Patent Application
20240162694
The present invention has its field of application in electrical power distribution systems, in particular, it relates to an electrical switchgear integrated inside a gas-insulated enclosure that comprises a series of elements, among others, a means of operation that allows performing the operating functions of breaking, making, disconnecting and grounding of the electrical circuit, so that said switchgear integrated in the aforementioned enclosure allows configuring different electrical diagrams.
Currently, the electrical switchgear used in electrical power distribution networks is installed in usually metal enclosures, called cells. Said switchgear comprises operating means that perform the functions of breaking-making-disconnecting-grounding the system. In this way, in cases where there is, for example, a fault in the distribution line, an interruption due to works, maintenance or optimization of load distribution, such operating means can be activated to obtain the desired distribution of electrical power, prevent consumers from being left without voltage or to guarantee the protection of people and electrical equipment, such as transformers.
In addition to the operating means, the electrical switchgear incorporated within the enclosures also includes main circuit bars, which allow the input/output of electrical power to the electrical switchgear and which are located upstream of the operating means allowing the entry of said power to said operating means, and branch bars that are located downstream of the operating means and that output the electrical power that passes through said operating means.
Currently, part of the electrical switchgear, such as the operating means, the main circuit bars and the branch bars, are incorporated in a metal enclosure insulated in a gas, such as air, the enclosure being airtight in those cases in which the gas used is not air, such as sulfur hexafluoride (SF6), dry air, nitrogen, CO2, etc. The purpose of the insulation gas is to reduce the distance between phases and thus achieve an enclosure being compact and insensitive to external or environmental conditions such as pollution or humidity. Regarding the type of gas used, it is worth mentioning that the most used gas in recent years is SF6 gas due to its excellent dielectric properties and, among many other advantages, because it is not toxic to people. However, this gas has a great environmental impact due to its high greenhouse effect potential (GWP=22,800). For this reason, in recent years alternative gases have been sought, such as dry air, N2, O2 or CO2, or mixtures of fluoroketones with gases such as CO2, N2, O2, air or mixtures thereof, which can replace this SF6 gas in this type of electrical switchgear.
Also, the same insulating medium, such as a dielectric gas from those mentioned above, in some cases also allows the extinction of the electric arc generated between the contacts of the switch in the opening and closing operations.
One of the objectives of the use of an insulating gas is to be able to reduce the distance between phases, that is, the distance between the active parts under voltage, such as the distance between the bars of the main circuit or between the branch bars, to thus achieve a more compact enclosure.
As an alternative to the use of a gas as an insulating medium, which has a great environmental impact, it is common for part of this electrical switchgear to be encapsulated in solid insulation, such as insulating resin, thus reducing the distance between phases. In these cases, the dielectric medium used to extinguish the electric arc is usually vacuum or a fluid, such as a gas or a liquid, to perform the required operating functions mentioned above: breaking-making-disconnecting-grounding executed correspondingly by the operating means, such as switches. In short, the electrical switchgear is insulated in an insulation medium with high electrical resistance and a compact structure, managing to reduce the insulation distance between the different elements that make up the switchgear and the size of the systems.
In this sense, examples can be cited in which solid insulation is used as a means of insulation in electrical switchgear. It is worth mentioning as an example the patent application WO0150563A1 that deals with a plurality of insulating resin bodies, wherein several vacuum switches are encapsulated: some, corresponding to the making-disconnecting-grounding functions, are encapsulated in an insulating body together with their respective actuators, while a different insulating body encapsulates the vacuum switch that performs the breaking-making functions together with its corresponding actuator. Likewise, the branch bars and the bars of the main circuit are also encapsulated in independent insulating bodies. Each one of these independent insulating bodies is installed inside a different compartment of the cell, joining said insulating bodies through bushings that are part of the same insulating bodies.
However, one of the drawbacks of the invention described in WO0150563A1 is that for each of the breaking-making-disconnecting-grounding functions it is necessary to use a different module with its respective actuator and, in addition to the need of encapsulating more than one operating means in each of the modules and integrating said modules in different compartments within a cell, it entails an increase in the dimensions of the electrical switchgear, thus creating space problems within the electrical distribution facilities. The considerable cost due to the large amount of resin that is necessary to make the encapsulations and the long manufacturing time are added thereto.
