Decoding of LAP - Abbreviation from the phrase "power line". The LEP is the most important component of energy systems that serves to transmit electricity from generating devices to distribution, converting and, ultimately, to consumers.
The transmission of electrical energy is carried out in metal wires, where the conductor is copper or aluminum. Located method of laying wires:
Listed Types of LEP are the main. Experiments on wireless transmission of energy are carried out, but at present this method did not find distribution in practice, with the exception of low-power devices.
Air lines of power lines, VLEP are characterized by high complexity. Their design, the order of operation is regulated by special documentation. Wl is characterized by the fact that electricity is transmitted by wires laid outdoors. To ensure safety, reduce losses, the composition of the VL is quite complicated.
What is? This is not a high-voltage line, as sometimes consider. VL is a whole range of designs and equipment. The main elements from which there is any power line:
Other components are also important, but their type, nomenclature and quantity depend on various factors:
The fittings include fasteners for connecting insulators, wires, fastening them to supports.
For your information. Dischargers, grounding and reduction devices are used to ensure safety and improve reliability in the occurrence of voltage jumps, including during a thunderstorm.
Sectioning devices allow you to shut down a part of the lept for the period of regulatory or emergency work.
The high-frequency and fiber optic equipment is designed to implement dispatching remote control and management of the work of the line, partitioning devices, substation and distribution devices.
The main documents that regulate any power lines are Construction norms and the rules (SNiP), as well as the rules of the installation of PUE electrical installations. These documents regulate design, design, construction and operation of air lines.
A wide variety of the designs and types of air lines allows you to allocate groups in them, combined with general features.
Most of the existing LEPs are designed to work with alternating current, which is associated with the simplicity of voltage conversion.
Separate types of lines are working with a constant current. They are intended for some applications (power supply of the contact network, powerful consumers direct current), But the overall length is small, despite smaller losses on the capacitive and inductive components.
The main mode of operation Vl is normal when all wires and cables are in good condition. There may be cases when part of the wires are missing, but the LAP is operated:
What cable LP.? This type of power lines is different from the fact that the wires of different phases are isolated and combined into a single cable.
Under the conditions of the passage of CL divide on:
In addition to the fact that the cable can be in water or land, part of it necessarily passes through cable structures, which include:
This list is incomplete, the main difference of cable structures from others - they are intended exclusively for mounting the cable along with fastening devices, power couplings and branches.
Solid insulation cable lines obtained the greatest distribution:
Less frequently encounter liquid and gas isolation.
Losses in transmitted lines have different nature and are divided into:
The main element for fastening the wires of the power line - support. LEP supports are divided into two types:
Supports can be installed directly into the ground or foundation. By manufacturing material:
Insulators are designed for fastening and isolating the wires of the LPP. Suspension insulators, which allow from individual elements to make any length, depending on the requirements. As a rule, the higher the voltage in the kV, the greater length is the garland of insulators.
Move from:
Armature is used to connect the chains of insulators, fastening them to supports and wires. Cable lines to fittings also include couplings.
The protection uses lightning guides, arresters and grounding devices. Grounding metal supports is made by mechanical fastening carrier design To grounding contour. Especially important grounding reinforced concrete supportsBecause when current leaks, it begins to flow through concrete reinforcement, having a destroying effect. Harm caused by a support is visually visible.
Important! For the best protection, the security wire is placed above all the others.
The technical characteristics of the LEP depends not only on the transmitted voltage and power. The following factors must be taken into account:
What is LEP? Any power line is a powerful source of electromagnetic field. Located near housing, high-voltage lines adversely affect health. The definition of minimum harm to health and the environment plays an important role in the design of the LPP.
Technical calculations are produced in order to determine which type of line should be used to achieve the greatest efficiency.
Many people do not even think about this issue. After all, the most commonly ordinary citizen is interested in electricity inside the house, and external lines (LPP), as he thinks, should be engaged in ...
Skill Recognize LEP Voltage
Many people do not even think about this issue. After all, the most commonly ordinary citizen is interested in electricity inside the house, and external lines (LPP), as he thinks, should be engaged in specialists. But it is important to take into account everyone that the ignorance of simple differences between the power lines of the power lines (VL) can cause an injury or even the death of a person.
There are standard safety standards, according to which the minimum permissible distance of the person to the current-generating parts should be as follows:
Violation of these rules is deadly.
