At present, the probability of OPGW being struck by lightning has increased, so it is very important to improve the lightning resistance level of OPGW. Measures to improve lightning tolerance include:
(1) Use a good conductor ground wire with good matching ability with OPGW as much as possible to increase the shunt capacity to protect OPGW; minimize the grounding resistance of the tower and erect coupling ground wires, and properly unbalance the insulation for double-circuit lines on the same tower technology to reduce the probability of simultaneous lightning tripping of double circuit lines.
(2) In areas with strong lightning activities, high soil resistivity, and complex terrain, it is difficult to use methods such as reducing the grounding resistance of towers, increasing the number of insulators, and unbalanced insulation systems, etc., you can consider using line arresters to reduce the damage of lightning strikes . From the OPGW structural design to improve the lightning resistance capability, the following improvements can be made:
1. A certain air gap is designed between the outer strands and the inner strands, which is conducive to the rapid dissipation of heat generated by high temperature lightning strikes, preventing heat from being transmitted from the outer strands to the inner strands and optical fibers, and preventing damage to the optical fibers. cause communication interruption.
2. The material of the outer layer strands should be aluminum-clad steel wire with good electrical conductivity. The melting point of steel is high, and it is not easy to fuse under the high temperature of the arc. The aluminum-clad steel wire has high mechanical strength.
3. In order to increase the ratio of aluminum to steel, aluminum clad steel with higher conductivity is used to thicken the aluminum layer thickness of the outer aluminum clad steel wire, so that more energy can be absorbed when the aluminum melts, and the inner steel wire can be protected to maintain the strength of the strand. the required strength of the line. In this way, aluminum alloy can be used as little as possible, and the melting point of the entire OPGW can be increased.
4. While satisfying the requirement of the outer diameter of the entire OPGW, try to use a larger diameter outer strand, and reduce the probability of strand breakage by increasing the cross section of the strand. Experts suggest that AA (3.0mm) or ACS (2.5mm) monofilament with larger outer diameter should be considered in the strong lightning strike area, and the diameter of the outer metal monofilament should not be too small in the weak lightning strike area. (5) When designing the OPGW structure, it is generally considered that the diameter of the inner monofilament is greater than or equal to the diameter of the outer monofilament. In order to improve the lightning resistance level, it can be designed so that the diameter of the outer monofilament is larger than the diameter of the inner monofilament.