Frequency of major repairs of cable ducts. Maintenance and repair of cable power lines. Repair of cabinet areas

Technical condition and operational maintenance cable lines must ensure uninterrupted high-quality operation of communication structures and their maximum durability. Cables, cable fittings, equipment, protection devices and other structures in their mechanical and electrical characteristics must comply with the current state standards GOST, and in their absence - departmental OST or technical specifications. All structures and devices must meet labor protection, safety and industrial sanitation requirements.
On the slopes of ravines and river banks, in order to avoid erosion and landslides, the soil along the route must be secured (with turf, paving, etc.). The cable route should run at a safe distance from steep slopes of ravines and river banks; where necessary, measures should be taken to eliminate the possibility of landslides and collapses. The normal cable depth is maintained throughout the entire route.
When expanding roads and constructing improved road surfaces (asphalt, concrete), the cable is laid in the telephone sewer or transferred to another place. At the intersections of existing cable routes with highways, exits from them, tram tracks, etc. Cables are laid in pipes, and an additional pipe is laid for backup. At the intersections of navigable and raftable rivers, as well as non-navigable and non-raftable rivers up to 3 m deep, cables must be buried in the bottom. The depth of burial is determined by the project. On reservoirs and lakes outside the shipping lane, as well as on non-navigable and non-raftable rivers with a depth of more than 3 m, cables can be laid without burial. The crossing point must be chosen on a straight section of the river. When the cable route crosses reclamation channels, the cables are buried in the bottom of the channel or protected with concrete slabs.
Transitions of main lines through navigable and rafting rivers should have two cables: the main one and the backup one, if possible of the same length. The distance between cables must be at least 300 m. One cable can be laid over a bridge. Coastal branch couplings must be located in non-flooded areas. Each cable uses 50% of the capacity.
When approaching and crossing with other underground and above-ground structures, the distance from the latter to the cable must strictly comply with established standards. Measuring posts are installed at such a distance from each other that there are at least two posts in the line of sight, and the sighting line drawn between them runs parallel to the cable route. On straight sections of the route, posts are installed every 250-300 m. In addition to measuring and indicator posts, warning signs are installed in the most vulnerable places of the route. Signs are installed at intersections with other underground structures (water supply, sewerage, cables, gas pipelines), near quarries, at canal intersections, in places where construction work is planned, etc. In addition, warning signs are installed in suburban sections of the route at a certain distance from each other within line of sight.
The earthen embankment (embankment) of the above-ground parts of the underground NUP is covered with turf or sown with grass. A blind area is made around the NUP, and a concrete or gravel path is made at the entrance to the ground part of the NUP.
Technical operation of cable communication lines includes:
– ensuring the uninterrupted operation of all serviced structures, as well as preparing them for work in particularly difficult conditions;
– maintenance of all structures within the limits of current standards and technical conditions, as well as every possible improvement of their technical condition;
– strict implementation of current rules, guidelines and instructions on technical operation issues;
– increasing the profitability of enterprises, systematically reducing labor and material costs for the maintenance of maintained structures;
– implementation new technology, advanced methods and scientific organization of labor, the development of socialist competition;
– advanced training and personnel training;
– introduction of operational and technical accounting:
– carrying out explanatory work to ensure the safety of linear structures.
Depending on the characteristics of the cable line route, the presence and condition of roads at different times of the year, the technical equipment of the site, etc., the following methods of organizing the maintenance of linear structures are used: centralized, decentralized (precinct) and combined.
The centralized method involves the concentration of all cable-splitter personnel at the location of the control unit, motorized inspection of the route, repair and maintenance by specialized teams, and the use of radio stations to communicate between teams and the control unit.
The decentralized method is used in cases where it is impossible to organize a motorized inspection of the route. In this case, the route to be maintained is divided into sections, in each of which, i.e. in the immediate vicinity, personnel are stationed.
The combined method involves organizing maintenance of one part of the route centrally, and the other - by local installers.
The maintenance of cable communication lines includes maintenance and repair.
Maintenance is divided into routine (daily and periodic) and planned preventative.
During routine and scheduled preventative maintenance, the following is carried out:
– technical supervision over the condition of the route and compliance with the rules for the protection of national communications;
– technical supervision of all structures and operation of automation, alarm and telemechanics devices;
– carrying out preventive work;
– control over the electrical characteristics of the cable;
– elimination of identified faults;
– ensuring an emergency supply of cables, fittings and materials (including lightweight cables)
– for quick elimination of faults on the line;
– maintaining in good working order and operational condition mechanisms, vehicles, devices, fixtures, tools and special clothing necessary for carrying out planned preventative and emergency recovery work;
– elimination of accidents and damage;
– carrying out security and explanatory work;
– installation of warning signs;
– preparation of linear structures for operation in winter conditions and during floods;
– maintaining technical records;
– prevention of damage associated with ice blasting, soil excavation, cleaning the bottom of reservoirs, and construction of structures in the cable line area.
When carrying out technical supervision during operation it is necessary:
– notify local bodies, authorities, organizations, enterprises, collective farms, state farms and construction sites on the territory or near which the route passes, about the location of the cable and the need for them to comply with the rules for the safety of national communications;
– carry out explanatory work among the population, workers of construction and other organizations and enterprises located along the cable line route on compliance with precautionary measures when working in the cable security zone;
