Switchgear with high voltage - SpeedyLook encyclopedia

The switchgear with high voltage is the whole of the electricals appliance which allow the setting under or except tension of portions of a Electrical communication high voltage (including for operations of unballasting).

The switchgear is an essential component which makes it possible to obtain protection and a sure exploitation and without interruption of a network with high voltage. This type of material is very important insofar as multiple activities require to have of an electricity supply which are permanent and quality.

Name high voltage gather the old Medium Average one (HTA) and the old high voltage (HTB), it thus relates to the apparatuses of assigned tension higher than: 1000 V, in Alternative course, and higher than 1500 V in the case of current continuous. The industrial applications of the circuit breakers to high voltage for the moment are limited to the alternative course because they are more economic, it exists however disconnecting switches with high voltage for connections with D.C. current.

The switchgear with high voltage was created as of the end of the 19th century, at the beginning for the operation of driving and other electric machines. It did not cease developing, equipment is currently used in any range of the high voltages, up to 1100 Kv.

Historical prospect

The evolution of equipment with high voltage, in particular the techniques of cut which were used, was influenced by the technological advancements, the development of the means of calculation which made it possible to optimize dimensions of the apparatuses, the competition which pushed the manufacturers to produce increasingly economic apparatuses, but also by the evolution of the networks which required to produce equipment for increasingly high tensions.

The following table shows the evolution of the maximum tension of the networks with high voltage, starting from 1912, year of startup of the first line of tension higher than 100 Kv.

The chapter of the Technical used for insulation and the cut describes in a detailed way the various techniques developed to produce the equipment with high voltage which made it possible to answer the constraints and requirements increasingly severe which accompanied this evolution by the networks with high voltage.

The increase in the current of short-circuit in the networks with high voltage supported the advent of the compressed-air circuit breakers in the Années 1960, indeed the increase in consumption and thus of the working installed capacities required to have apparatuses able to shut off currents higher than 40 kA, which was the possible maximum breaking capacity with the circuit breakers with oil in extra-high tension.

During the Years 1970, it is rather the lower costs and the simplicity of the SF₆ circuit breakers which made it possible the latter to supplant in their turn the compressed-air apparatuses, the two techniques making it possible to obtain the most raised breaking capacities, 50 kA or 63 kA, then required in high voltage.

Into Medium Average, the apparatuses with oil were replaced by the apparatuses in SF₆ or with vacuum because the latter have higher performances in cut, an extended electric endurance and require less maintenance in service.

The consumption of electricity and consequently the requirements in working installed capacity and equipment with high voltage is in strong increase since 2005, it is particularly the case in China whose working installed capacity is of: 600000 MW (Méga Watt S) in 2006 and should reach: 1300000 MW in 2020, China will then have the installed capacity working highest in the world, and will exceed the the United States. For its part, the India envisages to multiply by 3 its installed capacity working between 2012 and 2025, it will be then of: 600000 MW.

Classifications

The switchgear with high voltage can be classified in several categories according to its function, its tension, its destination, its installation and its type of insulation.

Classification by function

Disconnecting switches

Switches

See also: Interruptory with high voltage

The Interrupteur S are apparatuses intended to establish and stop a circuit under normal conditions of load. Certain switches are designed to also fulfill the functions of disconnecting switch. Their performances are however limited because they are able to establish a current of short-circuit but cannot in no case to stop it.

Contactors

Cutout with fusible

The fuses make it possible automatically to stop a circuit traversed by an overcurrent during a given time interval. The interruption of the current is obtained by the fusion of a gauged conducting metal.

They are especially used for the protection against the short-circuits of which they limit the peak value of the fault current.

In mode Triphasé, they eliminate only the phases traversed by a current fault, which can present a danger to the material and the personnel. To mitigate this disadvantage, the fuses can be associated with switches or contactors with which they constitute compounds able to ensure protection in the event of overload of the network or short-circuits.

One only meets them in HTA.

Circuit breakers

A circuit breaker with high voltage is intended at the same time to establish, support and stop current under its assigned tension (the maximum tension of the Electrical communication that it protects):

under normal conditions of service, for example to connect or disconnect a line in an electrical communication;
under specified abnormal conditions, to eliminate a Short-circuit in particular.

