The hottest power system special optical cable

2022-08-12
  • Detail

Abstract: ADSS (all dielectric self support) is a non-metallic special optical cable developed to meet the requirements of power system. China's power system began to be applied in the mid-1990s, and has developed rapidly since then. It is the most widely used special optical cable in China's power system at present. Optical power grounded cable OPGW (optical power grounded waveguide), also known as optical fiber overhead ground wire, is an optical fiber unit for communication in the ground wire of power transmission line

key words: ADSS OP constitutes an efficient platform GW special optical cables. At present, the power special optical cables that are widely used mainly include ADSS and OPGW. 1. Metal free self-supporting optical cable (ADSS optical cable) ADSS (all dielectric self support) is a non-metallic special optical cable developed to meet the requirements of power system. China's power system began to be applied in the mid-1990s, and has developed rapidly since then. It is the most widely used special optical cable in China's power system at present. 1.1 characteristics of ADSS optical cable ADSS is developed on the basis of "8" shaped self-supporting optical cable. It is both completely non-metallic and self-supporting. High strength aramid yarn with high elastic modulus is used as tensile component in manufacturing. Aramid yarn has high elastic modulus, light weight, negative expansion coefficient, bulletproof ability and small optical cable expansion rate. At the same time, the geometric size of the optical cable is small, and the cable weight is only one third of that of the ordinary optical cable. It can be directly hung on the appropriate position of the power tower. The additional load added to the tower is very small, and the maximum span can reach 1500m. Its outer sheath is treated by neutral ionization impregnation, so that the optical cable has strong electric corrosion resistance, which can ensure the service life of the optical cable in strong electric field; The optical cable is made of non-metallic materials with good insulation performance, which can avoid lightning strike, and will not affect the normal operation of the optical cable in case of power line failure; Using the existing power poles and towers, the construction can be carried out without power failure and erected on the same pole as the power line, which can reduce the project cost; The operating temperature range is -40 ~ +70 ℃. 1.2 special problems that should be paid attention to when using ADSS optical cable. Using ADSS optical cable in power system has many advantages. However, according to many years of operation experience and research findings of ADSS optical cable, in addition to considering the electric field strength of the cable hanging point and the stress on the tower, measures should also be taken to reduce the damage caused to ADSS optical cable by the following two factors. (1) "Dry charged" discharge phenomenon: under the action of air pollution and rain, the surface of optical cables will form a pollution layer, which will generate leakage current and heat the pollution layer in an uneven electric field. Due to the uneven distribution of the fouling layer along the surface, the heating of the fouling layer by the leakage current is also unbalanced. Where the current density is the largest and the pollution layer is the thinnest, the water evaporates and dries rapidly, the resistance increases, and the voltage distribution along the surface will change accordingly. Most of the voltage will fall on this part of the NJS change experimental machine. As a result, spark discharge channels will appear in this part, forming a discharge arc. If the leakage current further increases, the arc will gradually lengthen and develop into flashover along the surface of the optical cable, which will burn and carbonize the outer sheath of the optical cable, and then damage the optical cable. At the connection of light relative to SBR, NBR, Cr and other foamed products near the tower, the distribution of electric field voltage changes the most. Due to the effect of gravity and sag, the pollution layer is the most uneven, so it is the most prone to discharge. (2) "Whip" phenomenon of Conductor: under the action of wind, the conductor will swing and hit the optical cable. Because there is a dirty layer, humidity, etc. on the surface of the optical cable, when the conductor contacts the dirty layer medium on the surface of the optical cable, it will produce discharge and burn the surface of the optical cable, which can cause burning of the optical cable in serious cases. 1.3 problems to be considered in the engineering design of ADSS optical cable (1) choose the place with low electric field strength (≤ 25kV) as the hanging point of optical cable. During the project design, the optical cable manufacturer shall be informed of the line data (line voltage level, circuit number, wire arrangement, tower structure, routing parameters, wire parameters, etc.), line environment data (atmospheric temperature range, maximum wind speed, icing thickness, pollution degree, etc.) and the number of optical fiber cores, so that the optical cable manufacturer can make a spatial potential distribution map according to the tower structure and propose the best hanging point of the optical cable on the tower. (2) The outer sheath material of the optical cable shall be selected according to the electric field strength of the optical cable. When the space potential is ≤ 12kV, the outer sheath of optical cable adopts black high-density polyethylene outer sheath (HDPE), which generally occurs in 110kV and below lines. When the space potential is 12 ~ 25kV, the outer sheath of optical cable adopts black high-density anti electric trace outer sheath (at), which generally occurs in lines above 110kV. (3) In heavily polluted areas, special treatment is required for optical cables to reduce the formation of surface pollution layer. Route selection should try to avoid salt fog polluted areas. (4) According to the temperature characteristics and operating conditions of wires and optical cables, the hanging points and sags of optical cables shall be reasonably determined to avoid the phenomenon of "whipping" of wires on optical cables as far as possible. At the same time, the minimum vertical distance and crossing distance between ADSS optical cable and other buildings, trees and power lines should also be considered, The safety distance requirements for various situations are as follows: for residential areas> 6m for non residential areas> 5.5m for crossing the roof of houses> 1m for crossing the top of trees> 1.5m for crossing the communication line> 1m for crossing the highway> 6m for crossing the building at the maximum wind deviation> 1m for crossing the 10kV power line> 2m for crossing the 35kV Power Line> 3M for crossing the low voltage line> 1m for crossing the iron The crossing distance of the road is more than 7.5m, and the distance from the top of the mast of the opposite ship is more than 1m (5). In order to facilitate installation and maintenance, the joint position of the ADSS optical cable must fall on the tension tower through the distribution panel. 2 overhead ground wire composite optical cable (OPGW) ground wire composite optical cable OPGW (optical power grounded waveguide), also known as optical fiber overhead ground wire, is an optical fiber single that contains credit in the ground wire of power transmission lines. China's material technology research level is still relatively high. It has two functions: first, as the lightning protection line of transmission line, it provides shielding protection against lightning discharge of transmission line; Second, through the optical fiber compounded in the ground wire, as the medium for transmitting optical signals, audio and video can be transmitted

Copyright © 2011 JIN SHI