optical cable

The optical cable consists of three parts: reinforced core and cable core, sheath and outer protective layer. There are two types of cable core structures: single core type and multi-core type. Single core type has two types: solid core type and bundle core type; There are two types of multi-core types: strip type and unit type. There are two types of outer protective layers: metal armor and non armor.

basic structure

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optical cableIt is composed of several parts such as cable core, reinforced steel wire, filling material, and sheath, as well as components such as waterproof layer, buffer layer, and insulated metal wire as needed.

optical cableIt consists of three parts: reinforced core and cable core, sheath and outer protective layer. There are two types of cable core structures: single core type and multi-core type. Single core type has two types: solid core type and bundle core type; There are two types of multi-core types: strip type and unit type. There are two types of outer protective layers: metal armor and non armor.

common sense

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1. General provisions

1．1optical cableThe bending radius should not be less thanoptical cable15 times the outer diameter should not be less than 20 times during construction.

1.2 Layoutoptical cableThe traction force should not exceedoptical cableAllow 80% of the tension. The maximum instantaneous traction force shall not exceedoptical cableAllow 100% tension. The main traction should be addedoptical cableOn the reinforcement component (core).

1．3optical cableThe traction end can be prefabricated or made on site. Directly buried or underwater armoroptical cableIt can be used as a net cover or a traction end.

1.4 To prevent torsional damage during tractionoptical cableA swivel should be added between the traction end and the traction cable.

1.5 Placementoptical cableWhen,optical cableIt must be released from above the cable reel and maintain a relaxed arc shape.optical cableDuring the laying process, there should be no twisting, and it is strictly prohibited to cause small circles, surges, or other phenomena.

1．6optical cableWhen using mechanical traction for laying, centralized traction, intermediate auxiliary traction, or dispersed traction should be selected based on factors such as traction length, terrain conditions, and traction tension.

1.7 The traction machine used for mechanical traction shall meet the following requirements:

1) The traction speed adjustment range should be 0-20 meters per minute, and the adjustment method should be stepless speed regulation;

2) The traction tension can be adjusted and has automatic stopping performance, which means that when the traction force exceeds the specified value, an alarm can be automatically issued and the traction can be stopped.

1.8 Placementoptical cableIt must be tightly organized and commanded by a dedicated person. There should be good communication methods during the traction process. Untrained personnel are prohibited from taking up their posts and working without contact tools.

1．9optical cableAfter laying, check if the optical fiber is in good condition.optical cableThe end should be sealed and moisture-proof, and should not be immersed in water.

2. Pipelineoptical cable

2.1 Pipelineoptical cableBefore laying, the following preparations should be made

1) Verify according to the designoptical cablePosition of occupied pipe holes;

2) The selected hole positions on the same route should not be changed, and when changing or turning, they should meet the requirementsoptical cableRequirements for bending radius;

3) The pipe holes used must be cleaned thoroughly.

2.2 Manual Placementoptical cableEach manhole should have someone on duty; Mechanical placementoptical cableThere should be someone on duty at the turning manhole.

2．3optical cableWhen entering a pipe hole or when the pipe bends or intersects, a guiding device or horn mouth should be used to protect the pipe and prevent damageoptical cableOuter protective layer. Can be accessed as neededoptical cableApply neutral lubricant around.

2．4optical cableThe length of a single traction is generally not greater than 1000 meters. When it is too long, 8-character segmented traction or intermediate auxiliary traction should be adopted.

2．5optical cableAfter deployment, a dedicated person should be responsible for unified command and carry out individual hole by hole operationsoptical cablePlace on the designated pallet with appropriate allowance to avoidoptical cableTightly tense.

2.6 The manhole where the joint is locatedoptical cableThe reserved length should comply with the specifications in the table; Design requirements for special reservationsoptical cableTightly tense.

2.7 Pipelineoptical cableThe protective measures should meet the following requirements:

1) Inside the manholeoptical cableSerpentine hoses (or soft plastic pipes) can be used for protection and tied onto cable trays or treated according to design requirements;

2) The pipe mouth should be blocked;

3) Inside the manholeoptical cableThere should be identification marks;

4) Anti freezing measures should be taken according to design requirements in cold regions to preventoptical cableDamage.

The laying method of plastic sub pipes in section 2.8 is basically the same asoptical cableThe same layout should also meet the following requirements:

1) When laying two or more colorless labeled sub tubes, markings should be made at the ends;

2) The ambient temperature for laying plastic sub pipes should be between -5oC and+35oC;

3) The length of continuous plastic sub pipes should not exceed 300 meters;

4) The maximum tensile force of the traction tube should not exceed the tensile strength of the pipe material, and the traction speed should be uniform;

5) The remaining length of the sub tube in the manhole should meet the design requirements;

6) Plastic pipe plugs (other methods can also be used) should be installed in the pipe holes where plastic sub pipes are inserted to secure the sub pipes;

7) There shall be no joints in the middle of the pipeline for the sub pipe;

8) After the sub pipe is laid out, the pipe mouth should be temporarily blocked; The sub pipes that are not used in this project must be installed with plugs (caps) at the pipe ends.

3. Directly buriedoptical cable

3．1optical cableThe burial depth should meet the requirements of Table 3.1.

Directly buriedoptical cableBuried depth Table 3.1

Laying location or soil quality

Burial depth (meters)

Remarks

Ordinary soil (hard soil) ≥ 1.2

Half stone (gravel soil, weathered stone) ≥ 1.0

All stone ≥ 0.8

Starting from adding 10 centimeters of fine soil to the bottom of the ditch

Flowing sand ≥ 0.8

Suburban and rural areas ≥ 1.2

Urban pedestrian walkway ≥ 1.0

Crossing railways and highways ≥ 1.2

Distance from the bottom of the ballast or road surface

Ditch, canal, pond ≥ 1.2

Farmland drainage ditch (ditch width within 1 meter)

≥0.8

3.2 Direct burialoptical cableThe distance from other buildings and underground pipelines should comply with regulatory requirements.