From its characteristics, a circuit breaker is the apparatus of protection essential of a network with High voltage, because it is only able to stop a Courant of short-circuit and thus to prevent that the material connected on the network is damaged by this short-circuit. The international standard CEI 62271-100 defines the requirements relating to the characteristics of the circuit breakers in high voltage.

In their current configuration, the circuit breakers can be equipped with apparatuses electronic S making it possible constantly to know their state (wear, pressure of gas for the cut, etc) and possibly to detect defects by drifts of characteristics, which makes it possible the owner to program the maintenance actions and to prevent the default risks.

For the operation of the long lines, the circuit breakers are generally equipped with resistances of closing for the limitation of the Surtension S.

They can also be equipped with devices of synchronization to closing and/or the opening to limit overpressures or the ringing currents to the operation of lines, of Transformateur S with vacuum, of Réactance S Shunt and batteries of Condensateur S.

Apparatuses were designed to fulfill the functions of circuit breaker and of disconnecting switch, they are called circuit breaker-disconnecting switches. Their use is however limited.

Classification by tension

According to the international standard CEI 62271 the high voltage is, for the alternative courses, any tension higher than 1 Kv.

Although the following terms are not standardized, they are used in the language running:

the Medium Average one for the tensions higher than 1 Kv and lower or equal to 52 Kv;
the high voltage for the tensions higher than 52 Kv and lower than 362 Kv;
the extra-high tension for the tensions higher or equal to 362 Kv and lower or equal to 800 Kv;
the ultra-high tension for the tensions higher than 800 Kv.

The assigned tension of an apparatus is the maximum value of the network in which it can function. The assigned values of tension were harmonized between standards CEI and ANSI/IEEE:

: 3,6 - 4,76 (1) - 7,2 - 8,25 (1) - 12 - 15 (1) - 17,5 - 24 - 25,8 (1) - 36 - 38 (1) - 48,3 (1) - 52 Kv;

(1): values used only in North America

High voltage: 72,5 - 100 - 123 - 145 - 170 - 245 - 300 - 362 - 420 - 550 - 800 Kv.

The level of tension assigned of 800 Kv is used for apparatuses in service in the networks of Russia, of AEP to the the United States, Hydro-Quebec to the Canada, of EDELCA to the Venezuela, Furnas to the Brésil, ESCOM in South Africa and of State Grid Corporation off Clouded in China.

The maximum level of tension for the countries of the European Community is of 420 Kv; this level is most economic, taking into account the exchanged powers and the length of the lines of interconnection. A study had been made as of the beginning of the Années 1970 in Italy for a network of 1100 Kv, but this project did not succeed because the initial forecast of increase in the consumption of electricity was revised with the fall after the oil crisis of 1973.

Classification by field of application

Equipment high voltage is intended to function mainly in three types of networks or electrical installations according to the objectives of transport use, distribution and distribution.

The grid systems (for the tensions higher than 52 the purpose of Kv) are to transport the energy of the great centers of production towards the areas consuming electricity. The forwarded great powers impose electric lines of strong capacity of transit, as well as a structure with a grid (or inter-connected). The mesh networks guarantee a very good safety of food, because the loss of any element (electric line, transformer or groups production) does not involve any cut of electricity if the owner of the grid system complies with the rule known as of the “N-1” (possibility of losing any element of the network without unacceptable consequence for the consumers).

The networks of distribution ensure the regional scales the supply of electricity. Energy is injected there primarily by the grid system via stations with high voltage, but also by power station S of average powers (lower than approximately 100 MW). The networks of distribution are distributed in a rather homogeneous way on the territory of an area.

The distribution networks (for the tensions lower or equal to 52 the purpose of Kv) are to feed the whole of the consumers. Contrary to the distribution and grid systems, the distribution networks have a great diversity of technical solutions at the same time according to the countries concerned, like according to the population density. The networks with Medium Average (MT) have in a very majority way a tree structure, which authorizes simple and inexpensive protections. Starting from a source station, itself supplied with the network of distribution, electricity traverses an artery on which is directly connected branches of derivation to the end of which stations MT/BT of public distribution are. The latter feed the networks low tension (BT) on which the smallest consumers are connected. The tree structure of these networks implies that a defect on a MT electric line inevitably involves the cut of the customers supplied with this line, even if more or less fast possibilities of help exist.