– provide notices to the following organizations and persons about the passage of underground cables with a warning about responsibility for the safety of the cable during the performance of work;
– install warning signs in places where the cable approaches other above-ground and underground structures and in areas of expected construction work;
– carry out continuous supervision in places where excavation and other work is carried out in the cable protection zone and take measures to protect it from damage;
– prevent landslides and soil erosion along the cable route;
– monitor the condition of measuring posts, signal and warning signs, instrumentation and other devices and eliminate any deficiencies noticed.
Repair of cable structures is divided into current and major.
Current repairs are carried out by operational staff according to the approved annual plan and include the following work:
– route planning, installation of additional warning signs, restoration of measuring posts, painting of fittings (brackets, consoles, cable boxes), checking the cable depth, checking backup channels in pipelines, etc.;
– detection and elimination of damage to cable sheaths and plastic anti-corrosion covers;
– preparation of structures for operation in winter conditions and during spring floods; burying the cable near the coast, breaking off coastal ice, temporarily installing the cable under excess pressure, etc.;
– checking the condition and eliminating identified deficiencies in cable protection devices;
– replacement and repair of gas-permeable and insulating couplings, protectors, instrumentation;
– deepening and cable extension within up to one construction length;
– installation of additional measuring posts;
– clarification and adjustment technical documentation.
Acceptance of cable structures after routine repairs is carried out by a commission appointed by the head of the operating enterprise, and is documented in an act that assesses the quality of the repair work performed and the condition of the linear structures in the accepted area.
Major repairs include the following work:
– replacement of cables that have become unusable on certain sections of lines (more than construction length);
– replacement of worn-out equipment or fittings;
– reconstruction of sewerage and inspection devices;
– deepening the cable at river crossings or in the ground;
– laying backup cables at river crossings;
– work to protect cables from corrosion, lightning strikes, etc.;
– reconstruction of the line (additional wiring, balancing of the cable in more wide range frequencies);
– bringing electrical characteristics to normal;
– replacement of cables and equipment with new, more advanced ones.
Acceptance of major repair work is carried out by a commission appointed by the head of the operating organization. The acceptance certificate indicates the scope of work, an assessment of the quality of its implementation and the estimated cost. All work on the repair of cable structures associated with the dismantling of couplings or terminal devices must be carried out with the prior permission of the territorial control centers (TCUMS).
If cable damage or accidents occur, the maintenance personnel will organize work to eliminate them; at the same time, damaged connections are switched to free, serviceable pairs in this or other cables using inter-cabinet connections, suspension of temporary lines from other directions, etc. First of all, payphones, special services (01, 02, 03) and other important connections are subject to switching.
The maximum permissible duration for repairing cable faults depends on the capacity of the damaged cable. Damage to terminal devices and cables is repaired on the same day by replacing pairs with existing serviceable ones. In cables with a capacity of up to 200x2, damage with replacement of the cable span must be eliminated within 36 hours, with a capacity of up to 400x2-48 hours, up to 600x2-60 hours, up to 800x2-72 hours and up to 1200x2-80 hours. In high-frequency cables (without balancing) the duration repair of damage is 24 hours.
The main types of cable damage are the following: “ground” - connection of conductors with a shell (screen) or grounded fittings of structures; “short” - connection of the cores of a pair with each other, “message” - connection of the cores of neighboring pairs with each other; “break” is a break in one or both wires of a pair. Combinations of several or all of these types of damage may also occur.
Troubleshooting cable faults begins with electrical measurements to determine the location of the fault. In the event of an accident, the cable route is simultaneously inspected, inspection devices are opened, the openings in the cable route are thoroughly checked, and the air pressure in the cable is determined.
When performing work in inspection devices, it is necessary to install a fence, open the hatch, check the air in the inspection device for gas contamination with a gas analyzer, drain the water, ventilate and illuminate the inspection device, descend into the well using a ladder, drain the walls and ceiling, etc. After this, you should find the required one. cable according to its numbering ring and the number of the occupied sewer channel, wipe and carefully inspect the cable from channel to channel, paying special attention to the places where couplings are sealed, dents and pinches, and places where the cable exits the channels. In this case, it is recommended to touch the cable (coupling) with your hand and detect some heating at the point of moisture penetration. Such heating occurs when connections are not switched off and the cable is completely or partially damaged due to the beginning of the electrolysis process (due to moisture penetration).
If the damaged area of the cable is within the viewing device, then after removing the sheath (coupling) from the damaged section of the cable, it must be dried.
Wet cables of small containers, as well as, if necessary, cables of large containers with paper insulation, are scalded (washed) with cable mass heated to a temperature of 130°C. Drying of cables with polyethylene and styroflex insulation can only be done by heating (at a low temperature) or by blowing the cable with nitrogen or dried air.
If it is determined that the cable is damaged in a sewer span, carefully inspect the street covering along its route in this area and specify the location of the damage using measuring instruments or the air pressure method.
When repairing damage to cables laid on the walls of buildings, after electrical measurements, they are thoroughly inspected using an extension ladder.
If there is reduced insulation in the terminal device, it is advisable to dry it with hot air from an electric heater.
If individual pairs of conductors in a cable box, box, or distribution box are damaged, the plinth is opened and inspected from the inside. Identified damage is eliminated by soldering the cores, smoothing out burrs, solder sagging, isolating the core or pin, adjusting the pins, replacing the ligation of the core bundle, etc.
If necessary, the plinths are washed (scalded) with cable mass or dried with hot air. Damaged terminals are replaced. After all work is completed, the operation of the connections is checked from the measuring table of the repair bureau.