In this same line, mention can be made of the inventions contained in WO02082606A1 and EP0393733A1, wherein various operating means are described that perform the functions of making-disconnecting-grounding and other components, such as fuses, that perform the function of breaking in the event of fault, all of them being encapsulated in an insulating body integrated inside a compartment of the cell, while, in another different compartment of said cell, the actuating element of each of the necessary operating means is integrated.
In these last two solutions, however, the aforementioned problem of having to use various operating means to carry out the different functions of breaking-making-disconnecting-grounding is repeated, so that the cells that incorporate the switchgear tend to be bulky. In addition, the problem that the cells are bulky is reinforced due to the fact that the actuation elements of such operating means are integrated in compartments different from those that integrate the operating means, increasing the number of compartments in the cells, their size and therefore that of said electrical switchgear in the electrical distribution network.
In addition to the examples cited above, other examples can be cited in which solid insulation is used as a means of insulation in electrical switchgear, such as, for example, CN207896544U, 0N205911661U, CN205901163U, CN106329320B, CN205753147U, CN105846335B, etc., which show disadvantages similar to those already mentioned.
In addition, another added drawback that this type of solutions that use solid insulation may have is that related to the encapsulation of the different elements. Due to the thermal stress that appears at the joint of the body having insulating material with the element to be encapsulated, specifically due to the different coefficients of thermal expansion of the materials, interstices or air bubbles may appear between the different surfaces, and therefore cause partial discharges that would deteriorate the insulating materials and could end up with the dielectric breakdown of the insulating medium. Likewise, there could be problems in shielding the elements to be encapsulated, for example adhesion problems.
In addition, the fact of arranging the encapsulated elements, in the same module or in different modules, entails the inconvenience that in case of needing to replace it, the replacement of the complete encapsulated module may be mandatory, with the consequences that all this entails, high time involved replacement, labor cost, etc.
On the other hand, regarding the geometry of the bars of the main circuit or of the branch bars and the coupling between them, patent U.S. Pat. No. 6,433,271B1 discloses a system of bars of the main circuit with tubular geometry and a solution for the coupling between said bars for air-insulated electrical switchgear. In this sense, it is explained that the connection between bars can be carried out in such a way that one end of a tubular bar with an insertion end, which includes grooves for the location of a contact element (such as an annular spring) and for the location of a sealing element, is attached or inserted into the receiving end of another bar. The bars have a tubular and hollow geometry, so that they can be cooled by the passage of a gas through their interior. The area of joint between bars, as mentioned above, is sealed by a sealing element, so that the interior space of the tubular bars is totally protected from the surrounding atmosphere, and the hollow tubular bars can be optionally filled with a gas. The sealing of joints also provides protection against corrosion. The area of joint is finally also protected with an external protection element, such as a retractable sleeve, placed on the reception and insertion ends of the tubular bars. In said patent two other embodiments of coupling between bars of the main circuit are also explained, wherein in one embodiment the coupling is achieved by a tubular joining means that is inserted inside the ends (receivers) of both bars to be coupled, while in the other embodiment coupling is achieved by means of a tubular joining means that receives at each of its ends the ends (insertion) of both bars to be coupled.
Said patent U.S. Pat. No. 6,433,271 B1, as mentioned therein, is aimed at reducing the space required by air-insulated cells that have a main circuit bar system, as well as to simplify the connection between bars, their manufacturing and assembly. However, nothing is mentioned about the reduction of the distance between phases or between bars, so enclosures or cells that comprise the electrical switchgear will not have their sizes reduced either, this problem being aggravated in this case due to the fact that the electrical switchgear is air-insulated, a gas that comprises lower dielectric rigidity than other gases.
The application JP2004056844A with its solution aims to improve the insulation performance against ground, as well as between phases in conductive joints. In this way, it shows a particular embodiment of the joints between bars, which comprise a rounded shape in order to optimize the geometry of the electric field and avoid the so-called peak effect in the joints or avoid the concentration of the electric field at said points. However, having rounded geometries to avoid the peak effect or the concentration of the electric field is something well known and common in the state of the art.
For its part, the utility model CN209217565U aims to improve the insulation between phases inside a switch tank that is insulated in nitrogen or dry air. The switch is partially enclosed in a U-shaped insulating box (made of epoxy resin). Even the electrical joints are provided with a protective apron, so that the insulation between phases is improved and therefore the distances between phases are reduced making electrical switchgear less bulky and more compact.
