①Loss caused by the installation of irregular optical cables. The layer-twisted loose-tube structure optical cable is prone to such losses. The reason is that one is that multiple loose tubes are twisted with each other at the upper shelf of the optical cable; When the port is opened, the loose tube will be bent sharply; the third is that the metal reinforcing member and the optical fiber loose tube will be dislocated up and down when the optical cable is put on the shelf. These factors cause increased losses.

② Loss caused by poor thermal shrinkage and thermal melt protection. The main reasons are: one is the quality problem of the hot-melt protection tube itself, distortion occurs after hot-melting, and bubbles are generated; the other is that when the heater of the welding machine is heated, the heating parameters are improperly set, resulting in the deformation of the hot-melt protection tube or the generation of bubbles ; The third is that the heat shrinkable tube is not clean, there is dust or gravel, and the connection point is damaged during hot melting, resulting in increased loss.

③The loss caused by the non-standard construction of the direct buried optical cable. The reason is that one is that the optical cable is not buried deep enough and is damaged after being crushed by a load-bearing object; the other is that the optical cable is not properly routed, and the optical cable is subjected to external forces beyond its allowable load range due to changes in the environment and terrain; the third is the bottom of the optical cable trench. Uneven, the optical cable appears arched and hung, and there is residual stress after backfilling; the fourth is that the outer sheath of the optical cable is damaged by other reasons and water enters, resulting in hydrogen loss.