Starting any activity near LEP should also take into account the installed sanitary and control zones. There are many restrictions in such places. Prohibited:
The limits of the sanitary zone are as follows:
Some deviations are possible, but in most cases, given certain parameters, it is possible to easily determine the power supply voltage in appearance.
The main rule is here: "The more powerful LEP, the more insulators you will see on the garland."
Fig.1 External insulators LEP 0.4 kV, 10 kV, 35 kV
The most common VL-0.4KV insulators. On the view they are small, usually from glass or porcelain.
VL-6 and VL-10 on the form of the same form, but much more is much longer. In addition to the pin mount, it is sometimes used by insulators like a garlands one / two samples.
On VL-35KV, the suspended insulators are mainly mounted, although sometimes there are still pins. Garland consists of three or five copies.
Fig.2 Garlands type insulators
Garlands type insulators are characteristic exclusively for VL-110KV, 220QV, 330KV, 500KV, 750KV. The number of samples in the garland is the following:
Fig.3 Types of supports of high voltage lines
Today, the reinforced concrete racks of the SC 26 are used as a support for power lines with a voltage of 35-750 kV.
If you have an intention to spend any serious work on a certain site, and you doubt the protective zone of the LEP, then it will be more reliable for information in the energy company of your settlement.
Cable line (CL) - A line for transmitting electricity consisting of one or more parallel cables, made in any way of laying (Fig. 1.29). Cable lines are packed where the construction of the WL is impossible due to the constrained territory, is unacceptable under the safety conditions, it is impractical on economic, architectural and planning indicators and other requirements. The greatest application of the CL was found in transmission and distribution of EE in industrial enterprises and in cities (internal power supply systems) when transferring EE through large water spaces
The advantages and advantages of cable lines compared to air: the inconsistency of atmospheric influences, the highway and inaccessibility for unauthorized persons, less damage, the compactness of the line and the possibility of widespread power supply to the power supply of consumers of urban and industrial areas. However, CL is much more expensive than the air of the same voltage (on average 2-3 times for lines of 6-35 kV and 5-6 times for lines of 110 kV and higher), harder during construction and operation.
Fig. 1.29. Methods of laying cables and cable structures: A - earthy trench; B-_Collector; in-tunnel; Mr. Channel; estakada; E - Block
IN composition CL Enter: cable, equipment for connecting and partitioning cable sections and connecting cable ends to equipment and boss bins (cable fittings - mainly different clutches), building structures, fastening elements, as well as oil or gas feeding equipment (for oil and gas-filled cables ).
Classification of cable lines mainly corresponds to the classification of cables included in it. The main features are:
Current;
Rated voltage;
Number of current-handing elements;
Electrical insulating material;
The nature of impregnation and a way to increase the electrical strength of paper insulation;
Material shells.
(These features covers only cables operating under natural cooling. There are cables with forced cooling with water or oil, as well as cryogenic cables.)
Cable - The finished factory product consisting of isolated current-conducting cores enclosed in a protective hermetic shell and armor protecting them from moisture, acids and mechanical damage. Power cables have from one to four aluminum or copper lived with a cross section of 1.5-2000 mm 2. Veins with a cross section of up to 16 mm 2 - single-wire, over - multi-proper. On the shape of the cross section of the core round, segment or sectorals.
Cables with a voltage up to 1 kV are performed, as a rule, four-core, 6-35 sq. - three-core voltages, and a voltage of 110-220 kV - one-core.
Protective shells are made from lead, aluminum, rubber and polychlorvinyl. In cables with a voltage of 35 kV, each lived additionally lies in a lead shell, which creates more uniform electric field And improves heat dissipation. Alignment electric field At cables with plastic insulation and shell is achieved by shielding of each vein with semiconducting paper.
In cables on a voltage of 1-35 kV to increase the electrical strength between insulated cores and the shell, a layer of waist isolation is laid.
The cable armor, made of steel tapes or steel galvanized wires, is protected from corrosion by outer cover from cable yarn impregnated with bitumen and coated with chalk composition.
In cables with voltage 110kv and above to increase the electrical strength of paper insulation, they are filled with gas or oil under excess pressure (gas-filled and oil-filled cables).
High voltage cable lines
Cable lines with viscous impregnation at voltages over 35 kV are not applied. This is due to the fact that air inclusions always remain in the insulation of the finished cable. Their presence significantly reduces the electrical strength of isolation. Air inclusions, depending on the location of their location, the ionization with all the consequences arising from here, or their negative role is manifested in connection with the flow of thermal processes. The cable is periodically undergoing heating and cooling due to change of power transmitted. The increase and decrease in the volume of the cable leads to an increase in air inclusions, their migration to conductive core and subsequent breakdown.
