EP4625463A1

EP4625463A1 - Circuit-breaker

Info

Publication number: EP4625463A1
Application number: EP24165996.0A
Authority: EP
Inventors: Marcelo Buffoni; Paulo Cristini; Bernardo Galletti; Michael Schwinne
Original assignee: Hitachi Energy Ltd
Current assignee: Hitachi Energy Ltd
Priority date: 2024-03-25
Filing date: 2024-03-25
Publication date: 2025-10-01
Also published as: WO2025201824A1; WO2025201825A1

Abstract

The invention relates to a circuit-breaker (1), comprising
at least two contacts (3, 3.1, 4, 4.1) with at least one of the at least two contacts (3, 3.1, 4, 4.1) movable and with an arcing zone (5) between the at least two contacts (3, 3.1, 4, 4.1);
at least one exhaust (8, 9) in fluid connection to the arcing zone (5) and including an outlet (12) for letting out insulating gas; and
a gas mixing structure (20) installed in a gas flow path between the arcing zone (5) and the outlet (12); wherein
the gas mixing structure (20) includes a static mixer (40) forming a plurality of gas passages (41, 42) at least sectionally and/or partially arranged oblique to each other and configured for mixing the insulating gas passing the plurality of gas passages (41, 42).

Description

Technical Field

The invention relates to a circuit-breaker comprising at least two contacts with at least one of the at least two contacts movable with an arcing zone between the at least two contacts, and comprising at least one exhaust in fluid connection to the arcing zone for insulating gas.

Background Art

Electrical systems of various types, e.g., circuit-breakers, remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. For example, in some gas-insulated circuit-breakers, improvements in their construction and/or electrical properties for a better reliability may be made. In addition, costs need to be optimized. Accordingly, there remains a need for further contributions in this area of technology.
In the operation of a circuit-breaker arcing occurs. The high temperatures of an arc result in heating of the gas or insulating gas in the circuit-breaker, which then can be guided away from the contacts and from an arcing zone through an exhaust. It is a problem to deal with hot gas. Particularly, it is a problem to provide continuous enhancement in circuit-breakers with regard to lifetime and wear of the circuit-breaker, particularly of parts in direct contact with hot gas.

Summary of invention

It is therefore an object of the invention to provide solutions with respect to circuit-breakers that provide an enhanced maintenance, reduced cost, and increased lifetime. Particularly it is an object to avoid or reduce disadvantages of known solutions.
The object of the invention is solved by the features of the independent claims. Preferred implementations are detailed in the dependent claims, the description, and the figures.
The object is particularly solved by a circuit-breaker, e.g. configured as a medium-voltage and/or high-voltage circuit-breaker, comprising

at least two contacts with at least one of the at least two contacts movable and with an arcing zone between the at least two contacts;
at least one exhaust in fluid connection to the arcing zone and including an outlet for letting out insulating gas; and
a gas mixing structure installed in a gas flow path between the arcing zone and the outlet; wherein
the gas mixing structure includes a static mixer forming a plurality of particularly elongated gas passages at least sectionally and/or partially arranged oblique to each other and configured for mixing the insulating gas passing the plurality of gas passages.

