With the development of the network, optical fiber is used as a medium for transmitting data in the integrated wiring system, because it has the advantages of high transmission rate and long distance, it is more and more used by people. As we all know, the optical fiber is non-conductive and can be protected from the impact current. The optical cable also has good protection performance. The direct buried optical cable has an armor layer, so when the optical cable line is struck by lightning, the optical cable can also be burned or damaged. Here I will explain in detail the main measures for lightning protection of optical cables and optical fibers in the construction of integrated wiring projects.
Measure 1. For the lightning protection of direct-type optical cable lines: ① In the local grounding method, the metal parts in the optical cable should be connected at the joints, so that the reinforced core, moisture-proof layer, and armored layer of the optical cable in the trunk section remain connected. ②The moisture-proof layer, armor layer and reinforcing core at the joint of the optical cable should be electrically disconnected, and they are not grounded, and they are insulated from the ground, which can avoid the accumulation of induced lightning current in the optical cable, and also avoid the discharge due to lightning protection. The ground loop impedance difference between the wire and the metal components of the optical cable causes the lightning current in the ground to be introduced into the optical cable by the grounding device.
Measure 2. For overhead optical cables: overhead suspension wires should be electrically connected and grounded every 2km. When grounding, they can be grounded directly or through a suitable surge protection device. In this way, the suspension wire has the protective effect of the overhead ground wire.
Measure 3. After the optical cable enters the terminal box, the terminal box should be grounded. After the lightning current enters the metal layer of the optical cable, the grounding of the terminal box can quickly release the lightning current and play a protective role. The directly buried optical cable has an armored layer and a reinforced core, and the outer sheath is a PE (polyethylene) sheath, which can effectively prevent corrosion and rodent bites.