Industrial facilities (3,6 with 24 Kv), for example, are used in industries which produce chemicals or materials (works aluminum smelting) and the railway installations for example).

Classification by type of installation

Two cases are distinguished:

the material for the interior, which as its name indicates it is intended to be only installed inside one building. It is not subjected to the bad weather or pollution, according to standard CEI the room temperature is normally not lower than - 5 °C.
the material for outside is designed to be installed except buildings, consequently it must function under climatic conditions and atmospheric (for example: temperature, pollution, wind, precipitations) specified by standards.

In the field of HTB, the switchgear was traditionally installed in outside, the air playing a central role of insulation, for example for the insulation between phases. In parallel, since the Years 1970, the second technology developed, said “under metal envelope” or “to gas insulation”, where the gas Hexafluorure of sulfur (SF₆) plays a paramount role for the isolation^,.

the hybrid material which includes/understands equipment with insulation in the air and insulation in SF₆. A typical example is a cell including/understanding a circuit breaker and disconnecting switches under envelope metal, combined with an earthing external and crossed air for connection with the lines.

After the Second world war, they were replaced by apparatuses with low volume of oil which are more economic and present less fire hazards or explosion in the event of failure of the cut.

Circuit breakers with low volume of oil with two elements of cut in series per pole were developed to equip the first network 420 Kv in the world, precisely the Harsprånget line - Halsberg in Sweden, brought into service in 1952.

Compressed-air apparatuses

The compressed-air circuit breakers supplanted the circuit breakers with oil in the field of high efficiencies thanks to high the dielectric Rigidité and with the good thermal properties of the fluid used. The compressed air under a pressure from 20 to 35 bar is evacuated inside tubes to make it possible to obtain an effective cooling of the arc.

They were developed starting from the beginning of the Années 1950 and as of 1960 reached the highest performances which were necessary for the networks to extra-high tension which developed at that time: 525 Kv: 25000 Mva for the Russian network, the Moscow connection - Volgograd being then the first in the world exploited with this level of tension.

These circuit breakers were provided with resistances which were inserted in the circuit into the opening in order to reduce the constraints in cut of strong currents and also to limit overpressures likely to be generated during the cut.

The compressed-air circuit breakers had for a long time the monopoly of very high efficiencies: capacity breaking up to 100 kA, lasted of cut reduced, low level of overpressure thanks to the use of resistances for closing. These circuit breakers require a periodic maintenance however, in particular that of the compressing .

The compressed-air technique only is always used for the circuit breakers of generators to capacity breaking very high (275 kA under 36 Kv).

Apparatuses with pressure of SF₆

The technique of cut in SF₆ was developed in high voltage at the end of the Années 1950, it gave place to the first applications in 245 Kv in the Années 1960 (armor-plated Station of Vaise in 1966) then it was essential and became the technique used for all the new developments in high voltage starting from the Années 1970.

Currently apparatuses integrating of the bulbs into vacuum are in service until 84 Kv, with the Japan, the capacity breaking of a circuit breaker with vacuum can reach 63 kA.

Assigned characteristics

The standard CEI 60694 (future 62271-1) defines the characteristics applicable to equipment in high voltage. It lists the characteristics to which a value must be assigned, generally by the manufacturer, for specified conditions of operation of equipment. The assigned characteristics are mainly:

the tension;
the level of insulation;
the frequency;
the running in continuous service;
the current of short duration and the peak value of the acceptable current.

Level of assigned insulation

The level of insulation of an apparatus is defined by several values:

the tension of behavior to industrial frequency;
the tension of behavior to the shocks of the Lightning;
in extra-high tension: the tension of behavior to the shocks of operation.

The switchgear is subjected in service to these three types of tension (and with their combination between input-output).

