The junction of the cable installation is called the clutch. Inserting the cable into terminal devices called charging. The following requirements apply to cable solder joints: The ohmic resistance of the cores must not increase. The soldering point should not be too thick compared to the cable diameter.
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LECTURE 11, 12, 13. INSTALLATION OF COMMUNICATION CABLES
General requirements to the installation of communication cables.
Separate building lengths, sections, spans of laid cables are spliced, connected in one line and included in terminal devices. The junction (mounting) of the cable is called the clutch. The inclusion of a cable in terminal devices is called charging.
Installation is a responsible job in the construction of cable structures. High quality installation ensures the reliability of the cable line.
The following requirements apply to cable splices:
- The ohmic resistance of the conductors must not increase.
- The insulation resistance must not decrease.
- Pairs and lays must be maintained. Breaking pairs and mixing them up is not allowed.
- Reliable mechanical strength of the connection must be ensured at the splice site.
- Screen continuity (if any) should be restored.
- The sealing of the shell must be strong and tight.
- The soldering point should not be too thick compared to the cable diameter.
When splicing cables, you must:
- Splice the cores with each other in the same order as they are in the corresponding layers of the cable.
- Connect the control groups of one end of the cable to the control groups of the other.
- Connect cores with insulation of the same color to each other.
Before and after installation, the quality of the cable is monitored. The finally assembled line is subjected to control electrical measurements.
Mounting materials, tools and fixtures.
Checking cables before installation.
Installation of urban telephone cables.
Cutting cable ends for installation
The ends of the cable are laid in the well and fixed on the consoles so that the end of one cable overlaps the end of the other to the required length, which is determined by the capacity of the cable and the diameter of the cores.
Annular cuts are made at the place where the cable sheaths are removed. After the sheath is cut, the low-capacity TG cable is slightly bent 2-3 times, from which the lead sheath breaks along the notch and is easily pulled off the cable. The sheath of a cable with a capacity of 300 pairs or more is removed using one or two longitudinal cuts.
After removing the lead sheath from the ends of the cable, the cores at the edge of the lead sheath are tied with calico tape or threads, which protects the insulation of the cable cores from damage on the edges of the sheath, after which the belt insulation is removed.
When cutting polyethylene casings, it is not allowed to tighten the casing. To remove it, it is enough to make one or two longitudinal incisions. Removing the polyethylene casing is much easier if it is preheated. Belt insulation, screen tapes and screen wire are kept by carefully twisting into rolls and tying them to the edge of the shell.
A coupling or parts thereof are pushed onto the prepared ends. Then the pairs of each layer are divided into two parts, smoothly bent and attached to the shell. In bundled cables, each bundle is bent and attached to the sheath.
Splicing cable cores
The cores are connected in pairs color to color, twisting into a twist or bundle into a bundle, the control pairs of each layer (bundle) are connected to the control pairs of another layer (bundle). Damaged pairs are connected last.
The connection of the cores starts from the bottom of the upper layer. After connecting the pairs of the lower bundle, the lower pairs of the next layer are spliced, etc. Then pairs of the central layer are spliced and then the upper half in the order they follow from the center.
Splicing of a pair of cores with paper insulation is carried out as follows. Previously, paper or polyethylene sleeves are put on both cores. The cores are connected by twisting with the capture of two or three turns of paper insulation. Then, insulation is removed from each core and twisted together for a length of 12-15 mm, and at the beginning the twist is made weaker, and at the end it is denser. As soon as the strands are twisted to the desired length, the excess strands are bitten off and the twist is bent tightly to the strand. Paper sleeves are pushed into place of the twists, after which the pair is tied up on both sides with threads.
Further connection takes place in the same order, only it is necessary to place the twists and paper sleeves in a checkerboard pattern along the entire length of the coupling.
The cores of GTS cables with polyethylene insulation are spliced in a similar way using polyethylene sleeves.
The cores of cables with polyethylene insulation can be twisted using the PSZH-4 device or connected with individual or multi-pair compressible connectors. With these methods, it is not necessary to remove the insulation from the connected cores.
After splicing of all paper-insulated wires (T cables), the splice is dried with hot air from a blowtorch or gas burner (using a metal casing). Plastic insulation should not be dried as it is neither heat resistant nor hygroscopic. Then the belt insulation is restored. The splice is wrapped with two or three layers of paper or calico tape (T cables) or plastic tape(TP cables). In addition, it is necessary to restore the electrical integrity of the screen. To do this, the splice is wrapped with the saved screen tapes, which are connected into a “lock”. The screen wire is connected by twisting at a length of 15-20 mm.
Installation of intercity symmetrical communication cables.
INSTALLATION OF THE CORE OF A SYMMETRIC CABLE
Before cutting the ends of the cable, the tightness and insulation resistance of the hose insulating covers of the spliced cable sections are checked. Then an electrical check of the cable core is carried out; the ends of the spliced cables are laid on the mounting goats, fixed and cut according to the specified dimensions. Near the edge of the jute (outer hose), the armor is cleaned to a shine and tinned for one third of the circumference by capturing both tapes. A copper wire bandage is applied to the tinned places, the ends of which are not cut off, since they are used for soldering the armor of spliced cables, and in cables - without insulating covers and with a sheath (coupling). The bandage is soldered to the armor. According to the cut marks of the sheath, circular cuts are made and from them to the ends of the cable - two longitudinal cuts with a distance of 5-6 mm between them. The incised strip of the lead sheath is removed with pliers (Fig. 11.1), the sheath is moved apart and removed. The cutting of the cable ends before installation is shown in fig. 11.2. Prior to installation, the cylindrical sleeve is pushed onto one of the ends of the cable. Fours and pairs are divided into layers. The splicing of the veins begins with the central layer. Splicing technology and splice isolation are shown in fig. 11.3. In multi-quad cables, the twist points of adjacent quads are shifted relative to each other so that they are distributed evenly along the entire length of the splice. The soldering of the strands is carried out in a glass tin-lead solder of the POS type.
After drying over the flame of a blowtorch (especially cables with paper core insulation), the splice is wrapped with two layers of cable paper, between which a passport is placed on the mounted sleeve (Fig. 11.4).
Rice. 11.1. Lead Sheath Removal
Rice. 11.2. Cutting the ends of the cable before mounting the coupling:
1 - jute; 2 - wire bandage; 3 - armor; 4 - shell; 5 - thread bandage; 6 - veins; 7 - about water for soldering armor and shell; 8 - bandage soldering
Rice. 11.3. Splicing of intercity cable cores
The splicing of the cores of the GTS cables is carried out either by twisting or by compressible type connectors. Hot soldering of cores is usually used. On fig. Figure 11.5 shows stranded splicing. There are many varieties of compressible type connectors, but the multi-pair connector is most commonly used. Figure 11.6 shows a 20-core cable connector. The contact of spliced cores is ensured by compressing the connectors using press technology. In this case, the insulation of the cores is cut through at the tips of the contacts and there is a reliable electrical connection all lived at the same time. The advantage of such connectors is good and stable contact resistance and reliable core insulation. Multi-pair connectors are especially effective when installing large communication cables (over 500X2).
Rice. 11.4. Splice before soldering the lead sleeve
Rice. 11.5. Splicing of GTS cable cores
Rice. 11.6. Ten-pair connector for GTS cables
Features of the installation of cables with aluminum conductors consist in welding the ends of twisted conductors on the flame of a blowtorch or gas burner using a special flux, for example flux F-54A with operating temperature melting point 200°C. The connection of aluminum conductors with copper is carried out using a copper-aluminum insert, which is a piece of aluminum wire coated at one end with a layer of copper
INSTALLATION OF COAXIAL CABLES
Features of the installation of coaxial cables are reduced to methods of splicing coaxial pairs, which, unlike symmetrical ones, require special care during laying out and installation, which excludes metal filings from entering the splice, the formation of dents, pinches and other deformations that lead to a violation of electrical characteristics.
Pairs are spliced directly, i.e. the first with the first, the second with the second, etc. For ease of installation, symmetrical fours and pairs are bent to the side, and spacer discs are installed between the coaxial pairs.
The cutting of coaxial pairs is carried out according to the template (Fig. 11.7). Three or four polyethylene washers are removed from each pair using a heated special fork. Instead, heat-resistant fluoroplastic washers are installed, which protect the coaxial pairs from deformation during subsequent mounting processes (soldering, crimping).
Rice. 11.7. Installation of coaxial pair type 2.6/9.5: o) splicing of the inner conductor; b) splicing of the outer conductor; screen restoration; c) splice
Splicing of the inner conductor is carried out using a copper sleeve with a slot, and the outer conductor and the screen - using copper and steel split couplings, the necks of which are crimped with rings. The splice is isolated with a polyethylene sleeve. Then symmetrical fours are spliced. After the repair of symmetrical quadruples, the splice is wrapped with three or four layers of cable paper or glass tape, between which a passport is placed. The sealing of the lead sleeve, the installation and pouring of the cast-iron sleeve are carried out in the same way as on symmetrical cables.
For the installation of small-sized coaxial pairs of type 1.2 / 4.6, special tools and parts are used, mainly similar to those used on pairs of type 2.6 / 9.5. The peculiarity of the installation of pairs of type 1.2 / 4.6 is that after cutting the coaxial pairs, a brass support sleeve (Fig. 11.8) is pushed onto each of them, fastening the ends of the screen tapes and creating support for copper and steel backup couplings during their crimping in the process of splicing the outer conductor and screen tapes
Rice. 11.8. Cutting a small-sized coaxial cable type 1.2 / 4.6 (one coaxial and one symmetrical pair is shown): / - sheath; 2 - isolation of a coaxial pair; 3 - screen; 4 - support sleeve; 5 - external conductor; 6 - polyethylene insulation; 7 - inner conductor; S- symmetrical pair
In addition, to create a support under the outer conductors at the places of their cutting, plastic tubes are pushed onto the inner conductors until they stop at the pinch of the balloon insulation.
