The erection of the power cable on the power transmission and distribution line tower

Engineering Technology Power transmission and distribution line Tower under the power cable erected by Liu Sanxiu (Fujian Longyan City Water Conservancy and Electric Power Engineering Office, Fujian Longyan 364000 cited, is a common way of transmission and distribution line construction and transformation. Power cable in the tower When setting down the installation, attention should be paid to the selection and installation of lightning protection devices, the fixing of cables on the tower, and the design and processing of the tower fixtures.

Key 诃Transmission and Distribution Lines; Towers; Power Cables; Downsizing With the development of science and technology and society, people's demand for electricity is increasing. The country has spared no effort in the construction and transformation of the power system. The power system is divided into two major parts: power supply and power distribution. The power distribution system plays a very important role in power system construction and transformation. The substation generally refers to the substations at various levels. It is usually built in a densely populated and centrally-charged central area. Therefore, during the laying of power cables, it is necessary to use a tower device such as a power tower to make The problem of electrical circuit channel can be effectively solved. The erection of power cables on the towers directly affects the safety of transmission and distribution lines. Therefore, when erecting the power cable on the tower, attention should be paid to the selection and installation of the lightning protection device, the fixing of the cable on the tower, and the design and processing of the tower fixture.

1 The installation of lightning protection devices on the iron tower is generally exposed to the natural environment and is vulnerable to lightning strikes. Therefore, special attention should be paid to the installation of the lightning protection device when installing the power cable on the tower. Generally, in lightning protection, the following points should be taken into account in the overhead transmission lines: First, prevent direct transmission and distribution lines from being hit by lightning, second, prevent flashover of the insulation of the power lines after lightning strike, and third, prevent the power lines from being damaged. A stable power frequency arc is established after the flashover occurs, and the fourth is to prevent the power line from interrupting the power supply after the power frequency arc is established. The lightning protection measures on the tower are mainly through the installation of lightning protection lines, installation of lightning arresters, strengthening of the insulation of the line, and the use of the margin method to carry out lightning protection. Therefore, when installing the lightning protection device on the tower, it is necessary to fully consider the maximum effect of the device, and adopt the best equipment and the best process for installation.

When installing the lightning conductor, the protection angle of the lightning conductor to the side conductor should be smaller, generally between 20° and 30°. The line protection angles of 220KV and 330KV double lightning protection lines should be around 20°, and the protection angle of 500KV and above should be around 15°. When installing surge arresters, it is best to use a synthetic insulating zinc oxide surge arrester MOA. Compared with the porcelain casing arrester, it has the characteristics of safety, pollution resistance, good heat dissipation performance, light weight, etc., large through-flow capacity, and strong ability to absorb excess voltage and energy. , but also can be made with a gap or no gap arrester, high lightning resistance level. At the same time, in order to facilitate the installation on the tower, the use of line arrester for flip-up, such as U-rings and towers with suspension connection. By strengthening the line insulation to avoid lightning, you can increase the number of strings of insulators on the tower. In 35KV and below lines, porcelain cross arm can be used to reduce the tripping rate of lightning strikes. Using poor insulation for lightning protection, one insulator can be added to each of the two phases below. In regions where lightning strike activity is intense, the overhead lines above 35KV can effectively increase the lightning resistance level of the line by adding coupling ground lines.

For lines below 10KV, the lightning resistance level of overhead insulated conductors is generally low. The use of new types of lightning protection post insulators, anti-arc clips and other line lightning protection fixtures can increase the lightning resistance level of cables.

2 Cable fixing on the tower When laying the power cable tower, the first consideration is the selection of the power cable, which is directly related to the normal operation of the power transmission and distribution system. Since overhead lines are limited by factors such as the natural environment and passage, when selecting a power cable, the insulation, corrosion resistance, rated voltage, weight, etc. of the cable and the shockproof and windproof performance of the tower should be fully taken into consideration. In transmission and distribution lines, the general rated voltage is relatively large, so generally used is a high-reliability loop power cable, the specific use of cross-linked polyethylene insulated copper core power cable.