In other words, particularly, a gas-insulated breaker is suggested that has two or more contacts and an exhaust for insulating gas to be guided away from the arc, particularly from the arcing zone. In the exhaust there is arranged a static mixer configured for mixing the insulating gas flowing through the exhaust along a main flow direction. The static mixer forms an intricate and/or non-parallel structure of paths for insulating gas flowing through the static mixer, thereby at least partially rearranging the insulating gas and providing a mixing effect.
The invention realizes that the hot insulating gas coming from the arcing zone can be cooled down rapidly, firstly by being mixed with colder insulating gas in the gas mixing structure and secondly by heat transfer to the gas mixing structure. The invention is based on the idea that hot insulating gas is not merely guided along a substantially straight or elongated path towards the outlet, but rather guided along an intricate structure of paths or labyrinth inside the static mixer with passages that substantially provide mixing to the gas flow and/or partial rearrangement thereof.
The invention not only realizes a mixing of hot insulating gas with other hot insulating gas, but particularly realizes a mixing of hot insulating gas with cold insulating gas. Flows of hot and cold insulating gas that particularly run in parallel can be mixed in the static mixer. For example, flows a flow of hot insulating gas in a middle of the exhaust originating from the arcing zone may be cooled down by being mixed with a flow of cold insulating gas in a circumferential area, e.g. closer to a surface or wall of the exhaust. The cold insulating gas may have rested in the circuit-breaker before the operation of the circuit-breaker or may be drawn with the flow of hot insulating gas, particularly surrounding the hot insulating gas. The invention provides that higher volume flows of cold insulating gas can be mixed with relatively lower volume flows of hot insulating gas. A potentially bigger volume of colder gas can be mixed with a potentially smaller volume of hot gas. Thereby, the average temperature of the insulating gas leaving the outlet can be reduced by means of the present invention.
The static mixer is, particularly the paths or gas passages are, configured to promote secondary transverse flows of insulating gas that enhance the transfer of mass and hear in the cross-section, e.g. transverse to a main flow direction of insulating gas.
The invention is based on the idea that in the circuit-breaker, typically, a high-energy gas (e.g. with high pressure and/or temperature) can be blown onto the arc between the at least two contacts (e.g. arcing contacts), or 'the contacts' or 'the two contacts' for short, that develops between the contacts as soon as the contacts are separated when operating the circuit-breaker. Hot gas may dominantly be generated by the evaporation of a part of the circuit-breaker, e.g. a nozzle surrounding the arcing zone that typically separates the arcing contacts in an insulating manner. During contact separation, a part of the gas may fill an upstream volume, where it builds up at high pressure, and typically at least a part of the gas flows downstream towards the at least one exhaust, wherein the invention has found that there it can undermine the dielectric recovery performance of the circuit-breaker. This can result in electric discharges between the contacts and optionally in the case of a metal enclosed circuit-breaker in flashovers to the metal tank. The hot gas coming from the arcing zone may reduce the dielectric strength in the at least one exhaust, e.g. adjacent to the tank and/or to the contacts, due to high temperature and maybe also due to carrying metal particles. The invention provides advancement with respects to reducing temperature of the gas and possibly to reducing the number of particles in the gas.
The invention can provide a delay of the output of hot gas from the at least one exhaust. The arrival of the gas in a fluid volume delimited by the interrupter of the circuit-breaker and the containing tank or enclosure of the circuit-breaker is particularly delayed. The temperature of hot gas leaving the at least one exhaust can be reduced. Further, a minimization of dust content in the insulating gas leaving the at least one exhaust can occur.
Particularly, the present invention provides that insulating gas can be reduced in temperature quickly without a complex reconstruction of the circuit-breaker, but rather with a solution by means of implementing a device in the exhaust.
The present invention furthermore provides that solid particles or dust from hot gas can be separated in the gas mixing structure due to inertial forces applied to the flow through the oblique passages. The gas mixing structure may act as a particle filter.
The invention significantly reduces the occurrence of dielectric breakdowns, e.g. towards the enclosure of metal enclosed circuit-breakers, particularly high-voltage circuit-breakers (HVCBs). This is achieved by a large reduction in the temperature of the gas exiting the interrupter as well as the reduction of dust carried by such gas. The decrease in temperature and dust content markedly improves the overall dielectric strength of the circuit breaker.
By means of the invention and by means of aspects described in the present application, an enhanced circuit-breaker can provided that can be produced/manufactured more easily. It may be possible to reduce parts in size due to the gas mixing structure reducing temperature in a small space relative to using no gas mixing structure. The effects and advantages named herein may be improved further by adoption of preferred features or a combination thereof.
The circuit-breaker is preferably configured for medium and/or high voltage switching applications. The circuit-breaker may be used to interrupt the nominal current and the current caused by an electrical fault. The circuit-breaker may have to be capable of carrying high nominal currents of 3000 A to 6300 A and switching very high short-circuit currents of 31.5 kA to 80 kA at high voltages of 72.5 kV, particularly up to 1200 kV. The term medium voltage may refer to a voltage from 1 kV to 72.5 kV, and the term high voltage to a voltage greater than 72.5 kV. The term high voltage means preferably a voltage above 12 kV or 36 kV or 72 kV or 1100 kV. A high voltage preferably relates to nominal voltages in the range from above 12 kV, 36 kV or 72 kV to 550 kV or 1100 kV, like 145 kV, 245 kV or 420 kV, or more. The term medium voltage means preferably a voltage above 1 kV or 12 kV or 36 kV. A medium voltage preferably relates to nominal voltages in the range from above 1 kV, 12 kV or 36 kV to 72 kV, like 5 kV, 10 kV, 25 kV or 70 kV.
High or medium voltage devices and/or switchgear, particularly circuit-breakers, are essential for the protection of technical equipment, especially in the medium or high voltage ranges. For example, circuit-breakers are predominantly used for interrupting a current, when an electrical fault occurs. As an example, circuit-breakers have the task of opening arcing contacts, quench an arc, and keeping the arcing contacts apart from each other in order to avoid a current flow even in case of high electrical potential originating from the electrical fault itself. The circuit-breaker may be configured as a puffer-type circuit breaker, a self-blast circuit breaker, or a combined puffer-type and self-blast circuit breaker.