Lastly, US patent application US2018366925A1 shows the solution of a busbar inside an enclosure, said busbar also being incorporated inside a cylindrical-shaped cover insulated in a gas. The cover is sealed and contains a dielectric gas, and the cover can be made of metallic or non-metallic material (such as fiberglass). Each cover is a module that corresponds to a busbar section and the different busbar sections are interconnected with each other through bushing-type interconnections on the adjoining end faces of the cover modules. Likewise, various operating means are described that perform the functions of breaking-making-disconnecting-grounding. The interconnection between said operating means and the busbar is also carried out by means of second connectors outside the cover modules.
On this occasion, the problem of having to use various operating means to carry out the different functions of breaking-making-disconnecting-grounding is also repeated, so that the cells that incorporate the electrical switchgear tend to be bulky. On the other hand, the different components of the electrical switchgear, such as the busbar or bars of the main circuit and the operating means, are incorporated inside different enclosures or compartments, using connectors for the interconnection between said components, thereby reinforcing the problem that the cells are voluminous.
Therefore, there is a need in the state of the art to have electrical switchgears for their application in electrical power distribution systems that, solving the problems of impact on the environment, insulation distances between the different elements that make up the electrical switchgear, sizes of the same electrical switchgear and size of the systems, costs, manufacturing times, etc. mentioned above, are capable of providing a compact, economical, easy-to-manufacture and environmentally friendly solution.
The present invention relates to an electrical switchgear for its application in electrical power distribution systems, such as, for example, electrical transformation centers, distribution centers, substations, etc., for the protection and operation of electrical circuits, and which is intended to solve each and every one of the problems mentioned above.
Said electrical switchgear comprises a first enclosure, which may be sealed, shielded and grounded, and insulated in a gas with a relative pressure, that is, higher than atmospheric pressure, such as, for example, air, dry air, N2, O2, CO2, or gas mixtures such as fluoroketones with carrier gases such as CO2, N2, O2, air or mixtures thereof, or gas mixtures such as non-flammable hydrofluoroolefins with carrier gases such as N2, O2, dry air, helium, CO2 or mixtures thereof, etc., thus avoiding the use of any other type of insulation medium, such as SF6 gas, which has an environmental impact.
This first enclosure comprises at least one means of electrical connection, such as a bushing, and at least one means of mechanical connection accessible both from the inside and from the outside, the electrical switchgear of the invention being installed inside said first enclosure and therefore isolated in the same gas that contains the enclosure. This electrical switchgear includes:
In accordance with the present invention, the electrical switchgear also comprises at least one cover that incorporates inside, concentrically, the bars of the main circuit and the branch bars, wherein the existing medium between said bars (of the main circuit and the branch ones) and the cover is a gas. The cover may comprise one or more hollow pieces of cylindrical geometry and comprise a plastic material or other electrically non-conductive material. The covers and the operating means are incorporated inside the first gas-insulated enclosure. For its part, the operating means can be mounted inside a second enclosure and this second enclosure in turn be mounted inside the first gas-insulated enclosure, so that the same insulating gas contained in the first enclosure also allows the extinction of the electric arc generated between the switch contacts in the opening and closing operations. As mentioned above, the electrical switchgear of the invention only comprises a single operating means, which performs all the operating functions, which are the functions of breaking, making, disconnecting and grounding, for which reason the cells or enclosures that incorporate this electrical switchgear will be less voluminous and more compact.
The parts of the cover are attached to each other by means of at least one first joining means, said first joining means being able to comprise an elastic material, such as silicone, in the form of a ring, which allows the joining and sealing between the different pieces of the cover.
The main circuit bars and the branch bars comprise a cylindrical geometry, and furthermore comprise at least one second connection means that allows the connection between bars of the main circuit or the connection between branch bars. The second joining means comprises a rounded piece, such as a ball or ball joint, at least one fixing point such as a bolt and may include at least one through hole which can be traversed, for example, by a screw or a threaded stud, in such a way that it allows joining between bars, thus obtaining, for example, T-bar joints, elbow joints, straight joints or crossed joints. In this sense, this second joining means allows different layouts/distributions of both the main circuit bars and the branch bars to be obtained inside the first enclosure in a simple and quick way to assemble, thus being able to choose the best layout/distribution of bars inside the first enclosure in order to reduce sizes and obtain a more compact electrical switchgear. Likewise, this second joining means, due to its rounded shape, allows optimizing the geometry of the electric field in the joints, and these joints also have a high thermal-dynamic resistance. These bars for both the main and branch circuits are installed concentrically inside the covers, so that they are isolated from one another, thus reducing the distances between phases and, ultimately, the sizes of the electrical switchgear, resulting in more compact enclosures or cells incorporating said electrical switchgear.
