EP4738416A1

EP4738416A1 - Circuit-breaker

Info

Publication number: EP4738416A1
Application number: EP24210281.2A
Authority: EP
Inventors: Patrick Stoller; Arthouros Iordanidis; Martin Seeger; Bernardo Galletti; Mahesh DHOTRE
Original assignee: Hitachi Energy Ltd
Current assignee: Hitachi Energy Ltd
Priority date: 2024-10-31
Filing date: 2024-10-31
Publication date: 2026-05-06

Abstract

The invention relates to a circuit-breaker (1), comprising
a gas compression arrangement (4) configured for compressing a quenching gas to be contained therein and which quenching gas is free of sulphur hexafluoride;
a first contact (20) and a second contact (30) movable relative to one another along a switching axis (2);
a nozzle (40) providing an inflow channel (IN) connecting the gas compression arrangement (4) to an arc zone (3), the inflow channel (IN) constituting a minimal inflow area to be passed by the quenching gas, the nozzle (40) radially restricting the arc zone (3) between the first contact (20) and the second contact (30);
wherein, for the quenching gas to exit the arc zone (3), the circuit-breaker (1) provides at least one outlet (OUT1, OUT2) constituting a minimal outflow area, and
the minimal inflow area divided by the minimal outflow area defines an inflow-outflow-ratio being at least 0.5.

Description

Technical Field

The invention relates to a circuit-breaker with an inflow channel connecting a gas compression arrangement with an arc zone, the inflow channel to be passed by quenching gas, and with at least one outlet for the quenching gas to exit the arc zone.

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, such as quenching gas or insulating gas, in the circuit-breaker, which then can be guided away from the contacts and from an arc zone. There is a continuous demand to optimize the flow of quenching gas through the circuit-breaker, especially in light of compatibility with different types of quenching gas. Particularly, it is a problem to provide continuous enhancement with regard to lifetime and wear, particularly of parts in direct contact with the quenching 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 invention is defined 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 gas-insulated circuit-breaker comprising

a gas compression arrangement, e.g. a gas compression device, configured for compressing a quenching gas to be contained therein, wherein the quenching gas is at least substantially free of sulphur hexafluoride or SF6 and/or does not contain sulphur hexafluoride;
a first contact and a second contact movable relative to one another along a switching axis; and
a nozzle providing an inflow channel connecting the gas compression arrangement, e.g. indirectly or directly, with/to an arc zone, the inflow channel constituting a minimal inflow area to be passed by the quenching gas, the nozzle radially restricting the arc zone between the first contact and the second contact;
wherein, for the quenching gas to exit the arc zone, the circuit-breaker provides at least one outlet constituting a minimal outflow area, and
wherein the minimal inflow area divided by the minimal outflow area defines an inflow-outflow-ratio, the inflow-outflow-ratio being at least 0.5.