The circuit-breaker may have two contacts or more than two contacts, i.e. at least two contacts. For readability, the phrase 'at least' is mostly omitted, although it is typically referred to 'the at least two contacts' when discussing 'the contacts'.
One or two of the contacts, particularly arcing contacts, of the circuit-breaker is/are arranged movable, especially movable along a switching axis. The contacts referred to herein may be arcing contacts. The circuit-breaker may as well have corresponding nominal contacts. The contact or contacts may extend along the switching axis at least in part. One contact can be fixed relative to the housing, but can also be arranged movable along the switching axis. The contact(s) typically can assume a closed position meaning an electrical connection is connected or established and an open position meaning that an electrical connection is interrupted or disconnected. Typically, at least one of the contacts is movable along the switching axis between the closed position and the open position. For example, operating the circuit breaker, especially interrupting, means that the contacts are moved out of the closed position quickly into the open position.
The circuit-breaker may have a tank, enclosure and/or housing that is preferably provided gas-tight and/or comprises a tube-like or cylinder like form extending along the switching axis. The circuit-breaker may be a metal-enclosed and/or three-pole circuit-breaker, particularly a high-voltage one (HVCB). A drive device may be provided that is motorized and/or provided outside of the housing. The drive device may be configured to move one or both of the contacts. In such implementation the drive device can be connected to one contact e.g. via a pull rod.
When the circuit-breaker is operated an arc can be formed in the arcing zone. The arc heats up its surrounding, e.g. the insulating gas and the contacts, among other parts of the circuit-breaker like a nozzle. This leads to an expansion of the gas in the vicinity of the arcing zone and thereby an automatic movement of gas away from the arcing zone into the exhaust and preferably at least at some point to the outlet, wherein during operation gas may as well be pushed mechanically through the circuit-breaker and/or away from the arcing zone into the exhaust and preferably at least at some point to the outlet. The circuit-breaker may have a gas compression device in order to mechanically move insulating gas inside the circuit-breaker, e.g. configured to be actuated during operation of the circuit-breaker. During operation, the insulating gas passing or flowing through the exhaust may be a mixture of hot gas originating from the arcing zone and cold gas originating from areas away from the arcing zone.
In other words, particularly, an arc is formed between the two contacts or between the at least two contacts, particularly arcing contacts, during the opening or closing process of the circuit-breaker. In order to interrupt the current, the circuit-breaker typically contains in a tank and/or enclosure insulating gas used as an insulating medium and/or dielectric medium (for example, SF6 gas or CO2 Gas or C4FN gas) and used to extinguish the arc. Thus, a portion of the insulating gas located in the region where the arc is generated, which is referred to as the arc extinguishing volume and/or arcing zone, is substantially heated over a very short period of time. This portion of the gas/fluid increases the pressure and may be injected from the arc extinguishing volume into a so-called exhaust volume of the at least one exhaust to be preferably at least at some let out at the outlet. Here, the invention may be applied in order to enhance the circuit-breaker's ability to cool down the insulating gas more quickly and/or within a smaller space.
The arcing zone or region is typically surrounded by an insulating nozzle. The nozzle typically also serves for guiding a stream of the insulation gas for extinguishing, or blowing off, the arc. Thereby, the insulation gas is typically guided by a dedicated passage in the nozzle, also called heating channel, which ends close to the arcing region. Thus, the insulation gas can be guided directly onto the developing arc to further be guided in a hot state towards the exhaust, to be mixed there with cold insulating gas, and be let out, e.g. into a tank or housing. In other words, particularly, hot insulating gas from the arcing zone may escape towards the exhaust or an exhaust volume therein, particularly provided at an end portion of the circuit-breaker. The insulating gas is then cooled by mixing with cold insulating gas and can be released through the outlet into a/the tank or enclosure of the circuit breaker.
Insulating gas is typically used in a circuit-breaker to insulate conductors from other components and/or to improve quenching of an arc when operating the circuit-breaker. In particular the insulating gas is used for extinguishing an arc generated in the arcing zone between the contacts when a current is interrupted and is thus also called arc extinguishing gas. Preferably, the insulating gas comprises SF6, CO2, O2, N2, C4FN and/or CF4, particularly mixtures thereof, and/or comprises an organic fluorine compound selected from the group consisting of fluoroethers (especially hydrofluoromonoethers), fluoroamines, fluororings Ethylene oxide, fluoroketone (especially perfluoroketone), fluoroolefin (especially hydrofluoroolefin), fluoronitrile (especially perfluoronitrile), and mixtures of the above compounds (especially in mixtures with background gases). The insulating gas and/or a dielectric insulation medium can be any suitable gas that enables to adequately extinguish the electric arc formed between contact elements during a current interruption operation, such as, but not limited, to an inert gas as, for example, sulphur hexafluoride SF6 or carbon dioxide CO2. The insulating gas may be based on CO2, i.e. may include CO2 and further gas components, such as SF6, CF4, O2, N2, and/or C4FN. Specifically, the insulating gas used can any dielectric insulation medium and/or insulating gas, may it be gaseous and/or liquid, and in particular can be a dielectric insulation gas or arc quenching gas. Such dielectric insulation medium and/or insulating gas can for example encompass media comprising an organofluorine compound, such organofluorine compound being selected from the group consisting of: a fluoroether, an oxirane, a fluoroamine, a fluoroketone, a fluoroolefin, a fluoronitrile, and mixtures and/or decomposition products thereof. The insulating gas and/or dielectric insulation medium can be selected from the group consisting of: a hydrofluoroether, a perfluoroketone, a hydrofluoroolefin, a perfluoronitrile, and mixtures thereof.
The circuit-breaker may have the at least one exhaust in fluid connection to the arcing zone. To be in fluid connection, the at least one exhaust may be arranged to receive insulating gas from the arcing zone, e.g. coupled thereto in terms of fluid transfer. The at least one exhaust includes an outlet for letting out insulating gas. The outlet may not be always open, for example may be open or closed as a function of the movement of the contact(s), particularly may be closed in the closed position and/or open in the open position. The outlet may comprise a hole or a plurality of holes, e.g. connecting an exhaust volume with a tank interior. There may be an exhaust arranged on one end portion of the circuit-breaker, e.g. on one axial side of one contact opposite the arcing zone. There may be two exhausts, e.g. one exhaust per contact. The at least one exhaust can receive the insulating gas originating from the arcing zone, and is particularly configured for guiding the insulating gas through the gas mixing structure, particularly through at least one static mixer thereof. The at least one exhaust is typically meant for handling and cooling down the flow of insulating gas present during operation of the circuit-breaker. Insulating gas may flow on one or both axial sides of the arcing zone into the at least one exhaust, particularly into the exhaust or the exhausts thereof.