3.3 Laying in the same trenchoptical cableIt is not allowed to cross or overlap, and it is advisable to use separate traction and simultaneous deployment methods.

3.4 Direct burialoptical cableThe laying should meet the following requirements:

1)optical cableThe depth of the ditch should comply with regulations, and the bottom of the ditch should be flat and free of gravel; The bottom of stone and semi stone ditches should be covered with 10 centimeters thick fine soil or sandy soil;

2) When using mechanical traction, ground pulleys should be used;

3) When manually lifting and placing,optical cableThere should be no bending smaller than the specified curvature radius, as well as phenomena such as dragging the ground and pulling too tightly;

4)optical cableIt must be placed flat at the bottom of the ditch and must not be lifted or arched;

5)optical cableWhen laid on slopes with a gradient greater than 20 ° and a slope length greater than 30 meters, it is advisable to use an "S" shape for laying or take measures according to design requirements;

6) During or after the laying process, it should be checked in a timely manneroptical cableIf there is any damage to the outer skin, it should be repaired immediately; Directly buriedoptical cableAfter laying, it should be checkedoptical cableThe insulation resistance of the protective layer to the ground.

7)optical cableThe fiber optic cable and copper wire must be inspected and confirmed to meet the quality acceptance standards before the entire trench can be backfilled.

3．5optical cableThe backfill soil of the ditch shall meet the following requirements:

1) Firstly, backfill with 15cm thick crushed or fine soil. It is strictly prohibited to push stones, bricks, frozen soil, etc. into the ditch, and they should be manually leveled;

2) The backfill soil should be 10 centimeters above the ground level.

3.6 Buried typeoptical cableThe protective measures should be in accordance with the design specifications and meet the following requirements:

1)optical cableWhen the line crosses railways and highways without excavating the road surface, the pipe jacking method is adopted. The top pipe should be kept straight, and the specifications and position of the steel pipe should meet the design requirements. The position where soil is allowed to break can be protected by burying the pipe. When the top pipe or burying the protective pipe, the pipe mouth should be blocked.

2)optical cableWhen the line passes through machine cultivated roads, rural roads, urban areas, residential areas, or sections of movable land, it should be constructed according to the protection methods required by the design. inoptical cableWhen laying red bricks on top, a 20cm thick layer of crushed soil should be covered first, and then the red bricks should be laid vertically, with two pipes laid in the same trenchoptical cableRed bricks should be laid horizontally.

3)optical cableWhen the line crosses ditches, canals, and ponds with dredging and fertilizationoptical cableThe upper part should be covered with cement boards or cement sandbags for protection.

4)optical cableWhen crossing ditches and terraces over 0.8 meters (including 0.8 meters), slope protection should be carried out according to the design requirements. When crossing ditches and ridges below 0.8 meters, unless there are special design requirements, slope protection is generally not done, but it must be compacted layer by layer to restore the original state.

5)optical cableThe line passing through the termite activity area should be treated with anti termite measures according to regulations.

6)optical cableThe lightning protection measures for the line must be handled according to the design regulations. When using lightning protection drainage lines, they should beoptical cableLay a single or double drainage line 30 centimeters above; When backfill soil is excavated again due to unforeseen circumstancesoptical cableWhen laying again, it is necessary to strictly check whether the drainage line is locatedoptical cableAbove, it is strictly prohibited to have the phenomenon of inversion.

7) The laying of signage in special areas should comply with design requirements.

3.7 Reservation of Joint Pointsoptical cableIt should be properly placed in the joint pit, and the end must be sealed and moisture-proof to preventoptical cableImmersion or human damage.

3．8optical cableThe burial of line markers should meet the following requirements:

1)optical cableConnectorsoptical cableTurning points, starting and ending points of drainage lines, and laying in the same trenchoptical cableThe starting and ending pointsoptical cableSpecial reserved points, crossing points with other cables, locations crossing obstacles, and straight sections should be marked with ordinary markers every 200 meters in urban areas, and every 250 meters in suburban and long-distance areas.

2) Need to monitoroptical cableMonitoring markers should be set up at the connection points between the inner metal protective layer and the ground insulation and potential.

3) When there are usable signs, fixed signs can be used instead of markers.

4) The marker stone should be buried at a depth of 60 centimeters and excavated at a depth of 40 centimeters. The soil around the marker stone should be compacted.

5) Ordinary marker stones should be buried inoptical cableRight above. The marker stone at the joint should be buried inoptical cableOn the route of the line, the side of the marker with words should faceoptical cableThe connector. The marker stone at the turning point should be buriedoptical cableAt the intersection of the turning point of the route, the marker facesoptical cableThe side with a smaller bend angle. whenoptical cableWhen laying along the highway with a spacing of no more than 100 meters, the marker stone can face the highway.

6) The marker stone is made of solid stone or reinforced concrete, with two specifications: short marker stone is generally used in general areas, with a specification of 100 × 14 × 14 centimeters; Long marker stones with a specification of 150 × 14 × 14 centimeters are used in areas with soft soil and slopes.

7) The marker number is in regular script with white background and red (or black) lacquer, with neat font and a clean surface. The numbering should be arranged from end A to end B according to the transmission direction. Generally, a relay segment is used as an independent numbering unit.

4. Underwateroptical cable

4.1 Underwateroptical cableThe laying method should be based on the riverbed soil, river width, water depth, flow velocity, and site conditions. Different methods can be used, such as underwater excavation machine, manual excavation or flushing pump flushing groove, slow anchoring, fast towing, manual laying, etc. Regardless of the construction method used, it should meet the design requirements.