Maintenance of cable lines is necessary in any case as it guarantees long service life. Not only the cables themselves, but also the connecting and shut-off valves, installed equipment, equipment must not only comply with the standards, but also be constantly maintained in this condition.

Routes are laid at the required distance from ravines, cliffs, and reservoirs. Some soils require strengthening in order to avoid collapses and landslides, as they can change the depth determined by the project, which is unacceptable.

When the route crosses roads, other utility networks, cables are laid in the main pipe and are additionally protected by an additional pipe. In those places on the route where it is especially vulnerable, warning signs will certainly be installed. The above-ground parts of the route are protected by embanking, covering with turf and sowing with grass.

What does proper operation of cable communication lines mean?

The process of operating cable lines means that the object is guaranteed to be characterized by:

uninterrupted operation of structures, including dangerous, emergency, and particularly difficult conditions;
keeping them in a condition that complies with current technical and safety standards;
compliance with all standards regarding operating technology issues;
increasing the profitability of enterprises by reducing costs for unforeseen repairs and additional maintenance;
introduction of innovation, new technology and equipment;
mandatory and timely maintenance of cable communication lines.

The volume, methods, composition and schedule of technical services are established and changed individually for each facility, depending on its length, composition and technical characteristics.

Maintenance of cable lines. Production methods and organization

The use of one method or another depends on the seasonal conditions, the equipment of the site, and many other factors.

There are three maintenance methods:

Centralized, in which all personnel are concentrated in the control department. In this case, a motorized inspection is performed. Special teams are being created and are actively working, providing them with modern means of communication and transportation.
Decentralized (precinct) - applicable if there is no real opportunity to carry out a full inspection. The route is divided into sections, each of which is assigned a maintenance team located in close proximity to the section being serviced.
Combined. When maintenance of different parts of the route is carried out using both methods.