In other words, particularly, an SF6-free breaker is suggested in which an inflow cross section area divided by an outflow cross section area is chosen to exhibit a minimal threshold value, said areas respectively representing narrowest sections for the quenching gas to flow through. Taking into account that the inflow typically comes as compressed gas from a localized path/channel and that the outflow may be directed along one or more paths/channels (e.g. passing both contacts on opposite sides), it is particularly considered that all paths are respected in this ratio.
The invention realizes that an enhanced interruption performance can be provided that makes efficient use of quenching gas. Particularly, the circuit-breaker can be used with various sorts of quenching gases, particularly those quenching gases containing less sulphur hexafluoride (SF6) and/or those quenching gases having a lower GWP than SF6. It is also possible that a higher maximum short-circuit current can be realized with quenching gases different from SF gases, e.g. using a quenching gas with CO2 gas. At least substantially free of sulphur hexafluoride particularly means that the volume, mass or molar content of SF6 in the quenching gas is below 1 % or below 0.1 % or below 0.01 % or lower, particularly is zero.
The effects and advantages named herein may be improved further by adoption of preferred features or a combination thereof. The features named in the implementations may be individually combined with each other or considered alone.
It is noted that same names for features are meant to stand for same features as mentioned in the claims and throughout the description. This is particularly mentioned with respect to some features being referred to with indefinite articles despite having possibly being introduced in a preceding section. Accordingly, with matching feature names in cases with for example two or more indefinite articles of the feature names, the skilled person may adopt the corresponding description in each case.
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 first contact and the second contact (e.g. arcing contacts), or 'the 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. the nozzle surrounding the arc zone that typically separates the arcing contacts in an insulating manner. During contact separation, a part of the gas may fill an upstream volume, e.g. of the gas compression arrangement, where it builds up at high pressure, and typically at least a part or the majority or all of the gas flows downstream via the arc zone and, for example, towards an exhaust. A goal is to generate a high pressure difference that can sustain high-speed, ideally transonic, flows. High temperatures, especially above a certain temperature limit, are detrimental to the cooling effectiveness of the gas flow.
The 'inflow-outflow-ratio' may be understood as a nomenclature for a ratio. The term 'wherein the minimal inflow area divided by the minimal outflow area defines an inflow-outflow-ratio, the inflow-outflow-ratio being at least 0.5' may translate to 'wherein the minimal inflow area divided by the minimal outflow area is at least 0.5'
The invention is based on the idea that the narrowest cross section of (the) path(s) for the quenching gas to flow through after having passed the arc zone, should be in a certain relation to the narrowest cross section of (the) path(s) before reaching the arc zone. For example, the invention suggests by the inflow-outflow-ratio being at least 0.5 that an inflow cross section is at least half of the outflow cross section, particularly with the inflow being upstream and the outflow being downstream to the arc zone. The invention aims to provide a smooth flow of the quenching gas through the circuit breaker.
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, quenching 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 gas compression arrangement may be connected directly or indirectly to the inflow channel or the arc zone.
Especially in case of a self-blast circuit-breaker, an intermediate volume, e.g. heating volume, may be arranged between gas compression arrangement, e.g. compression volume, and inflow channel. The compression volume of a self-blast circuit-breaker is typically connected indirectly to the arc zone via the heating volume. The heating volume and the compression volume may be separated by a flap valve that opens to allow flow from the volume with higher pressure to the one with lower pressure.
Typically, in a puffer-type circuit-breaker, the inflow channel directly connects the gas compression arrangement, e.g. compression volume, to the inflow channel or the arc zone.
One or two of the contacts of the circuit-breaker is/are arranged movable, especially movable along a switching axis. The contacts referred to herein may particularly include 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 a housing of the circuit breaker, but can also be arranged movable along the switching axis, particularly relative to said housing. 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. In the closed position, one or both of the contacts can extend into the arc zone. 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 arc zone. The arc heats up its surrounding, e.g. the quenching gas, the nozzle and the contacts, among other parts of the circuit-breaker. This leads to an expansion of the gas in the vicinity of the arc zone and thereby an automatic movement of gas away from the arc zone or downstream, wherein during operation gas may as well be pushed mechanically through the circuit-breaker and/or away from the arc zone.