Installation of coaxial pairs of a combined cable is carried out with tools and parts used for KMB-4 and MKTSB-4 cables. For the convenience of cutting and splicing coaxial pairs 2.6/9.5, a spacer cone with a through longitudinal hole is used, through which a layer of small-sized coaxial pairs is passed. After cutting pairs 2.6/9.5 and removing the spacer cone, pairs 1.2/4.6 and single cores are removed from the inner layer in the intervals between pairs 2.6/9.5 and temporarily go around. First, pairs 2.6 / 9.5 are spliced, then pairs 1.2 / 4.6, and lastly symmetrical elements. For installation, a lead coupling with cutting cones is used.
SOLDERING THE LEAD CLUTCH AND BACKING THE PIT
The lead sleeve is pushed onto the splice and with the help of wooden hammer its edges are formed in the form of cones, tightly adjacent to the cable sheath. When using a split sleeve, the edges of the longitudinal seam are located one above the other, while the lead overlap is made from top to bottom so that the solder does not get inside the sleeve. Solder type POS is used for soldering the coupling.
Solders are marked depending on the percentage of tin in them, for example, POS-30 (30% tin), POS-40 (40%), etc. In addition, the grade of solder indicates the content of antimony in it, for example, POSSU-40- 0.5 (i.e. antimony 0.5%). On fig. 11.9 shows a state diagram of a tin-lead alloy depending on the ratio of components and temperature. At a content of less than 16% tin, the POS is coarse-grained, and the soldering turns out to be fragile. The most durable and fine-grained lead soldering is obtained at 29-31% tin (POS-30). (When soldering the conductive elements of the cable, solder grades POS-40 and POS-61 are used.)
When soldering lead sleeves, the temperature of the solder should be close to the melting point of lead - this achieves the best molecular adhesion. But since in this case POS-30 is very liquid (see Fig. 11.9), it is necessary to tin the surfaces to be soldered at a temperature of about 250-260 ° C, and then, gradually lowering the temperature, give the soldering the necessary shape. This is achieved relatively easily, since the interval of the plastic state of POS-30 is 73°C (256–183°C).
The coupling is sealed as follows: the places to be soldered are heated with the flame of a blowtorch (gas burner) and wiped with stearin; a solder bar is heated above the soldering point (at the same time the soldering point is heated) until softened, applying it to the future seam. After sealing, the tightness of the seams is checked by pumping the coupling with air (through a valve soldered into it) and covering the seam soap foam. After checking, the valve is removed and the hole is sealed.
% tin O
% lead 100
Rice. 11.9. State diagram of tin-lead alloys
Rice. 11.10. Resoldering of armor and cable sheath
On cables without insulating covers, the ends of the copper wires from the bandages on the armor are twisted together and soldered to the sleeve (Fig. 11.10). When mounting couplings with insulating covers in order to monitor their condition during operation, soldering of the armor with the coupling is not performed: the end of the lead conductor is soldered to the coupling, the insulating cover is restored, on top of which the conductors from the bandages are laid and soldered together.
Rice. 11.11. Cast iron clutch
The cast-iron sleeve (Fig. 11.11) is designed to protect the lead sleeve from mechanical damage, as well as from soil corrosion. Before installing the coupling, a resin tape is wound on the cable in such a way that it lies tightly in the necks of the cast-iron coupling. Then the coupling is poured with bituminous mass heated to 130-140 °C and cooled to the required temperature (depending on the type of cable and the permissible temperature of its heating) through the hatch in the upper half of the coupling. Then the hatch is closed, and all bolts, nuts and places where the cable exits the coupling are filled with the same mass.
Before backfilling the pit, the location of the measuring post is fixed, which is usually installed against the middle of the cable sleeve No. 1 at a distance of 10 cm from the axis of the route towards the field.
In places where a measuring column cannot be installed (for example, on city streets, etc.), before backfilling the pit, it is necessary to fix the location of the couplings in the pit with drawing distances to permanent landmarks on the sketch drawing. Then the pit is filled up to about half the depth, a measuring column is installed and the previously excavated soil is laid in the pit.
INSTALLATION OF CABLES IN ALUMINUM SHEATH
Compared to cables in sheaths made of other materials, and especially of lead, cables in an aluminum sheath have a number of significant advantages: shielding properties are improved, mechanical strength is increased, weight is reduced, cost is reduced, etc. The disadvantages of aluminum sheaths include their low corrosion resistance and complexity of installation.
Splicing of aluminum shells can be carried out by the following main methods: hot soldering, gluing and crimping.
When hot soldering a layer of zinc-tin solder (CTS) is applied to the aluminum shell at the points of articulation with the lead sleeve, and a layer of tin-lead solder (POS) is applied on top of it. This process is called tinning. The lead sleeve is then soldered to the tinned sheath using PIC in the usual manner.
The combination of different metals (aluminum, lead, tin, zinc, etc.) with this installation method often leads to corrosion, soldering destruction and depressurization of the couplings, which complicates the maintenance of the cable under excessive pressure. Given these shortcomings, the hot soldering method has received limited application.
Feature of the adhesive method consists in the fact that the cutting cones of the lead coupling are connected to the aluminum shell with glue by manual crimping (Fig. 11.12). Then, after mounting the core, the lead cylinder of the coupling is soldered to the lead cones in the usual way (Fig. 11.13).
Rice. 11.12. Manual crimping for adhesive method
Rice. 11.13. Cable installation in aluminum sheath adhesive method:
1 - cable sheath; 2 - glue line; 3 - lead cone; 4 - place of soldering; 5 - soldering of the shell with the clutch; 6 - lead cylinder; 7 - splice of the core
By crimping method(Fig. 11.14) splicing of the ends of the aluminum tube-coupling with the aluminum sheath of the cable is carried out by pressing. Before pressing, the ends of the shell are expanded with a special device to approximately the diameter of an aluminum tube-coupling. To protect the cable core from deformation during the pressing process and to create the necessary support, steel support sleeves are inserted under the expanded part of the sheath. The contact surfaces of the shell and tube are carefully cleaned.
Pressing is done with a manual hydraulic press and special punch and matrix, providing a mechanically strong, tight connection.
Rice. 11.14. Installation of a cable in an aluminum sheath by pressing:
1 - hose; 2 - shell; 3 - place of pressing; 4 - support sleeve; 5—aluminum tube; 6 - splice core
INSTALLATION OF STEEL SHEATH CABLES
For installation, a conventional lead sleeve is used, the soldering of which is carried out after preliminary tinning of the steel shell with a special paste of the brand PMKN-40.
The installation technology is as follows: after removing the hose along the top of the corrugation, make a circular incision of the shell with a file, carefully clean it with a brush, wipe it with a rag soaked in gasoline, dry it, protect the end of the hose with two or three layers of glass tape; a layer of paste 0.5 - 1 mm thick is applied to the cleaned surface of the shell, heated evenly with a blowtorch until the paste ignites and changes its color to brown, carefully remove slag from the surface and the tinning process. The installation of the cable core and the soldering of the lead sleeve are carried out in the usual way.
Restoration of INSULATION COVERS
To protect the bare aluminum or steel shell and the mounted coupling from corrosion, regardless of the method of shell splicing, the insulating cover is restored. Recovery is carried out in a hot or cold way, as well as with the help of heat-shrinkable tubes. The hot method provides for the application of several layers of a moisture-repellent sticky polyisobutylene compound (PPC) to the bare sheath, alternating with a winding of polyethylene tapes, splices, parts of a plastic sleeve welded to the cable sheath.
cold way differs from the hot one in that after applying to the splice of the CLP, instead of a plastic sleeve, several layers of heated bitumen-rubber mastic (MBR) are applied to it, alternating with winding with plastic tapes and protected by a layer of glass tape. Methods for splicing plastic hose covers with plastic sleeves or heat shrink tubing are described in the following paragraph.
INSTALLATION OF CABLES IN PLASTIC SHELL
Polyethylene shells are restored:
welding parts of a polyethylene sleeve with a cable sheath by wrapping the welding site with several layers of polyethylene tape and fiberglass; through which the open flame of a blowtorch (burner) heats the surfaces to be welded to a viscous state, forming a monolithic joint;
pressing the splice of the cable core with the capture of the sheath heated to a viscous state with low molecular weight polyethylene (Fig. 11.15);
welding of parts of a polyethylene sleeve with a shell using an electric spiral placed between the surfaces to be welded (electric heating method);
multilayer winding of the splice of the core with the capture of the shell, with lubrication with a polyisobutylene compound, i.e., in a cold way.
At present, the most progressive and technologically advanced way of restoring the insulating covers of cables with metal sheaths and splicing cables in plastic sheaths is the use of heat-shrinkable tubes made of thermoplastic materials (polyethylene, polypropylene) and subjected to radiation vulcanization (irradiation with γ- and β-rays). If a tube made of such a material is heated and stretched, and then cooled in the expanded state, then the shape given to the part will turn out to be, as it were, “frozen”.
Rice. 11.15. Pressing the splice with molten polyethylene:
1 - manual press; 2 - molten polyethylene; 3 - mold; 4 - joint; 5 - cable
Rice. 11.16. Heat-shrinkable tube: a) in the initial position; b) after heating; 1 - cable; 2 - tube
If such a tube is pushed onto a cable splice and heated to a temperature higher than that at which the expansion (blowing) was performed, the tube shrinks, taking its original state, and tightly compresses the splice (Fig. 11.16).