The fixing of the power cable on the tower is actually the fixing of the cable protection pipe on the tower. The cable fixing method is rigid and flexible. In cable fixing, the cable protection tube must meet certain mechanical strength and durability, and the inner wall should be smooth without burrs. In general, for the requirements of the cable bracket, if it is a single-phase operating current is not more than 1000A AC cable, should use steel bracket, if it is greater than 1000A large-section cable, should use stainless steel, aluminum alloy and other non-magnetic bracket. Terminals and cable connection points for high-voltage cables of 35 kV or higher should have telescopic joints. Rigidity should be given or serpentines should be laid in appropriate lengths. At the terminals, joints and turns, there shall be no less than one rigid fixation on the cable immediately adjacent to the fixed part, and no less than two rigid fixations on the sloped or vertical part; each of the cables shall be laid serpentinely. A pitch part should be flexibly fixed; a serpentine transition should be rigidly fixed when it is converted into a transitional part laid on a straight line.

When the power cable is fixed by the bracket, the required length of the cable bracket is not the same due to the different positions of the tower. Different parts of the fixed cable and the protective tube have different outer diameter dimensions, different shapes, and the size of the opening on the bracket is also different. They must be matched with each other, and if necessary, cable protection hoops should be used to ensure that the cable is secure and reliable. In the actual project, according to the actual situation, choose a cable bracket that is both strong and light, with less deflection, and strengthen the fixing of the cable on the tower.

3 The main function of the design and processing fixture of the tower fixture is to fix the cable and the lightning protection equipment on the tower. The fixture of the tower mainly includes the lightning protection equipment assembly fixture and the cable and the protection tube bracket fixture. At present, the structures of power cable towers for power transmission and distribution lines are increasingly complex, mainly in the form of angle steel and plate assembly welding. This has also brought certain challenges to the design and processing of iron tower fixtures. Therefore, in the design of the tower fixture, it is necessary to fully consider the fixture type, specifications, bearing capacity, bending force, and the convenience of the line transformation and overhaul. When the fixture is being processed, scientific inspections must be conducted to create a special angle control template and strict processing techniques are required to achieve the design accuracy.

In order to facilitate the installation on the tower, the lightning arrester generally adopts a flip-type method. The arrester fittings are generally suspended and fixed under the crossbar of the iron tower. Therefore, when designing the lightning arrester tower fixture, it is necessary to consider the angle iron of the iron tower crossbar at the fixed location and Fixture hole reservation. At the same time, according to the actual situation, it is necessary to properly add reinforcing plates to enhance the bending bearing capacity of the fixture.

Because the cable and the protection tube bracket are fixed on the main material angle iron of the tower tower, the angle of the main material of the tower is different in different positions. Therefore, when designing the tower fixture, it is necessary to fully consider this point. Fixture size is not the same. At the same time taking into account the performance of the tower bearing and wind and earthquake resistance, the material and weight of the bracket must be fully taken into account. Lightweight and corrosion resistant materials should be selected for design and processing.

For the erection of the power cable on the power transmission and distribution line tower, fully consider the structure and characteristics of the tower itself, select the type of power cable that best meets the actual needs, and pay attention to the selection and installation of lightning protection equipment, and carry out power cable fixing and fixture design. When selecting and selecting, the corrosion resistance of each component must be taken into consideration, and scientific selection and scientific installation should be conducted to ensure the safety and reliability of the cable laying process and results on the tower.

Cui Jun, Wang Qinghua, Ma Xuelian, Wang Lizhen. The power cable is erected under the lead of the transmission and distribution line tower.

Inner Mongolia Petrochemical, 2010. Zhao Shiyu. Discussion on Lightning Protection Measures for Overhead Power Lines . Modern Economic Information, 2009. Yang Hongyu. Elementary Discussion on Laying Mode of Distribution Overhead Power Lines . China Science and Technology Expo, 2009. Ni Jianping. Application of High Voltage Cable Transmission Line in Power System . China Science and Technology Expo, 2009. Li Wenbin. Analysis of Several Ways of Leading Down Conversion Cable by 110KV High Voltage Overhead Line . Science and Technology, 2009. Yin Dengzhi, Jiang Baoguo. Discussion on the Processing Method of Angle Lines for Combined Wire Hanging of Ultra High Voltage Transmission Towers . Silicon Valley, 2009.71994-2015 China AcademicournalElectronic