The circuit-breaker may have the gas compression arrangement in order to mechanically move quenching gas inside the circuit-breaker, e.g. configured to be actuated during operation of the circuit-breaker.
Typically, the first and/or second contact is or has an arcing contact. Additionally, a/the nominal contact may be provided. The arcing contacts are meant for withstanding arcs during opening or closing of the circuit-breaker and are typically arranged inside the nozzle. The nominal contacts are meant for nominal current conduction when the circuit-breaker is closed. The first and/or second contact, particularly the respective arcing contact, may be formed at least substantially cylindrical and/or round. A first nominal contact may be arranged radially outside the nozzle and/or the first arcing contact. The second contact particularly includes a second nominal contact corresponding to the first nominal contact. By way of nominal contacts, high electrical currents can be conducted. The main purpose of the nominal contacts may be to conduct the current normally flowing through the power grid, and thus the circuit-breaker, over long periods of time with minimal losses. The nominal contacts can conduct very high, e.g. short-circuit, electrical currents for a short period of time, e.g. less than ten or five seconds.
Particularly, an arc can be formed between the 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, housing and/or enclosure quenching gas used as an insulating medium and/or dielectric medium and used to extinguish the arc. Thus, a portion of the gas located in the region where the arc is generated, which is referred to as the arc extinguishing volume, arcing zone, arc zone, or arc region is substantially heated over a very short period of time.
The arc zone is typically surrounded by the nozzle or insulating nozzle. The nozzle typically also serves for guiding a stream of the quenching gas for extinguishing or blowing off the arc, especially via the inflow channel and/or via the at least one outlet. Particularly, the nozzle provides the inflow channel or heating channel. The nozzle may as well provide the at least one outlet or a section thereof. To reach the arc zone, the quenching gas is typically guided by a dedicated passage in the nozzle, which ends close to or into the arc zone. Thus, the quenching gas can be guided directly onto the developing arc to further be guided in a hot state towards the at least one outlet, to be mixed there with cold quenching gas, and be let out, e.g. again through the nozzle and/or through one or both of the contacts, e.g. into a tank or housing. Hot quenching gas from the arc zone may escape through the at least one outlet, e.g. two outlets, and thereafter towards or through an exhaust. The quenching gas can then be cooled by mixing with cold quenching gas and can be released through into a tank, housing or enclosure of the circuit breaker.
Quenching 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 quenching gas is used for extinguishing an arc generated in the arc zone between the contacts when a current is interrupted and is thus also called arc extinguishing gas. The quenching gas may comprise 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 quenching 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, carbon dioxide CO2. The quenching gas may be based on CO2, i.e. may include CO2 and further gas components, such as CF4, O2, N2, and/or C4FN. The quenching gas is at least substantially free of SF6 or does not contain it. Specifically, the quenching 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 quenching 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 quenching gas medium can be selected from the group consisting of: a hydrofluoroether, a perfluoroketone, a hydrofluoroolefin, a perfluoronitrile, and mixtures thereof.
The gas compression arrangement, particularly gas compression device, is configured for compressing a quenching gas to be contained therein. Particularly, the gas compression arrangement can compress the quenching gas in order to push the quenching gas through the inflow channel or heating channel. The compressed quenching gas can be blown out of the inflow channel, particularly directly, into the arc zone. For example, the gas compression arrangement may comprise a piston in a cylinder. The gas compression arrangement may comprise a heating volume or self-blast volume, particularly which is separated from a puffer volume by a flap valve. The gas compression arrangement itself is known in the art.