To improve the tightness and strength of the joint on inner surface tubes apply an adhesive layer, which softens during heating, filling the gaps between the tube and the cable. The tube is delivered to the consumer in an expanded state with "elastic shape memory", the radial shrinkage is at least 50% of the inflated state.
For splicing cables with dissimilar sheaths - metal with plastic. For this purpose, metal-plastic tubes (TMP) are used, consisting of steel tubes, on outer surface which a layer of polyethylene is applied by hot spraying (Fig. 11.17).
During installation, the metal sheath of the cable is soldered with a steel tube using a lead cone, and the polyethylene sheath is welded to the polyethylene layer of the TMP tube using a polyethylene sleeve.
Rice. 11.17. metal-plastic tube:
1 - a layer of polyethylene; 2 - steel tube; 3- epoxy compound; 4 - place of soldering; 5 - lead cone
FEATURES OF INSTALLATION OF OPTICAL CABLES
The installation of optical cables is the most critical operation that determines the quality and range of communication over optical cable lines. The connection of fibers and the installation of cables is carried out both in the production process and during construction and operation. cable lines.
Installation of OK is divided into permanent (stationary) and temporary (detachable). Permanent installation is carried out on fixed cable lines laid for a long time, and temporary - on mobile lines, where it is necessary to repeatedly connect and disconnect the construction lengths of cables.
An optical fiber connector, as a rule, is a fitting designed to align and fix the fibers being connected, as well as to mechanically protect the splice. The main requirements for the connector are simplicity of design, low transient losses, resistance to external mechanical and climatic influences, reliability. In addition to detachable connectors, requirements are imposed on the stability of parameters during multiple docking.
Rice. 11.18. Displacement of spliced fibers: but) radial displacement; b) angular; c) axial
The main task of connecting single optical fibers is to ensure their strict coaxiality, the identity of the geometry of the ends, the perpendicularity of the surfaces of the latter to the optical axes of the fibers, and a high degree of smoothness of the ends. An important requirement is also high stability of the state of the optical contact and low losses introduced by the splice. On fig. 7.81 shows the main possible displacement defects of optical fibers (radial, angular and axial displacement). The most stringent requirements are imposed by radial b and angular 0 displacement. The presence of a gap s between the ends of the fibers has less effect on the amount of losses.
CONNECTION OF OPTICAL FIBER
The most common ways of connecting optical fibers (OF) are:
Application of connecting tubes;
Detachable connectors;
Mechanical joints;
electric welding and the use of metal tips.
IN Lately for fixed installation of optical cables, the electric arc welding method has firmly established itself, and for detachable installation of multiple use, detachable connectors.
Consider some typical ways of connecting optical fibers.
Application of connecting pipes- one of the most common ways to permanently connect fibers. It consists in the use of precision bushings or tubes, which, being made exactly to the outer diameter of the optical fiber, give it the required position and fix it. Tubes are mostly glass. The tapered ends of the tubes facilitate the insertion of the optical fiber. The design of one of these connections is shown in Fig. 11.19. The connector consists of a hollow glass sleeve / with a hole for pouring the immersion liquid 2, which also serves to match the refractive indices of the fibers being joined 3 and 4. The splice introduces an attenuation of about 0.3-0.4 dB.
plug connectorreusable, designed to connect optical fibers, is shown in fig. 11.20. Pre-prepared ends of optical fibers are inserted into the socket and the pin part of the connector. When performing the splicing operation, the ends of the optical fibers are closely connected to each other. Outside there is a sealed housing of the plug.
The most characteristic designmechanical jointshown in fig. 11.21. Connected fibers in splice 1, 2 inserted into a plastic sleeve 3 And free space filled with immersion liquid 4. providing a bonding and immersion effect (reduction of reflection losses from the ends). Outside, the splice is hermetically sealed and mechanically protected by coupling halves 5, 6.
Electric welding It is produced using an electric arc or a laser by heating the ends of the spliced optical fibers. The splicing process of OM consists of the following operations (Fig. 11.22, a):
Adjustment of the alignment of the location of the ends of the OF, placed at a distance of several millimeters from each other;
Preliminary melting of the ends of the OF with an electric arc;
Tight pressing to each other of the ends of the OF, which are in a continuous arc discharge;
Final splicing step
Rice. 11.20. Mounting with connecting pipes:
1 - glass tube; 2 - immersion liquid 3 and 4 - connectable fibers
Rice. 11.21. Detachable connection: a) socket; B) pin
1 - fiber; 2 - fiber coating; 3 - connector body
Rice. 11.22. Mechanical splice: 1 and 2 fibers; 3 - plastic tube; 4, 5 - coupling halves
Rice. 11.23. Electric arc welding of fibers: a) splicing process; b) welding device;
1, 2, 3, 4 — splicing stages; 5 and 6 - fibers; 7—device; 8 - microscope
The welding device is an easily portable device (Fig. 11.23, b) with overall dimensions 20X30X15 cm. Outside there is a microscope for adjustment and visual observation of the welding process.
This method of fiber welding makes it possible to obtain a joint with a loss of the order of 0.1–0.3 dB and a breaking strength of at least 70% of the whole fiber. It is easily implemented in the field, since it does not require pre-treatment of the end surfaces before splicing.
At the end of each optical fiber is mountedmetal on tip (Fig. 11.24, a).
Rice. 11.24. Splicing with metal tips.: a) tip; b) fiber connection;
1 - tip; 2 - hole for pouring epoxy resin; 3 - fiberglass; 4 - capillary; 5 - sleeve; 6 - washers
To do this, from the end of the OF at a distance of 44 mm is removed protective covering. Then put on the tip 1 so that the glass fiber 3 protrudes from it by about 15-20 mm. A capillary is put on the protruding end of the OF 4 (glass tube with hole) 10 mm long. The capillary is inserted into the tip so that the end of the capillary protrudes by 1–2 mm. A layer of epoxy resin is applied to the glass fiber and capillary 2. Epoxy resin is also poured into the holes of the tip. Then the end face of the OF is polished on a glass plate using abrasive powder and polished on a polishing wheel.
The connection of optical fibers is made using a sleeve 5 and split washers 6 (Fig. 11.24, b). The bushing and washers have threads, with the help of which the spliced optical fibers are tightly joined.
INSTALLATION METHODS FOR OPTICAL CABLES
When installing an OK optical cable, it is generally necessary to ensure high moisture resistance of the splice, reliable mechanical characteristics for breaking and crushing, and suitability of the splice for a long stay in the ground.
Currently, various methods of mounting OK have been developed. Let's consider the most characteristic of them.
Frame assembly.Used for optical cable installation. metal carcass with the number of longitudinal rods equal to the number of spliced fibers (Fig. 7. 87, a). Optical fibers spliced in one of the above ways. Splices of fibers are placed on ebonite plates and fastened so that the splice does not experience a longitudinal effect on the gap (Fig. 11.25.6). Several layers of polyethylene tape are applied over the frame, and then a heat-shrinkable sleeve with an adhesive layer is put on (Fig. 11.25, c). The advantage of the coupling is the tight compression of the splice cones.
Installation of flat optical cables.The installation of cables made in the form of multi-fiber flat tapes with a common plastic coating is carried out as follows. The fibers at the end of the tape are exposed to a distance of 1 cm, and the tape is placed in a matrix, as shown in Fig. 11.26, but. The ends of the fibers are laid on a section having precision grooves, and a plastic material is poured into the matrix. Fibers filled with plastic are kept in the matrix until it solidifies and then torn by bending and stretching them. The hardened plastic fixes the fibers at the end of the tape. The ends of the two tapes are laid in a template (Fig. 11.26, b), and in the gap between the ends to fasten the tapes to each other, they are filled with an epoxy compoundwith the correspondingrefractive index. The mold is detachable and is made ofbrass. According to the test results, the losses in such connectors are no more than 0.2 dB.
Rice. 11.25. Frame mounting: but) frame for six splices; b) fastening spliced fibers; c) cable box;
1 - frame; 2 - fibers; 3 - splices; 4 - protective shell
Rice. 11.26. Installation of flat cables installation process; b") coupling;
1 - precision grooves; 2- template; 3 - tape with fibers; 4 - splice
Application of a curly connector.
A connector designed for multi-fiber cables and does not require grinding, polishing and gluing the fibers is shown in fig. 11.27.
Rice. 11.27. Curly connector: 1 - fiber; 2 - elastic plastic; 3 - frame
Each fiberglass 1 securely held in the space formed by three cylindrical surfaces 2, made of flexible plastic. These surfaces create a centrally directed pressure on the fiber like a three-jaw drill chuck that holds the drill bit. After the two halves of the connector are installed, they are fastened together and each fiber is in its proper position between the three cylindrical surfaces. The frame is outside 3. Losses in the connector do not exceed 0.3 dB, transient losses exceed 70 dB. Outside, the splice is insulated with a heat-shrinkable sleeve with preliminary wrapping with plastic tapes.
Safety precautions when performing installation work
Installation work.Adhesive work is allowed for persons not younger than 18 years of age. Particular attention must be paid to fulfilling the requirements for the safe handling of blowtorches and gas burners. The mass for pouring cast-iron couplings should be heated on braziers without open fire, while using a bucket with a spout and a lid. The temperature of the mass must be controlled by a thermometer.
Adhesives must be stored in a sealed container: do not allow the adhesive to come into contact with the skin or inhalation.
The work manager gives the order to start work only after a personal check of the absence of voltage on the cable. When cutting the cable, the hacksaw must be grounded to a metal pin driven into the ground to a depth of 0.5 m.