Routine and performance tests (of type) (on the apparatuses manufactured) are carried out to check this level of insulation. They are carried out between phase and ground, phases and terminals of the open apparatus.

Higher values for the behavior between open contacts are specified for the disconnecting switches because they must satisfy safety requirements.

For the apparatuses of tension higher than 245 Kv, the tension of behavior to the shocks of the lightning (or operation) between open contacts are tested by applying a shock of the lightning (or operation) to a terminal and a tension at industrial frequency (50 Hz or 60 Hz) on the other limits. For example in the case of an apparatus of assigned tension 800 Kv, the tension of 2555 Kv indicated in the table above is obtained by applying a shock of the lightning of 2100 Kv on a terminal and a tension of 455 Kv on the other limits. That makes it possible to reproduce the real situation in service where the tension of the shock of the lightning is transmitted on a terminal of the apparatus whereas the tension of the network is applied on the other terminal.

Assigned frequency

The normal values of the frequency assigned with equipment high voltage are 50 Hz and 60 Hz. They by far is used, the use of one or the other value results from historically made choices when the values were rationalized. Little before 1892, Westinghouse in the United States chose the 60 Hz, whereas AEG in Germany chose the 50 Hz in 1899, leading to a world mainly cut into two. The Japan has networks with 50 Hz and 60 Hz.

Other values of frequency are sometimes used for railway traction: 16 2/3 Hz and 25 Hz. The Germany, the Austria and the Suisse use alternative course single-phase current with 16 2/3 Hz for the power channel. The frequency of 25 Hz was used on certain lines of the German railroads ( Mariazeller Bahn ) and some lines in the states of New York and Pennsylvania (Amtrak) to the the United States.

Running in continuous service

The current assigned in continuous service is the current one that an apparatus can support indefinitely under normal conditions of service. The components of an electrical appliance warm up when this last forwards current, the temperature should not exceed limiting values definite by the standards so that the materials preserve their mechanical characteristics.

The possible values of assigned current must be selected in the following series of Fox (or with their multiples by ten):

160 - 200 - 250 - 400 - 630 - 800 - 1250 - 1600 - 2000 - 2500 - 3150 - 4000 With

Current of short duration and peak value of the acceptable current

The current of short duration which must be supported by an apparatus in service is characterized by two parameters: the maximum amplitude of the current during the establishment of a current of short-circuit, as well as the effective value of the current of short-circuit which must be supported for one specified length of time.

When a short-circuit occurs in a network with the passage by zero of the tension, the current which is established is known as asymmetrical because it is appeared as a sinusoid shifted compared to the zero line of. The apparatus must support the maximum amplitude of the current then the current throughout one 1 or 3 seconds.

The relationship between the maximum amplitude of the current and the effective value of the current of current of short-circuit depends on the time-constant (L/R) of the network and the assigned frequency. It is equal to:

2,5 for the networks with 50 Hz with a time-constant 45 ms;

2,6 for the networks with 60 Hz with a time-constant 45 ms;

2,7 for the particular applications with a time-constant higher than 45 ms.

Operating conditions

Concerning the temperature of service and according to standard CEI, equipment is designed to function under the following normal conditions of service:

the maximum temperature of the ambient air does not exceed 40 °C and its median value, measured for one period of 24:00, does not exceed 35 °C;
the minimal temperature of the ambient air is not lower than - 25 °C or - 40 °C. Other values of minimal temperature are possible, such as - 30 °C (for example in North America) or - 50 °C (Canada, Russia, etc).

To guarantee a good performance at very low temperature, the Pression of SF₆ must be reduced and specific measures must be taken to allow a good performance of the body of operation and to ensure good a sealing.

Operation at high temperature of the ambient air requires to make sure that the temperature and the heating of the components do not exceed the acceptable limits fixed by the standards.

Other particular operating conditions are to be taken into account in the design of the material: wind, pollution, seisms, etc

Tests of equipment

Tests of the type, or performance tests of the type, are carried out to show that an apparatus has the assigned characteristics which were allotted to him. They are made on duly identified representative specimens.