The nozzle is typically, at least sectionally or partially, and preferably at least in a section forming the inflow channel and/or in a section forming the arc zone, made of a polymer compound, especially a thermoplastic polymer compound, e.g. Polytetrafluoroethylene, PTFE for short. The nozzle may be formed at least substantially annular, particularly around the switching axis. The nozzle is typically configured for arc quenching and/or for guiding a fluid or a gas from or to the arc zone. Also, the nozzle is typically configured for surrounding an arc established between the contacts.
The nozzle provides the inflow channel, particularly at least partially or entirely. The inflow channel, particularly at least partially, connects the gas compression arrangement with or to the arc zone. The inflow channel can guide the compressed quenching gas from the gas compression arrangement to the arc zone. The inflow channel may extend sectionally along the switching axis and/or sectionally obliquely or perpendicularly to the switching axis. The inflow channel may be shaped substantially annular with respect to the switching axis.
Typically, the arc zone is arranged directly adjacent to the first contact preferably along the switching axis. The arc zone is typically configured for surrounding the second contact and/or the second contact can be inserted into the arc zone. For example, the arc zone surrounds the second contact upon closing or opening the circuit-breaker, especially with the second contact located inside the nozzle, especially inside an auxiliary nozzle and/or a main nozzle thereof.
The inflow channel constitutes the minimal inflow area to be passed by the quenching gas. There may be more than one inflow channel or parallel sections of the inflow channel. Along the extension of the inflow channel, the inflow channel typically comprises a plurality of sections of different cross section areas or inflow areas, particularly one of which understood to be minimal in the sense of the minimal inflow area. It may be considered that in case of more than one inflow channel and/or parallel sections of an inflow channel, that a sum of areas could constitute the minimal inflow area. Especially, the minimal inflow area is the tightest or narrowest point, especially the sum of said points in case of more than one inflow channel and/or in case of parallel sections of an inflow channel, through which the quenching gas to reach the arc zone flows, thereby creating a relatively high resistance for the quenching gas along the extension of the inflow channel. For example, the inflow channel may be shaped to tighten more and more towards the arc zone, so that the minimal inflow area is located close or proximal to the arc zone. As another example, the inflow channel may comprise a localized restriction at its beginning, thereby the inflow area can be located close to the gas compression arrangement or distant to the arc zone.
The nozzle radially restricts the arc zone between the first contact and the second contact, particularly when the contacts are in an open position or disconnected. In a direction perpendicular to the switching axis, the nozzle can delimit the arc zone. For example, the nozzle may have one or more throats, e.g. with a cylindrical shape, in order to restrict the arc zone.
For the quenching gas to exit the arc zone, the circuit-breaker provides at least one outlet. There may more than one outlet, all of which to be part of 'the at least one outlet'. The at least one outlet may include a channel, a passage, an opening and/or the like. The at least one outlet constitutes the minimal outflow area, particularly to be passed by the quenching gas, e.g. a part or all of the quenching gas let into the arc zone through the inflow channel, and typically to be passed by gas or debris generated in the arc zone by means of an arc. Especially, the minimal outflow area is the tightest or narrowest point, especially the sum of said points in case of more than one outlet and/or in case of parallel sections of one outlet, through which the quenching gas to be let out from the arc zone flows, thereby possibly creating a relatively high resistance for the quenching gas along the extension of the at least one outlet.
The minimal inflow area divided by the minimal outflow area defines an inflow-outflow-ratio, the inflow-outflow-ratio being at least 0.5. It has been found with the minimal inflow area or the narrowest point of the inflow channel leading to the arc zone being at least half as large as the minimal outflow area or the narrowest point(s) of the at least one outlet guiding gas away from the arc zone an improvement of the circuit-breaker could be achieved. Additionally, the inflow-outflow-ratio may be increased to no more than 2.0 so that an optimal corridor is suggested for improvements of the circuit-breaker.
In practice, the minimal inflow area and the minimal outflow area may be considered by differentiating, in terms of the flow of quenching gas during operation, between paths that lead towards the arc zone or which are upstream from the arc zone, and by paths that lead away from the arc zone or which are downstream from the arc zone. Both upstream and downstream narrowest sections can be determined, with the narrowest sections to be added up to the minimal inflow area or minimal outflow area, respectively.