Principles of technical maintenance of cable communication lines

Maintenance, as with many other systems and networks, is carried out in two types:

current;
planned and preventive.
Both types of maintenance are performed, including:
technical supervision of serviceability and compliance with the rules for ensuring the protection and creation of all conditions for the safety of both the route itself and all its parts;
prevention of malfunctions;
monitoring the stability of cable characteristics;
minor repairs;
ensuring constant emergency maintenance of materials reserves;
routine and prompt repair of accidents and damages;
maintaining machinery and other entrusted property in proper condition;
installation and maintenance of warning signs in the proper quantity and condition;
preparatory work for the change of season, ensuring safety during demolition, excavation, hydro-treatment and construction work in the area where the lines lie.

All actions and data related to maintenance are recorded in a special log.

Work on the operation of line-cable structures of local communication networks includes maintenance and current repair of line-cable structures, elimination of damage and breakdowns of communication lines in cable ducts and is carried out by communication enterprises. Also, their responsibilities include monitoring the activities of third-party organizations performing construction, reconstruction and major repairs of linear cable structures, for the safety of cable and sewer structures and their acceptance into operation.

All work related to the need to carry out overhaul line-cable structures should always be carried out by a special team or contractor.
Depending on the types and volumes of linear cable structures, the capacity and structure of the communication network, teams of workers are formed. As a rule, to service cable duct sections on city telephone networks, a joint team is created, which includes two teams of cable welders and a team of electricians. One of the teams of cable solders is engaged in maintenance, repair and elimination of cable damage, and the second team carries out routine repairs and is responsible for maintaining the cables under constant excess gas pressure (sealing). A team of electricians carries out routine repairs and maintenance of sewer communication structures, eliminates damage to cable ducts, and ensures the safety of cable and sewer structures.

On large GTS, line-cable structures are usually divided into technical areas, which in turn are divided into sections. A team of cable solders is assigned to each section and is responsible for the technical condition of cable structures.

The list of main works for carrying out preventive maintenance of linear cable structures includes:

inspection of the condition of cable lines;
checking the state of lighting and ventilation;
monitoring for the absence of displacements, tensions and sagging of cables and straightening their position;
inspection of the anti-corrosion coating of cables;
control over the safety of line-cable structures;
inspection of the external condition of the couplings and their straightening in cable wells;
checking the serviceability of arresters and fuses.

To ensure the smooth operation of telephone communication networks, it is very important to properly organize technical operation linear cable structures, periodically inspect cable ducting routes and carefully monitor cable loads.

Cable load monitoring

Cable load monitoring must be carried out at least twice a year in order to establish the optimal operating mode of the cables to ensure their reliable and economical operation. Constant overloads will lead to a decrease in the quality of cable insulation and significantly reduce their service life. The maximum possible load for cables is calculated over a section of the route at least 10 m long, which has poor thermal conditions.

In case of failure of the cable line for cables with voltage up to 10 kV for no more than 120 hours, loads from 15 to 30% above the established standards are allowed. For cables with a voltage of 20-35 kV, overload is not allowed.

To find out the actual temperature of the current-carrying wires of the cable, it is necessary to measure the temperature of its metal sheath and, if strong heating is detected, measures must be taken to reduce the temperature:

reduce the load on cables;
increase the distance between cables;
improve ventilation in ducts;
replace with cables with a larger cross-sectional area.

Inspection of cable duct routes

Before starting the inspection, it is necessary to check the line-cable structures for the presence of gas. The cable line route must be kept clean, and the air temperature in cable structures should not be more than 10° higher than the outside air temperature.
The frequency of inspections depends on climatic conditions and the location of underground communication cables and is carried out more often at places where cable lines intersect with communications and during periods of rainfall, when there is a risk of cable damage.

In a special technical inspection log, the employee inspecting cable routes records faults discovered during preventive maintenance of linear cable structures and requiring elimination during repairs.
The frequency of inspections of cable and sewer communication structures is presented in the table.