The gas mixing structure is meant to include one or more static mixers. The gas mixing structure may be arranged in one exhaust or in more than one exhausts. The gas mixing structure relates to (all) the static mixer(s) included in the circuit-breaker or to the static mixers included in one exhaust.
The static mixer forms a plurality of paths, passages, or gas passages. The gas passages may be configured to extend from one side to another side of the static mixer, e.g. along a main flow direction between the arcing zone and the outlet, especially in the at least one exhaust. The plurality may comprise two or more gas passages, particularly five, ten, twenty or more gas passages. In principle, each gas passage or gas channel may be configured to redirect a part of a main flow of insulating gas away from the arcing zone. The gas passages may be provided as a plurality of tubes or rods of the static mixer which are obliquely arranged. The static mixer may be provided by fixing several components, such as rods, tubes, sheets or the like, to each other, e.g. each component providing one or more of the gas passages.
Particularly, the gas passage can be substantially and/or sectionally elongated. Thus, the gas passage can have length substantially larger than its width. The gas passage may be substantially and/or sectionally elongated along one direction, e.g. being two, four or eight or more times longer along one direction than the two directions perpendicular thereto.
The gas passages are at least sectionally and/or partially arranged oblique to each other. For example, two of the plurality of gas passages may direct gas into different directions so that a gas mixing effect can be achieved when gas passes said plurality and/or when it exits said plurality. The static mixer is particularly configured for mixing without moving components that provide a mixing effect, thus its name 'static'. The static mixer may comprise a tube or channel with a specific, particularly static or fixed, geometrical construction that can influence the flow structure in a manner to promote a transverse flow that enhances mass and heat transfer within the flow in the cross-section. The static mixer may be of an insert-type configuration, e.g. comprising a series of identical, stationary inserts, called elements, which can be installed in pipes, channels, or ducts, particularly in he at least one exhaust. The elements may form the gas passages. The purpose of the elements and/or passages may be to redistribute the fluid in directions oblique or perpendicular to the main flow, e.g. the radial and tangential directions. The static mixer may be configured to redistribute streamlines in a sequential fashion using mainly or only the pumping energy of the flowing fluid.
The gas mixing structure being installed in a gas flow path between the arcing zone and the outlet preferably relates to a static mixer of the gas mixing structure being fastened or fixed in the at least one exhaust and/or next to the at least one exhaust.
It may be that the static mixer comprises a series of fixed elements within a cylindrical tube or pipe. The fixed elements can be baffles or other shapes that can continuously divide and recombine gas passing through the static mixer. The fixed elements may serve to provide the gas passages. As the gas moves through the series of these fixed elements, it may be repeatedly split, expanded, compressed, and reoriented, promoting the mixing process of hot and cold gas.
It is preferred that the gas mixing structure, particularly the static mixer(s) or at least one static mixer thereof, is arranged to extend across an entire cross section of the at least one exhaust. The gas mixing structure may substantially occupy the at least one exhaust so that the insulating gas passing the at least one exhaust must pass and/or flow through the gas mixing structure, particularly the at least one static mixer thereof. This particularly is provided in order to have the insulating gas coming from the arcing zone be forced through the plurality of gas passages. This assures a mixing of the insulating gas to cool down more rapidly and with little to no bypasses.
The plurality of gas passages has (a) first gas passage(s) and (a) second gas passage(s). First gas passages may be substantially parallel to each other. Second gas passages may be substantially parallel to each other. Particularly, the first and the second gas passage(s) may be oblique to each other at least in sections and/or arranged at an angle with respect to each other. First and/or second gas passages may at least sectionally be straight and/or curved. Particularly, the first and the second gas passage(s) may intersect with each other, for example in one or more spots or sections along the length of the passages, for example laterally, e.g. to provide an exchange of gas between adjacent passages. The static mixer can thereby be configured for cross-current mixing, two-by-two division, and/or back mixing. In this way, a consistent mixing effect can be achieved throughout each static mixer which has been found advantageous in the circuit-breaker for a quick cooling down of insulating gas. The insulating gas may be thermally homogenized by the static mixer, e.g. in order to reduce peak temperature in the flow of gas.
The static mixer may comprise a series of stacked sheets, particularly metal sheets, forming the plurality of gas passages. Each stacked sheet may form first gas passages or second gas passages or both. The sheets are preferably made of bent and/or profiled metal. For example, the sheets can be made of aluminum or steel. The sheets may be rippled and/or grooved in order to form the plurality of gas passages. The sheets may have a repetitive form in a cross section. The sheets of the series of stacked sheets may be connected to each other. For example, adjacent sheets may be bonded and/or welded together. Such a configuration assures a long lifetime of the static mixer in that the quick variation in temperature during its use has insignificant effect on the structure.
The series of stacked sheets may have at least four, particularly eight or more, of the sheets. The more sheets are used the more passages can be formed and the mixing effect can be sized accordingly. Additionally, the passages can be formed more intricate to enhance the gas mixing effect.
The sheets preferably comprise a thickness or plate thickness of at least 0.5 mm, at least 1.0 mm or at least 2.0 mm or more. Alternatively or additionally, a/the thickness of the sheets may be up to 3.0 mm, up to 4.0 mm or up to 5 mm. Particularly, the thickness may be 2.25 mm ± 1.5 mm. The thickness may be at least substantially constant across the extension of the sheet. However, the thickness may be lower or higher in some areas, e.g. in areas of fixation of sheets with each other or with the at least one exhaust. The thickness may be considered as an average. The thickness may follow deformations of the sheet, for example if bent, profiled, ripped and/or grooved. In this way, the gas mixing effect can be adjusted efficiently.