These tests are carried out on a new apparatus and are the report/ratio object of tests which contain the identification of the specimen under test and all information making it possible to show that the apparatus satisfied the requirements of the standards into force. The specifications common to equipment with high voltage are defined in standard CEI 60694 (future 62271-1). Specific requirements to each type of material are specified in the standards of products, such as the CEI 62271-100 for the circuit breakers with high voltage.

Taking into account the high values of tensions and/or required currents, the high-voltage tests and of cut of equipment with high voltage must be carried out in specialized laboratories.

Tests known as of routine are also carried out to control the quality of the production, they are composed primarily of mechanical tests of control of the characteristics of functional calculuses, of high-voltage tests of behavior at the industrial frequency and a control of the sealing for the SF₆ apparatuses.

When an apparatus is assembled for the first time on site, it must also undergo commissioning tests (control of the characteristics of functional calculuses and/or high-voltage tests).

High-voltage tests

The purpose of the high-voltage tests of type are to check the level of insulation assigned of an electrical appliance. If the Electric field exceeds the dielectric behavior of the apparatus, a Claquage (or disruptive discharge) occurs and the apparatus can see its physical properties modified in a reversible or irreversible way. In the case of apparatuses with high voltage, the dielectric held must be regenerated after any possible breakdown due to an excessive overpressure, in order to ensure the continuity of service after the elimination of the defect.

The dielectric behavior must be checked under the following conditions:

held between input-output of the open apparatus;
held compared to the mass of the open apparatus;
held compared to the mass of the closed apparatus.

The apparatuses which use a gas under pressure for insulation must be tested in the most unfavourable case, i.e. with the minimal gas pressure.

Tests of tension of shock of the lightning

These tests are required for all the assigned tensions and are carried out only on one dry apparatus. According to procedure CEI, a series of 15 shocks is applied for each configuration of test and each polarity of tension. The tests of tension to the shocks of the lightning are satisfactory if the number of disruptive discharges does not exceed two during each series of 15 shocks.

A shock wave of the lightning is characterized by a very fast face, the tension peak is reached after approximately 1,2 microsecond. The peak value of the tension is defined by standard CEI according to the assigned tension, of the values are given as example by the table of the chapter Niveau of insulation assigned.

Tests of tension of shock of operation

These tests are only required for the assigned tensions higher than 245 Kv. They are carried out, dry and under rain, for the two polarities of tension. According to procedure CEI, a series of 15 shocks is applied for each configuration of test. The criterion of success to the tests is the same one as for the tests of tension of shocks of the lightning.

The duration of rise of a shock wave of operation is much slower than that of a shock wave of the lightning, about 250 microseconds. With tension equal peak, the behavior in tension of an insulation is generally lower with this type of shock wave.

Tests of tension at industrial frequency

The purpose of these tests are to check the behavior of the apparatus if an overpressure at industrial frequency (50 or 60 Hz) occurs on the network, for example following a loss of load. They are required for all the assigned tensions. According to standard CEI, a behavior during one minute is required dry and under rain. No Electric shock (or disruptive discharge) is allowed during the dry test. The test under rain can be repeated if a discharge occurs, but no other discharge is allowed.

Temperature-rise tests

The purpose of these tests are to check that there is no excessive heating of the parts of an apparatus when it permanently leads its current assigned in continuous service. The following table gives as an indication maximum values of temperatures and acceptable heating for the switchgear.

The tests are carried out by maintaining the current required one under a reduced tension and by measuring the heating obtained in various points of the apparatus until stabilization of the values, generally after ten hours of maintenance of the current.

Endurance tests mechanical

The purpose of the endurance tests mechanical are to check the robustness of an apparatus and its capacity to function normally during all its lifespan, is during approximately 25 years. At the end of the lifetime, it must still be able to lead its current assigned in continuous service, to carry its assigned current of acceptable short duration and to preserve its level of assigned insulation.

During the endurance tests, the apparatus must function only on order and its functional characteristics must remain in the tolerances given by the manufacturer. After the tests there should not be excessive wear of the parts, in particular of the contacts.

