are capable of reliable performance. A key element to planning is modeling the installation conditions. In addition to the geometry of the high-voltage line, such a model needs to consider the climatic environment and potential pollutants on the cable. In this paper, a model is built based on the commercial software current distribution, electromagnetic fields, grounding and soil structure analysis which is widely used in the power industry. The model developed is shown to be consistent with a number of previously published models. It is demonstrated that the relative sags of all-dielectric self-supporting cable and conductors are key to the severity of the installed situation. It is also shown that the towers do not need to be modeled for the most severe cases of high pollution, but are required for accuracy in medium and low pollution cases

Engineering a solution to the aging of HV self-supporting cables by dry-band arcing

The retrofit rod of controlled resistivity clearly has the potential to remove the threat of dry-band arc damage on all-dielectric, self-supporting (ADSS) cables. This is achieved by reducing the maximum current available on the cable for arcing activity. Rods can be applied to polyethylene sheathed cables or arc-resistant sheathed cables and can improve the performance of both. Extensive trials in the UK have shown that the rod works and have confirmed predictions of computer models. However, the engineering of the application of such as solution is complex. Individual spans of different geometry, including cable sag, must be considered. In particular, local variation in pollution is critical; so knowledge of the proximity of the sea or industry must be considered. It is also very likely areas that do not experience much rainfall will be particularly onerous because the cable will not be naturally washed regularly, so the pollution on its surface will tend to build up, reducing its resistance in times of high humidity, fog, and dew

Development of the Dry-Band Arc on All-Dielectric Self-Supporting Cables During Laboratory Tests

Utilities frequently install All-Dielectric Self-Supporting (ADSS) fiber-optic cables on transmission lines. The cable jackets suffer damage due to dry-band arcing caused by high electric fields and pollution on the cable. A test method to determine cable resistance to dry-band arcing is being considered for standardization by the IEEE. A new nozzle arrangement for the test is proposed in this paper. Using this nozzle the repeatability of the test is significantly improved over previous arrangements. Each test cycle consists of three stages: wetting, drying, and arcing. The three stages are examined in detail. Development of the dry-band arc on the cable jacket during the arcing period is presented. It is shown that the length of the arc increases exponentially with time and reaches a stable length. The stable length is shown to be a function of the applied voltage.

Electrical ageing and testing of dielectric self-supporting cables for overhead power lines

Long-span, all-dielectric, self-supporting cables have been developed as a result of demand for optical fibre based communication systems on overhead power lines. After considerable experience and successful operation on towers carrying circuits whose system voltages are less than 150 kV, these cables have been installed on higher voltage lines. In such circumstances, degradation of sheathing materials has occurred and this has been attributed to gradual erosion by dry-band arcing. New results of ageing by dry-band arcing are presented and conclusions are reached which are important in the testing of materials. A new feature is added to the dry-band arc model of failure. This allows the length of an arc to be gradually reduced by the movement of moisture along the cable. It is shown experimentally that if such arc compression does take place, the cable can be severely damaged by only a few seconds of this activity. It is suggested that the lifetime of a cable might be effectively determined by the time to one such period of activity rather than the ability of a cable to withstand long periods of stable dry-band arcing.

Suppression of galloping oscillation for a self-supporting optical fiber cable

Estimation formulas for wind force coefficients for self-supporting (SS) optical fiber cable are derived. Using these formulas, a procedure for evaluating the critical wind velocity that triggers galloping oscillation is provided. An SS cable with projections is designed to increase the critical wind velocity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Satellite Elongation into a True "Sky-Hook"

The theoretical possibility of self-supporting cables extending into space from earth and from extraterrestrial rotating or revolving bodies is examined. In principle, augmentation (and duplication) of the installation and the launching of masses into orbit or into space could be accomplished with energy derived entirely from the rotation of the central body. In practice, a portion of the total energy requirement would probably be supplied by simple mechanical devices.