Once the main circuit bars and the branch bars have been installed with their respective covers inside the first enclosure, that is, once the desired layout/distribution of both the main circuit bars and the branch bars has been obtained inside of the first enclosure or when it is not necessary to pass the bars of the main circuit and/or the branch bars, those ends of the covers that remain open are closed by means of a closing means or plug, which is coupled by means of the first joining means to said covers at their open ends. Like the covers, the closing means or plug comprises a plastic material or other electrically non-conductive material. The electrical connection means and the mechanical connection means are accessible from the outside of the first enclosure, in such a way that the coupling of other elements with the first enclosure is facilitated, such as the operating mechanism by means of the mechanical connection means and cables of the electrical network or other electrical switchgear through the means of electrical connection. Some electrical connection means are connected to the bars of the main circuit and other electrical connection means connected to the branch bars, these electrical connections being of the plug-in type and comprising around them, surrounding the electrical connections, at least one diffuser, made of conductive material or with a conductive or semiconductive surface, in order to control the electric field and to dissipate the heat generated in said electrical connections. Likewise, the electrical connection means are coupled with the covers, which incorporate the bars of the main and branch circuit, by means of the first joining means, thus leaving the joint between both parts sealed.
The possibility has been considered that the electrical connection between the bars of the main circuit or the branch bars and the electrical connection means may comprise a connector configured to connect at one of its ends to the electrical connection means and at another of its ends to the main circuit bar or branch bar. Likewise, this connector may comprise at least one conductive part and at least one tightening means, such as a spring, so that the electrical connection between said at least one conductive part and the main circuit bar or the branch bar is of the plug-in type. The conductive parts are tightened against the bars (of the main or branch circuit) by means of the tightening means, guaranteeing an appropriate electrical contact between said bars and the conductive parts. This connector may also comprise a conductive terminal arranged between the main circuit bar or the branch bar and said, at least one, conductive part of the connector, such that, in this case, the bars are connected to said conductive terminal and the latter connects to conductive parts.
The electrical switchgear of the invention may comprise a cable compartment where the electrical connection means of the first gas-insulated enclosure are accessible to be able to make the connection with the cables of the electrical network. Likewise, the possibility has been contemplated that the operating mechanism can be mounted inside another enclosure, different from the first gas-insulated enclosure and the second enclosure of the operating means, said third enclosure of the operating mechanism being mounted above the cable compartment.
In short, through the joint use of the second joining means, the covers and the first joining means, a compact, lower-cost electrical switchgear is achieved, immersed in an environmentally friendly gas with a pressure greater than atmospheric pressure that allows the isolation between phases or active parts under voltage, as well as the extinction of the electric arc generated between the contacts of the operating means in the opening and closing operations.
A preferred embodiment is described below with reference to the figures cited above, without limiting or reducing the scope of protection of the present invention.
The electrical switchgear object of the present invention is applied in electrical power distribution systems such as, for example, electrical transformation centers, distribution centers, substations, etc., for the protection and operation of electrical circuits. As shown in
This first enclosure (1) comprises at least one electrical connection means (2, 3), such as a bushing, and at least one mechanical connection means (4) accessible both from the inside and from the outside, with the switchgear of the invention installed inside said first enclosure (1) and therefore insulated in the same gas contained by the enclosure (1).
As shown in
The electrical switchgear of the invention only comprises a single operating means (5), as can be seen in
The electrical switchgear also comprises at least one cover (10) that incorporates inside, concentrically, the bars (6) of the main circuit and the branch bars (7), see
As can be seen in
The bars (6) of the main circuit and the branch bars (7) comprise a cylindrical geometry, and also comprise at least one second joining means (14) that allows joining between bars (6) of the main circuit or joining between branch bars (7). As shown in
As mentioned above, see
As can be seen in
As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| U202130573 | Mar 2021 | ES | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/ES2022/070164 | 3/22/2022 | WO |