It may be provided that the inflow-outflow-ratio is at least 0.7, or at least 0.9. Particularly, the inflow-outflow-ratio may be at least 1.0. It may be provided that the inflow-outflow ratio is 2.0 or less, 1.8 or less, or 1.6 or less, or 1.4 or less. Particularly, the inflow-outflow-ratio may be 1.2 or less. It is preferred that the inflow-outflow-ratio is at least 1.0 and up to 1.2, e.g. is substantially between 1.0 and 1.2. For example, the inflow-outflow-ratio may be 1.1 ± 0.3 or 1.1 ± 0.1.
It may be provided that the at least one outlet includes a first outlet and a second outlet. The first outlet may be provided by the nozzle and/or the first contact. The second outlet may be arranged axially opposite the first outlet. For example, the first outlet is on the side of the first contact and/or the second outlet is on the side of the second contact. Thus, quenching gas may leave the arc zone via two or more different outlets, thereby making it possible to increase the minimal outflow area and adapt the inflow-outflow ratio. The first outlet may exhibit a first outflow area of the minimal outflow area and the second outlet may exhibit a second outflow area of the minimal outflow area. The first outflow area plus the second outflow area can together equal the minimal outflow area.
It may be provided that the first contact comprises a central opening corresponding in shape to the second contact for mating therewith. The first contact may have a tulip shape with the central opening. The second contact can be inserted into the central opening and make electrical contact therewith. Particularly, the central opening may constitute at least a first part of the first outflow area. Alternatively, the central opening may constitute the entire first outflow area. In this respect, the central opening may be a or the narrowest point of the at least one outlet, particularly of the first outlet.
The first contact may have contact arms, e.g. the contact arms forming the tulip shape and surrounding the central opening. It may be provided that the first contact comprises axial slits for provision of an elastic movement of the first contact, particularly of (the) contact arms of the first contact, when mating or unmating with the second contact. For example, the second contact may push away the contact arms in a radial direction when being pushed into the central opening. The axial slits may constitute a further part of the first outflow area, e.g. such that the first outflow area is the sum of the further part and the first part of the first outflow area.
It may be considered to define or calculate the further part of the first outflow area taking into account elastic movement of the contact arms. For example, with the contact arms being elastically moved or deformed, the size of the further part of the first outflow area may change. There may be cases where the axial slits will change in area, e.g. they may be compressed together or bent inwards by electromagnetic and pressure forces, changing the available flow area, i.e. changing the further part of the first outflow area in size or reduce it. This change in flow area based on the contact arms being pulled or bent radially inward, narrowing the axial slits between them, may occur occur when high short-circuit currents are interrupted, since these can result in the force required for such deformation. Alternatively, the contact arms could be pushed or bent radially outward somehow, likely widening the axial slits between them. As such, the further part of the first outflow area may be calculated or estimated when the contacts are mated with one another, when they are unmated from one another, and/or when high short-circuit currents are being interrupted, e.g. which might be done based on a computer simulation or an experiment or the like.
It may be provided that the nozzle comprises a main nozzle and an auxiliary nozzle, with both nozzles, e.g. a main nozzle throat and an auxiliary nozzle throat, radially restricting the arc zone. The main nozzle throat and particularly the auxiliary nozzle throat may comprise an annular and/or cylindrical inner surface. The main nozzle throat and/or the auxiliary nozzle throat may have a diameter of at least 5 mm or at least 10 mm or at least 20 mm and/or of up to 40 mm or up to 50 mm. The main nozzle throat and the auxiliary nozzle throat may be in diameter at least substantially of the same size, i.e. by 10% or 5% or less difference in diameter. More particularly, the main nozzle throat may be at least 0,5 mm, 1 mm, 2 mm or more, and may be up to 1 mm, 2 mm, 3 mm or more larger than the auxiliary nozzle throat.
The main nozzle and/or the auxiliary nozzle may surround the first contact and/or may have an annular shape. The auxiliary nozzle may be inserted into the main nozzle, particularly along the switching axis. The main nozzle throat may constitute the second outflow area. The auxiliary nozzle throat may be larger in area than the first outflow area, e.g. may not constitute the first outflow area or may not be the narrowest section of the outlet on the side of the first contact. In contrast to the auxiliary nozzle throat, the main nozzle throat may hence be the narrowest section of the outlet on the side of the second contact.