4.2 Underwateroptical cableThe burial depth should be determined according to the specific conditions of the river, such as water depth, navigation, and riverbed soil, as specified in the design documents, and should meet the following requirements:

1) Sections with a water depth of less than 8 meters (referring to the dry season): When the riverbed is unstable or the soil is soft, the burial depth should not be less than 1.5 meters; When the riverbed is stable or the soil is hard, the burial depth should not be less than 1.2 meters; Stone and semi stone riverbeds should be buried at a depth of not less than 0.5 meters;

2) Sections with a water depth exceeding 8 meters: Generallyoptical cableDirectly placed at the bottom of the river without burial, and handled according to the design requirements for special areas.

4.3 Laying underwateroptical cableShould meet the following requirements:

1) Should be controlledoptical cableLaying speed and designated position;

2) During the laying process,optical cableDo not empty the riverbed or make small circles;

3) During and after the laying process, it is necessary to monitor whether the optical fiber is in good condition, and promptly address any issues found to ensure underwater stabilityoptical cableThe quality of laying;

4) The laying length should be determined according to the retest routeoptical cableLength, usually underwateroptical cableShould extend 50 meters beyond the embankment or shore;

5) When the design specifiesoptical cableWhen laying in an arc shape at the bottom of the river, the baseline at the time of measurement should be used as a reference to lay in an arc shape upstream.

4.4 The burial depth and protection of the beach section should meet the following requirements:

1) The burial depth of the beach location should not be less than 1.5 meters. For rocky and semi rocky areas, fill the bottom of the ditch with 10-20 centimeters of fine soil or sandy soil,optical cableFill with crushed soil or sand above, compact and then fill to a height above the ground. The beach is affected by flood erosion, unstable areas, and areas where ships dockoptical cableAfter filling with crushed soil or sand above, it should be covered with cement boards or sandbags for protection.

2) The slope of the beach should be less than 30 degrees, and if it exceeds this, reinforcement measures should be taken according to the design requirements.

4.5 All underwater installationsoptical cableFor navigable rivers, areas where anchoring is prohibited should be designated according to design requirements, and waterline signs should be set up on riverbanks or embankments crossing the river section, and the following requirements should be met:

1) Water line signs should be single or double pole signs according to design requirements or river size, and should be installed at the designated position in the design before laying the water line;

2) The waterline sign should be placed in a high terrain and unobstructed area, and the front of the sign should be at an angle of 250-300 degrees to the upstream or downstream direction;

3) When the waterline sign is set in soft soil areas or buried below the specified depth, a pull line should be added, and reinforcement measures such as chassis and clamps should be added to the root of the cement pole.

5. Overheadoptical cable

5.1 Overheadoptical cableThe determination of sag should be very careful and should be taken into considerationoptical cableThe elongation rate generated during and after installation under maximum load should be less than 0.2%. In engineering, it should be based onoptical cableCalculation of structure and hanging method for overheadoptical cableSag and should be accounted foroptical cableElongation, so as to take a fixed valueoptical cableThe verticality can be guaranteedoptical cableThe elongation rate shall not exceed the specified value.

5.2 Overheadoptical cableThe placement should be pulled by pulleys, and excessive bending is not allowed during the placement process.

5.3 Layout of suspended overhead structures in medium load areas, heavy load areas, and overweight load areasoptical cableReserved space should be made on each pole, and a space should be reserved every 3-5 poles in the light load area. The reservation and protection methods can refer to Figure 5.3-1.optical cableProtective pipes should also be installed at the locations where cross hanging wires or T-shaped hanging wires are used, as shown in Figure 5.3-2.

Figure 5.3-1optical cableReserved and protected schematic diagram on the pole

Figure 5.3-2optical cableSchematic diagram of protection at the cross hanging line

5.4 Suspended overhead structureoptical cableAfter laying, it should be adjusted uniformly, and the hooking program can be adjusted according tooptical cableRefer to Table 5.4 for outer diameter selection.optical cableThe spacing between the hooks is 50 centimeters, and the allowable deviation should not exceed ± 3 centimeters. The direction of the buckle attached to the suspension line should be consistent, and the hook support plate should be complete.

Table 5.4: Selection of Hooking Programs

Hook programoptical cableOuter diameter (mm)

65 and above 32

55 25～32

45 19～24

35 13～18

25, 12 and below

5.5 Suspended overhead structureoptical cableThe introductionoptical cableThe installation method and requirements can refer to Figure 5.5.

5.6 Overheadoptical cableThe measures for preventing strong electricity and lightning should comply with the design specifications. Hanging overhead structureoptical cableWhen crossing with power lines, rubber hoses or bamboo strips should be used to insulate the steel strands.optical cableThe parts in contact with trees should be protected with rubber hoses or serpentine tubes.

Figure 5.5 cited aboveoptical cableInstallation and Protection Diagram

6. Within the bureauoptical cable

6.1 Internal Affairsoptical cableGenerally, it is led from the front hole of the bureau to the optical transceiver through the underground inlet room. Due to the complexity of routing, manual deployment is recommended. When laying, dedicated personnel should be assigned to the upper and lower corridors as well as each turning point to follow unified command for traction, and maintain consistency during tractionoptical cableIn a relaxed state, it is strictly prohibited to make small circles or dead bends.

6.2 Internal Affairsoptical cableIt should be marked for easy identification.

6.3optical cableA safe location should be selected inside the incoming room, and protective measures should be taken when in a position that is susceptible to external damage.

6.4optical cableThe cable trays and turning points (front and back) should be tied. Rubber hoses should be placed at the binding points of the upper and lower walkways or climbing walls to avoidoptical cableUnder lateral pressure.