Name of structures	Inspection frequency
Cable drain wells, collectors, tunnels	Once every 3 years
Cables in sewers, sewers, tunnels	Once every 3 years
Cable entry rooms and station wells	Once a year
Cables in cable entry rooms and station wells	Once a year
Cables in trenches, sewers and tunnels	Once every 3 months
Cables in manholes and terminations on lines with voltages above 1000 V	Once every 6 months
Cable terminations for voltages up to 1000 V	Once a year

The ground cover along the route must be free of dips and erosions, since as a result of external and mechanical influences on the optical cable, a cable line break may occur. Excavation work using various mechanisms is allowed at a distance of at least 1 m from the cable route and must ensure the integrity and safety of the cables. At a distance of less than 1 m, work is carried out manually with shovels.

During operation of line-cable structures, a violation may occur. telephone communication- damage in underground cables. Damage to cable ducts includes mechanical damage to pipelines, inspection devices and jumpers between channels. Failure of the most important network cables and damage to at least 20% of the pairs in the cable line is considered an accident.

When eliminating an accident, it is necessary to relieve excess pressure in the cable to atmospheric pressure before opening the couplings. It is necessary to repair cable damage as soon as possible, performing the work efficiently, taking into account the presence of dangerous and harmful production factors in the cable duct and strictly observing safety regulations.

Time frame for eliminating damage in cables with big amount pairs are presented in the table.

Cable capacity, pairs	Maximum duration of damage in a cable duct, hour
Cable capacity, pairs	With opening of couplings, without span replacement	With opening of couplings, with replacement of span
up to 200	18	36
From 200 to 400	24	48
From 400 to 600	30	60
From 600 to 800	36	72
From 800 to 1200	60	100
From 1200 to 1400	70	120
From 1400 to 1600	80	140
From 1600 to 1800	96	150
From 1800 to 2000	120	170
From 2000 to 2400	144	190

Damage to the optical cable coupling must be repaired within 48 hours.

If a cable in a cable duct is damaged, it is necessary to remove water from the wells and prevent its further entry, ensure good ventilation of the viewing device and heat the walls of the well with the flame of a blowtorch or gas torch. Before starting soldering and installation work, it is imperative to turn off the remote power, and when performing work, it is not recommended to open capacitor and balun couplings.

In order to eliminate cable damage in the coupling, you must:

Find the damaged cable using the number rings.
Inspect the damaged cable and determine the location of the damage.
Remove the coupling from the well and bring it into the installation machine if no damage was found during an external inspection of the cable.
Open the coupling or sheath of the damaged cable. To open the couplings, their seams are unsoldered.
Determine the boundaries of moisture distribution.
Remove moisture by drying.
Restore damaged optical fibers of cables by inserting new optical fibers with identical characteristics to the damaged cable.
Measure the attenuation of optical fibers of the cable line.
Carry out control measurements of insulation resistance.
Fill small cracks, punctures and cuts in couplings or cable sheathing. Weld patches of the same material as the shell in case of large holes.
Lower and place the optical coupling along with the reserve coils into the well.
Carry out control measurements with a reflectometer to check the quality of the cables and compliance of the characteristics with established standards. A reflectometer is used to determine the location of damage to fiber optic lines.

In order to eliminate cable damage in a sewer span, it is necessary:

Inspect the route of this section of cable duct.
Open the coupling closest to the suspected location of damage.
Determine the limits of the channel's passability, the amount of work associated with eliminating the damage and the amount of cable required to replace the damaged span.
Open the damaged section of the sewer or pull the cable out of the channel of the damaged span. When inserting a cable along the length of a damaged section or replacing a span by laying a new one, it is necessary to measure the insulation resistance of the cores and check the integrity of the cable sheath. If a damaged cable is laid in pipes, it must be removed from the channels along with the pipes and armored optical cables of the OK ST, OM ZKG, OZKG brands must be used as a new cable. If it is not possible to remove the damaged cable from the channel, then a new one is laid in the same channel.
Repair damage to the cable.
Repair damaged sewer lines.

Technical characteristics and conditions for laying cables in the ground, data on previous repairs can be found in the line protocol, which must be regularly maintained during the operation of cable lines.

It is always necessary to have a reserve stock of all types of communication cables, wires, tools, materials and equipment for the prompt elimination of accidents that arise during the operation of line cable structures.