It may be provided that the inflow channel is at least in a section or in its entirety formed by a gap between the main nozzle and the auxiliary nozzle. The inflow channel may open out into the arc zone perpendicularly or obliquely to the switching axis. The inflow channel may be arranged or formed obliquely to the switching axis to let out the quenching gas in a direction substantially leaning towards either one of the contacts, preferably towards the first contact. For example, in order to be perpendicular or oblique, an angle between the switching axis and the respective section, e.g. a radially extending section, of the inflow channel may be 90° ± 45° or 90° ± 30° or 90° ± 15°.
It may be provided that the minimal inflow area is arranged proximal to the arc zone, e.g. may be arranged close to the arc zone or closer to the arc zone than to the gas compression arrangement. The minimal inflow area may be arranged in a substantially radially extending section of the inflow channel. Thus, along the inflow channel, the narrowest section of the inflow channel may be arranged substantially at its end or second half.
It may be provided that the minimal inflow area is arranged distal to the arc zone, e.g. may be arranged remote from the arc zone or closer to the gas compression arrangement than to the arc zone. The minimal inflow area may be arranged in a substantially axially extending section of the inflow channel. Thus, along the inflow channel, the narrowest section of the inflow channel may be arranged substantially at its beginning or first half.
The minimal inflow area may be defined by a gap size, e.g. measured along the switching axis or obliquely/perpendicularly thereto. The minimal inflow area may be further constituted or defined by one or more openings along the inflow channel, e.g. the one or more openings forming parallel channels.
It may be provided that the at least one outlet, particularly the first outlet and/or the second outlet, has an at least substantially circular and/or cylindrical cross-section, e.g. with a radius measured perpendicularly to the switching axis of at least 5 mm, e.g. the radius ranging from 5 mm to 50 mm or 5 mm to 30 mm.
It may be provided that the inflow channel opens out into the arc zone with a rounded edge(s), particularly where the curvature of the rounded edge(s) is defined by a radius. For example, the radius of the rounded edge(s) may be at least 0.5 mm and/or up to 100 mm or at least 0.5 mm and/or up to 60 mm. The rounded edge(s) can improve an aerodynamic resistance. The radius of the rounded edges divided by the radius of the first or second outlet defines a radius ratio, preferably the radius ratio being at least 0.1 and/or up to 2.0.
It may be provided that the quenching gas comprises at least 2.5 mol% C4-FN, at least 7.5 mol% O2, and/or at least 65 mol% CO2, and particularly comprises at least approximately 3.5 mol% C4-FN, 10 mol% O2, and/or 86.5 mol% CO2, or consists thereof, e.g. with a tolerance of ± 20% of the given value or ± 3 mol% in each case. A content of C4-FN may be less than 5 mol% or less than 2.5 mol% or less than 1 mol% or may be zero. It is particularly provided that the quenching gas is free of sulphur hexafluoride or SF6. This gas composition provides an environmentally friendly alternative to SF6 while aiming to maintain effective arc-quenching performance.
The quenching gas may comprise at least 80 mol% CO2 and/or at least 5 mol% O2 or consist thereof. The quenching gas may comprise 5 to 20 mol% 02. The quenching gas may comprise 80 to 95 mol% CO2. For example, the quenching gas may comprise 90mol% ± 5 mol% CO2 and/or 10 mol% ± 5 mol% O2 and may particularly consist thereof. The quenching gas may comprise less than 5 mol% C4-FN or less than 2.5 mol% C4-FN or less than 1 mol% C4-FN or at least substantially zero or no C4-FN. The circuit-breaker or the quenching gas may be free of C4-FN. This may be the case in some circuit-breakers, specifically live-tank circuit breakers, e.g. where the outer dimensions are defined by the dielectric insulation properties of the surrounding air and where customers frequently insist on low minimum operating temperatures that may only be achieved with very low C4-FN concentrations, like lower than 5 mol% or less than 2.5 mol% or less than 1 mol%.
The quenching gas may be understood to be a part of the circuit-breaker, e.g. may be comprised by the claimed subject-matter. The invention may as well be directed to a use of the circuit-breaker, wherein the circuit breaker is used for making or breaking in combination or filled quenching gas that does not contain SF6. Additionally, the invention may as well be directed to a method to operate the circuit-breaker, wherein the circuit-breaker is filled with quenching gas that does not contain SF6, and especially wherein is the circuit-breaker is being operated afterwards. This protects the environment and may fulfil technical requirements.
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 section; and
Fig. 2 shows another circuit-breaker in a schematic section.