The sheets may be stacked along a normal direction of the sheets with a spacing of at least 1 mm, at least 2.5 mm, at least 5 mm or at least 7.5 mm. Alternatively or additionally, a/the spacing of the stacked sheets may be up 5 mm, up to 7.5 mm, up to 10 mm, up to 12.5 mm or up to 15 mm. The spacing may be 8 mm ± 3 mm. Particularly, the spacing may be 7.7 mm ± 10 %. The spacing may be at least substantially constant across the extension of the stacked sheets. However, the spacing may be lower or higher in some areas, e.g. in areas of fixation. The spacing may be considered as an average. The spacing may be considered from lowest-to-lowest point or highest to highest point of two adjacent sheets. In this way, the gas mixing effect can be adjusted efficiently.
Particularly, the sheets each may comprise a shape that repeats itself with translational periodicity along a planar direction of the sheets in order to form the plurality of gas passages. The shape may be chevron-like. The chevron-like shape may have an increasing section, a top turn, a decreasing section and a bottom turn, the turns connecting two adjacent sections. The bottom turn may be connected to a next increasing section and the pattern may be repeated along the planar direction. Throughout the chevron-like shape the thickness may be substantially constant. The spacing may be considered from a bottom turn to the adjacent bottom turn of the adjacent sheet. The chevron-like shape may thus comprise a plurality of grooves.
The top turn and/or the bottom turn may be defined by a concave inside face having a radius of at least 0.5 mm and/or lower than 5 mm. The radius may be 1.5 mm ± 0.5 mm. The top turn and the bottom turn may have a similar or equal shape and arranged on opposite sides of the sheet. Two adjacent sheets may be connected via bottom turns and top turns facing towards each other. Two adjacent sheets may be in punctual contact via top and bottom turns touching each other multiply.
The sheets may comprise a camber defined by the distance between the bottom turn and the top turn in a/the normal direction of the sheets. The camber may be considered as a depth of grooves formed in the chevron-like shape. The sheets may be stacked such that the spacing is smaller, equal, or greater than the camber. Particularly, the camber equals the spacing so that the sheets are in contact with each other. Alternatively or additionally, the camber may be at least 1 mm, at least 2.5 mm, at least 5 mm or at least 7.5 mm. Alternatively or additionally, the camber may be up 5 mm, up to 7.5 mm, up to 10 mm, up to 12.5 mm or up to 15 mm. The camber may be 8 mm ± 3 mm. Particularly, the camber may be 7.7 mm ± 10 %. Particularly, the camber may be substantially the same as the spacing. Thus, passages can be formed which are effective in gas mixing.
The sheets may comprise a bend angle between the increasing section and the planar direction. The sheets may comprise a/the bend angle between the decreasing section and the planar direction. The bend angle may be greater than 0°, greater than 5°, greater than 10°, greater than 20° or greater than 30°. The bend angle may be lower than 90°, lower than 85°, lower than 70°, lower than 50° or lower than 40°. Particularly, the bend angle may be 35° ± 15°. In this way, a plurality of sheets can be arranged in a small space to form a large number of passages.
The sheets may be stacked along a/the normal direction of the sheets with at least one sheet oriented relative to an adjacent sheet by an angle about the normal direction being between 0° and 90° for passages of the plurality of gas passages to be oblique relative to each other. The angle may be greater than 0°, greater than 5°, greater than 10°, greater than 20° or greater than 30°. The angle may be lower than 90°, lower than 85°, lower than 70°, lower than 50° or lower than 40°. Particularly, the angle may be 35° ± 15°. Thus, passages can be formed which are effective in gas mixing.
The static mixer may have a form including a substantially cylindrical shape with a mean diameter of at least 20 mm, at least 50 mm, at least 75 mm or at least 100 mm. A/the mean diameter of the static mixer may be up to 75 mm, up to 100 mm, up to 200 mm, up to 300 mm or up to 500 mm. The static mixer may have a substantially oval shape with a mean diameter of at least 20 mm and/or up to 500 mm. The static mixer may have a substantially triangular, rectangular, or square shape. Particularly the shape of the static mixer may correspond to a surface, particularly an inner and/or concave surface, of the at least one exhaust. The at least one exhaust may comprise a mean diameter as named above. The mean diameter of the at least one exhaust and/or of the static mixer may be 132 mm ± 30 mm.
The form of the static mixer may have a length of at least 10 mm, at least 20 mm, or at least 100 mm. A/the length of the form of the static mixer may up to 50 mm, up to 100 mm or up to 150 mm. Particularly, the length may be 40 mm ± 10 %. The length may be considered along a/the switching axis of the circuit-breaker and/or along the extension of the at least one exhaust. A ratio between the length and the mean diameter may be at least 0.05 and/or up to 3.
The gas mixing structure may comprise two, three or more of the static mixer configured to be arranged adjacent to each other in an exhaust chamber of the circuit-breaker, particularly of the at least one exhaust, either at a distance to each other or in contact to each other. The static mixers may be connected to each other to form a structural unit, e.g. to be fixed relative to each other. Also, in order to enhance lifetime, the static mixer may be configured as a structural unit, e.g. with an inner structure that holds the static mixer itself and/or all the gas passages together.
The static mixers, e.g. the two or more of the static mixer, may be configured to be oriented substantially parallel to each other, especially by an angle about a/the switching axis and/or the extension of the at least one exhaust of greater than 0° and/or lower than 180°. The angle may be 90° ± 15°. Preferably, the angle is measured between the planes defined by the stacked sheets of the corresponding static mixers, which preferably extend along the planar direction. In other words, particularly, static mixers may be put next to each other and rotated relative to each other somewhat to be rotated differently. In this way, the gas mixing effect is enhanced. The effect may be improved by arranging the static mixers at a distance to each other, the distance being above 0 mm and/or below 100 mm, especially being above 2 mm and/or below 50 mm.
Further, the objects are solved by means of a use of a gas mixing structure, e.g. that one describe herein, including a static mixer forming a plurality of gas passages arranged oblique to each other and configured for mixing insulating gas, wherein the gas mixing structure is used for mixing the insulating gas in the circuit-breaker in a gas flow path between the arcing zone and an outlet of at least one exhaust of the circuit-breaker.
The term 'or' may be replaced by 'and/or' throughout the present disclosure. As such, where 'or' is used, it is not necessarily meant that merely alternatives are named.