Eliminate the specified phenomena in two ways:
Eliminate air inclusions;
Increase pressure in air (gas) inclusions.
The first method is used in oil-filled cables (MNC) low pressurehaving Channels for oil inside the veins, the second - in MN high pressuredeployed in steel pipelines.
Oil filled low pressure cables .
Low pressure MNA (up to 0.05 MPa) is single-core, they are serially manufactured on voltage 110, 150 and 220 kV and have copper veins with a cross section of 120-800 in lead or aluminum shells.
Depending on the laying conditions - in the ground (in trenches), when the cable is not subjected to tensile conditions and is protected from mechanical damage; Or under water, in swampy terrain and where it is subjected to stretching efforts, various tines of the oil-filled cable are used.
Oil filled high pressure cables .
Oil-filled cables (MNC) of high pressure are manufactured on the voltage 110, 220, 330, 380 and 500 square meters.
Veins of such a cable release:
a) in the time lead shell, protecting insulation from moisturizing and damage during transportation and removed during installation;
b) without a shell. In this case, cable veins are delivered on the track in a hermetic container filled with oil.
When installing, isolated and shielded copper cores with a cross section of 120-700 with aluminum gliding with semicircular wires are tightened into steel pipes. At \u003d 500 kV, the outer diameter of the pipe is 273 mm with a wall thickness of 10 mm.
For such cable lines, oil pressure is 1.08 - 1.57 MPa. Due to the high pressure, electrical strength increases. Pipes are good protection against mechanical damage.
Pipelines are welded from segments of a length of 12 m. Compensation of changes in the volume of oil when the temperature changes and maintaining the oil pressure in the pipeline is carried out automatically feeding device, which is located at one end of the line (with small lengths) or on both (at large lengths).
There are also oil-filled medium pressure cables, cables with polymeric materials as isolation, etc.
In the brand, the cable designation indicates information about its design, the rated voltage, the amount and cross section of the core. In four-core cables with a voltage up to 1 kV, the cross-section of the fourth ("zero") veins are less than the phase. For example, an HPV cable-1- 3x35 + 1x25 is a cable with three copper cores with a cross section of 35 mm 2 and a fourth cross section of 25 mm ", polyethylene (P) isolation by 1 square membrane from polychlorvinyl (B), unsonent, without external cover (d) "_ for laying indoors, in channels, tunnels, in the absence of mechanical influences on the cable; Cable AOSB-35-3x70 - cable with three aluminum (a) veins 70 mm 2, with 35 kV insulation, with separately disconnected (o) veins, in lead (c) shell, armored (b) steel ribbons, with outdoor protective cover - for laying in the earthen trench;
OSB-35__3x70 is the same cable, but with copper veins.
The designs of some cables are presented in Fig. 1.30. In fig. 1.30, a, b Dana power cables with voltage up to 10 square meters.
The four-core cable with a voltage of 380 V (see Fig. 1.30, a) contains elements: 1 - conductive phase veins; 2 - paper phase and waist insulation; 3 - protective shell; 4 - steel armor; 5 - protective cover; 6 - paper filler; 7 - zero lived.
Three-core cable with paper insulation with a voltage of 10 kV (Fig. 1.30, b) contains elements: 1 - current-carrying veins; 2 - phase isolation; 3 - total belt isolation; 4 - protective shell; 5 - cushion under armor; 6 - steel armor; 7 - protective cover; 8 - aggregate.
35 kV three-lit cable is depicted in fig. 1.30, c. It includes: 1 - round conductive veins; 2 - semiconducting screens; 3 - phase isolation; 4 - lead shell; 5 - pillow; 6 - cable yarn aggregate; 7 - steel armor; 8 - protective cover.
In fig. 1.30, g is represented by an oil-filled medium and high pressure cable with a voltage of 110-220 kV. Oil pressure prevents air and its ionization, eliminating one of the main causes of isolation breakdown. Three single-phase cables are placed in a steel pipe 4 filled with oil 2 under excess pressure. The current-carrying veins 6Stomates from copper round wires and covered with paper insulation 1 with a viscous impregnation; On top of the insulation, the screen 3 is applied in the form of copper perforated tape and bronze wire, protecting insulation from mechanical damage while stretching the cable in the pipe. Outside steel pipe Protected by cover 5.