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 and Fig. 2 each show a section of a circuit-breaker 1 which is cut along a switching axis 2. The section shows an upper half with respect to the switching axis 2, with the lower half not shown in detail, but formed substantially symmetrically compared to the upper half. Fig. 1 and Fig. 2 are not drawn to scale.
The circuit-breaker 1, cf. Fig. 1 or Fig. 2, comprises a gas compression arrangement 4 which is configured for compressing a quenching gas that is contained in the gas compression arrangement 4. The circuit-breaker 1 comprises a first contact 20 and a second contact 30, wherein the contacts 20, 30 are arranged movable relative to one another along the switching axis 2 in order to make or break an electrical connection. The circuit-breaker 1 also includes a first nominal contact 26 and a second nominal contact 36, each of which nominal contacts 26, 36 are arranged radially outside the first 20 and second 30 contacts, respectively. The circuit-breaker 1 comprises a nozzle 40 made of an electrically insulating material. The nozzle 40 provides an inflow channel IN connecting the gas compression arrangement 4 directly or indirectly to arc zone 3.
The circuit-breaker 1, cf. Fig. 1 or Fig. 2, may be a self-blast or puffer-type circuit-breaker.
In the case of a self-blast circuit-breaker 1, the gas compression arrangement 4 may be connected to the arc zone 3 or the inflow channel IN indirectly, namely via an intermediate volume, heating volume or self-blast volume that is separated from a puffer volume by a flap valve.
In the case of a puffer-type circuit-breaker 1, the gas compression arrangement 4 may be connected substantially directly to the arc zone 3 or the inflow channel IN.
The inflow channel IN constitutes a minimal inflow area A or B to be passed by the quenching gas. The nozzle 40 radially restricts the arc zone 3 between the first contact 20 and the second contact 30.
For the quenching gas to exit the arc zone 3, the circuit-breaker 1 provides at least one outlet OUT1, OUT2, including a first outlet OUT1 and a second outlet OUT2, the at least one outlet OUT1, OUT 2 constituting a minimal outflow area.
The minimal inflow area divided by both of the minimal outflow area defines an inflow-outflow-ratio which is at least 0.5, particularly is at least 1.0 and up to 1.2.
With respect to Fig. 1, the first outlet OUT1 is provided by the first contact 20 and exhibits a first outflow area C1, CT of the minimal outflow area.
Optionally, for example, the first outlet OUT1 may be provided by the nozzle 40 exhibiting the first outflow area C2 of the minimal outflow area substantially at the location of an auxiliary nozzle throat 62. However, in the case shown and at reference C2, the cross section or area is relatively large and not contributing to the inflow-outflow-ratio.
With respect to Fig. 2, the first outlet OUT1 is provided by the first contact 20 and exhibits a first outflow area C1 of the minimal outflow area.
With respect to Fig. 1 and Fig. 2, the second outlet OUT2 is arranged axially opposite the first outlet OUT1 and is provided by the nozzle 40 and exhibits a second outflow area C3 of the minimal outflow area.
With respect to Fig. 1, the first outflow area C1, CT plus the second outflow area C3 is the minimal outflow area. Quenching gas exiting the arc zone 3 will pass the first C1, CT and the second C3 outflow areas.
With respect to Fig. 2, the first outflow area C1 plus the second outflow area C3 is the minimal outflow area. Quenching gas exiting the arc zone 3 will pass the first C1 and the second C3 outflow areas.
With respect to Fig. 1 and Fig. 2, the first contact 20 comprises a central opening 22 corresponding in shape to the second contact 30 for mating with the second contact 30.
With respect to Fig. 1, the central opening 22 constitutes a first part C1 of the first outflow area C1, CT, but in this case does not constitute the entire first outflow area C1, CT as there are axial slits in the first contact 20 which provide a further part CT of the first outflow area C1, CT.
Particularly and with respect to Fig. 1, the first contact 20 comprises the axial slits for provision of elastic movement of contact arms 24 of the first contact 20 when mating or unmating with the second contact 30. The axial slits constitute the further part CT of the first outflow area C1, CT. For example, there is a number of further parts CT given which surround the central opening 22. In particular, the first part C1 and the further part(s) CT together constitute the entire first outflow area C1, CT.
With respect to Fig. 2, the central opening 22 constitutes the entire first outflow area C1.
With respect to Fig. 1 and Fig. 2, the nozzle 40 comprises a main nozzle 50 and an auxiliary nozzle 60. A main nozzle throat 52 of the main nozzle 50 and an auxiliary nozzle throat 62 of the auxiliary nozzle 60 radially restrict the arc zone 3. The main nozzle throat 52 constitutes or forms in its entirety the second outflow area C3. The auxiliary nozzle throat 62 is larger than the first outflow area C1, CT or C1 and is arranged substantially between the first outflow area C1, CT or C1 and the second outflow area C3.
With respect to Fig. 1, the inflow channel IN is formed by a gap between the main nozzle 50 and the auxiliary nozzle 60. The inflow channel IN opens out into the arc zone 3 obliquely to the switching axis 2.
With respect to Fig. 2, the inflow channel IN is formed by a gap between the main nozzle 50 and the auxiliary nozzle 60. The inflow channel IN opens out into the arc zone 3 obliquely, particularly substantially perpendicularly, to the switching axis 2.
In Fig. 1, the minimal inflow area is arranged proximal to the arc zone 3 and is arranged in a substantially radially extending section of the inflow channel IN and is defined by a gap size B. The minimal inflow area may be calculated as a ring shape which is substantially cylindrical or conical.
In Fig. 2, the minimal inflow area is arranged distal to the arc zone 3 and is arranged in a substantially axially extending section of the inflow channel IN and is defined by a gap size A. The minimal inflow area may be calculated as a ring shape which is substantially flat.
With respect to Fig. 1 and Fig. 2, the first outlet OUT1 and the second outlet OUT2 each may have a circular cross section defined by a radius RO to be measured perpendicularly to the switching axis 2, the radius RO ranging from 5 mm to 30 mm.
In Fig. 1 and in Fig. 2, the inflow channel IN opens out into the arc zone 3 with rounded edges, the curvature of the rounded edges being defined by a radius RE. The radius RE of the rounded edges divided by the radius RO of the first OUT1 or second OUT2 outlet may define a radius ratio that is between 0.1 and 2.0.
With respect to Fig. 1 and Fig. 2, the quenching gas of the circuit-breaker 1 consists of 3.5 mol% C4-FN, 10 mol% O2, and 86.5 mol% CO2 and is free of SF6.
Alternatively, the quenching gas may consist of 90 mol% CO2 and 10 mol% O2 and is free of SF6 and C4-FN.

