The Lightning Protection Measures For Outdoor Optical Fiber Cables

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 outdoor optical fiber cable also has good protection performance. The metal components in the optical cable have a high insulation value to the ground, and the lightning current is not easy to enter the optical cable. However, because the optical cable has a strengthening core, especially the direct-buried optical cable has an armor layer, the optical cable may also be burned or damaged when the optical cable line is struck by lightning. Let me explain in detail the main measures for lightning protection of optical cables and optical fibers in the construction of integrated wiring projects.

Measure 1. Lightning protection for direct-type outdoor fiber optic cable lines:

① In the local grounding mode, 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 relay section remain connected. ②According to the provisions of YDJ14-91, the 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 It can avoid the lightning current in the ground being introduced into the optical cable by the grounding device due to the difference in the impedance of the ground loop between the lightning protection drain line and the metal component of the optical cable.

Measure 2. For overhead optical cables:

The overhead suspension wires should be electrically connected and grounded every 2km. When grounding, it 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.