6.5 Reserved on the end machine side according to regulationsoptical cableYou can stay in the optical transceiver room or cable entry room. Reserved with special requirementsoptical cableAdequate space should be reserved according to the design requirements.

optical cableManufacturing of

optical cableThe manufacturing process is generally divided into the following steps:

1. Fiber selection: Select fibers with excellent transmission characteristics and qualified performance.

2. Dyeing of optical fibers: Standard full spectrum chromatography should be used for identification, requiring no color fading or migration at high temperatures.

3. Secondary extrusion: Select plastic with high elastic modulus and low linear expansion coefficient to extrude into a certain size of tube, and insert the optical fiber into it and fill it with moisture-proof materialThe gel of water shall be stored for several days (not less than two days).

4.optical cableTwisting: Twist several extruded optical fibers together with reinforcement units.

5. Squeezingoptical cableOuter sheath: twistedoptical cableAdd an extra layer of protective sheath.

1. Depending on the transmission performance, distance, and purpose,optical cableCan be divided into usersoptical cableLocal dialectoptical cableLong distanceoptical cableAnd underwateroptical cable.

2. According tooptical cableThe types of optical fibers used internally are different,optical cableIt can also be divided into single-modeoptical cableAnd multi-modeoptical cable.

3. According tooptical cableHow many inner fiber cores are there,optical cableIt can also be divided into single coreoptical cableDual coreoptical cableWait.

4. According to the different methods of configuring reinforcement components,optical cableCan be divided into central strengthening componentsoptical cableDistributed strengthening componentsoptical cableStrengthening components of protective layeroptical cableAnd the comprehensive outer protective layeroptical cable.

5. Depending on the condition of the transmission conductor and medium,optical cableCan be classified as non-metallicoptical cableOrdinaryoptical cableComprehensiveoptical cable(Mainly used for railway communication lines).

6. Depending on the laying method,optical cableCan be divided into pipelinesoptical cableDirectly buriedoptical cable, elevatedoptical cableAnd underwateroptical cable.

According to different structural methods,optical cableCan be divided into flat structuresoptical cableLayer twisting typeoptical cableSkeleton styleoptical cableArmoroptical cableAnd high-density usersoptical cable~~

For many years, doingoptical cableConstruction has provided us with a mature set of methods and experience.

optical cableTool usage: 1. Double port fiber stripping pliers 1. Stripping fiber coating/tight wrapping 2. Combination socket wrench 1 set for installationoptical cableSplicing box/terminal box 3 2m tape measure 1, measure and peel offoptical cableLength 4, art knife 1, peel openoptical cableAuxiliary Tool 5 Snake Head Pliers 1 Cut offoptical cableStrengthen core 6, horizontally open cable cutter 1, vertically and horizontally peel offoptical cable7 tweezers, 1 reel of fiber optic cable, 8 scissors, 1 cut of fiber optic cable, 9 pliers, 1 cut of fiber optic cableoptical cable10 pointed pliers for medium steel wire, 1 auxiliary tool for splicing, 11 micro screwdriver, 2 fastening screws, 12 hex wrench, 1 set for installing hex screws, 13 adjustable wrench, 1 auxiliary tool for splicing, 14 combination screwdriver, 2 loading and unloading toolsoptical cableSplicing box 15, alcohol pump bottle 1, cleaning fiber 16, marking pen 1, marking fiber number 17, flashlight 1, night construction lighting 18, diagonal pliers 1, auxiliary construction tool

(1)optical cableOutdoor construction:

Long distanceoptical cableThe most important thing in laying is to choose a suitable path. The shortest path here may not necessarily be good, and attention should also be paid to the land use rights, the possibility of installation or burial, etc.

optical cableWhen turning, its turning radius should be greater thanoptical cable20 times its own diameter.

1. Outdoor elevated structureoptical cableConstruction:

A. The hanging wire hanging overhead method is simple and inexpensive, widely used in China, but it is time-consuming to add hooks and organize them.

B. The suspended wire winding overhead method is more stable and requires less maintenance work. But specialized wrapping machines are needed.

C. The self-supporting overhead method has high requirements for poles, difficult construction and maintenance, and high cost, and is rarely used in China.

D. When suspended,optical cableA guiding device must be added at the point where the wire rod is led, and measures should be taken to avoid itoptical cableDragging the floor.optical cablePay attention to reducing friction when towing. Each pole should have a section left for expansion and contractionoptical cable.

E. Be carefuloptical cableReliable grounding of medium metal objects. Especially in mountainous areas, high-voltage power grid areas, and areas with frequent thunderstorms, there are generally three grounding points per kilometer, and even non-metallic materials are usedoptical cable.

2. Outdoor pipelinesoptical cableConstruction:

A. Before construction, the occupation of pipelines should be checked, plastic sub pipes should be cleaned and placed, and traction lines should be placed at the same time.

B. When calculating the placement length, there must be sufficient reserved length. Please refer to the table below for details:

C. The length of one laying should not be too long (usually 2KM), and the wiring should be pulled from the middle to both sides.

D. The traction force of the cable is generally not greater than 120kg, and it should be pulledoptical cableStrengthen the heart part and do welloptical cableWaterproof reinforcement treatment for the head.

E.optical cableThe introduction and exit points must be equipped with a guide device and cannot be directly dragged to the ground.

D. Pipelineoptical cableAlso pay attention to reliable grounding.

3. Directly buried undergroundoptical cableInstallation:

A. Directly buriedoptical cableThe depth of the ditch should be excavated according to the standards, as shown in the table below:

B. Areas that cannot be excavated can be elevated or pre buried by drilling.

C. The bottom of the ditch should be smooth and sturdy, and a portion of sand, cement, or support can be pre filled if necessary.