Maintenance and repair. To ensure uninterrupted operation of cable lines and automation, telemechanics and communication networks at signaling and communication distances, teams of cable workers and cable shops are organized. Cable shop workers monitor the technical condition of cable lines and networks, repair cables, terminal and intermediate devices, underground wells and cable ducts, prepare cable facilities for work in winter, and also repair damage to cables.

Planned and control electrical measurements of all types of cable at distances with large cable networks are carried out by employees of the RTU measuring group.

A certain procedure for maintenance and major repairs has been established.

During routine maintenance of cable lines, the condition of the cable route, cable structures, cable fittings (cabinets, boxes, plinths, various couplings, etc.) is checked and identified defects are eliminated. They ensure that excavation work that has not been agreed upon in advance is not carried out on the cable laying route, eliminate damage, take measures to protect the cable from corrosion, etc. More complex and labor-intensive work that cannot be performed by personnel conducting routine maintenance is carried out during major repairs of cable lines.

Major repairs are carried out according to pre-compiled projects and estimates. The estimates include relaying and replacing individual sections of cables with reduced core insulation resistance that cannot be restored. Major repairs are planned in advance and carried out by special teams for labor-intensive work.

At distances that have telephone sewerage, during major repairs, dilapidated cable wells are rebuilt, damaged channels are restored and additional channels are laid from asbestos-cement pipes.

The overhaul plan provides for deepening the cable trench in certain areas and connecting to the air pressure cable. They carry out work to protect against electrical and soil corrosion with the inclusion of drains, replace measuring posts, repair or replace faulty boxes, replace non-standard hatches with standard ones, take measures to isolate wells from water ingress, etc.

Upon completion of the work, the repaired sections of the cable line are accepted by a special commission.

Rice. 96. Installation diagram of type USKD-1

cable problems arise due to the penetration of moisture into it when the seal of the sheath is broken due to corrosion, violation of laying rules, poor-quality soldering of cable couplings and mechanical damage caused by soil displacements or careless excavation work on the cable route. To protect the cable from moisture penetration into it if the integrity of the sheath is damaged, the cable lines are kept under constant excess pressure, which allows you to control the tightness of the sheath and determine the location of its damage. In addition, in case of minor damage to the sheath, the gas flow escaping at the site of its damage prevents moisture from penetrating into the cable, which increases the reliability of cable lines.

When the cable is kept under constant excess pressure, the cable line is divided into sealed sections called gas sections. For multichannel communication cables, the length of the sections is usually equal to the length of the amplifying section of the high-frequency circuits. Gas-tight couplings are installed at the ends of the gas section, as well as at all branches from the main cable. Excessive gas pressure is created inside the gas sections.

There are two systems for maintaining cables under excess pressure: with automatic and periodic filling of cables with gas. On cable lines of multichannel communication of the MPS, the system with automatic filling is most widely used. In this system, automatic control and drying units AKOU are placed at the ends of the gas section, and, more recently, USKD units. Dry air is used as gas.

The USKD-1 type installation (Fig. 96) provides automatic supply of dry air to the cable, control of gas flow, and a signal about a leak and a decrease in pressure in the gas cylinder. From a high-pressure cylinder 1 (10, 15 or 20 MPa) (or from a compressor) through a high-pressure drying chamber 2, gas is supplied to a reducer 4 with a check valve (the check valve is necessary to disconnect the cylinder from the installation when the pressure drops to 2 MPa), then into the low pressure reducer 5, at the output of which a stable pressure of 50+ 2 kPa is formed, maintained automatically at a gas flow rate of no more than 3 m/min. Next, the gas passes through the low-pressure drying chamber 12, the pneumatic alarm 6 and the rotameters block 7. In the rotameters block, after passing through the humidity indicator 10, the gas enters the rotameters 9 to monitor the gas flow of each cable and through the fittings 8 into the cables. The safety of the installation is ensured by safety valves. The cable tightness control alarm is carried out using a pneumatic signaling device 6, and the pressure reduction alarm in the cylinder is indicated by an electric contact pressure gauge 3. The pressure gauge 11 controls the gas pressure supplied to the cable.

Equipment type USK.D-1 provides for the connection of an air control device type VKP-1 to determine the area of cable sheath leakage based on gas flow.

