The design of transmission lines must implement the national basic construction policy and technical and economic policies, and be safe, reliable, economical and applicable, in line with national conditions. Transmission line design must proceed from reality, combine with regional characteristics, actively and cautiously promote the use of advanced technologies such as mature new materials and new structures. This paper briefly introduces the design, construction organization and safety management of 1 10kV transmission line, as well as matters needing attention in the construction process. Line design; Construction Management 1 Transmission Line Routing When selecting transmission line routing, factors such as construction, operation, traffic conditions and line length should be comprehensively considered, and schemes should be compared to be safe, reliable, economical and reasonable. The route selection should try to avoid heavy ice areas, bad geological areas, virgin forest areas and other areas that seriously affect the safe operation. Interaction with neighboring facilities such as radio stations, airports and weak current lines. Should be considered. The incoming and outgoing lines of large power plants and hub substations should be planned in a unified way according to the overall layout of power plants and substations. For the planned second ring road or multi-ring road line, the same iron tower should be erected on a narrow path. The length of tensioning section should not be greater than 5 km. Split conductor line should not be greater than10 km; ; Split conductor and above lines shall not exceed 20km. If the operation and construction conditions permit, the length of the tension section can be appropriately extended. When the working conditions in mountainous areas or heavy ice areas are poor, such as the height difference or span difference, the length of the tension section should be appropriately reduced. For a large span of 700 meters, the drop between lines is 7 meters. For the control calculation of various spans below 700m: (1), where: d-horizontal distance of conductor, MLA-length of suspension insulator, mu-line voltage, kvf-maximum radian of conductor, and m-span transmission line, the path scheme shall be determined through comprehensive technical and economic comparison. Generally, long-span towers are installed. Considering the influence of river bank erosion change in 30 ~ 50 years. 2. In addition to the economic current density, the conductor section of transmission line should be checked according to corona and radio interference. The section of large span conductor should be selected according to the allowable current carrying capacity, and should be determined through technical and economic comparison. If the current national standard of steel-cored aluminum stranded wire is adopted in the area with an altitude of less than 1000m, and the outer diameter of the wire is not less than 9.6mm, it is not necessary to check the corona. When checking the allowable current carrying capacity of the conductor, the allowable temperature of the conductor: +70℃(+90℃ can be used for large span) can be used for steel-core aluminum stranded wire; Steel-core aluminum-clad steel strand (including aluminum-clad steel strand) can adopt +80℃ (long-span steel strand adopts+100℃), or it can be decided through experiments; Galvanized steel strand can be+125℃. The ambient temperature shall be the highest average temperature in the highest temperature month. The wind speed should be 0.5m/s (long span is 0.6m/s); The solar radiation power density should be 0. 1W/cm2. The design safety factor of conductor and ground wire (hereinafter referred to as conductor and ground wire) shall not be less than 2.5. The design safety factor of grounding wire should be greater than that of conductor. For wires and ground wires erected on pulleys, additional tension caused by local bending of suspension points should also be calculated. Under the condition of rare wind speed or rare icing weather, the maximum pulling force at the lowest point of sag should not exceed 60% of the pulling force. The maximum pulling force of the suspension point should not exceed 66% of the pulling force. Grounding wire should meet the requirements of electrical and mechanical conditions, and galvanized steel strand or composite steel strand can be selected. When the short circuit is thermally stable, the allowable temperature of the grounding wire is +200℃. Steel core aluminum-clad steel strand (including aluminum-clad steel strand) can be used at +300℃; Galvanized steel strand can be used at +400℃. The calculation time and the corresponding short-circuit current value should be determined according to the system conditions. Conductor sag value is based on LGJ-70 conductor, K=2.5, and air temperature +400℃. R = 10m/s, and the wind speed is 25m/s. Check the sag calculation table to get the result. When the block spacing is more than 500m and less than 7000m. At 650m, f = 42.30m; At 700m, f = 45.86 m, the line adopts three different specifications of iron cross arms, single-pole single-line cross arm and double-pole 6 m long double cross arm cross line. The cement pole chassis is 800×800×l00mm. The stay wire chassis is 600×300×200mm and 800×400×200mm. If it is a muddy paddy field, the foundation is reinforced with concrete. 3. Insulation coordination between lightning protection and grounding 1 10kV transmission lines should make the lines run safely and reliably under various conditions such as power frequency voltage, operating overvoltage and lightning overvoltage. The altitude is 65438. The number of insulator pieces of suspension insulator string required for operating overvoltage and lightning overvoltage should not be less than 7 pieces. The number of insulator pieces of tensile insulator string should be increased on the basis of 7 pieces. In order to maintain the lightning-proof level of the tower, for every increase of 10m in the height of the tower with the ground wire exceeding 40m, the number of insulators with the same value should be increased by 1 0, and the total height should exceed 100. The number of insulators shall be calculated and determined according to operating experience. When the number of insulators is increased due to the tower, the minimum gap of lightning overvoltage should also be increased accordingly. The lightning protection design of transmission lines should be based on the voltage, load nature and system operation mode of the lines, combined with the operation experience of local existing lines, the intensity of lightning activities in the area, the topographic features and soil resistivity, and after calculating the lightning withstand level, reasonable lightning protection methods should be adopted through technical and economic comparison. 