D. When laying, manual or mechanical traction can be used, but attention should be paid to guidance and lubrication.

E. After the laying is completed, the soil should be backfilled and compacted as soon as possible.

4. Inside the buildingoptical cableInstallation:

A. When laying vertically, special attention should be paid tooptical cableThe load-bearing issue usually requires every two layers to be addressedoptical cableFixed once.

B.optical cableWhen passing through walls or floors, plastic pipes with protective openings should be added, and the pipes should be filled with flame-retardant fillers.

C. A certain amount of plastic pipes can also be pre laid inside the building, which will be laid lateroptical cableThen use traction or vacuum fab to release itoptical cable.

1、 User receivedoptical cableAfterwards, checkoptical cableCertificate of conformity and accompanying optical data, verificationoptical cablePlate number, model, number of cores, length, etc., and check for any damage to the outer packaging.

IIoptical cableWhen laying, a length of traction rope must be used tooptical cableStrengthen the components, connect them together, and fix them with mesh or tape to the protective sheath. If it were a pipelineoptical cableTraction rope andoptical cableSpecial rotating traction heads must be added between reinforcement components, and direct pulling is not allowedoptical cableTraction of outer sheath.

3、 For segments longer than 2KMoptical cableThe defense is not allowed to be fully deployed at once, and it is necessary tooptical cableHang it in the middle of the area and place it in an inverted figure eight shape towards both ends.

4、 Unloading from the caroptical cableIt is best to use a forklift or crane hoist to handle itoptical cableGently place it on the ground from the car

5、 Unloading from vehicles in outdoor construction sitesoptical cableIt is advisable to place a flat board between the car platform and the ground, forming a slope of 45 degrees, and thread a rope through itoptical cableThe middle hole, where a person pulls the rope at both ends of the car, isoptical cableSlowly slide down the wooden board slope. uninstalloptical cableIt is time to strictly stack and lay flat, and it is strictly prohibited to directly dispose of itoptical cableFalling vertically from a high place and placing a strong impactoptical cableCausing damage.

6、 Need to scrolloptical cableRolling should be done in the direction of the rotation arrow indicated on the cable reel, but long-distance rolling is not allowed.

7、 Before construction, it is necessary tooptical cableConduct single disc testing, such as the quality of the outer sheath and attenuation indicators.

8、 Pipeline or overheadoptical cableThe maximum tensile force during laying shall not exceed 1500N, and it shall be directly buriedoptical cableThe maximum tensile force during installation shall not exceed 3000N.

Nineoptical cableDuring construction and layout positioning, it is not allowed to bend or form a 90 degree right angle bend; Dynamic bending (such as during construction), affecting pipelines and overhead structuresoptical cableThe bending radius should be greater than 20 timesoptical cableOuter diameter; Directly buriedoptical cableThe bending radius should be greater than 25 timesoptical cableOuter diameter; When laying and positioning, for pipelines and overhead structuresoptical cableThe bending radius should be greater than 10 timesoptical cableRadius; Directly buriedoptical cableThe bending radius should be greater than 12.5 timesoptical cableOuter diameter. avoidoptical cableSevere bending leads to a "dead button".

Tenoptical cableDuring construction, the tensile force shall not exceed the allowable short-term force it can withstand (pipeline, overhead)optical cable: 1500N; direct burialoptical cable：3000N； ADSSoptical cable：20%RTS）, During operation and use, the allowable long-term force should not exceed the regulations for pipelines and overhead structuresoptical cable600N; direct burialoptical cable1000N； ADSSoptical cable：MAT）。optical cableConstruction should be carried out under the guidance of qualified technical personnel.

optical cableIt is very important to wire according to the correct method. Improper construction can easily cause increased attenuation, shortened service life, fiber breakage, skin breakage, armor breakage, etc.optical cableEspecially the power supplyoptical cableThis type of wire has a larger diameter and heavier weight, so it is necessary to use a bracket when laying it outoptical cableGet the tray up and roll it on one sideoptical cablePull the cable on one side of the disc, if not equippedoptical cableThe loose wires of the reel must be straightened out before wiring. Cable pulling personnel and defense personnel should be equipped with walkie talkies to maintain contact. When they cannot be pulled, do not use brute force to pull. It is necessary to slowly straighten them out before continuing, so as to ensure that we are "fragile"optical cableSafely placed.

optical cableThe allowable tensile and compressive forces are shown in Table 1.

Table 1-optical cableMechanical properties that allow tensile and compressive forces

connection method

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The main methods are sexual connection and emergency connection.

1. Fiber optic connection (also known as thermal fusion):

This connection is achieved by melting and connecting the connection points of two optical fibers together through discharge. Usually used for long-distance connections. Its main feature is that the connection attenuation is low among all connection methods, with a typical value of 0.01~0.03dB/point. But when connecting, specialized equipment (fusion splicer) and professional personnel are required for operation, and the connection point also needs to be protected by a dedicated container.

2. Emergency connection (also known as cold fusion):

The emergency connection mainly uses mechanical and chemical methods to fix and bond two optical fibers together. The main feature of this method is that the connection is fast and reliable, with a typical attenuation of 0.1~0.3dB/point. But long-term use of the connection point will be unstable and the attenuation will increase significantly, so it can only be urgently needed in a short period of time.

3. Activity Connection:

Activity connection is the use of various fiber optic connection devices (plugs and sockets) to connect sites to each other or sites to each otheroptical cableA method of connecting together. This method is flexible, simple, convenient, and reliable, and is often used in wiring inside buildings. Its typical attenuation is 1dB/joint.

select

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optical cableThe selection should not only be based on the number of fiber cores and the type of fiber, but also onoptical cableChoose based on the usage environmentoptical cableThe outer sheath.

