What are the causes of cable failure?

1, Cable routing line length due to the physical characteristics of the cable itself and the non-uniformity of the production process, so that the propagation of the optical signal at all times are diffused and absorbed. When the cable link is too long, it will cause the overall attenuation of the optical signal of the whole link exceeds the requirements of the network planning. The attenuation of the optical signal is too large, and the communication effect will be reduced. 

2, The cable placed bending Angle is too large cable bending failure and compression failure of its essence is due to the cable deformation resulting in the process of light transmission can not meet the total reflection generated. Fiber has certain bendability, but when the fiber is bent to a certain Angle, it will cause the change of optical signal propagation direction in the cable, resulting in bending decay. This requires that in the construction of wiring, special attention should be paid to reserving sufficient Angle for the line. 

3, Optical cable compression or fracture this is the most prone to failure of optical cable, optical fiber by external factors or natural disasters, the cause of small irregular bending and even fracture, when the fracture occurs in the joint box or the cable inside, from the appearance is unable to find the breakpoint, but in the fiber fracture point will change the refractive index, or even form reflection loss, The transmission signal quality of optical fiber deteriorates. At this time, use OTDR cable tester to detect the reflection peak way to find the fiber internal bending failure. 

4, Optical fiber connector construction fusion failure In the process of cable laying, often use the optical fiber fusion machine will melt two sections of optical fiber into a. Due to the fiber optic cable core layer of glass fiber welding, so in the construction site welding process according to the type of cable to use the correct welding machine, due to the operation does not meet the construction specifications and changes in the construction environment, easy to make the fiber is contaminated with dirt, resulting in the fusion process mixed with impurities, resulting in the communication quality of the whole link decline. 

5, The core line diameter of optical fiber laying is different often use a variety of active connection laying, such as flange connection, often used in the building of the computer network laying. The loss of active connection is generally low, but the end face of the fiber or the end face of the flange is not clean when the active connection is made. The diameter of the core fiber is different and the joint is lax, which will greatly increase the joint loss. The failure of core diameter mismatch can be found through OTDR or dual-terminal power testing. It should be noted that single-mode fiber and multi-mode fiber have completely different transmission mode, wavelength and decay mode except the diameter of the core fiber, so they cannot be mixed. 

6, Pollution of optical fiber connectors. Pollution of pigtail connectors and dampness of jumper are the main causes of optical cable failures. Especially in the indoor network there are a lot of short fiber, and a variety of network switching equipment, fiber connector plug, flange replacement, conversion is very frequent. During operation, the optical fiber connector may become dirty due to excessive dust, insertion and removal loss, or finger touch. As a result, the optical path cannot be switched on or the optical attenuation is too large. Alcohol cotton should be used for cleaning. Poor polishing of joints 

7,Poor polishing of joints is also one of the main faults of optical fiber links. In the real physical environment, there is no ideal fiber section, there are some ups and downs or inclined planes. When the light in the optical cable link encounters such a section, the diffuse scattering and reflection of light due to the irregular junction surface will greatly increase the attenuation of light. On the curve of the OTDR tester, the attenuation area of the poorly polished section is much larger than that of the normal section. 

8,Cable connector point contact fault connector poor contact mainly appears in ODF cable distribution box and optical switch. The main reason is that the construction operation does not meet the standards or the quality of the connecting equipment, or the connection flange failure, resulting in the optical fiber connector seal is not strict, resulting in light reflection loss and leakage attenuation. Excessive use of optical fiber connectors will lead to a significant decline in cable transmission quality. To sum up, the use of optical cable has many advantages, but its physical characteristics make the optical fiber communication has trouble potential. External factors and natural disasters can cause cable compression or rupture; The impurity mixed in the fusion will cause the quality change of the optical path. Core wire diameter is different; The fiber section pollution and poor polishing will cause the change of optical transmission direction. The precision of optical fiber communication makes optical fiber fault difficult to be detected by the naked eye, which requires that in the process of optical fiber wiring, unnecessary optical fiber fault caused by human causes should be avoided as far as possible.