1, ready?
(1) Check whether the design data, raw materials, construction machines and equipment are complete.
(2) Establish a high-quality construction team. This is very important, because the requirements of optical fiber construction are much stricter than those of optical fiber construction, and any negligence in construction may lead to the increase of optical fiber loss or even core breakage. ?
2. Routing engineering?
(1) Before laying the optical cable, carefully investigate the route through which the optical cable passes, understand the local road construction and planning, and try to avoid potential hazards such as potholes, threshing floors and gas stations. After the route is determined, actually measure its length to within 50 meters. When laying, natural bending and various reserved lengths should be added, and all kinds of reservations also include other special reservations such as bending in the insertion hole, reservation on the rod, reservation at both ends of the joint, and increase of horizontal radian. In order to connect the optical cable when it breaks, a certain allowance should be left every 100 meters, and the length of the allowance is generally 5% ~ 10%. Order according to the actual length, and indicate when winding. ?
(2) Draw the path construction drawing. Number the embedded poles, draw the path construction drawing, explain the number and pipeline length of each pole or underground pipeline outlet pole, and determine the length and position where the allowance is needed. This can effectively use the length of optical cable and reduce welding points as much as possible. ?
(3) The joint of two optical fibers should be located in a flat and stable place, avoiding ponds, rivers, ditches and roads, and at the exit of poles or pipelines. The overhead cable connector should be located about 0.5 ~ 1m beside the pole. This work is called "distribution". Reasonable plate matching can reduce welding points. In addition, the location of the welding point should also be indicated on the construction drawing, so that when the optical cable breaks, it is convenient for the instrument to quickly find the breakpoint for maintenance. ?
3. Optical cable laying?
(1) The mode field diameters of the same batch of optical fibers are basically the same. After the fiber is disconnected at a certain point, the mode fields at both ends can be regarded as the same, so splicing at this disconnection point can minimize the influence of the mode field diameter on the fiber welding loss. Therefore, the optical cable manufacturers are required to use the same batch of bare optical fibers for continuous production according to the required optical cable length, and number each disc in turn, indicating the A (red) end and the B (green) end respectively, and skipping numbers are not allowed. When erecting optical cables, it is necessary to arrange them according to the number in a certain routing order, and ensure that the B end of the front cable is connected with the A end of the rear cable, so as to ensure that the end-face mode field diameters of the two optical fibers are basically the same during connection and minimize the welding loss. ?
(2) Overhead cables can use 7? 2.2 mm galvanized steel strand is used as suspension wire for hanging optical cable. Messenger wire and optical cable shall be well grounded, provided with lightning protection measures, and have mechanical properties of shockproof and windproof. The horizontal and vertical distance between the overhead messenger wire and the power line should be more than 2m, the minimum height from the ground is 5m, and the minimum distance from the roof is1.5m. There are three suspension modes for overhead cables: messenger wire suspension, messenger wire winding and self-supporting. Self-supporting type does not need steel strand to hang wires, and the optical cable is drooping and bears poor wind load, so it is often hung. ?
(3) Overhead cable cloth. Because the length of the reel of the optical cable is much longer than that of the optical cable, and the length may reach several kilometers, it is limited by the allowable rated tension and bending radius, so special attention should be paid not to pull and kink during construction. In general, the allowable tension of optical cable is about 150 ~ 200 kg, the bending radius of optical cable during turning should be greater than or equal to 10 ~ 15 times of the outer diameter of optical cable, and the bending radius during construction and laying should be greater than or equal to 20 times. In order to avoid putting the optical cable in the middle of the road section, it is about 20m away from the pole, and it is erected in opposite directions. First, the first half of the optical cable is erected, and then the second half of the optical cable is put down from the tray, placed on the ground in a figure of eight, and then laid. ?
(4) When laying optical cables, it is forbidden to make small circles, bend or twist optical cables, and a certain number of walkie-talkies are equipped. The cable laying mode of "walking with the shoulder in front of the optical cable" can effectively prevent the occurrence of back-off, and pay attention to uniform stress, with the traction not exceeding 80% of the allowable cable and the instantaneous maximum traction not exceeding 100%.
In addition, when erecting, there should be a special person responsible for the corner of the optical cable or the complex terrain, and it is strictly forbidden for vehicles to crush it. Pulley trucks are used for overhead laying of optical cables, and pulleys are hung on the mast and suspension line in advance (generally one pulley is hung every 10~20m ~ 20m) to reduce the sag and tension at the upper and lower lead-in points of optical cables. Then put a traction rope between the pulleys, and tie the traction head of the optical cable with the traction rope, so that the optical cable can climb up the pole and hang on the suspension cable with a certain traction. The spacing between optical cable hooks is 40cm, and the direction of hooks on the suspension line should be consistent. Each pole should have a raised drip ditch, and the length of each optical cable should have a 3m margin at the joint to facilitate the grounding welding operation of the box, and a certain number of plates should be left every few hundred meters. ?
4. Optical cable connection?
Common optical cables are stranded, skeleton and central bundle cable. The color of fiber core is divided into Ben, orange, green, brown, gray, white, black, red, yellow, purple, pink and turquoise, which is called the full color spectrum of fiber core color. Some optical cable manufacturers use "blue" instead of a certain color in the color spectrum. Multi-core optical cable puts optical fibers of different colors in the same bundle to form a group, so there may be several bundles in a multi-core optical cable. Facing the cross section of the optical cable, the red bundle tube is regarded as the first bundle tube of the optical cable, followed by white one, white two and white three clockwise ... and the last bundle tube is the green bundle tube. The principle of optical fiber splicing should be followed: when the number of cores is equal, the corresponding colored optical fibers in the same bundle are butted; when the number of cores is different, the ones with more cores are spliced first, and then the ones with less cores are spliced.