1. Outdoor useoptical cableWhen buried directly. When overhead, a black plastic outer sheath with two or more reinforcing ribs can be selectedoptical cable.

2. Used inside buildingsoptical cableWhen selecting, attention should be paid to its flame retardant, toxic, and smoke characteristics. Generally, flame retardant materials can be used in pipelines or areas with forced ventilationBut for types with smoke (Plenum), flame-retardant, non-toxic, and smoke-free types (Riser) should be selected in the exposed environment.

When laying cables vertically inside the building, layer twisting type can be usedoptical cable（Distribution Cables）； When wiring horizontally, branching options can be usedoptical cable（Breakout Cables）。

Directly buriedoptical cableBurial depth standard

Laying location or soil burial depth (m) Remarks

Ordinary soil (hard soil) ≥ 1.2

Half stone (gravel soil, weathered stone) ≥ 1.0

All stone ≥ 0.8, add 10cm fine soil or sandy soil from the bottom of the ditch

Flowing sand ≥ 0.8

Suburban and rural areas ≥ 1.2

The pedestrian walkway in the city is ≥ 1.0

Crossing railways and highways at a distance of ≥ 1.2 from the bottom of the ballast or from the road surface

Ditch, canal, pond ≥ 1.2

Farmland drainage ditch ≥ 0.8

Model identification

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Example:

Classification code

Note: Between Part One and Part Two: Code for Reinforcing Components (Reinforcing Cores)

Strengthening components refer to those inside or embedded in the sheath for enhancingoptical cableComponents with tensile strength:

Unsigned - metal reinforced components; G-metal heavy-duty reinforced components

F - Non metallic reinforcement components; H-Non metallic heavy-duty reinforced components

(For example: GYTA: metal reinforced core; GYFTA: Non metallic reinforced core

Cable core andoptical cableCode for internal filling structural features

optical cableThe structural characteristics of the cable core should indicate the main types andoptical cableThe derived structure, whenoptical cableWhen there are several structural features that need to be specified, they can be represented by combination codes.

Code for protective sheath

Note: Between Part Four and Part Five:

Its code is represented by two sets of numbers, the first set representing the armor layer, which can be one or two digits; The second group represents the coating layer, which is a one digit number

Armor layer code

Coating layer code

Part Six:optical cableSpecification Model

A multimode fiber

B single-mode fiber

fiber optic testing

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1. Simple manual measurement:

This method is generally used to quickly detect the continuity of optical fibers and to distinguish the optical fibers made during construction. It is achieved by injecting visible light from one end of an optical fiber using a simple light source and observing which one emits light from the other end. Although this method is simple, it cannot quantitatively measure the attenuation and properties of optical fibers.

2. Precision instrument measurement:

Identify advantages and disadvantages

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1、 Exterior: Indooroptical cableGenerally, polyvinyl chloride or flame-retardant polyvinyl chloride is used, and the surface should be smooth, shiny, and easy to peel off. poor qualityoptical cablePoor surface finish of the outer layer can easily lead to tight fitting and adhesion with the inner sleeve.

outdoorsoptical cableThe PE sheath should be made of high-quality black polyethylene, with a flat, shiny, uniform thickness, and no small bubbles after cable formation. inferioroptical cableThe outer skin is usually produced from recycled materials, which can save a lot of costsoptical cableThe surface is not smooth due to the presence of many impurities in the raw materialsoptical cableThere are many tiny pits on the outer skin, which can crack and cause water ingress over time.

2、 Fiber optic

3、 Strengthening steel wire: outdoor production by legitimate manufacturersoptical cableThe steel wire is phosphated and has a gray surface. After being cabled, this type of steel wire does not increase hydrogen damage, does not rust, and has high strength. inferioroptical cableGenerally, thin iron wire or aluminum wire is used instead, and the identification method is easy - it has a white appearance and can be bent freely when pinched in the hand. Produced with this type of steel wireoptical cableHydrogen loss is significant, and over time, both ends of the fiber optic box will rust and break.

4、 Steel armor: Regular production enterprises use double-sided brushed anti rust coating for longitudinal wrapped steel strips, which are of poor qualityoptical cableIt is made of ordinary iron sheet, usually with only one side treated for rust prevention.

5、 Loose casing:optical cableThe loose tube of medium mounted optical fiber should be made of PBT material, which has high strength, no deformation and anti-aging. inferioroptical cableGenerally, PVC is used as the sleeve, which has a very thin outer diameter and can be flattened by hand, similar to the straws we use for drinking beverages.

6、 Oil paste: Oil paste mainly includes fiber paste and cable paste. Under normal circumstances, fiber paste should fill the entire loose tube, while cable paste should be filled under pressureoptical cableEvery gap in the cable core. Fiber paste can be filled to half full or less, while cable paste can be applied as a layer on the outside of the cable core, or as a layer on top of itoptical cableCharge both ends without charging in the middle. This will result in poor protection of the optical fiber, affecting its transmission performance such as attenuation, and poor waterproof performance that does not meet national standards. Onceoptical cableUnexpected water seepage can cause the entire chain to become unusable due to water seepage. Under normal circumstances, even if there is accidental water seepage, only one section of the seepage needs to be repaired, and there is no need to start over. The national standard requires a water blocking performance of three metersoptical cableOne meter of water column pressure, no water seepage for 24 hours. ）If poor oil paste is used, the above problems may also occur, and the poor thixotropy of the oil paste may cause micro bending loss in the optical fiber, resulting in unqualified transmission characteristics of the entire link; If the ointment is acidic, it will also mix withoptical cableThe metal material in the fiber undergoes an H evolution reaction to release hydrogen molecules, while the attenuation of the fiber in the presence of H rapidly increases, causing the entire transmission link to be interrupted.

