The 21st century is the high-speed development information age, there are optical communication projects everywhere, and optical cables have become more and more popular of modern communication and power engineering. However, expect the interruption of optical cables, another problem is that the cables are exposed to thunderstorms. There may be a phenomenon of being struck by lightning. To ensure the normal operation of the fiber cable, we will simply analyze how the cable is protected against lightning strikes.
Many people believe that the optical fiber is made of non-metallic materials, and it is put in a loose tube made of polyester material. It transmits optical signals, not electromagnetic signals, so it is basically not struck by lightning. However, in the power engineering projects, we use optical cables with metal materials as strength member. Fibers are the core part of optical cables, and optical fibers cable also includes parts of protection components. FO cables including overhead optical cables, pipeline optical cables, direct buried underground cable or flame retardant mining cable, they are all affected by the external environment, such as stretching, bending, impact, high and low temperatures, rain and snow, ice and mud, and so on . In order to ensure the normal use and service life of optical cables, we usually make optical cables with metal armoring or steel wire reinforcing cores to make sure it can be used in various environments. Therefore, safety measures must be taken according to the site conditions and the local climate environment of the optical cable installation.
1, according to lightning environment to choose fiber optic cable
For those areas where lightning is frequent, optical cables with high-strength dielectrics and better lightning protection is the first choice. At the same time, it can also reduce the loss and try to ensure that the optical cable is not damaged by lightning strike through.
2, metal sheath grounding
Make the metal sheath of directly buried cable contacted to the ground at the joint closure places, this forming a multi-point repeated grounding mode. This helps prevent lightning strikes. In addition, cable metal sheath is connected with ground at the end of each cable via lightning arrester.
3, install lightning rod antenna
In lightning areas, selecting the appropriate optical cable is not enough, generally we will use the method of installing a lightning rod antenna to avoid lightning. The principle of lightning protection of the lightning rod antenna is the same as that of common lightning protection. The install location of the lightning rod antenna is is very important, in order to avoid destroying underground cable when lightning entering the ground, the rod antenna position must be away from the position of the optical cable more than 20 meters.
4, overhead cable insulation and grounding
For aerial installation cable, because the steel messenger is close to the optical cable and they’re connected through the hook, when the steel messenger is struck by lightning, the cable will be burned due to power discharge. Therefore, it is necessary to use insulated ropes to bundle the cable and hanging steel wire. And the hanging steel wire should be contacted with ground. The hanging wire with two points grounding or multi-point (interval) grounding is with the magnetic shielding effect of the overhead ground wire, which can reduce the possibility and damage of the lightning strike.
With the progress of China’s industrial, the scientific research and technology of China’s electric and optical cable manufacturers have been greatly improved. Great achievements have also been made in the research of cable lightning protection. However, we still have to pay attention to the lightning strikes when installing optical fiber cables and take appropriate measures to prev
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