Cables in polychlorvinyl insulation, produced by three-, four- and five-housing (1.30, E) or single-core (1.30, E) or single-core (Fig. 1.30, e) are widespread. More detailed data on the various types and brands of cables, their applications are given in.
Cables are made by segments of limited length depending on the voltage and section. When laying, the segments are connected by connecting couplings, sealing the connection locations. At the same time, the ends of the cores are exempt from isolation and close up in connecting clamps.
When laying in the land of cables 0.38-10 kV to protect against corrosion and mechanical damage, the connection location is a protective cast iron plug-in cover. For 35 kV cables, steel or fiberglass covers are also used.
The reliability of the entire cable line is largely determined by the reliability of its reinforcement, i.e. of different types and destination.
High voltage cable clutches are classified for three main features.
By appointment Couplings are divided into three main groups - end, connective and stop Moreover, among the terminal, open couplings and cable glands to transformers and high-voltage devices are distinguished, and among connecting connectives - actually connecting, branching and connecting - branching couplings.
By the type of electrical insulation The couplings are divided into two groups: with layeredand monolithic Insulation. Layered isolation It is performed by winding the ribbons from cable paper, synthetic film or their compositions and is filled with a medium (oil, gas) under redundant pressure or without it. Monolithic isolation It is formed by extrusion or sintering of insulating materials in heated molds.
By the nature of the current There are clutches for variable, constant and pulse current cables. Cups of alternating current cables can be performed single-phase and three-phase.
The design of the High voltage power cables is first determined by the cable type for which they are intended.
At the ends of the cables apply end couplings or end sealing.
Fig. 1.30. Power cables: A - four-core voltage of 380 V;
broatshile with paper insulation with a voltage of 10 kV; in - three-core voltage of 35 kV; G - Oil-filled high pressure; d - single-core with plastic insulation
In fig. 1.31A shows a 3-core low-voltage cable 2 in the cast-iron coupling 1. The cable ends are fixed by porcelain strut 3 and joined the clip 4. Cable clutches up to 10 kV with paper insulation are filled with bituminous compositions, 20-35 kV cables - oil-filled. For plastic insulation cables, connecting couplings from heat-suite insulating tubes are used, the number of which corresponds to the number of phases, and one heat-suite tube for zero cores seated in a sealed coupling (Fig. 1.31, b).
Fig. 1.31. Connecting clutches for three- and four-core cables voltage to 1 sq .: A - cast iron; B - from heat-suite insulating tubes
In fig. 1.32, and a mastic-filled three-phase coupling of outdoor installation with porcelain insulators for cables with a voltage of 10 square meters is shown. For three-core cables with plastic insulation, an end coupling is used, presented in Fig. 1.32, b. It consists of a thermal shrinkable glove 1, resistant to the effects of the environment, and semiconducting heat-shrinkable tubes 2, with which three single-core cables are created at the end of the three-core cable. Insulating heat-superstitable tubes are put on separate cores 3. They are mounted on them the desired amount of heat-sustainable insulators 4.
Fig. 1.32. End clutches for three-core cables with a voltage of 10 sq. A - outdoor installation with porcelain insulators; b - outdoor installation with plastic isolation; in - internal Installation With dry cutting
For 10 kV cables and below with plastic insulation in the interior, a dry cutter is used (Fig. 1.32, E). The shaved ends of the cable with insulation 3 are wrapped with a sticky polychlorvinyl ribbon 5 and lacquer; The ends of the cable are sealed with cable weight of 7 and an insulating glove 1, overlapping cable sheath 2, the ends of gloves and cores are additionally compacted and wrapped with a polychlorvinyl tape 4, 5, the latter to prevent the lag and unwinding is fixed with twine bands 6.
Method of cable laying Determined by the terms of the line route. Cables are laid in earthy trenches, blocks, tunnels, cable tunnels, reservoirs, by cable overaps, as well as on floors of buildings (Fig. 1.29).
Most often in the territory of cities, industrial enterprises Cables are paving B. earthy trenches . To prevent damage due to the deflection at the bottom of the trench, create a soft pillow from a layer of sifted land or sand. When laying in one trench of several cables up to 10 kV, the horizontal distance between them should be at least 0.1 m, between 20-35 kV cables - 0.25 m. The cable is covered with a small layer of the same soil and closed with brick or concrete slabs To protect against mechanical damage. After that, the cable trench falls asleep the earth. In places of transition through roads and in inputs in the building, the cable is paved in asbestos-cement or other pipes. It protects the cable from vibrations and provides the ability to repair without opening the canvas. Trench gasket is the least costly method of cable sewage EE.