7

8、 Waterproof strip:optical cableThe strong water absorption performance of high water absorbing resin, which is uniformly distributed inside the product through waterproof tape or waterproof yarn, can quickly absorb water several times its own weight under the combined action of immersion pressure, affinity, and rubber elasticity. In addition, once the water blocking powder meets water, it will immediately expand the gel. At this time, no matter how much pressure is applied to it, the water will not be squeezed out. Therefore, using a waterproof tape containing absorbent resin to wrap the cable core, in caseoptical cableThe outer wall is damaged, and the highly absorbent resin in the wound area exerts a sealing effect due to expansion, which can minimize the entry of water. inferioroptical cableUsually non-woven fabric or paper tape is used, onceoptical cableIf the outer skin is damaged, the consequences will be very serious.

Obstacle repair

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Use OTDR testing and judgment at endpoints or relay stationsoptical cableThe general steps for identifying obstacles on the route are as follows:

1) Use OTDR to test the maximum distance from the obstacle point to the testing end.

2) When affected by natural disasters or external construction, etcoptical cableWhen blocking, search for personnel based on the obstacle location provided by the maintenance personnel. If it is not for the above situation, it will be difficult for inspectors to find obstacles from the road surface. At this point, it is necessary to verify the distance from the obstacle point measured by OTDR to the testing end with the original test data, and find out which marker (or two joints) the obstacle point is probably located between. After necessary conversion, the specific position of the obstacle can be determined by accurately measuring the length of the ground between them.

3) If the fiber breakage is due tooptical cableDue to structural defects or fiber aging, it is difficult to accurately measure the breakpoint using OTDR, and only the obstructed section can be measured. Therefore, a replacement section should be usedoptical cable.

improveoptical cableMethods for accurately locating line faults

Firstly, it is important to understand how to use the instrument and master its usage methods, which can help with accurate measurements.

1. Set the parameters of OTDR. When using OTDR testing, it is necessary to first set the instrument parameters, the most important of which are the refractive index and testing wavelength of the testing fiber. Only by accurately setting the basic parameters of the testing instrument can conditions be created for accurate testing.

2. Use the amplification function of the instrument panel. By using the amplification function of OTDR, the optical standard can be set at the corresponding inflection point. By using the amplification function key, the graph can be enlarged to 25 meters per grid, which can obtain more accurate test results with a resolution of less than 1 meter.

3. Adjust the accurate testing range file. The distance resolution of OTDR testing varies for different test range ranges. When measuring fiber optic obstacle points, the closest test range range that is greater than the measured distance should be selected in order to fully utilize the accuracy of the instrument for measurement.

Secondly, accurate and completed original documentation should be established during the maintenance and management process. These accurately completedoptical cableThe line file is the basic basis for fault measurement and location. Therefore, in the maintenance and management process, we cannot be careless and should establish authentic, trustworthy, and complete line information.

whileoptical cableWhen monitoring the connection, record the cumulative length of the optical fiber from the testing end to each joint point position and the total attenuation value of the relay section optical fiber. At the same time, register the testing instrument model and the set refractive index during testing. Accurately record variousoptical cableRemaining. Detailed records of each joint pit, special section, S-shaped laying, entry room, etcoptical cableThe reserved length of the fiber optic disc, as well as the reserved length of the splice box, terminal box, ODF rack and other parts, shall be deducted when converting the routing length of the fault point.

In addition, consistency of testing conditions should be maintained during the measurement process. During obstacle testing, it is important to ensure consistency in the model, operation method, and parameter settings of the testing instruments, in order to ensure comparability of the test results. Therefore, detailed records of the model of the testing instrument and the setting of testing parameters should be kept for future use.

Finally, a comprehensive analysis. The testing of obstacles requires operators to have clear thinking and flexible problem-solving methods. Clear logical thinking is very useful no matter where it is. In general, optical fiberoptical cableThe two ends of the line undergo bidirectional fault testing, and then analyze the raw data to determine the specific location of the fault. When there are no obvious features in the links around the fault point and the specific site cannot be determined, we can adopt the measurement method at the nearest joint. We can excavate at the obstacle point of preliminary testing, and the end station testing instrument is in real-time measurement state.

optical cableIf there is an obstacle in the line, we must seize every second and temporarily connect the circuit or set up an emergency planoptical cableTemporarily connect the circuit and organize efforts to repair it as soon as possible.

1. Emergency repair

1) In a certain directionoptical cableAll lines are blocked

Immediately and temporarily connect all or part of the main circuit according to the predetermined circuit plan.

2) In a certain directionoptical cableIndividual optical fibers in the line are blocked

If there is a spare fiber or a bypass circuit in the optical fiber, immediately use the spare fiber or bypass circuit to temporarily connect the obstacle circuit;optical cableIf there is a backup fiber optic cable and no bypass circuit, it shall be handled according to the prescribed scheduling principles to ensure the smooth operation of important circuits and suspend secondary circuits.

3) In a certain directionoptical cablePartial fiber optic blockage in the circuit

optical cableIf there is a backup fiber optic cable, in addition to temporarily connecting the circuit with the backup fiber optic cable, unobstructed fiber optic cables can be selected for temporary pairing. According to the prescribed scheduling principles and sequence, the circuit can be temporarily connected. If the temporarily paired fiber optic cables are still insufficient and there is no bypass circuit, the secondary circuit will be suspended.

Notes:

1. The temporary scheduling of the above fiber optic cables must be jointly discussed and approved by both parties, and completed with close cooperation from both parties.

