Building of cable lines

Building of cable lines

Designing of cable lines and networks. Designing consists of working out of the contract design of building and working drawings. Work on the contract design begin with researches and district inspection where building of cable lines and networks is supposed. During researches choose variants of a line main, lines or networks, measure specific resistance грунтов, define conditions of rapprochement of a planned line of a cable with the electrified railways and transmission lines, find ways of crossing iron and highways, and also water barriers, etc. In the project choose type (mark) of a cable, its capacity taking into account prospect of development of devices.

At designing of cable networks of automatics and telemechanics, for example a cable network of electric centralisation, plan the most favourable line of a lining of a cable on station territory, choose sites where it is better to lay group and individual cables.

Depending on number of centralised arrows and signals count capacity of cables for inclusion of arrows, a food of traffic lights and rail chains, and also capacity межпостовых alarm and power cables. Together with a choice of type and capacities of cables carry out electric calculations of the area of cross-section section of veins power and numbers of duplicated veins of alarm cables.

The contract design of cable lines or networks should contain estimates on the equipment, the data about requirement for materials and labour, the plan of the organisation of works and a building overall cost. The main attention is given to questions of mechanisation of works at a cable lining.

On the basis of the confirmed contract design develop working drawings which include detailed drawings of a line of laid cables. On drawings put a cable line, specifying its distance from tracks, facades and other constructions of passenger and travelling buildings, contours of woods and green plantings, a line of communication lines, automatic lock-out and high-voltage lines.

Choice and line breakdown, digging and preparation of tranches and foundation ditches. A line of underground cable lines choose proceeding from that the length of the cable laid between set points, was the least and conveniences of work on a lining of a cable both its maintenance service and operation were provided. On stages of the railways the cable line, as a rule, passes in a tap strip.

Before line breakdown plan district, cut down a bush, separate trees, root out stubs etc. After reception of the written permission a line of an underground cable line break with conformity with working drawings.

On the plan of a line of the cables placed on a stage along a cloth of the railway, show: a track with ' kilometre and пикетными signs; borders of a strip of tap of woods and bushes with instructions of volumes of cutting down; the data about a sort грунтов; the underground and elevated constructions crossed and approaching with projected cable lines, with instructions of ordinates of constructions on the existing kilometric area; natural barriers; borders землепользований with the name of land users; boiling devices STSB, entrance traffic lights and points of power supplies with instructions of ordinates.

The line of alarm and power cables of automatics and telemechanics can pass in station limits sideways railroad tracks and in междупутье. The distance between the nearest rail and a cable should be not less than 1,6 m.

Alarm cables it is possible to lay without restriction in one траншее with power cables with working pressure to 500 Century Power cables pressure above 500 In lay in separate траншее or in general траншее with alarm, but thus the power cable is stacked on depth by of 1,5 m and from above close a brick or concrete plates, and alarm — over it on distance of 0,45 m, shifting aside on 0,15 m. Distance between power cables and communication cables there should be not less than 0,5 m.

At crossing of tracks depth of a lining of cables of automatics, telemechanics and communication should be not less than 1 m from a rail sole, and with highways — not less than 2 m from a road cloth. In a place of crossing cables lay in асбестоцементных pipes. In places of crossing of cables of communication with power cables the distance between them should be not less than 0,25 m if the communication cable is laid in асбестоцементной to a pipe, and 0,5 m — at its absence.

At crossing of alarm cables with power cables and their other underground constructions it is necessary to lay on distance of 0,5 m from these constructions. In a place of crossing of an alarm cable with power it is necessary to lay it in асбестоцементной to a pipe. The distance between crossed alarm cables should be not less than 0,1 m.

Depth of tranches for a lining of signalno-blocking, control, power cables on pressure to 1 кВ and communication cables (except for main) out of ways and in междупутье — 0,8 m; under tracks, automobile and soil roads - of 1,05 m; in rocky грунтах under condition of protection of a cable by a brick or ferro-concrete plates — 0,5 m.

In cities and settlements, at railway stations to digging of tranches usually apply траншеекопатели, and there, where their use is complicated (at crossing of tracks, in междупутьях, on slopes of embankments, etc.), a trench dig manually so that lateral walls of a trench had some slope.

On turns of a line of a trench dig so that the radius of a bend of a cable with a lead cover was not less than 15-fold diameter of a cable, with an aluminium cover — not less 25-fold, and with a plastic cover — not less 10-fold. On slopes of embankments, ravines a trench dig in zigzag fashion with a deviation of bends from the accepted line in both parties on 1,5 m; the length of bends is accepted by equal 5 m.

In installation sites connecting and разветвительных муфт a trench expand, tearing off a foundation ditch for carrying out of the subsequent installation works. Depth of a foundation ditch do on 10 sm more deeply a trench bottom.

At a choice of a line of an underwater cable on crossings of water barriers choose places where the water barrier has the least width, an equal bottom and low coasts. It is impossible to lay a cable in places of winter parking of courts on anchors, around parking of rafts, in places of a watering place and cattle bathing, and also there where jams of ice or the river are observed changes a channel.

At the mechanised digging of tranches by open way use self-propelled траншеекопатели, траншейные dredges and other mechanisms.