Brief description of drawings

These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.
In the drawings:

Fig. 1 shows a circuit-breaker in a schematic view;
Fig. 2 shows a further circuit-breaker in a schematic view;
Fig. 3 shows a static mixer in a schematic view with respect to flow of insulating gas passing gas passages of the static mixer;
Fig. 4 shows a gas mixing structure for a circuit-breaker in a perspective view;
Fig. 5 shows the gas mixing structure of Fig. 4 in a front view;
Fig. 6 shows sheets for forming the gas mixing structure of Fig. 4 in a top view; and
Fig. 7 shows the arrangement of two sheets for forming a gas mixing structure in a front view.

Description of implementations

The description contains procedural or methodical aspects upon describing structural features of the invention; the structural features can be understood well in that way. It is emphasized to the reader that such structural features can be lifted from the described context without hesitation or the question of an intermediate generalization to form aspects of the invention. It is also emphasized to the reader that any the structural features described in the following can be understood as individual aspects of the invention to distinguish from known solutions, despite being possibly lifted from the context.
Fig. 1 shows a medium voltage circuit-breaker 1 with a gas compression device 2 and comprising two contacts 3, 4 with the contact 4 movable along a switching axis 10 and with an arcing zone 5 between the two contacts 3, 4 in which an arc can form during operation. The circuit-breaker 1 contains insulating gas, e.g. a gas including at least C4FN. The arcing zone 5 is restricted by a nozzle 7 configured to surround the contact 4 and the arc and to guide the insulating gas. The circuit-breaker 1 has on the side of the contact 3 an exhaust 8 with an outlet 12 and on the side of the contact 4 an exhaust 9 with an outlet 12, both of which exhausts 8 and 9 are configured to be in fluid connection to the arcing zone 5 and have their outlets 12 for letting out insulating gas out of an exhaust volume 8.1 or 9.1, respectively, into an enclosure (not shown).
In the exhaust 9 there is a gas mixing structure 20 installed, which gas mixing structure 20 is arranged in a gas flow path between the arcing zone 5 and the outlet 12, especially on the side of the contact 4 that is a pin contact and/or that is movable.
The gas mixing structure 20 includes a static mixer 40 forming a plurality of gas passages 41, 42 arranged oblique to each other and configured for mixing the insulating gas passing and/or flowing through the plurality of gas passages 41, 42. Heated or hot insulating gas that originates from the arcing zone 5 automatically passes the static mixer 40 that extends across an entire cross section of the exhaust 9, namely along an inside surface 11 of the exhaust 9, in order to have said gas be forced through the plurality of gas passages 41, 42.
Fig. 2 shows a high voltage circuit-breaker 1 with a gas compression device 2 and comprising two contacts 3, 4 with one or both of the contacts 3, 4 movable along a switching axis 10 and with an arcing zone 5 between the two contacts 3, 4 in which an arc can form during operation. It is shown that an arc is present, wherein the circuit-breaker is being operated and insulating gas is actively moving away from the arcing zone 5. The contacts 3 and 4 are arcing contacts. The circuit-breaker 1 has further contacts 3.1 and 4.1 besides the two contacts 3 and 4. The contacts 3.1 and 4.1 are provided which are nominal contacts.
The circuit-breaker 1 contains insulating gas, e.g. a gas including at least CO2. The arcing zone 5 is restricted by a nozzle 7 configured for ablation by means of an arc, configured to surround the contact 4 and the arc and to guide the insulating gas. The circuit-breaker 1 has on the side of the contact 3 an exhaust 8 with an outlet 12 and on the side of the contact 4 an exhaust 9 with an outlet 12, both of which exhausts 8 and 9 are configured to be in fluid connection to the arcing zone 5 and have their outlets 12 for letting out insulating gas out of an exhaust volume 8.1 or 9.1, respectively, into an enclosure 13 made of metal.
In both exhausts 8 and 9 there is a gas mixing structure 20 installed, which gas mixing structure 20 is arranged in a gas flow path between the arcing zone 5 and the outlet 12. Each gas mixing structure 20 includes one static mixer 40 forming a plurality of gas passages 41, 42 arranged oblique to each other and configured for mixing the insulating gas passing and/or flowing through the plurality of gas passages 41, 42. Thus, heated or hot insulating gas that originates from the arcing zone 5 automatically passes in both exhausts 8 and 9 or on both sides of the arcing zone 5 a static mixer 40 that extends across the exhaust 8 or 9 on a corresponding inside surface 11 of the exhaust 8 or 9, in order to have said gas be forced through the plurality of gas passages 41, 42.
In both Fig. 1 and Fig. 2, for example, the static mixers 40 comprise a series of stacked metal sheets that extend along a planar direction Z, which planar direction is substantially parallel to the switching axis 10. Arrows running in the respective circuit-breaker 1 indicate the path insulating gas assumes on its way away from the arcing zone 5.
Fig. 3 illustrates the function of a static mixer 40 through which gas can pass. Fig. 3 shows a flow of insulating gas in a duct flowing from the left to the right into the static mixer 40 arranged in the duct, particularly wherein the static mixer 40 extends in the duct along the length H and transversely thereto across the entire cross section of the duct with the diameter or width reference with D. The static mixer 40 has a plurality of gas passages 41, 42 which are elongated along the length H, in this case not in parallel to the length but obliquely thereto. The duct may be an exhaust. The flow of insulating gas before entering the static mixer 40 comprises different temperature levels across its cross section in the duct. Here, a core section of the flow is hotter than the surrounding section of the core, which is indicated by the arrows surrounding the arrows implying the core section being dotted. The core section may originate from the arcing zone and the surrounding section may be gas originally resting inside the duct or exhaust. Upon entering the static mixer 40, each individual arrow or flow gets redirected, depending on which passage 41 or 42 is being entered. The passages 41 go in one direction (in this case downwards) and the passages 42 go in a different, oblique direction (in this case upwards). Particularly, the passages 41 and 42 intersect with each other laterally at multiple spots along the length H, thereby causing all sections of the flow to be mixed with each other, so that a flow is acquired that is reduced in maximum temperature. Thus, a cross-current mixing can be achieved. The (first) gas passages 41 are substantially parallel to each other and the (second) gas passages 42 are substantially parallel to each other. Here, the first 41 and the second 42 gas passages are oblique to each other. Further, particles may be filtered by the static mixer 40. Instead of primarily creating turbulence, flow streams are created, pushed from bottom to top and vice versa, thereby mixing the flow transversely.