1 10kV transmission line shall be equipped with grounding wire. In areas where the annual average number of thunderstorm days does not exceed 15 or the operation experience proves that the lightning activity is slight, the grounding wire may not be installed. For transmission lines without grounding wire, 1 ~ 2 km grounding wire should be installed at the incoming line of substation or power plant. For mountain 1 10kV single-wire transmission lines, the protective angle of the ground wire on the tower to the opposite conductor should be about 25. The distance between two grounding wires on the tower should not exceed 5 times the vertical distance between the grounding wire and the conductor. At the center of general span, the distance between conductor and ground wire shall be checked according to the following formula (calculation condition: air temperature+15℃, no wind), and s ≥ 0.066. The tower with grounding wire should be grounded. When the thunderstorm season is dry, the power frequency grounding resistance of each tower without grounding wire should not be greater than 15 ohm. Grounding reinforced concrete poles and towers of neutral point indirect grounding system in residential areas should be grounded, and their grounding resistance should not exceed 30 Ω. The iron cross arm, grounding wire bracket, ladder and other iron accessories of reinforced concrete poles should be reliably and electrically connected with the grounding down lead. Reinforced concrete poles should be used as grounding downlead. There should be reliable electrical connection between the steel bar and the grounding nut, iron cross arm or grounding wire bracket. Galvanized steel strand can be used for external grounding down lead, and its cross section should be selected according to the requirements of thermal stability, and should not be less than 25mm2. The section of the lead-out wire of the grounding body shall not be less than 50mm2, and the thermal stability shall be checked. The surface of the lead-out wire should be effectively treated with anti-corrosion, such as hot dip galvanizing. For transmission lines crossing cultivated land, the grounding body should be buried below the tillage depth. Grounding bodies located in residential areas and paddy fields should be laid in a ring shape. When using insulated grounding wire, the electromagnetic induced voltage and current on the grounding wire should be limited, and a reliable grounding wire gap should be selected to ensure the safe operation of the insulated grounding wire. Grounding leads and grounding devices that supply power to insulated grounding wires for a long time must be checked for thermal stability and personal safety protection measures. 4. Foundation construction organization 1 10KV power transmission and transformation construction project is complex and diverse according to the terrain and engineering, and the construction has the characteristics of many points, long lines and wide areas. More points are due to the complexity and many operating points in the construction; Line length refers to long line length, and area width refers to a wide area, including new construction, expansion, reconstruction and rush construction; Construction is mobile. There are national power outlets all over the country, and there are construction projects all over the country. Due to the high mobility and dispersion of construction, construction management is difficult and coordination is poor, and construction personnel, tools and equipment frequently flow between construction projects. The construction is complicated, because it is outdoor operation, and the weather change has a great influence on the construction. Poor outdoor working conditions, changing geological and hydrological conditions, harsh geographical conditions and complicated crossing. To sum up, the power transmission and transformation construction project is a high-intensity and high-risk operation in the construction industry, so strengthening the construction organization in the whole construction process is the premise to ensure safe and effective construction. (1) on-site inspection, get ready, check the brake device, ground anchor, fixture, wire rope. Don't loosen the cable until it is ready. (2) Closely monitor the construction joints, pay close attention to the control of cable bridge bracket and cable slide when laying cables, and stop immediately if there is any precursor out of control; (3) Ensure personal safety. If the cable falls out of control, be sure to pay attention to the cable control personnel and evacuate in advance to prevent life danger; (4) to prevent leakage, do a good job of inspection. When laying cables, you should pay attention to the fact that the cable sheath is not cut. If cutting, you should brush antirust paint on the outer steel wire of the cable to prevent corrosion and wrap it with insulating tape. Conclusion According to the characteristics of 1 100 kV power transmission and transformation construction project, the line selection, conductor design, insulation coordination, lightning protection and grounding, and basic construction organization of the power transmission and transformation construction project are discussed. A complete set of safety management system for power transmission and transformation construction projects is constructed. References: [1] GBJ 233-90, 1 10 ~ 500 kV overhead power line construction and acceptance specification [S]. [2] Gu Jijiang. 1 10 kV transmission line engineering design and construction. Feng Bingwen. Risk prediction and pre-control measures of power grid construction projects [M]. Beijing: China Electric Power Press, 2004. 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