Transportation and lining of cables. At first check an integrity of a metal cover, resistance of isolation, establish absence of breakage of veins and the message between veins. If the cable arrives from factory with air pumped up under a cover under superfluous pressure and the soldered in gate a cover integrity check, connecting to the gate a manometre. The manometre indication will testify to a cover integrity.

Alarm cables with a metal cover and all types of cables with plastic covers under superfluous pressure do not put. Therefore their condition check only electric measurements and external examination at раскатке from drums.

Resistance of isolation of veins, working capacity of cable chains and other electric parametres measure by cable devices and measuring bridges. After the termination of tests a metal cover solder, and the ends of cables with a nonmetallic cover carefully isolate.

Preparation of a cable for a lining begin with развозки drums with a cable on a line on cars or special carts. If the line passes close from railroad tracks a cable carry on railway platforms. At loading of drums, and also at перекатывании them by the ground it is necessary to watch that the direction of rotation of drums coincided with an arrow direction on a drum cheek.

Cable unwind from drums and then stack in a trench in the mechanised or manual way. At a manual way for раскатки a cable a drum establish on jacks or special supports so that it could rotate freely, не* touching the earth. Then remove from a drum an external covering and release the cable end. At a lining of a cable a drum rotate, thus it is necessary not to suppose a cable tension. Workers bear an unwound cable on hands and stack at first on бровке trenches, and then lower in a trench. In траншее a cable stack wavy to exclude its tension at усадке and ground displacement.

In soft грунтах a trench fall asleep the ground which has been taken out from a trench, and in stony and rocky грунтах a cable a layer of sand or a soft ground in the thickness of 10 sm, forming the top bed preliminary fall asleep. At first fill a layer of earth in the thickness 0,2 — 0,3 m and densely stamp it. Then fill the following layer of earth of the same thickness and as stamp etc. In settlements and in territory of stations a trench fall asleep and stamp, simultaneously watering a ground for its decrease further deposits.

Underwater cable transitions lay below bridges on a watercourse. If bridges through the navigable rivers and channels of the main value the distance between the bridge and a cable should be equal 1000 m, on the floatable rivers — 90 m and on non-navigable — 50—100 m. From bridges of local value these distances are equal 200 m on the navigable rivers, 50 m — on non-navigable and floatable. The distance of underwater cable transition from small railway bridges should be not less than 20 m.

Ways of a lining of underwater cables through the rivers and reservoirs depend on character of a water barrier (depth and width of a reservoir, speed of a current, a season etc.). The cable can be laid with the help кабелеукладчиков, the barge, launches, pontoons, boats and other floating crafts.

On bridges a cable lay in ferro-concrete or steel trenches, strengthening them to farms or bridge foundations. Metal a trench should be isolated from metal covers of a cable. It is supposed to lay a cable in the wooden trenches upholstered with a tin and to close ferro-concrete plates. A trench have under a foot part of the bridge.

On the bridge it is necessary to lay a cable the whole piece as растрескивание cable covers it is observed most often at connecting муфт. At a lining of cables with a lead cover it is expedient to use cables with the wire reservation, better resisting vibrations.

In tunnels and collectors a cable usually lay by means of arms from a strip steel with number of hooks on number of laid cables. Arms establish on distance of 1,0 m from each other and strengthen them to tunnel walls. Sometimes a cable lay in the ferro-concrete trenches established in a ballast.

Laid cable protect from mechanical damages at its lining under railway and tram ways on crossing with automobile and dirt roads, under travellers parts of streets, in places of crossings with underground constructions and other cables. On a site of crossing a cable conclude in асбестоцементные pipes so that they fell outside the limits crossing on 1 m.

Especially often in pipelines of the cable water drain lay communication cables. Depth of a trench for a lining of pipelines of the cable water drain choose such that the distance between the top part of the pipeline and a ground surface under sidewalk was not less than 0,4 m, under a roadway — not less than 0,6 m. the Width of a trench depends on the general capacity of the pipeline of the water drain.

The asbestotsementnye pipes stacked in a trench, connect end-to-end with the help асбестоцементных муфт. For survey, протягивания and connections of the separate ends of a cable establish wells.

The cable water drain (fig. 82) consists of pipelines 2, employees for a lining of a cable 3, and viewing wells 4. Viewing wells have hatches 5 which are closed by pig-iron covers


All water drain settles down underground, and on a surface deduce only the hatches of viewing wells closed by covers.

Cable stretch in the water drain on sites between adjacent wells (fig. 83) for what over one of wells on goats 5 establish a drum 4 with a cable, and at the next well — manual or mechanised лебедку 3; then a cable 2, having stretched through the channel of the pipeline and having passed it through the block 1, fasten to the end of a cable by means of a steel cable stocking 7 and, rotating the handle лебедки, stretch a cable on the channel. That the cable was not damaged about pipeline edges, on an input and a pipeline exit establish a cable knee 6 or the plug.

Inputs of cables of communication in buildings happen underground and air. Air input of a cable carry out in that case when it is necessary to enter into a building no more than one-two cables of small capacity.

Inputs of cables of multichannel communication, and also cables of local communication of the big capacity in a building of station, intermediate and terminal points, as a rule, do underground — through the base. At input of a great number of cables in a basement equip special mine.