The exact location of the shell damage is determined using tracer gases. To do this, a valve is soldered into the coupling closest to the border of the damaged area and the excess pressure is reduced (the valve is opened for 20-30 minutes). Freon is injected into the cable within 5-10 minutes at a pressure of 50-60 kPa. To ensure gas movement along the cable, dry air is pumped at a pressure of 50-60 kPa. 12-15 hours after the introduction of freon, they begin to inspect the route, for which purpose holes with a diameter of 2 cm and a depth of 25-30 cm are first made 1.5-2 m above the cable. Using a leak detector (a device that reacts to the presence of freon), an air sample is taken in pits. The maximum gas concentration will be directly above the cable damage.

The most typical damage to a cable in service is a gradual or sudden decrease in the insulation resistance between the cable cores and between the cores and the ground (metal sheath). The cause of these damages is the penetration of moisture into the cable if it is not kept under constant air pressure. Damages such as breakage of one or more cable cores, short circuit of part of the wires with each other or with the lead sheath are also observed.

First you need to accurately determine the location of the damage. If the cable is under excess air pressure, in a system with automatic feeding gas, it is enough to know the number of doses of gas supplied to the cable when its sheath is damaged. This is determined using automatic dispensers of AKOU or USKD installations located at stations bordering the damaged section of the cable. If the cable is not kept under excess gas pressure, the location of cable damage is determined by electrical measurements or using tracer gas. A more advanced method is to detect the location of the damage using freon, when the cable route in the area of its damage is precisely marked.

To find the cable route, it is most convenient to use a cable finder, which consists of a tone frequency generator that can operate in pulse mode and in continuous oscillation mode. One terminal of the generator is connected to the cable cores, which are grounded at the opposite end, and the other terminal is connected to ground. From generator alternating current passes through the conductors of the cable, the route of which is being sought, and returns along the ground to the generator. In this case, the current around the cores creates an alternating magnetic field, changing with a frequency of about 1000 Hz.

The cable trace indicator is the finder coil (ferrite antenna) connected to the input transistor amplifier tone frequency, the output of which is connected to the headphone. The ferrite antenna is mounted on a sector, which in turn is hinged on the finder handle (rod). By rotating the sector, the ferrite antenna can be rotated to a vertical and horizontal position, as well as fixed at angles of 30, 45 and 60°.

The cable route is first found by the maximum signal volume in the phone when the antenna axis is perpendicular to the cable axis, and it is refined by the minimum signal volume when the antenna axis is parallel to the cable axis.

After determining the cable route, on straight sections it is marked with poles installed every 5-10 m, on curved sections - at shorter intervals. Then, along the route, holes are made in the ground every 1.5-2 m - holes with a diameter of 1.5-2 cm and a depth of 30 cm and the location of the leak in the cable sheath is determined using freon. To do this, near the supposed place of damage to the shell, the connecting cast iron coupling is opened, and a valve is soldered into the lead coupling, through which from 400 to 800 g of freon is introduced under a pressure of about 60 10 3 Pa. Freon is introduced using a field installation for the introduction of tracer gas (PUVIG), consisting of a cylinder with freon, a drying chamber with a humidity indicator and two pressure gauges. Air is pumped from the ends of the cable, which accelerates the spread of freon. Freon spreads along the cable and through the place of damage to the sheath to the surface of the earth from 12-15 hours to one day, depending on the density of the soil.

After this time, the location of the shell damage is determined. To do this, use a battery-powered halide leak detector, consisting of a measuring unit, a power supply and a remote probe. Moving along the cable route, one by one insert the probe of the device into the previously prepared holes. At the point where the cable sheath is damaged, freon will accumulate in the pit and the halide leak detector will signal this. Having discovered where the cable sheath is damaged, they begin to repair it.

If other damage occurs in the cable (broken wires or short circuit between wires), the location of the cable damage is determined using electrical measurements.

Operation of cable lines and networks in winter conditions. To ensure trouble-free operation of cable lines and networks in winter conditions, a number of preventive measures and preparatory work are carried out even before the onset of cold weather. First of all, cable lines, networks and cable inserts are inspected, the weakest points are identified and the detected defects are eliminated. To check the condition of the operating cable, electrical measurements of the cable circuits are carried out. Carefully inspect cable termination devices (termination boxes, boxes, cable boxes, etc.). Check that the doors and covers in the cable boxes fit tightly, since if there are cracks in the winter, snow can get in there; inspect cable supports, supports and guy wires.

