Fiber optic maintenance for 20 years, value file sorting (I)
Fiber optic maintenance is a seemingly tedious but actually more tedious work, it involves different external environment, different areas will also have a variety of natural environmental factors.I once learned about an operation and maintenance worker in a sudden situation, even in the cold night to the site of the fault for timely repair work.
Therefore, in the maintenance of a pile of heavy and complicated information comb some some information about the optical fiber maintenance, main contents involved in line fault reason analysis, test methods, exclusion principle, repair process, and so on aspects to restore a more realistic scenarios, learned directly, if there are any optical maintenance emergency should be how to deal with.
When exploring the operation and maintenance of optical fiber, first of all, we need to know what kind of faults will occur in optical fiber. In fact, there are many reasons for optical fiber faults. Through the summary, predecessors mainly obtained the following failures
① One or a few fiber original connection point loss increases, broken fiber
② One or several optical fiber attenuation curve appears step
③ The decay step of the original connection point is lengthened horizontally
④ All the fiber optic block
When encountering these common fault phenomena, the operation and maintenance staff with rich experience may have a general cognition, such as the fault may be caused by a problem in the connector box, the fault may be the sprench of the optical fiber mechanical force, which makes part of the optical fiber stressed but not yet disconnected.But this is only a general empirical judgment. To know the situation more accurately, we need to know the location of the fault point first. At this time, we need to use OTDR to test the fault cable route in the machine room.
Through the OTDR curve, we can preliminarily determine the cause of the fault. Generally speaking, for the cable fault not caused by external forces, there are more problems in the connector box. The reasons for fiber breakage or attenuation increase in the connector box are as follows:
(1) loose fiber in the capacity fiber disk, resulting in the fiber springs in the capacity fiber disk edge or screw on the disk is extruded, serious injury, pressure broken fiber
(2) when the residual fibers in the connector box are put in storage, the local bending radius is too small or the fiber is twisted seriously, resulting in large bending loss and static fatigue. The change is not obvious in the 1310 wavelength test, while the loss of the connector in the 1550nm wavelength test is significantly increased.
(3)When making the end face of the optical fiber, the bare fiber is too long or the position of the optical fiber protection is not appropriate when heating the heat shrink protection tube, which results in the fracture of the bare fiber outside the protection tube and when the connector box is acted on by external forces.
(4)Naked fiber is damaged when stripping the coating layer, the damage expands after a long time, the joint loss with the increase, serious will cause broken fiber
(5) Because the cable is not fixed tight, optical fiber internal or external forces due to the effect of displacement resulting in fiber fiber distortion or bending change caused by fiber loss
(6) connector box has the water, winter ice led to the increase of fiber loss, and even break fiber
In addition to non-external factors, what other factors can cause cable failure?They are external forces, natural disasters, cable defects and man-made factors.
Causes of optical cable line fault can be divided into four categories: external factors, natural disasters, optical cable defects and human factors, to understand these factors, in the future investigation of the heart will be more known.
External factors: to deal with the fault of excavator excavation, the pipeline cable due to open the fault point near the manual well to check whether the cable is damaged in the manual well, and two-way test interrupted the cable;When dealing with the vehicle hang up fault, should first of all fault point cable to both sides of the test, to confirm the number of fiber optic cable block, and then again targeted processing
Natural disasters: rat bite and bird peck, fire, flood, wind, ice, lightning, electric shock
Optical fiber's own defects (highlight)
As the fiber is made of glass and plastic fibers, it is relatively fragile. Static fatigue will occur as time goes by, and the aging of the fiber will lead to natural fiber breakage. Or the connector box water, resulting in increased fiber loss, or even fiber breakage; And the temperature is too low will lead to water and ice in the connector box, cable sheath longitudinal contraction, pressure on the optical fiber to produce micro-bending attenuation increase or optical fiber interruption, temperature is too high, and easy to make cable sheath and other protective materials loss affect the characteristics of the optical fiber.
Human factors: human faults caused by technical personnel during maintenance, installation and other activities, such as: the fiber is scratched when the fiber is connected, and the bending radius of the fiber is too small; Mistakenly cut the running cable while cutting it. When the fiber is connected, the connection is not firm, the connection box is sealed to strengthen the fixed core is not tight, and so on.
It can be seen from these factors that the fiber itself is also very fragile, such as easy to break fiber aging, and the temperature will also cause a certain degree of influence.In our construction operation and maintenance, if we are not skilled in cold connection, hot melt, will also bring about a variety of problems. Even when the fiber optic package is well connected, there will be a lot of problems. So the road of communication is not easy to walk, need to overcome a lot of difficulties.