In places of laying a large number of cables, aggressive soil and wandering currents limit the possibility of their gasket in the ground. Therefore, along with other underground communications, special structures are used: collectors, Tunnels, Channels, Blocks and Overaps .
Collector(Fig. 1.29, b)it serves to jointly place various underground communications in it: cable power lines and communications, water pipeline for city highways and on the territory of large enterprises.
With a large number of parallel cables, for example, a gasket is used from the building of a powerful power plant tunnels
(Fig. 1.29, B). At the same time, the operating conditions are improved, the surface area of \u200b\u200bthe Earth, necessary for laying cables, is reduced. However, the cost of tunnels is very large. Tunnel Designed only for laying cable lines. It is built under the ground from the precast concrete or sewer pipes of a large diameter, the tunnel capacity is from 20 to 50 cables.
With a smaller number of cables apply cable Channels (Fig. 1.29, d), closed Earth or leaving the surface level of the Earth.
Cable overaps and galleries (Fig. 1.29, e) are used for overhead cable laying. This type of cable structures are widely used where directly laying of power cables in the ground is dangerous due to landslides, collaps, permafrost, etc. In cable channels, tunnels, collectors and overpass cables are packed through the cable brackets.
In major cities and large enterprises, cables are sometimes laid in blocks (Fig. 1.29, e) representing asbestos-cement pipes, joints that are covered with concrete. However, the cables are poorly cooled in them, which reduces their bandwidth. Therefore, laying cables in blocks only when they are impossible to lay them in trenches.
In buildings, on walls and overlaps, large streams of cables are placed in metal trays and boxes. Single cables Can be laid open on walls and overlaps or hidden: in pipes, in hollow plates and other building parts of buildings.
Each of us is aware of how important the power lines (LEP) play in our lives. It can be said that the energy they is transferred to nourish our lives. Almost any work is impossible without the use of electricity.
Power lines - one of the foundations of the energy complex
The main advantage of the transfer of electrical energy is the minimum time, during which the receiving device will be powered. This is explained by the speed of distribution of the electromagnetic field and ensures the widespread distribution of the LPP. Electricity transmission is performed on sufficient long distances. This requires additional tricks aimed at reducing losses.
For the convenience of perception of information, as well as to properly document in the field of electric power industry, the power lines are classified by several indicators. Here is some of them.
The main criterion for which the power lines class is classified is a constructive way to transfer energy. The lines are divided into the following types:
Depending on the characteristics of the network, the length of the line, the number of consumers and their LEP needs are divided into the following stress classes:
According to this criterion, the LEP is divided into the following types:
DC lines did not receive widespreadAlthough there are less expenses when transmitting energy over long distances. This is primarily due to the high cost of equipment.
The composition of cable and air lines are different. For differentiation, consider each type of LEP separately.
There are many devices and structures in its composition. We list the main ones:
In addition to direct destination, air lines are used as engineering structures for the suspension of fiber optic communication cable. In this regard, on some lines, the number of components of the elements is constantly growing.
Cable lines are used to transmit electrical energy in places inaccessible to suspension in support of WL. It includes power cable and nodes of entering the substation and to end users.
Consumers are taken to deliver electric current with a voltage of 220 and 380 volts. However, in the conditions of extended lines, this is not profitable, since losses on sections of more than 2 km long can be incomparable with the necessary power consumed.
In order to reduce losses at large distances, the power increases and the current of high voltage transmits. For this, the transmission uses the raising substations, and in front of the consumer put lower transformers. Thus, the transmission line is as follows:
Structural scheme LEP.In general, it can be assumed that the power line (LEP) is an electric line that goes beyond the power plant or substation and intended for transmitting electrical energy to the distance; It consists of wires and cables, insulating elements and bearing structures.
The modern classification of the LEP for a number of signs is presented in Table. 13.1.