Before the onset of cold weather, the cable ducts are carefully checked. Special attention Pay attention to ensure that there is no water in sewer channels and wells, which in winter, when frozen, can severely compress the cable laid in the channels and damage it. After inspecting the wells top covers hatches are sealed to prevent water and dirt from entering the well during autumn rains.

Additional work on routine maintenance of cable lines and networks in winter includes: clearing snow from hatches of cable wells, distribution cabinets and other cable fittings installed outdoors; more careful monitoring to ensure that cracks do not appear in the cable mass that protects the end sleeves due to strong fluctuations in ambient temperature; ice chipping on underwater cables if, due to a significant drop in water level, the cable is frozen into the ice off the coast.

On cable and overhead lines that have submarine cable inserts, the condition of these inserts is inspected and it is determined whether there is a danger of damage to the submarine cable by ice drift. At local hydrometeorological stations, the time of the expected ice drift and the magnitude of the expected flood are determined. Strengthen cable supports that may be in the spill area. Before the onset of ice drift, in those places where the underwater cable is laid and there is a danger of its damage, workers and special teams are constantly on duty, provided with an emergency supply of materials, boats, etc. In sections of the route where landslides and soil erosion may occur, they also take measures to prevent damage - arrange drainage systems, etc.

Cable lines are divided into on-site, local, intrazonal, main, international.

on-site- networks on the territory of one facility (factory, oil depot...), purpose - providing technological and production communications within the facility. Example - there is a collection of tanks for storing liquid chemicals. The tanks have sensors for temperature, level, etc. The cable through which signals from the sensors are transmitted to the server room for monitoring and processing will be part of the on-site networks.
local- cable lines between buildings in the city (different enterprises) or nearby settlements (towns, villages...), purpose - providing communications at the local level, for example, telephone communication channels for connecting a departmental telephone exchange to a city telephone exchange.
intrazonal- cable lines within one edge, area, purpose - providing communications within a given zone.
main- cable lines passing (connecting) more than one entity, the purpose is to provide communication between entities.
international- cable lines passing across the border of a state(s), purpose - providing communications between countries (Internet).

Compound

Cable lines consist of communication centers, unattended regeneration (reinforcement) points - NRP, NUP, cable route.

communication center- communication structure in which transmission system equipment is installed. There are serviced, semi-serviced and unserviced. The serviced communication centers are manned 24 hours a day; engineering and technical personnel may be present during the day. Semi-serviced nodes are staffed during working hours; during non-working hours the node is closed. Maintenance of communication equipment in an unattended communication center is carried out according to a schedule or as needed. Physically looks like a building or block container.
unattended regeneration (reinforcement) points- points at which regeneration is carried out ( digital system transmission) or amplification (analog or digital transmission system) of the signal. Physically represents a container (for example, a barrel) buried in the ground at a shallow depth, in which a regenerator or amplifier is placed. A buried container usually has a superstructure (wooden, brick, iron or reinforced concrete). The location of the regenerator or amplifier in the upper part of the superstructure is also common. Within the city limits, it is possible to locate the NRP/NUP in a building, in an underground metro station or in a distribution cabinet.

In addition to regeneration/amplifier equipment, power supply equipment (external or remote) may be located at the NRP/NUP. rechargeable batteries, heating, ventilation and air conditioning devices, lighting devices, telemonitoring devices (control of air pressure in the cable and in the cylinder, control of closing doors and lids, control of the presence of water in the chamber, temperature control, humidity control, power control), equipment for maintaining cables under excess air pressure, electric compressor units, compressed air cylinders.

cable route (route)- cable laid in the ground (most often outside a populated area), in a sewer (most often throughout the territory of a large populated area). This also includes cable wells, pits, signal posts and signs, cable input rooms and other linear structures.

If we install a transmission system on a cable line, we get a communication network.

Links

Telephone Network User's Guide (Russian)
Guidelines for drawing up work projects (WPP) for the construction of linear structures of trunk and intra-zonal cable communication lines (Russian)

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