For example, for a circuit breaker, the apparatus must carry out: 2000 operating cycles to the room temperature, an operating cycle being an operation of opening of the circuit breaker followed by an operation of closing (it is one of the sequences of operations which the apparatus must carry out in service, because after having opened a circuit, by separating its contacts, it must be able to close again it to again make it possible the current to circulate and for example to feed a load).

A mechanical endurance extended with: 10000 operating cycles can be required in particular cases.

On request, mechanical tests can also be carried out with low and high temperature. The purpose of they are then to check the good performance and the sealing under extreme conditions of temperature.

These endurance tests mechanical, which are added to the other tests of the type described previously, make it possible to ensure a very good reliability in service, with a low level of major incidents as that could be checked by the studies made periodically by CIGRE. Consequently, there no was major accident on the networks with high voltage which could be charged to a defect of equipment, the important losses of food in a network (blackout) are generally due to defects on lines and the loss of part of the network by overloads in cascade on the other lines.

Specific tests

Specific tests for each function of equipment are specified by standards of the series CEI 62271. It is for example:

tests of establishment and cut for a circuit breaker;
of the tests of transfer of bars for a disconnecting switch;
of the tests of establishment and power cut induced for a ground disconnecting switch.

In addition additional tests can be required according to the operating conditions, for example of the tests of behavior to the seism S or of the operational tests under ice for disconnecting switches of stations BOARD.

Tests are of seismic qualification are carried out on request of the customer to check the capacity of an apparatus to support a seism of acceleration on the ground given (0,2 - 0,3 or 0,5 G, where G indicates acceleration due to the Pesanteur). A demonstration by calculation is in theory sufficient if it is based on an experimental checking of the Eigen frequencies and associated damping S. In the case of seism of strong intensity (0,5 G), of the full-scale tests on mobile plate are required if dimensions of the apparatus allow it. They are composed of a test of sweeping in frequency in each direction in order to determine the clean modes of vibration and their damping, and tests of one duration dynamic behavior of 30 seconds or a minute. For the circuit breakers, the CEI published the seismic guide of qualification TR 62271-300.

Design and construction

Standard CEI defines a certain number of requirements which must be respected by the manufacturer when designing material. They relate to the auxiliary equipments and of order, connection with the ground, the envelopes of the apparatuses of the armor-plated type, the bodies of operation, the locking mechanisms, the Isolateur S of outside, the sealing, the risk of fire, the electromagnetic Compatibilité (CEM) and the Corrosion.

In the case of apparatuses with autonomous gas pressure (without compressing), the relative leakage rate of each compartment should not exceed 0,5% and 1% per annum for SF₆ and the mixtures including/understanding of SF₆. These values result from a will of electric industry significantly to reduce the possible escapes towards the atmosphere. The interval between complements of filling must be at least 10 years for the apparatuses which use SF₆.

The sealed apparatuses with pressure are such as any gas filling is not necessary during their 20 years, 30 years or 40 years working life discounted. The leakage rate of those which are filled of SF₆ can be regarded as being lower than 0,1% per annum.

Producers and users

Producers/manufacturers

The number of major producers of equipment to high voltage is relatively weak because of many regroupings/acquisitions were made in years 1990/2000. For the transmission of energy, the principal producers are: ABB, Areva T&D, Siemens, Toshiba, Mitsubishi and HVB AE Power Systems (ex Hitachi). In the field of energy distribution it is necessary to add primarily Schneider Electric and Eaton/Cutler-Hammer.

Concerning France, the producers belong to a grouping called the GIMELEC (Grouping of industries of electrical equipment, control and services associated); the principal manufacturers are Areva T&D, Siemens, Schneider Electric, EGIC, Ferraz Shawmut and Ormazabal. For the whole of the profession, the sales turnover realized in 2006 starting from France rises to 10,7 billion Euro S.

On the European level, the manufacturers of switchgears belong to the CAPIEL (Coordination committee of associations of manufacturers of industrial switchgear of the European Union) and of ORGALIME ( European Engineering Industries Association representing the interests off the Mechanical, Electrical, Electronic and Metalworking Industries ).