On cable lines that have proximity to an electrified AC railway, it is necessary: a) to perform work only according to a previously issued order, which indicates the main safety measures; b) check the availability and serviceability protective equipment, fixtures and tools; c) carry out the work of teams Oh consisting of at least two people, one of whom is appointed responsible for the implementation of safety regulations; d) carry out all construction and repair work with the use of gloves, galoshes, rugs and tools with insulating handles; e) control the absence of voltage on the cores and sheaths of the cable using a voltage indicator with a neon lamp or a voltmeter.
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| Depending on the purpose of the application area, the conditions for laying and operating the spectrum of transmitted frequencies, the design of the material and the form of insulation of the system of twisting the kind of protective covers. Depending on the field of application, communication cables are divided into: trunk zone intra-regional rural urban submarine as well as cables for connecting lines and inserts. We also manufacture radio frequency cables for power feeders of radio station antennas and for the installation of radio engineering ... | |||
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| In single-mode optical fibers, the core diameter is commensurate with the wavelength d^λ and only one type of wave mode is transmitted through it. In multimode fibers, the core diameter is larger than the wavelength d λ and a large number of waves propagate along it. Information is transmitted through a dielectric fiber in the form electromagnetic wave. The direction of the wave is due to reflections from the boundary with different values of the refractive index at the core and cladding n1 and n2 of the fiber. | |||
| 2142. | INTRODUCTION OF COMMUNICATION CABLES INTO THE STATION BUILDING, INTO TELEPHONE CONNECTED BUILDINGS | 110.47KB | |
| Device for cable entry into the building of automatic telephone exchange equipment of the mine and cross. INTRODUCTION OF CABLES INTO ATS AND MTS BUILDINGS Entering intercity cables into the buildings of terminal and intermediate serviced amplifying points of the OP OUP is carried out either in cable shafts specially designed for this or directly into the premises for placing the equipment of the linear equipment shop. To protect station equipment and maintenance personnel from dangerous voltages of the shell and armor of all... | |||
| 6283. | Chemical bond. Characteristics of a chemical bond: energy, length, bond angle. Types of chemical bond. Communication polarity | 2.44MB | |
| Hybridization of atomic orbitals. The concept of the method of molecular orbitals. Energy diagrams of the formation of molecular orbitals for binary homonuclear molecules. At education chemical bond the properties of the interacting atoms change and, above all, the energy and occupation of their outer orbitals. | |||
| 10714. | CHANNELS OF CONNECTION. NETWORKS OF COMMUNICATION CHANNELS | 67.79KB | |
| Communication line is indispensable integral part each communication channel, through which the occurrence of electromagnetic oscillations from the transmitting point to the receiving point is carried out (in the general case, the channel may contain several lines, but more often the same line is part of several channels). | |||
| 2135. | KEEPING CABLES UNDER EXCESSIVE AIR PRESSURE | 79.25KB | |
| A constant overpressure in the cable can be maintained in two ways: by automatically pumping gas as it leaks, or by periodically pumping gas. Cylinders are used as a source of compressed gas high pressure or compressor units Fig. Efficiency of keeping the cable under overpressure largely depends on the amount of gas placed in the cable per unit length, as well as on the speed of gas propagation. the appearance of a hole, a jet of gas escaping through it protects the cable from ... | |||
| 4650. | Installation of apartment building | 7.3KB | |
| Installation of apartment building. Meta: learn about the features of the installation work of the apartment building; develop vminnya i novichki pіd hour praktії ї rabota; vikhovuvat the accuracy of that love to practice. Rules for the installation of electrical installation work in residential electrical installations For the installation of electrical installation work in Persh Cherga, it is necessary to be aware of the peculiarities of future applications and their recognized temperature and cooling conditions. Methods for the installation of apartment electrical installations. | |||
| 2138. | CABLE TERMINATION AND THEIR INSTALLATION | 80.14KB | |
| As a rule, 100 pairs of cable are included for each strip. consist of a metal case with a conical base in the center of which there is a hole with a tube for cable entry. They are made of porcelain or plastic and front side have two rows of screw clamps from which pins and feathers are passed through the body of the plinth for cable desoldering. The cable sheath is sealed in the box sleeve. | |||
| 18806. | BUDOVA TA INSTALLATION OF CABLE LINES | 23.8KB | |
| Traces of cable lines are stripped with the smallest cable lengths to protect them from mechanical damage, corrosion and vibration, with which the span of cables is unique with one cable of another recognized as pipelines. Cable insulation up to 1000 V humic and over 1000 V from perforated paper and other plastics, polyethylene, polyvinyl chloride and in. Power cables are let out with a cross section of 25 to 300 mm2. Cable cores can be round or sector-like. Cables are called sporadically recognized ... | |||
11.9.1 Copper conductors of cables of the TP type (diameters from 0.32 to 0.70 mm) in new construction should be spliced using mechanical connectors:
a) on cables with a capacity of up to 100x2 with direct splicing, it is recommended to use individual connectors of the UY-2 (ЗМ) and Tel-Splice types for two cores (tyco / Electronics / Raychem);
b) on cables up to 100x2 in parallel splicing, when three wires are spliced simultaneously, it is recommended to use individual UR-2 (ЗМ) and Tel-Splice connectors for three wires (tyco/Electronics/Raychem);
c) on cables with a capacity of 200x2 to 1200x2 for direct splicing, it is recommended to use:
Domestic multicore connectors SMZh-10; stranded connectors of ZM company: MS2 4000-D (25 pairs) and MS2 9700-10 (10 pairs);
tyco/Electronics/Raychem stranded connectors: AMP STACK direct splice 25 pair and 10 pair;
d) on cables with capacity from 200x2 to 1200x2 for parallel splicing it is recommended to use:
Stranded connectors of the ZM company: MS2 4008-D (25 pairs) and MS2 9708-10 (10 pairs);
Tyco/Electronics/Raychem stranded connectors: AMP STACK for 25-pair and 10-pair branching.
Connectors foreign manufacturers should be used when splicing cores with diameters from 0.4 to 0.7 mm.
When splicing cores with a diameter of 0.32 mm, domestic connectors SMZH-10 should be used.
It is allowed to use individual and group connectors of other types.
Manual twisting on cables TPPep, TPPepB, TG and TB during new construction is allowed only with the permission of the network operation services. Manual twisting of cores is insulated with polyethylene sleeves: individual and elongated.
11.9.2 Copper conductors of cables of the TP type with hydrophobic filling must be spliced only with mechanical connectors. Manual twisting during splicing is not allowed. Features of the installation of cables of the TP type with hydrophobic filling are given in 11.19.
11.9.3 The copper conductors of type T cables are spliced by hand-twisting with the insulation of the twists with paper sleeves: individual and elongated. It is allowed to splice the cores of T-type cables with porous-paper insulation with multi-core connectors of any type.
11.9.4 When splicing cores by manual twisting and during the operation of cables connected in this way, it is necessary to exclude the breakdown of pairs, that is, the scattering of connected pairs and quadruples. To do this, each pair or quadruple must be fastened with a dressing of harsh threads (used on T-type cables) or polyethylene group rings (used on TP-type cables).
In the case of using a common extended sleeve, group rings or thread knitting are not required.
11.9.5 When parallel splicing three cores of type T cables by manual twisting, paper sleeves are selected taking into account the diameter of the twists.
11.9.6 Before splicing each regular pair or quad, the splicer must determine their place in the splice. The strands closest to the sheath trims must be at least 40 mm apart from the sneeze. The twists of the cores of individual pairs (fours) or a group of such twists are evenly distributed along the entire length of the splice, displacing each subsequent group by half of the sleeve of the previous group. Placement of twists in a checkerboard pattern is allowed.
11.9.7 When hand-twisting strands of different dihedrons on cables of type T, the strands of strands must be soldered if the difference in diameters is equal to or exceeds 0.3 mm.
The twists are soldered with POSSu-40-2 solder using a solution of rosin in alcohol as a flux (three parts by weight of rosin per seven parts of alcohol). Soldering of twists is carried out in a glass soldering iron, heated by the flame of a gas burner or a blowtorch. Before soldering, the ends of the twists are smeared over a length of 8 to 10 mm with a solution of rosin in alcohol using a soft brush. The ends of the twists are immersed in molten solder for 20 mm. The length of the soldered area should be from 5 to 8 mm. Soldering is carried out in groups of 6-8 pairs as they are spliced.
11.9.8 For splicing conductors of different diameters on cables of the TP type, connectors of a suitable type are selected, taking into account the recommendations of the manufacturers. In this case, both individual and multi-pair connectors can be used.
11.9.9 The method of splicing cores using multi-pair connectors, in which 10 or 25 pairs are spliced at one time without preliminary cutting and stripping, provides high quality installation, the passage of signals from modern types of communication equipment and an increase in labor productivity compared to manual twisting of cores.
11.9.14 To ensure the high quality of the splices necessary for the transmission of modern types of communication equipment signals over cables, when installing low-capacity cables, single-core connectors listed in 11.9.1 should be used. The most widely used connector of this type is the UY-2 "Scotchlok" manufactured by the ZM company (Figure 11.16). It is designed to connect copper conductors with a diameter of 0.4 to 0.9 mm with paper and polyethylene insulation without their preliminary stripping, while the maximum diameter of the conductor in the insulation should be no more than 2.08 mm. The body of the connector is filled with a hydrophobic gel that prevents moisture from affecting the junction of the conductors.
Figure 11.16 - General view of the UY-2 connector
The connector allows you to connect conductors with different core diameters and types of insulation. They are recommended for mounting low capacity cables (up to 100x2) and for splicing spare cores in large bone cables, as well as for splicing screen wires.