2. Fiber optic cables paired in the original line sequence can be switched by the two ends of the locomotive station according to system scheduling and circuit switching; For temporary pairing of optical fibers, they should be connected to the connectors of the optical distribution racks (or terminal boxes) in the relay stations on both sides of the obstacle point.

3. If the main fiber is connected to an optical attenuator and the backup fiber is not pre connected to an attenuator, the corresponding optical attenuator should also be connected when calling on the backup fiber. Attention should also be paid to this issue when temporarily pairing optical fibers.

2. Emergency deploymentoptical cable

1) Emergency deploymentoptical cableThe conditions

When in a certain directionoptical cableAll lines are blocked, and after all circuits or main connections are made, it is possible to consider repairing them all at onceoptical cableThere is no need to use emergency circuit breakers. In situations where there are no conditions to temporarily turn on the circuit, or where the temporarily turned on part of the circuit cannot meet the needs, emergency measures should be deployedoptical cableAccording to the scheduling principles and sequence stipulated in the "Circuit Scheduling System", the circuit should be rushed through, communication should be temporarily restored, and then a new route should be selected and deployedoptical cableConduct formal repairs.

2) Emergency responseoptical cableDetermination of deployment range

optical cableWhen encountering or being affected by external forces to block obstacles, it is generally easier to find the obstacle point based on the abnormality of the road surface after determining the approximate location of the obstacle point, and then determine the emergency situationoptical cableThe distribution range. However, when using OTDR to measure only the obstacle point at the endpoint station or relay station, and cannot determine the specific location of the obstacle, it is difficult to determine the emergency situationoptical cableThe distribution range. If conditions permit, OTDR can be used for testing at the opposite relay station, and the test results from both sides can be comprehensively analyzed. If conditions do not permit OTDR testing from both directions, two situations can be addressed separately:

a) The obstacle point is relatively close to a certain joint, emergencyoptical cableStarting from this joint, open it and use an OTDR to test towards the obstacle direction at the joint. At this point, the testing distance is short and the specific position of the obstacle can be accurately measured, which can determine the emergency situationoptical cableWhere do you put the cloth.

b) The obstacle point is located in the center of two joints, and it is not advisable to start laying emergency supplies from one jointoptical cableIt is necessary to further determine the location of the obstacle point and place an emergency section on both sides of the obstacle pointoptical cableIn this situation, the gradual extension probing method can be used to find the specific location of the obstacle, that is, using OTDR to preliminarily measure the obstacle point at the end station or relay station, and digging out the obstacle point in front of itoptical cableCut off a certain optical fiber for retesting. If it is found that the obstacle point is not within the cutting range, the approximate difference should be determined and then dug forwardoptical cableCut off another fiber and retest again until the obstacle point is within the cutting point, then the emergency can be determinedoptical cableThe distribution range. Generally, by retesting twice, the specific location of the obstacle point can be determined.

c) Same modeloptical cableAccelerate emergency repair of connectors

anotheroptical cableEmergency repair methods, including use and obstaclesoptical cableSame modeloptical cableAs an emergency repairoptical cableUse a connector (flexible joint) with matching fluid for temporary connection and connect the circuit.

3) Formal repair

Formal repairoptical cableWhen there is a line obstacle, communication must be maintained as much as possible, especially the communication of important circuits cannot be interrupted, and the construction quality must meet the requirementsoptical cableRequirements for construction quality standards and maintenance quality standards of railway lines.

Formal repairoptical cableWhen there is a total obstruction in the line, the following issues should be noted:

1. Obstacles near the junction box or joint should be reserved with fiber optic cables or joint pits inside the junction boxoptical cableRepair without the need for additional connectors. There is a reservation near the obstacle pointoptical cableWhen it comes to time, reserved resources should be utilizedoptical cableConnect by adding only one connector.

2. Intervention or replacement is requiredoptical cableThe formal repair methodoptical cableWhen encountering obstacles, the same manufacturer and model should be usedoptical cable.

3. Intervention or replacementoptical cableThe length can be considered by the following three factors:

(1) Considering the formal repairoptical cableWhen connecting optical fibers, OTDR monitoring must be used by the end station or relay station, or it should be easy to distinguish obstacles between adjacent connection points during daily maintenance work; Intervention or replacementoptical cableThe minimum length of the OTDR instrument must meet the response resolution (two-point resolution) requirements, and generally should be greater than 100 meters.

(2) Considering that it will not affect the operation of single-mode optical fiber under single mode steady state conditions to ensure communication quality, intervene or replaceoptical cableThe minimum length should be greater than 22 meters.

(3) Intervention or replacementoptical cableThe length can refer to the principles and requirements of (1) and (2), and be flexibly controlled by considering the actual situation comprehensively. For example, when intervening or replacingoptical cableThere are already joints nearby, so we should try our best to connect themoptical cableExtend to the joint and add only one joint.

4. Intervention or replacementoptical cableThe general sequence of fiber optic splicing:

(1) Firstly, the fiber optic cutting scheme should be jointly agreed upon by both parties in accordance with the scheduling principles and sequence stipulated in the "Circuit Scheduling System", and submitted to the higher-level competent department for approval.

(2) The process of fiber optic cutting should try not to interrupt the circuit as much as possible (especially important circuits should not be interrupted). Emergency responseoptical cableWhen cutting over the newly laid fiber optic cable, the backup should be connected firstoptical cableUsing spare fiber optic as a substitute pair, cut and restore the circuit pair by pair according to the original cutting sequence, using the original obstaclesoptical cableTemporary pairing and debugging circuit of intact optical fibers in the middle, or originaloptical cableNo backup available in the middleoptical cableThe secondary circuit should be temporarily suspended, and the optical fiber of the system should be cut first as a substitute pair, and then cut in pairs according to the original cutting sequence to restore the circuit.