Fig. 4 shows a gas mixing structure 20 comprising two static mixers 40 forming a plurality of gas passages 41, 42 arranged oblique to each other and configured for mixing insulating gas passing the plurality of gas passages 41, 42. The two static mixers 40 are substantially identical or similar in shape and/or components. A length H of the static mixers 40 is 40 mm.
Fig .5 shows one of the static mixers 40 of Fig. 4 in a frontal view. The gas mixing structure 20 configured to extend across an entire cross section of the at least one exhaust 8, 9 of a circuit-breaker in order to have insulating gas coming from an arcing zone be forced through the plurality of gas passages 41, 42. The plurality of gas passages 41, 42 has first gas passages 41 parallel to each other and second gas passages 42 parallel to each other, with the first 41 and the second 42 gas passages being oblique to each other, wherein the first and the second gas passages intersect with each other laterally in at least one spot along their extension.
With reference to Fig. 4 and Fig. 5, each static mixer 40 comprises a series of stacked metal sheets 44 forming a plurality of gas passages 41, 42, each stacked metal sheet 44 forming first 41 or second 42 gas passages, wherein the sheets 44 are made of bent metal. In each static mixer 40, adjacent sheets 44 are bonded and/or welded together. Adjacent sheets 44 lay directly atop each other with punctual contacts. The sheets 44 comprise a thickness of 1.7 mm. The sheets 44 are stacked along a normal direction Y of the sheets 44 with a spacing h 7.7 mm.
Each sheet 44 comprises a shape that repeats itself with translational periodicity along a planar direction X, Z of the sheets 44 in order to form the plurality of gas passages 41, 42. The shape is chevron-like. The static mixers 40 have a substantially cylindrical shape with a mean diameter D of 132 mm, cf. Fig. 5. The ratio between a length H of a static mixer 40 and the mean diameter D is at least 0.05 and up to 3.
The two static mixers 40 are oriented substantially parallel to each other and rotated by an angle θ about a switching axis 10 and the planar axis 10 of between 0° and 180°, wherein the angle θ is measured between the planes defined by the stacked sheets 44 of the corresponding static mixers 40. Here, the angle θ is 90°.
Fig. 6 shows two sheets 44 used for forming or manufacturing a static mixer, for example that one of Fig. 4 and 5. It is illustrated how two adjacent sheets 44 can be arranged to provide the plurality of gas passages 41, 42 being oblique to each other. The sheets 44 are stacked along the normal direction Y of the sheets 44 with one sheet 44 oriented relative to the adjacent sheet 44 by an angle β about the normal direction Y for passages 41, 42 of the plurality of gas passages 41, 42 to be oblique relative to each other. Here, the angle β is 35° ± 15°.
Fig. 7 shows two adjacent sheets 44 in a sectional view which can be used for forming or manufacturing a static mixer, for example that one of Fig. 4 and 5. The sheets 44 comprise a thickness s of 2.25 mm ± 1.5 mm, e.g. 1.7 mm. The sheets 44 are stacked along a normal direction Y of the sheets 44 with a spacing h. The sheets 44 each comprise a shape that repeats itself with translational periodicity along a planar direction X of the sheets 44 in order to form a plurality of gas passages 41, 42, the shape being chevron-like with an increasing section 51, a top turn 52 a decreasing section 53 and a bottom turn 54, the turns 51, 52 connecting two adjacent sections 51, 53. The top turn 52 and the bottom turn 54 are defined by a concave inside face having a radius R of 1.5 mm. The sheets 44 comprise a camber b defined by the distance between the bottom turn 54 and the top turn 52 in the normal direction Y of the sheets 44, wherein the sheets 44 are stacked such that the spacing h is greater the camber b. Here, the camber b is 7.7 mm wherein the spacing h is more.
The sheets 44 comprise a bend angle α between the increasing section and the planar direction X. Here, the bend angle α is 35°.
Other relevant dimensions depicted in Fig. 7 are c, d and L. Particularly, they are dependent from the dimensions thickness s, bend angle α, camber b and radius R through the following relationships: $R = (c + R) \cos (α),$ $b = d + R, and/or$ $b + 2 c = L \tan (α) .$
With reference to Fig. 5, the sheets 44 are arranged with a spacing h along the normal direction Y or y-axis between them. With reference to Fig. 6, The sheets 44 are stacked, with each oriented relative to the adjacent layer by the angle β about the normal direction. The spacing h of the layers should be such that h > b or h = b. However, arrangements with h < b leading to material interpenetration and/or intersection of gas passages 41, 42 along their respective extensions are also to an option (not shown). The angle β or relative layer angle is the parameter which controls the pressure losses across the static mixer, particularly across the gas passages 41, 42.
The static mixers 40 of Fig. 4 and Fig. 5 are possibly implemented in a cylindrical-like exhaust volume having the mean diameter D. The number N of metal sheets in a static mixer 40 is preferably linked to the diameter of the corresponding exhaust. The spacing h and the thickness s may follow the relationship D = N (h+s).
The ratio of length H and diameter D, namely H/D, influences the mixing performance of a static mixer 40. A good gas mixing effect, particularly with a good efficiency, may possibly be achieved by placing a pair of static mixers 40 one after another with no gap between them. However, designs with static mixers 40 that are non in contact with each other, as in Fig. 4, are also possible.
As shown in Fig. 4, two static mixers 40 can be arranged with the relative angle θ around the planar direction Z or z-axis in order to enhance the gas mixing effect.
Upon development and physical validation of the design of sheets 44 for a static mixer 40 as shown in Figs. 4 to 7, the following individual ranges have been established as promising for enhancing the technical effects and advantages described herein. The ranges may be applied individually or in combination with each other.