To work with UY-2 connectors, E-9Y pressing tongs are supplied. With their help, the connectors are crimped and the excess cores are bitten off.
11.9.15 Splicing of cores of cables with polyethylene core insulation is carried out in the following sequence: pairs (fours) are selected from the selected bundles of spliced cables, corresponding to each other in color, and twisted in three turns at a distance of 40 mm from the sheath cuts (Figure 11.17a) . Then, from the twisted pairs (fours), the same-name cores "A" and "A1" are selected and, having put them together, they are trimmed, cut with press tongs at a distance of 40 mm from the place of twisting (Figure 11.17b). Having turned the connector with its transparent side towards itself, the prepared wires are inserted into it until it stops into the rear wall of the connector housing. The connector is crimped on the cores by the front working part of the press tongs. Next, two second same-name cores "B" and "B1" are selected from the spliced pair and, having put them together, they are cut at a distance of 45 mm from the place of twisting. The wires are inserted into the connector and crimped (Figure 17c, d). In a cable with a four-strand core, the third and fourth cores are similarly prepared, cutting them off, respectively, at a distance of 50 and 55 mm from the twist point.
Places of twists of subsequent pairs (fours) are placed every 30 mm along the entire length of the working area (Figure 17e). The remaining pairs (fours) are mounted against the places of twisting pairs (fours) of the first row. Having mounted the first bundle of veins, they tie it with a waxed thread in three places at regular intervals. Then the remaining bundles are mounted.
The connected bundles are tied together with waxed thread in three places at regular intervals. Groups of mounted connectors formed after ligation are evenly distributed around the circumference of the splice in a fan, starting from the first, and laid so that the connectors lie in one layer, and the diameter of the splice is the same along its entire length.
11.9.16 When splicing the cores of cables with paper insulation, the same pairs of cores are pulled inside the working area and bent at a right angle at a distance of 40 mm from one of the sheath cuts. In this case, damage to the insulation of the cores at the bend should not be allowed, the cores should be bent smoothly, holding at the bend with the thumb and forefinger.
a - spliced cores are twisted;
b - cores "A" and "A1" are prepared for splicing;
c-cores "A" and "A1" are connected in UY-2, cores "B" and "B1"
prepared for splicing;
g - a pair of cores is pressed in connectors;
d - the first row of mounted pairs of cores
Figure 11.17 - Splicing cores using single-core connectors
11.9.17 Restoration of core insulation characteristics is provided by the materials from which connectors and sleeves are made. The housings of the connectors are made of plastics, which ensure that the established norms for insulation resistance and test voltage are achieved during measurements. Paper sleeves must be made from cable paper.
Sleeves for TP type cables must be made of high pressure polyethylene. It is allowed to use TUT tubes made of radiation-modified polyethylene as sleeves on rural communication cables.
The use of pipe segments made of PVC compositions as sleeves is not allowed.
Cable installation in lead sheaths with copper conductors in paper insulation (TG grades). The cores are spliced by twisting or twisting with soldering, depending on their diameters. Splices are insulated with paper sleeves with pairwise knitting of cores on both sides of the sleeves. The entire bundle of strands is scalded with the MCP mass or dried with hot air, and then wrapped with a bandage of scalded calico. A lead sleeve is pushed onto the splice and the joints are soldered with tin-lead solder POSSU-30-2 with stearin as a flux.
Cable installation in lead sheaths under steel tapes of armor with copper veins in paper insulation (TB brand). When installing a TB brand cable, the same operations are performed as when installing a TG brand cable, but, in addition, armor tapes and jute (cable yarn) are fixed with wire bandages, and a protective cast-iron sleeve is installed on the lead sleeve, which is filled with MKB mass.
Installation of cables in plastic sheaths with polyethylene insulation. Copper cores of cables with polyethylene insulation are spliced either by twisting over a length of 12 ... 15 mm without soldering or with soldering, or by individual or multi-pair compressible connectors. The splices of the cores, carried out by twisting, are insulated with through polyethylene sleeves by cores, in pairs or in fours. In case of vein isolation, pairs or quadruples are tied at the sleeves with threads or fixed with group polyethylene rings. The entire bundle of spliced cores is tightly wrapped with two layers of polyethylene (polyvinyl chloride) tape. On the joint, screen tapes are restored, the ends of which are spliced “in a lock” or with a roof seam. The ends of the copper screen wire are connected by twisting. A polyethylene or polyvinyl chloride sleeve is pushed onto a bundle of spliced core conductors, depending on the material of the cable sheath.
Restoration of the outer covers of cables with homogeneous polyethylene sheaths. For welding polyethylene sleeves with polyethylene sheaths of cables and parts of the sleeves between themselves, the most widely used method is the fusing of polyethylene tape at the joints, heated through the protective layer of glass tape by the flame of a blowtorch or gas burner. Heating is carried out in cycles for a regulated time.
The thickness of the polyethylene tape winding layer should approximately correspond to the radial thickness of the cable sheath. Two layers of glass tape with 50% overlap are wound over the polyethylene tape under tension. The entire surface of the glass tape is evenly heated by the flame of a blowtorch or gas burner. The glass tape is removed from the hardened but not yet cooled joint.
For the same purposes, the so-called copper insert method can be successfully used. Copper insert heaters are inserted into the gap between the ends of the sleeve and the cable sheath or between the parts of the sleeve. The area under which they are wound is tightly wrapped with a rubber band, squeezing the surfaces to be welded. Then the tail of the liners is heated with a moderate flame from a blowtorch or gas burner. When molten polyethylene begins to protrude in the gaps between the halves of the liners, they are first turned at an angle of 35 ... 45 degrees, after which they are heated again for 0.5 ... 1.0 minutes and then forcibly removed from the joint using two pliers. This method is characterized by a sufficiently high quality and productivity, but requires an accurate selection of inserts according to the shape and size of cables and couplings.
Restoration of the outer covers of cables with homogeneous polyvinyl chloride sheaths (TPV). As a rule, the restoration of the outer sheaths of TPV cables is carried out by welding PVC sleeves with cable sheaths and parts of the sleeves to each other using copper liners heated by the flame of a blowtorch or gas burner.
When welding polyvinylchloride sheaths of cables and sleeves with liners, the technology differs from that described above for polyethylene sheaths and sleeves in that in this case, with sufficient heating (up to a temperature of 180 ... 200 ° C), the liners fall out spontaneously and they do not have to be removed from the joint forcibly. The rubber tourniquet is removed 2 ... 3 minutes after the inserts fall out. The requirements for the accuracy of the selection of liners in shape and size remain the same as in the case of polyethylene welding.
It should be noted that the need for welding PVC sheaths of cables and couplings occurs very rarely, since the laying of such cables in the sewers and the ground has been prohibited in our country for more than 10 years and their use (with a capacity of up to 100 pairs) is limited only to laying along the walls of buildings and suspension on ropes.
In world practice, heat-shrinkable tubes of various diameters are widely used for connecting both homogeneous and dissimilar sheaths of cables and couplings. These plastic tubes, previously exposed to radioactive irradiation and stretched when heated, are then fixed by cooling. When heated again, such tubes shrink spontaneously to the dimensions they had before being stretched. Depending on the degree of stretching during manufacture, these tubes are produced with a reheat shrinkage factor of two, three, or even five times. Such tubes are usually produced coated on the inside with an adhesive layer. Pushed over the joint of the coupling with the sheath of the cable or parts of the couplings between themselves and heated with a blowtorch, a gas burner or an infrared radiation source, such a tube, seated, tightly compresses the joint, and the gluing layer melted at the same time fills the gaps and reliably seals the joint.
Inside dry rooms, distribution cables in plastic sheaths with a number of pairs up to 100 inclusive can be connected with appropriate plastic sleeves without the use of welding. Joints are wrapped with at least four layers of adhesive plastic tape. Under the same conditions, plastic sheaths of cables with a number of pairs up to 20 inclusive can be restored without the use of couplings, but only with a connection winding of at least four layers of adhesive plastic tape.
Installation of cable sleeves in steel corrugated sheaths (TSShp and TPSShp). The cores of TSSHp cables are mounted similarly to TG cables, and TPSSHp - similarly to TPP and TPV cables. The ends of steel corrugated shells are tinned with PMKN-10 solder paste, and a lead sleeve of appropriate sizes is soldered to them with POSSu-30-2 solder. When laying directly in the ground, the lead sleeves of the cables are protected by cast-iron sleeves filled with MKB mass. When laying cables in the sewer, cast-iron couplings are not used. In this case, sections of the steel corrugated sheath between the cuts of the outer polyethylene hoses and the solder joints of the lead coupling are wrapped with several layers of adhesive polyethylene and PVC tape. The lead sleeve is protected by a polyethylene sleeve, welded by one of the listed methods to the outer polyethylene hose of the TSSHp or TPSShp cables.
Installation of overhead cable couplings of the TPPS brand with a built-in rope (cable). The polyethylene jumper between the rope and the cable is cut at a certain length with a knife, and the cable is separated from the rope. Splicing of cores and restoration of polyethylene sheaths of TPPS cables is carried out in the same way as for TPP cables. The ends of the built-in ropes (cables) are spliced in a steel sleeve crimped with special tongs, which is then protected by a polyethylene sleeve-tube, welded by one of the indicated methods to the rope sheath separated from the cable.
Coupling installation at the junction of cables in polyethylene (TPP) and lead (TG) shells. Installation is carried out using special cuffs, designed for reliable pairing of polyethylene with lead. Cuffs are made in workshops where they are tested for tightness. Complete with a cuff, both lead and polyethylene sleeves can be used, however, lead is preferable.