Classification of power lines
Table 13.1.
|
Sign |
Type of line |
Variety |
|
Rod Toka |
Direct current |
|
|
Three-phase alternating current |
||
|
Multiphase alternating current |
Six-phase |
|
|
Twelve phase |
||
|
Nominal voltage |
Low-voltage (up to 1 kV) |
|
|
High voltage (over 1 kV) |
CH (3-35 kV) |
|
|
VN (110-220 kV) |
||
|
SVN (330-750 kV) |
||
|
UVN (over 1000 kV) |
||
|
Constructive performance |
Air |
|
|
Cable |
||
|
Number of chains |
Disposal |
|
|
Two-chart |
||
|
Multilette |
||
|
Topological characteristics |
Radial |
|
|
Magistral |
||
|
Branch |
||
|
Functional purpose |
Distribution |
|
|
Powerful |
||
|
Intersi forces |
In the classification in the first place there is a genus. In accordance with this feature, DC lines are distinguished, as well as three-phase and multiphase alternating current.
Lines direct current Competed with the rest only with a sufficiently large length and transmitted power, since in the total cost of the transmission a significant proportion is the cost of the construction of end conversion substations.
The greatest distribution in the world got lines three-phase alternating currentAnd over a length among them, the air lines lead them. Lines multiphase alternating current (six- and twelve phase) currently refer to the category of non-traditional.
The most important feature that determines the difference in the design and electrical characteristics of the power supply, is the rated voltage. U. . To category low-voltage These are lines with a rated voltage of less than 1 kV. Lines S. U hou\u003e 1 kV belong to the category high-voltage, and among them highlighted lines average voltage (CH) with U iom \u003d 3-35 kV, high voltage (Hl) with U Nou. \u003d 110-220 kV, ultra high voltage (SVN) U h (m \u003d 330-750 kV and ultrawow Voltage (UVN) with U HOU\u003e 1000 sq. M.
By design, air and cable lines are distinguished. A-priory aerial line - This is a power line, the wires of which are maintained above the ground using supports, insulators and fittings. In turn, cable line It is defined as a power line made by one or more cables laid directly to the ground or laid in cable facilities (manifolds, tunnels, canals, blocks, etc.).
By the number of parallel chains (l c), paved on the total highway, distinguish disposal (P. =1), dual-chart (and c \u003d 2) and multilette(and C\u003e 2) lines. According to GOST 24291-9 B The same alternating current line is defined as a line having one set of phase wires, and two-charted VLs are two sets. Accordingly, the multirecasted ll is called a line having more than two sets of phase wires. These kits may have the same or different nominal voltages. In the latter case, the line is called combined.
Disposal air lines are constructed on monotoned supports, while two-charts can be constructed either with a suspension of each chain on individual supports, or with their suspension on a total (two-chart) support.
In the latter case, it is obviously reduced by the strip of the territory of the territory under the line of the line, but the vertical dimensions and the mass of support are increasing. The first circumstance is usually decisive if the line passes in the densely populated areas, where the value of the land is usually high enough. For the same reason, in a number of countries of the world, multi-specific supports with suspension chains of one nominal voltage are used (usually C and C \u003d 4) or different stresses (with I C
According to topological (circuit), the characteristics distinguish radial and main lines. Radial The line is considered to which the power comes only on the one hand, i.e. From a single power source. Magistral The line is determined by GOST as a line from which several branches depart. Under a branched It is understood by the line attached by one end to another LPP at its intermediate point.
Last Sign of Classification - functional purpose.Here are allocated distribution and food Lines, as well as a line of intersystem communications. The division of lines for distribution and supply is quite conditionally, for those and others serve to ensure the electrical energy of consumption points. Typically, the distribution includes lines of local electrical networks, and to the supply - line of networks of district values \u200b\u200bthat carry out the power supply of the power centers of the distribution networks. The line of intersystem communications directly connect different power systems and are intended for mutual exchange of power in both normal modes and accidents.
The process of electrification, the creation and merging of power systems into a single power system was accompanied by a gradual increase in the rated voltage of the LAM in order to increase their bandwidth. In this process in the territory former USSR Historically, two nominal stress systems have developed. The first, most common, includes the following number of values. U HWT:35-110-200-500- 1150 kV, and the second -35-150-330-750 kV. By the time of the collapse of the USSR, there were more than 600 thousand km of 35-1150 square meters in Russia. In the subsequent period, the growth of the length continued, albeit less intensively. The corresponding data is presented in Table. 13.2.
The dynamics of changes in the length of VL for 1990-1999.
Table 13.2.
|
and , sq. |
Length of VL, thousand km |
|||||
|
1990 |
1995 |
1996 |
1997 |
1998 |
1999 |
|
|
Total |
||||||