The thickness s may be between 0.5-5 mm, for example 1.7 mm ± 10 %.
The bend angle α may be between 5° and 85°, for example 35° ± 10 %.
The camber b to thickness s ratio b/s may be between 0.1-150.
The radius R to thickness s ratio R/s may be between 0.1-150.
The spacing h to thickness s ratio h/s may be between 0.1-150.
The bend angle β may be between 5° and 85°, for example 35° ± 10 %.
The length H to diameter D ratio H/D may be between 0.05-3.
The diameter D of the at least one exhaust and/or the static mixer may be between 5 and 350 mm, for example 132 mm ± 10 %.
The angle θ between two consecutive mixing elements may be between 5° and 85° or may be 90° ± 10 %.
The number of static mixers in series, particularly within one exhaust, may be between 1 and 4, for example may be 2.

Shown and described, cf. Fig. 1 or 2, is a use of a gas mixing structure 20 including a static mixer 40 forming a plurality of gas passages 41, 42 arranged oblique to each other and configured for mixing insulating gas, wherein the gas mixing structure 20 is used for mixing the insulating gas in the circuit-breaker 1 in a gas flow path between an arcing zone 5 and an outlet 12 of at least one exhaust 8, 9 of the circuit-breaker 1.

Reference signs list

1: circuit-breaker
2: gas compression device
3: contact
3.1: contact
4: contact
4.1: contact
5: arcing zone
7: nozzle
8: exhaust
8.1: exhaust volume
9: exhaust
9.1: exhaust volume
10: switching axis
11: surface
12: outlet
13: enclosure

20: gas mixing structure
40: static mixer
41: gas passage
42: gas passage
44: sheet

51: increasing section
52: top turn
53: decreasing section
54: bottom turn

b: camber (sheet)
D: diameter (static mixer)
h: spacing (sheets)
H: length (static mixer)
R: radius (sheet)
s: thickness (sheet)

α: angle
β: angle
θ: angle

X: planar direction
Y: normal direction
Z: planar direction

Claims

Circuit-breaker (1), comprising
at least two contacts (3, 3.1, 4, 4.1) with at least one of the at least two contacts (3, 3.1, 4, 4.1) movable and with an arcing zone (5) between the at least two contacts (3, 3.1, 4, 4.1);

at least one exhaust (8, 9) in fluid connection to the arcing zone (5) and including an outlet (12) for letting out insulating gas; and

a gas mixing structure (20) installed in a gas flow path between the arcing zone (5) and the outlet (12); wherein

the gas mixing structure (20) includes a static mixer (40) forming a plurality of gas passages (41, 42) at least sectionally and/or partially arranged oblique to each other and configured for mixing the insulating gas passing the plurality of gas passages (41, 42).
Circuit-breaker (1) according to the preceding claim, wherein
the gas mixing structure (20) is arranged to extend across an entire cross section of the at least one exhaust (8, 9) in order to have the insulating gas coming from the arcing zone (5) be forced through the plurality of gas passages (41, 42).
Circuit-breaker (1) according to any one the preceding claims, wherein
the plurality of gas passages (41, 42) has first gas passages (41) substantially parallel to each other and second gas passages (42) substantially parallel to each other, with the first (41) and the second (42) gas passages being oblique to each other, wherein the first and the second gas passages intersect with each other.
Circuit-breaker (1) according to any one the preceding claims, the static mixer (40) comprising a series of stacked metal sheets (44) forming the plurality of gas passages (41, 42), particularly each stacked metal sheet (44) forming first (41) or second (42) gas passages, wherein the sheets (44) are made of bent and/or profiled metal.
Circuit-breaker (1) according to the preceding claim, wherein adjacent sheets (44) are bonded and/or welded together.
Circuit-breaker (1) according to any one of the preceding two claims, wherein the series has at least four, particularly eight or more, of the sheets (44).
Circuit-breaker (1) according to any one of the preceding three claims, wherein the sheets (44) comprise a thickness (s) of at least 0.5 mm and/or of up to 5 mm, particularly the thickness (s) of 2.25 mm ± 1.5 mm.
Circuit-breaker (1) according to any one of the preceding four claims, wherein the sheets (44) are stacked along a normal direction (Y) of the sheets (44) with a spacing (h) of at least 1 mm and/or of up to 15 mm, particularly with the spacing (h) of 8 mm ± 3 mm.
Circuit-breaker (1) according to any one of the preceding five claims, wherein the sheets (44) each comprise a shape that repeats itself with translational periodicity along a planar direction (X, Z) of the sheets (44) in order to form the plurality of gas passages (41, 42), particularly the shape being chevron-like with an increasing section (51), a top turn (52) a decreasing section (53) and a bottom turn (54), the turns (51, 52) connecting two adjacent sections (51, 53).
Circuit-breaker (1) according to the preceding claim, the top turn (52) and/or the bottom turn (54) being defined by a concave inside face having a radius (R) of at least 0.5 mm and/or lower than 5 mm, particularly being 1.5 mm ± 0.5 mm.
Circuit-breaker (1) according to any one of the preceding two claims, wherein the sheets (44) comprise a camber (b) defined by the distance between the bottom turn (54) and the top turn (52) in a/the normal direction (Y) of the sheets (44), particularly wherein the sheets (44) are stacked such that the spacing (h) is smaller, equal or greater than the camber (b).
Circuit-breaker (1) according to the preceding claim, wherein the sheets (44) comprise a bend angle (α) between the increasing section and the planar direction (X, Z), the bend angle (α) being greater than 0° and/or lower than 90°, particularly at least 5° and/or up to 85°, particularly being 35° ± 15°.
Circuit-breaker (1) according to any one of the preceding two claims, wherein the sheets (44) are stacked along a/the normal direction (Y) of the sheets (44) with at least one sheet (44) oriented relative to an adjacent sheet (44) by an angle (β) about the normal direction (Y) being between 0° and 90° for passages of the plurality of gas passages (41, 42) to be oblique relative to each other, particularly the angle (β) being at least 5° and/or up to 85°, particularly the angle (β) being 35° ± 15°.
Circuit-breaker (1) according to any one of the preceding claims, wherein the static mixer (40) has a form including
a substantially cylindrical shape with a mean diameter (D) of at least 20 mm and/or up to 500 mm, or a substantially oval shape with a mean diameter (D) of at least 20 mm and/or up to 500 mm, or a substantially triangular, rectangular or square shape, the shape corresponding to a surface (11) of the at least one exhaust (8, 9).
Circuit-breaker (1) according to the preceding claim, wherein the form of the static mixer (40) includes
a length (H) of at least 10 mm and/or up to 150 mm along a switching axis (10), particularly wherein a ratio between the length (H) and the mean diameter (D) is at least 0.05 and/or up to 3.
Circuit-breaker (1) according to any one of the preceding claims, comprising two, three or more of the static mixer (40) configured to be arranged adjacent to each other in an exhaust chamber of the circuit-breaker (1), either at a distance to each other or in contact to each other, particularly the static mixers (40) being connected to each other to form a structural unit.
Circuit-breaker (1) according to the preceding claim, wherein the two or more of the static mixer (40) are configured to be oriented substantially parallel to each other and by an angle (θ) about a/the switching axis (10) of greater than 0° and/or lower than 180°, particularly being 90° ± 15°, wherein the angle (θ) is measured between the planes defined by the stacked sheets (44) of the corresponding static mixers (40).
Use of a gas mixing structure (20) including a static mixer (40) forming a plurality of gas passages (41, 42) arranged oblique to each other and configured for mixing insulating gas, wherein the gas mixing structure (20) is used for mixing the insulating gas in the circuit-breaker (1) in a gas flow path between the arcing zone (5) and an outlet (12) of at least one exhaust (8, 9) of the circuit breaker (1).