When mounted on the line, the cuff is put on one of the cables to be joined with the corresponding side (polyethylene or half-plated part of the metal tube) and either soldered to the lead sheath of the cable with POSSu-30-2 solder, or welded using one of the above methods with the polyethylene sheath of the cable on the other side of the splice. After mounting the splice, the sleeve is welded or soldered with one side to the adapter collar, and with the other side - to the sheath of the second of the joined cables.
The junction of cables in a steel corrugated sheath (TSShp or TPSShp) with cables in a polyethylene sheath (TPP) is carried out using the same special adapter cuffs as when installing the junction of cables in a polyethylene sheath (TPP) with cables in a lead sheath (TG).
Splicing of cable cores of local communication networks. The cores of local network cables can be spliced either by twisting or by soldering, depending on their diameters, or by using compressible connectors (see Fig. 2.35).
When splicing cores of local communication cables with core insulation of splices with paper (for TG cables) or polyethylene (for TPP, TPV cables) sleeves to fix the spliced pairs or quadruples and prevent displacement of the sleeves, the cores in paper insulation are connected on both sides with scalded harsh threads.
Instead of knitting, common group polyethylene rings put on in advance are put on pairs or fours of cores in polyethylene insulation - one on each side of a group of polyethylene sleeves.
Wide application received a method of isolating not an individual joint of each core, but a group of cores - a pair or a four - with one common polyethylene sleeve of a larger size and increased length.
More progressive than manual or mechanized stranding is the method of splicing the cores of cables of local communication networks using individual compressible connectors.
Distinctive feature of these connectors is that they eliminate the need to remove or warm up the insulation of the connected sections of the cores. The contact of the spliced cores is achieved by compressing the connectors; the sharp teeth of the inner, metal lining, insulated from the outside, cut into the copper conductors to a strictly defined depth. Compressible connectors provide more stable and lower contact resistance of strand splices compared to conventional strands.
Restoration on joints of the outer covers of cables in lead and steel sheaths with lead couplings. Due to the widespread use of cables in plastic sheaths, cables in lead sheaths are currently used to a limited extent and do not find application at all with a capacity of less than 50 pairs.
It should also be noted that for cables with a capacity of 50 pairs or more in steel corrugated and aluminum sheaths, lead connecting and branching couplings are used. They are also used at the joints of cables in dissimilar sheaths.
Couplings. For cables of the brand TG and TB with a number of pairs up to 100, one-piece lead couplings are used (Fig. 2.36, a). For the same cables with a number of pairs of 150 or more, lead couplings are used, made up of two parts (Fig. 2.36, b). In this case, not two, but three seams are sealed - the middle and two extreme ones.
Branching couplings. The design of a round lead junction box (glove) is shown schematically in Figure 2.36, c.
Typical lead branching couplings provide for branching of the main cable in no more than three directions (fingers).
Rice. 2.36. Lead Couplings:
but - solid connective; b - connecting of two halves; in- round branching; G - station branching; D- diameter of the coupling on the cone of the second half; d- coupling diameter in a straight section; d1- the diameter of the coupling on the cone; d2- diameter of the coupling on the straight section of the joint; d3- diameter of the coupling at the branching junction; d4- inner diameter of one branch; d5- inner diameter of one branch; L- total length of the coupling; l- the size of the coupling to the conical part; l 1- cone length; l 2 - the length of the joint of the two halves of the coupling; l 3- the length of the transition from the joint to one half; l 4 - branch length; l 5- joint length; l 6- the length of the transition from the junction to the branch
On fig. 2.36, d shows a station lead branching sleeve used in cases of input from the sewer into the mine of cables in lead sheaths (TG).
Restoration on joints of the outer covers of cables in polyethylene sheaths with polyethylene sleeves. The design and dimensions of polyethylene sleeves are regulated by TU 45-8-86.
Connecting polyethylene sleeves. On fig. 2.37, a sketch image of a polyethylene connecting MPS coupling for unarmored cables in a polyethylene sheath is given, and in fig. 2.37, b - MPSB, for armored cables in a polyethylene sheath.
Rice. 2.37. MPS polyethylene couplings: a - for unarmored cables in a polyethylene sheath, b - MPSB for armored cables in a polyethylene sheath: 1 - supporting rings.
Branching polyethylene couplings. On fig. 2.38 is a sketch of a polyethylene branching coupling in two directions 2MPR, and in fig. 2.38, b - in three directions of the 3MPR. The main dimensions of these couplings are according to TU 45-8-86.
Rice. 2.38. Polyethylene splitter couplings MPR: a - two, b - three directions.
Station branching polyethylene couplings. On fig. 2.39, but a sketch is given of MPRS station branching polyethylene couplings for 6, 8 and 12 directions, and in fig. 2.39, b and c, respectively - in 18 and 24 directions.
Rice. 2.39. MPRS station branching polyethylene couplings: a - for 6, 8 and 12 directions, b - 18 directions, c - 24 directions.
Copper cable installation technology
YES. Popov, Chief Specialist of the Communications Department of the GTSS
The organization of telecommunication networks based on fiber-optic transmission lines overshadowed the problems associated with the construction, installation and operation of copper cable lines. One of the most "sore" issues for copper-core cables with polyethylene or metal sheaths is the tightness of the sheath and control of its integrity during installation and operation.
Based on the experience of designing, building and operating the GTSS in 1986, he proposed a cable installation technology with the separation of the "trunk" of the main cable from the branch cables into relay cabinets and service facilities located on the stage using gas-tight insulating sleeves. At the same time, it was decided to ground the armor and sheaths of the main cables according to a three-point scheme - only at the inputs to the terminal (amplifying) points and in the middle of the amplifying section.
This solved a number of problems:
Electrically isolate the main cable from the branch cables, which eliminated the ingress of reverse traction current through the branch into the main cable;
Control on the amplifying section the resistance between the armor and the "ground", the armor and the shell and the shell and the "ground";
Put under control the integrity of the hose protective covers of cables with an outer cover of the Shp type;
Reduce the search time for leaks in the main cable sheath;
Reduce the cost and complexity of construction, since there is no need to ground the armor and cable sheath at each coupling.
The technology for installing the main cable is described in detail in typical materials for the design of “Cable lines for long-distance communication of railway transport. Linear structures, 410405-
TMP, ShP-43-04, developed in 2004. However, today new problems have arisen. One of them is organizational: escebists and signalmen operate lines for various purposes, and the requirements for parameters specified lines different. Whereas before, high-frequency, low-frequency communication circuits, as well as automation and telemechanics were combined in one trunk cable.
The second problem is that there are no fully developed cable installation technologies, and the process of their implementation is slow.
Consider the state of technology used for the installation of communication cables. VNIIAS developed the "Instructions for the installation, repair and restoration of railway cable lines using new technologies and materials", which was approved in 2002. We note some of its features. The first is the absence in the instructions of previously existing technologies for mounting couplings by soldering and explosion welding. The second is a change in the design of the splitter coupling: instead of the traditional T-shaped, we have a glove configuration. The third one is the use of “Armoplast” tape instead of cast-iron couplings for protection against mechanical influences. Fourth - the possibility of mounting direct sleeves when restoring the tightness of the sheath without cutting the cable using heat-shrinkable cuffs.
In the presence of positive factors, there are also some costs in new technologies and materials for installation. Thus, the mortise tee coupling “disappeared” from the range of couplings, in which the connection of the conductors of the branch cable with the main cable was carried out in parallel without cutting the conductors of the latter.
Let's analyze new technology installation of gas-tight insulating sleeves. According to clause 8.2 of the instruction for the installation of gas-tight insulating sleeves GMVI-4, GMVI-7, GMVI-40, a length of 4 or 6 m is used on the branch cables (hereinafter referred to as the stub cable). In its middle, protective covers are removed - aluminum sheath and belt insulation, and using a collapsible removable form, installed in place of the removed sheath of the cable section (without cutting the current-conducting cores), a polyurethane composition is poured. When mounting the sleeve with cutting the cable, after pouring the assembled splice, parts of the MPP brand sleeves and a heat-shrinkable tube HERE are pushed onto its ends. Thus, a branch is created without the use of GMVI.
When laying the cable in the body subgrade the recommended branch length is 6 m. In this case, when installing branches to relay cabinets for the GMVI device, no additional couplings are required. However, with a 4 m stabilizing cable, an additional coupling is required. If the segment of the stabile cable, representing the GMVI coupling, is soldered from one end into a branching coupling, the other end must be extended with a cable of a certain length in order to enter the relay cabinet or an object located on the stage.
A decision arises: the length of the branch cable should be such that it overlaps the distance from the installation site of the tee (branch) coupling to the box installed at the facility where the branch cable is inserted. In this case, the installation of the GMVI - the cut and removal of the sheath of the branch cable and the filling of this place with a polyurethane composition are carried out directly on the branch cable in one pit with a splitter. This eliminates the need for an additional coupling.
Gas-tight couplings HMS-4, HMS-7, GMSM-40, manufactured according to the classical scheme for cable installation technologies by hot soldering, are produced by OJSC Svyazstroydetal. Their transformation into gas-tight insulating sleeves is carried out in accordance with the instructions by removing a strip 10 mm wide from the middle of the gas-tight sleeve and restoring its tightness by slipping onto the remote section of the heat-shrinkable tube.
Thus, based on the analysis of new technologies for installation, repair and restoration of railway cable lines and the available design experience, it is advisable to recommend the following:
The installation of gas-tight insulating sleeves should be carried out directly on the branch cable in the same pit with a branch sleeve and refuse to standardize the length of the branch cables according to the instructions (stub cables). Similarly, it is necessary to install a gas-tight coupling directly on the main cable when it is entered into amplifying (terminal) points;
Supplement the instructions with a list of standard sets of consumables (sets for mounting various brands cables) and tools that must be purchased for the manufacture of gas-tight couplings and which must be provided for in the design.