The CAPIEL gathers twelve national associations of producers, such as Gimelec in France, and 550 manufacturers in Austria, Belgium, Finland, France, Germany, Italy, Netherlands, Spain and the United Kingdom. The companies employ a total of: 118000 people in Europe and have a sales turnover combined of 18,25 billion euros. On average 25% of their production are exported apart from Europe.

Users

In the high voltage B, the users are primarily productive enterprises of electricity like EDF or transport of electrical energy like RTE. Regroupings occurred between users of apparatuses with high voltage following the liberalization of the electric energy market, several national markets remained traditionally dominated by some companies of State. Among the principal users, one can also quote: RWE and E.ON in Germany, Tokyo Electric Power with the Japan, State Grid Corporation off Clouded in China, Power Grid Corporation off India in India, Enel and Terna in Italy, Edelca with the Venezuela, Furnas with the Brésil, ESCOM in South Africa, Hydro-Quebec and BC Hydro with Canada and AEP, Tennessee Valley Authority, Bonneville Power Administration (BPA) with the the United States.

The situation is appreciably different in the high voltage has with also large distributive firms of electricity, EDF for example, but also of many industrialists who are fed under a tension from 10 to 22 Kv, or more rarely in high voltage B. the railway companies are also of important users of switchgear to high voltage.

The users and producing European are gathered within Eurelectric ( The association off the electricity industry in Europe: electricity producers, suppliers, traders and distributers from the HAVE and other European countries ).

In Australia, where the market for electrical equipment with high voltage accounts for approximately 1,8 billion euros, of many users transports and distributes electricity by areas or States, one of principal is Transgrid in News-Wales-of-South.

It is in China that the consumption of electricity and consequently the requirements in working installed capacity and equipment with high voltage increase most quickly; the working installed capacity is of: 600000 MW (Méga Watt S) in 2006 and should reach: 1300000 MW in 2020. As comparison a section of nuclear plant provides approximately: 1200 MW. To face the increase in their consumption and to transport electrical energy at long distances, China envisages to bring into service since 2008 a network at ultra high voltage 1100 Kv.

The United States has in December 2005 the quarter of the installed capacity working in the world with 1067000 MW or 1,067 Téra Watts, their capacity should increase by 292000 MW until 2030 answering at the request of the consumers.

Environmental impact

Studies were undertaken to evaluate the environmental impact of equipment with high voltage. The purpose of they are at the end of the lifetime to measure this impact since the manufacture of the parts until the dismantling of the product. Software EIME is generally used to make this type of evaluation.

The studies undertaken to date concluded that the current solutions have an environmental impact lower than that of the former generations which used the air or oil as medium for the cut and insulation. Many factors can explain this reduction of the environmental impact, among them: the reduction of dimensions and the quantity of matter used for equipment, the reduction of energies of operation which made it possible to use orders with spring which have less environmental impact than the oil and air orders (with oil) used in the past.

In addition, these studies showed that in fact the losses by Joule effect have the most environmental impact, this impact is however limited insofar as the resistance of an apparatus to high voltage is worth only a few tens of micro - Ohm S.

Among the various types of installations, they are the GI and the compact solutions which would have less impact, because of their compactness, but the stations BOARD remain most economic and remain the generally adopted solution when there are no too demanding constraints of obstruction or pollution.

International agencies treating of equipment with high voltage

The switchgear with high voltage is the object of studies and of standards by several international agencies because it is an important component of any electrical communication with high voltage.

A3 study committee of CIGRÉ (International counsel of the great electrical communications) organizes conferences and carries out technical work of world range on the equipment of the stations with high voltage, in particular on the switchgear with high tension^,. CIRED (international Congress of the electrical communications of distribution) organizes biennial conferences for the materials of the distribution networks.

The international electrotechnical Commission (CEI), and more particularly its TC17^{study committee,}, writes standards on equipment with high voltage which are recognized in more than one hundred country.

The committee equipment of IEEE ( IEEE Switchgear Committee ) made studies and writes standards on the switchgear which are primarily used in North America. The standards CEI and IEEE for the switchgear with high voltage are in the course of harmonization.

See too

Switchgear
electric Station
Electrical communication
Protection of the electrical communications
Standards CEI 62271

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