Reference signs list

1: Circuit-breaker
2: Switching axis
3: Arc zone
4: Gas compression arrangement
20: First contact
22: Central opening
24: Contact arms
26: First nominal contact
30: Second contact
36: second nominal contact
40: Nozzle
50: Main nozzle
52: Main nozzle throat
60: Auxiliary nozzle
62: Auxiliary nozzle throat
A: Minimal inflow area
B: Minimal inflow area
C1: First outflow area
C2: First outflow area
C3: Second outflow area
CT: Further part of the first outflow area
IN: Inflow channel
OUT1: First outlet
OUT2: Second outlet
RO: Radius of outlet
RE: Radius of rounded edges

Claims

Gas-insulated circuit-breaker (1), comprising
a gas compression arrangement (4) configured for compressing a quenching gas to be contained therein and which quenching gas is free of sulphur hexafluoride;

a first contact (20) and a second contact (30) movable relative to one another along a switching axis (2); and

a nozzle (40) providing an inflow channel (IN) connecting the gas compression arrangement (4) to an arc zone (3), the inflow channel (IN) constituting a minimal inflow area to be passed by the quenching gas, the nozzle (40) radially restricting the arc zone (3) between the first contact (20) and the second contact (30);

wherein, for the quenching gas to exit the arc zone (3), the circuit-breaker (1) provides at least one outlet (OUT1, OUT2) constituting a minimal outflow area, and

wherein the minimal inflow area divided by the minimal outflow area defines an inflow-outflow-ratio, the inflow-outflow-ratio being at least 0.5.
Circuit-breaker (1) according to the preceding claim, wherein
the inflow-outflow-ratio is at least 0.7, or at least 0.9.
Circuit-breaker (1) according to any one of the preceding claims, wherein
the inflow-outflow-ratio is 2.0 or less, 1.8 or less, 1.6 or less, 1.4 or less.
Circuit-breaker (1) according to any one of the preceding claims, wherein
the inflow-outflow-ratio is at least 1.0 and up to 1.2.
Circuit-breaker (1) according to any one of the preceding claims, wherein
the at least one outlet (OUT1, OUT2) includes a first outlet (OUT1) and a second outlet (OUT2),

the first outlet (OUT1) is provided by the nozzle (40) and/or the first contact (20), the first outlet (OUT1) exhibiting a first outflow area (C1, C2, CT) of the minimal outflow area, and

the second outlet (OUT2) is arranged axially opposite the first outlet (OUT2), is provided by the nozzle (40) and exhibits a second outflow area (C3) of the minimal outflow area.
Circuit-breaker (1) according to the preceding claim, wherein
the first contact (20) comprises a central opening (22) corresponding in shape to the second contact (30) for mating therewith, the central opening (22) constituting a first part (C1) of the first outflow area (C1, C2, CT) or constituting the entire first outflow area (C1, C2, CT).
Circuit-breaker (1) according to the preceding claim, wherein
the first contact (20) comprises axial slits for provision of elastic movement of contact arms (24) of the first contact (20) when mating or unmating with the second contact (30), the axial slits constituting a further part (CT) of the first outflow area (C1, C2, CT), the first part (C1) and the further part (CT) together constituting the entire first outflow area (C1, C2, CT).
Circuit-breaker (1) according to any one of the preceding three claims, wherein
the nozzle (40) comprises a main nozzle (50) and an auxiliary nozzle (60) of which a main nozzle throat (52) and an auxiliary nozzle throat (62) radially restrict the arc zone (3), the main nozzle throat (52) constituting the second outflow area (C3) and the auxiliary nozzle throat (62) being larger than the first outflow area (C1, C2, CT).
Circuit-breaker (1) according to the preceding claim, wherein
the inflow channel (IN) is at least in a section formed by a gap between the main nozzle (50) and the auxiliary nozzle (60), and

the inflow channel (IN) opens out into the arc zone (3) perpendicularly or obliquely to the switching axis (2).
Circuit-breaker (1) according to the preceding claim, wherein
the minimal inflow area is arranged proximal to the arc zone (3) and/or is arranged in a substantially radially extending section of the inflow channel (IN) and is defined by a gap size (B).
Circuit-breaker (1) according to any of claims 1 to 9, wherein
the minimal inflow area is arranged distal to the arc zone (3) and/or is arranged in a substantially axially extending section of the inflow channel (IN) and is defined by a gap size (A).
Circuit-breaker (1) according to any one of the preceding claims, wherein
the at least one outlet (OUT1, OUT2), particularly the first outlet (OUT1) and/or the second outlet (OUT2), has a circular cross section defined by a radius (RO) to be measured perpendicularly to the switching axis (2) that ranges from 5 mm to 30 mm.
Circuit-breaker (1) according to the preceding claim, wherein
the inflow channel (IN) opens out into the arc zone (3) with rounded edges, the curvature of the rounded edges is defined by a radius (RE),
Circuit-breaker (1) according to the preceding claim, wherein
the radius (RE) of the rounded edges divided by the radius (RO) of the first (OUT1) or second (OUT2) outlet defines a radius ratio, the radius ratio being at least 0.1 and up to 2.0.
Circuit-breaker (1) according to any one of the preceding claims, wherein
the quenching gas comprises at least 2.5 mol% C4-FN, 7.5 mol% O2, and 65 mol% CO2, and particularly

the quenching gas consists of 3.5 mol% C4-FN, 10 mol% O2, and 86.5 mol% CO2.
Circuit-breaker (1) according to any one of the preceding claims, wherein
the quenching gas is free of C4-FN and comprises at least 80 mol% CO2 and at least 5 mol% O2, and particularly

the quenching gas consists of 90 mol% CO2 and 10 mol% O2.