INSTALLATION OF AUTOMATION AND TELEMECHANICS CABLES
No less questions arise regarding the technology of installing signaling cables. Today, these are independent cable lines that are laid both at stations and on hauls to organize automation and telemechanics circuits. Below we will talk about cable lines for organizing signal chains on hauls.
The fundamental difference between signaling and communication cable lines is that automation and telemechanics circuits are organized, as a rule, according to physical pairs, the frequency parameters of which are not standardized. Specialists may object, referring to the fact that cables in pairs are recommended for use. However, this objection is not justified, since there are no norms for the installed sections of signaling cable lines. It should be noted that in section 22 of the Rules for laying and installing cables of signaling devices, PR 32 TsSh 10.01-95, only norms of insulation resistance of cable cores are established before installation, after installation and during operation.
The second difference is the construction length of the cables. It is no more than 300 m for cables with polyethylene insulation in a plastic sheath (GOST R51312-99) and for cables with polyethylene insulation in a metal sheath with hydrophobic filling (TU 16.K71-297-2000). For cables with polyethylene insulation with water-blocking compounds in a plastic sheath, manufactured according to TU 16.K71-353-2005, the construction length is: for unarmoured - 1000 m, armored with the number of pairs up to 14 - 800 m, with the number of pairs 16 or more - 600 m.
Currently, the current regulatory documents for the installation of signaling cables are: "Rules for laying and installing cables of signaling devices, PR 32 TsSh 10.01-95"; "Rules for the installation of cables for signaling and interlocking with hydrophobic filling, M. 1995"; “Rules for the installation of cables for signaling and interlocking with aluminum sheaths and hydrophobic filling. PR 32 TsSh 10.11-2001.
A significant difference of the technology is also that the signaling cable lines are not kept under excessive pressure, they have a large range of connecting and branching couplings (floor, underground) and, as a result, different technologies for splicing construction lengths. In addition, they do not have branches and are inserted into service facilities and relay cabinets with a full cut, and due to short construction lengths, a large number of couplings.
Of the connecting underground couplings recommended in regulatory documents, the signal-blocking dead-end (MSBT) and straight for signal-blocking cables (MSB-A (u) b) are most often purchased, designed for cables with polyethylene and aluminum sheaths, respectively. They are supplied as cable mounting kits. The manufacturer, OJSC Svyazstroydetal, has developed appropriate instructions for their installation.
Technologies for connecting cables in underground direct couplings using frames and heat-shrinkable tubes, as well as a polyurethane composition, are fixed in the "Rules for the installation of cables for signaling and interlocking with hydrophobic filling", but consumable kits are not provided. At the same time, such kits are given in the "Rules for the installation of cables for signaling and interlocking with aluminum sheaths and hydrophobic filling PR 32 TsSh 10.112001".
Heat-shrinkable tubes and cuffs, as a rule, of foreign manufacturers are used. However, heat-shrinkable cuffs are not recommended for use by regulatory documents for the installation of signaling cables.
FEATURES AND CONTRADICTIONS IN THE TECHNOLOGY OF INSTALLATION OF COMMUNICATION CABLES AND STsB
The fundamental differences between communication cables and signaling cables, in addition to being kept under excessive pressure, installation of inputs and branches, are also found in the device for grounding armor and metal sheaths and in the standards of grounding devices, as well as the standards of induced voltages in the cores of cables on electrified railways ah AC.
The circumstance that forces us to analyze and evaluate the state of technology and installation of signaling cables is their length, as well as the presence of galvanically non-separated circuits in them (from station to station), which are subject to electromagnetic influences of AC electric traction.
This should be taken into account when choosing routes and brands of cables, as well as calculating the effect of the traction network of electrified AC railways on the signaling line.
In these calculations, it is necessary to take into account the requirements of regulatory documents for the installation of cables and, first of all, recommendations on the device for grounding their armor and sheath, subject to electromagnetic influences that affect the coefficient protective action sheath and the magnitude of the induced voltage in the conductors of the cables of the signaling system.
Institute "Giprotranssignalsvyaz" on the basis of regulatory documents developed and published in 2003 auxiliary materials "Calculation of the influence of the traction network of electrified AC railways on the signal line, 650219", which guide the designers.
The norms of induced voltages in the cores of the signaling cables are adopted in accordance with the “Guidelines for the design of automation, telemechanics and communication devices. Issue 37 contact network electrified AC railway. They are: for the forced mode of operation of the contact network - 250 V, for the short circuit mode - 1000 V.
The value of the induced voltage for the forced mode of operation of the contact network is confirmed in the "Standards for the technological design of automation and remote control devices at the federal railway transport, NTP STsB/MPS-99", and for the short circuit mode it is indicated that the permissible voltage in the relay circuits is regulated by the "Rules for protecting communication devices and wire broadcasting from the influence of the traction network of electrified AC railways". However, in table 3.2 of these rules, only the allowable induced voltage with respect to earth in the cable cores is given, when applied special measures on protection and safety measures, and it is 0.6 IISP - the test voltage of the insulation of the cores or input equipment in relation to the ground (shell), specified in specifications or in GOST.
For signaling cables manufactured in accordance with GOST R51312-99 and TU 16.K71-297-2000, the norm of test voltage between the conductors is 2500 V. Taking this norm to calculate the short circuit mode, taking into account the norm for the allowable induced voltage, we get: 0.6 x x2500 = 1500 V, i.e. we have conflicting standards for calculation in the short circuit mode.
For communication cables, the grounding of the armor and sheath is carried out according to a three-point scheme. In this case, the armor and the shell are not soldered at the inputs and in the couplings. The main cable is electrically insulated by gas-tight insulating sleeves against taps. The sheath and armor of the branch cables are grounded to a separate ground when entering the relay cabinet or an object on the run. The resistance of grounding devices in electrified sections for terminal amplifying points and combined buildings of communication centers with EC posts, according to Table 7.1 of the "Departmental norms for the technological design of telecommunications in railway transport, VNTP / MPS-91", as a rule, should be 4 Ohm. There is no specific standard for grounding devices for signaling cables in NTP STsB/MPS-99.
The rules for laying and installing cables of signaling devices - PR 32 TsSh 10.01-95 interpret the grounding device for the armor and sheaths of signaling cables both on lines and at inputs differently than for communication cables. So, in paragraph 21.2 of these rules it is said that in areas equipped with electric traction, both alternating and direct current, metal sheaths and armor of cables in relay cabinets and service buildings should be connected with wire segments of the PV2, PV3 or PV4 brand with a cross section of 2.5 mm2. In clause 21.3, an explanation is given that in underground couplings, the armor and cable sheaths are connected by separate insulated wires of the PV brand, that is, they are not connected to each other and are not grounded.
In addition, paragraph 21.4 states that in areas with DC electric traction, the wires connecting the armor and cable sheath in service buildings and in relay cabinets are connected by a common wire through the instrumentation to a protective grounding device, and in areas with AC electric traction the common wire is connected directly to the grounding device.
Clause 21.16 states that on armored signaling and blocking cables with or without metal sheaths, after entering the service and technical building (post ETs, GAC, etc.), it is necessary to arrange insulating sleeves. However, the design, installation technology of these insulating sleeves and the norms of grounding devices for input cables are not given. In addition, clause 21.11 states that for grounding the armor and cable sheaths at relay cabinets, transformer boxes, branching, universal and connecting couplings, standard signal grounding devices should be installed, the resistance of each of which should not exceed 10 Ohm.
Taking into account the absence of decisions on the design of the insulating sleeve, the SCSC developed and issued a local document - order No. 31 dated November 30, 2000, which prescribes cables with a metal sheath or armor to be cut on UPM or RM type ground sleeves and put into the EC- TM cable brand SBPZU.
Thus, it turns out that there is no clarity on the rationing of resistance and the installation of grounding devices for grounding the shells and armor of signaling cables in service buildings.
Signaling cable lines have armor and sheath integrity only from the EC post to the signal point (relay cabinet), then from the signal point to the next signal point, etc. At the same time, check the resistance in armored cables with metal sheaths of the "armor - ground" sections, "armor - shell" and "shell - ground" throughout the line from station to station is impossible (instrumentation is recommended only in areas with DC electric traction, but armor and shell are connected to the grounding device soldered together).
Based on the foregoing, the following conclusions can be drawn:
It is necessary to correct the mentioned normative documents on the laying and installation of signaling cables in terms of determining a clear range of used couplings and kits for mounting couplings on signaling cables;
Do not solder the armor and sheath at the inputs to relay cabinets, EC post buildings, service facilities by analogy with communication cables, grounding them (armor and sheath) element by element through the instrumentation, and give a clearer version of Section 21 PR 32 TsSh 10.01-95. Specify and legitimize the installation of insulating sleeves on armored cables and cables with metal sheaths, which will make it possible to control the integrity of the hose cover, and for armored cables to control the resistance between armor and "ground", armor and sheath and sheath and "ground" in the sections of the post EC - signal point and further from signal point to signal point;
To normalize the grounding resistance of the armor and sheath of cables when they are entered into service and technical buildings and objects on the stage, based on the installation scheme of the main cables of the signaling system (a complete section of the cable and its entry into the relay cabinet, the object on the stage);
To ensure the integrity of the armored cover and metal sheath when cutting the cable in cabinets at the terminals, which will allow maintaining its protective action coefficient throughout the entire length from station to station.
PERSPECTIVES
Many problems of laying and installation of communication cables and signaling systems should have a unified approach to their solution, and it is advisable to resolve the accumulated issues promptly.
As a first step in this direction, it would be necessary to consider these problems at a meeting of specialists, develop and agree on a program to eliminate them, develop norms, rules, recommendations, technologies and approve them for use in the design, construction and operation of cable communication lines and signaling systems. Moreover, first of all, it is necessary to normalize the parameters of lines and circuits of automation and telemechanics, establish the norms of induced voltage in the cores of the signaling cables to calculate the effect of the traction network of electrified AC railways on the signaling lines, the norms for grounding the armor and cable sheath and work out a clear technology for grounding the armor and cable sheaths.
In signaling systems, microprocessor and other electronic devices and they cannot be subject to the current norms of induced voltage, as well as grounding, arranged for equipment installed in buildings.
The second issue is the regulation of the types of couplings used for the installation of communication cables and automation and telemechanics. I would like to refer to an article published in Vestnik Svyaz No. 3, 2003 by S.M. Kuleshov, "Popular delusions of linemen". The author gives an overview of the current state of affairs in the application of technologies and sleeves for cable installation and emphasizes that electrical and optical cables can and should be supplied with sleeves that consumers will mount on communication lines.
The third question is to eliminate all contradictions and omissions regarding the installation of signaling cables, available in PR 32 TsSh 10.01-95.
Fourth, give green light» cables with water-blocking compounds, ensuring their implementation on the road network with support and competent use of technologies and materials for mounting couplings on them. Such cables include main high-frequency communication cables with three-layer film-porous insulation and water-blocking materials (TU 16.K71.358-2005), cables for signaling and blocking with polyethylene insulation with water-blocking materials in aluminum (TU 16 .K71.354-2005) and plastic (TU 16.K71.353-2005) shells. They are devoid of many of the shortcomings inherent in classic cables, and will be able to provide higher operational parameters of the lines.
A separate document has been issued on the laying of communication cables. Collection of related topics. At first glance, it seems that the rules for laying communication cables contradict the definitions. As you get acquainted, you begin to understand: the type of track is decisive. According to these aspects, a brand is selected that determines the methods of installation on the ground. Let's see how the communication cable is laid.
Cabling
Contrasting with power grids, communication cable is often underground. The right of way is traditionally used. The cable runs along roads, underground, along poles. Priority is given to highways of greater significance. If there is a choice to use a federal highway or a local one, the first one is used. The line length must be minimal. In some cases, it is allowed to lay communication cables in the ground by smoothing sharp corners, straight between individual sections of the highway. Only in the conditions of Siberia, Far East, Far North, getting access to the Internet in a private house, residents are forced to categorically deviate from the rules.
The road network is not developed everywhere. They lead lines through undeveloped terrain. It is allowed to lay the cable on the branches of the railways. They are trying to ensure that the connection is on opposite sides of the web with a high-voltage line. If not feasible, the power track runs closer to the railroad tracks. Finally, many are interested in what is meant by the term road diversion. The area starting behind the ditch, reserve (lies behind the berm).
Cable bays
Bookmarking, if possible, is carried out in a trenchless way. Have you seen how the majors pull the old cable over the steppes with the Urals, then rent it out and share it? Bookmarking is a similar method, only in the opposite direction. A decent-sized bulldozer is working, carrying a coil of communication cable. With the help of a special harrow, the vein lies immediately underground. After the technique, a more or less even seam remains. The use of mechanized labor during laying is strictly regulated. Let's look at VSN 116 on this matter (a separate normative act, RM 13-2):
- Volume earthworks performed by equipment - at least 80%.
- Cable laying is 87% mechanized.
- Pulling the line in the cable duct - at least 65%.
We consider the presence of regeneration points to be a distinctive feature of communication lines. The weakened signal is amplified again, reaching the standard level. Otherwise, it is impossible to lay an optical communication cable over long distances. The modem will simply be unable to recognize the signal. To optimize the network, special measures are taken, the cable for laying the communication line is taken of the appropriate brand. Allowing to reduce losses by reducing the number of track regenerators. Let's discuss what are the lines of communication, composition.
Communication cable
General organization of communication lines
Cable communication lines are usually divided:
- Trunk, usually laid between the nodes of the first class (large settlements of neighboring regions).
- Intrazonal, lying within one relatively small region (region).
- Trunk connecting capacities are not inferior to the first category, they will serve as a kind of bridge between larger segments.
- Local cable networks are laid within the framework of one city (laying a communication cable to a private house).
Inside the city, the network (called the backbone internal) reaches the indoor closet. Distribution board for the area. If we take telephone lines, a dozen houses can have a steel cabinet, inside there is a wiring to the buildings. Each building is equipped with another shield of a more modest size. The areas between houses are called distribution areas. At the entrance there is a subscriber wiring. Not a cable, a usual cord, a wire from two copper veins.
According to the signal of the chain, it is customary to divide:
- Lines of the first class I with voltage over 360 volts.
- Lines of the second class II with voltage up to 360 volts.
- Subscriber lines, the voltage varies 15 - 30 volts.
Laying, installation of communication cables is carried out:
- Directly in the ground.
- In various underground communications, undergrounds.
- Underwater.
- Mounted.
Little different from power grids. According to the classification of the scale of the line (first table), recommendations are given for laying lines with a fixed mark. There are two types of cables - electrical and optical.
Electrical cables
Consist of the usual copper wires. Aluminum bonding is rarely used due to high losses.
- The main (primary) lines are formed by a coaxial cable in aluminum sheaths KMA-4, in lead - KM-8/6 (only for reconstruction), coaxial small-sized aluminum - KMTA-4.
- Connecting main lines are built with similar products, with the exception of those provided with a lead sheath. Sometimes it is allowed to use ISS 4x4 communication cables.
- On intrazonal networks, MKT-4, VKAP, MKS-4x4x1.2, ZK-1x4x1.2 are used.
- Local networks (primary and secondary) are built from: MKS-4x4x1.2 and 7x4x1.2, KSP, KSPZ, BKSPZ, T, TP, PRPPM.
- Wired broadcasting networks (public radio, used by the USSR) are built on PRPPM, MRMP, RBPZEP, RBPZEPB, RMPZEP, RMPZEPB. The last four grades belong to the hydrophobic filled family. This includes products containing both aluminum and copper inclusions. When wet, the process of electrochemical corrosion begins.
Optical cables
Formed by glass filaments that propagate waves close to the visible spectrum. High frequencies enable efficient coding of a large amount of information. There are single- and two-mode conductors.
- Backbone networks are built from single-mode cables with a different number of cores (4, 8 or 16). At wavelengths of 1.3 and 1.55 µm.
- Intrazonal networks are based on the use of multimode gradient fibers of 4 or 8 pieces in a bundle. The working wavelength is 1.3 µm.
- Local networks differ from intrazonal networks by the assumption of the use of a wave of 0.85 microns.
unfashionable fashion
In practice, it is necessary to reduce the regeneration interval. As a result, more amplifiers would have to be installed on the highways. Sometimes unacceptable, expensive. Methods for laying communication cables under water cause many difficulties. They told how the Anglo-French concern Alcatel lays an optical cable under the ocean floor. Loading the ship takes three weeks, now imagine how long underwater installation takes.
The signal amplifier-regenerator weighs half a ton. While the cable goes along the route, things move quickly, then it stops, because the cores need to be cut into the case. Regenerator failure is a problem. The less it costs on the main line, the better. It is profitable to make a profit for the route laid, there is no benefit from repairs. Therefore, single-mode fibers must be used on the backbone.
The laying of a communication cable in the ground is carried out so that the regenerators are located in a flood-free area. Exceptions to the rules are allowed with justification of the technical side of the issue. Landslide, mudflow places are not used. To provide signal amplifiers with energy, the communication cable is laid in a special way:
- On intrazonal networks, existing points are used to the maximum. Equipped with ready-made energy sources.
- For local networks, the installation of associated equipment is allowed. Priority is given to equipped nodes. Everyone sees a key example in the entrance. Provider junction box containing amplifying equipment. Power is taken from the local power grid.
Laying a communication cable in the ground
The laying method is determined by the brand of cable, discussed in the sixth section of VSN 116. PRPPM is used by lines of the second class II with own sewerage, on subscriber lines - in the ground with rare exceptions. Depending on the type of line, the depth of laying the communication cable in the ground varies:
- Electric and optical cables of the primary network of any level outside settlements, class II lines and connecting lines lie at a depth of 1.2 meters.
- Other intrazonal networks are laid 0.9 meters underground.
- Electric cables of urban, rural telephone networks in the territory of settlements are buried by 0.7 meters, outside - 0.8. Smaller values \u200b\u200bare used - they use protection from bricks (slabs). Similar to the one used to equip the power lines (see the corresponding review).
- 0.8 meters is used by Class II broadcast cables.
You should know: soils are divided into groups, the requirements listed above apply to categories I - IV. The fifth includes permafrost, rocks: the depth of laying the communication cable decreases (0.4 - 0.6 meters, the depth of the trench is 10 cm more). VSN 600 contains a lot of thematic information. The width of trenches (developed by mechanized method) is indicated.
The slopes of the line crawls like a snake, the deviation to the side is 1.5 meters (the length of the linear sections is 5 meters). It is customary to use special armor cable brands. By air, it is allowed to lay subscriber, intrazonal networks with a technical justification. In the second case, existing columns are used. The laying of the communication cable in the building is carried out in accordance with the usual standards. Provides protection against induced interference.
We hope that we have conveyed to readers the main ways of laying communication cables. Line locations are often marked with signs. Commanding Kazakhs know the excavation sites, the signs act as warning signs. The installation organization will draw up a project so as not to touch neighboring lines. And special warning signs are called to help to make on the ground.
