Tulip contact for a circuit-breaker, circuit-breaker and use

Abstract

The invention relates to a tulip contact (10) for a gas-insulated circuit-breaker (1), comprising at least one contact section (12) having an inner contour (18) extending along a switching axis (X) between a tip (14) and a root (16), wherein the inner contour (18) forms a contact throat at the tip (14) and exhibits a first radius (R1) in respect to the switching axis (X) that defines a narrowest cross section of the contact throat; the inner contour (18) comprises a first curved segment (C1) and, optionally, adjacent to the first curved segment (C1) a first straight segment (S1), at least one of the first curved segment (C1) and the first straight segment (S1) form the contact throat; the first curved segment (C1) exhibits a curving radius (RU) defining a convexity of first curved segment (C1) towards the switching axis (X) in a longitudinal sectional view; and 1 ≤ RU / R1 and, optionally, RU / R1 ≤ 50.

Description

Technical Field

[0001] The invention relates to a tulip contact for a circuit-breaker, to a circuit-breaker, and to a use.Background Art

[0002] 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.

[0003] In the operation of a circuit-breaker arcing occurs. The high temperatures of an arc result in heating of the contacts or arcing contacts, thereby evaporating or eroding material thereof and changing the shape of the contacts. Thus, circuit-breakers can only be used for a certain number of breaking operations. There is a continuous demand to optimize the lifetime of the contacts for circuit-breakers.Summary of invention

[0004] It is therefore an object of the invention to provide solutions with respect to circuit-breakers that provide an increased lifetime. Particularly it is an object to avoid or reduce disadvantages of known solutions.

[0005] The invention is defined by the features of the independent claims. Preferred implementations are detailed in the dependent claims, the description, and the figures.

[0006] The object is particularly solved by a tulip contact for a gas-insulated circuit-breaker, the tulip contact comprising at least one contact section having an inner contour extending along a switching axis between a tip and a root, wherein the inner contour forms a contact throat at the tip; and wherein the inner contour comprises a first curved segment and, optionally, a first straight segment adjacent to or arranged adjacent to the first curved segment. The first straight segment may be substantially and / or in a section between the first curved segment and the tip. At least one of the first curved segment and the first straight segment may form the contact throat.

[0007] Particularly, if the first straight segment is present, the first straight segment and optionally the first curved segment may form the contact throat. Particularly, if the first straight segment is not present, the first curved segment, e.g. only the first curved segment, may form the contact throat.

[0008] The contact throat may exhibit a first radius R1 in respect to the switching axis that defines a narrowest cross section or substantially the narrowest cross section of the contact throat. For example, the first radius R1 substantially defines the smallest size or diameter of the throat.

[0009] The first curved segment may exhibit a curving radius RU defining a convexity of first curved segment towards the switching axis in the longitudinal sectional view. It may be provided that 1 ≤ RU / R1 or R1 ≤ RU, particularly meaning that 1 ≤ (curving radius) / (first radius). Particularly, the curving radius is equal to or larger than the first radius. Optionally, it is provided that RU / R1 ≤ 50 or RU ≤ 50*R1. The curving radius may be equal to up to 50 times the first radius or less than that.

[0010] The tulip contact may have a second curved segment adjacent to the root. In a downstream direction, i.e. from the tip to the root, the second curved segment may form an end of the inner contour. The second curved segment may be concave towards the switching axis in the longitudinal sectional view. The second curved segment may exhibit a curving radius RV, e.g. named second curving radius RV, defining a concavity of the second curved segment towards the switching axis in the longitudinal sectional view, wherein it may be provided that 1 ≤ RV / R1, particularly meaning that 1 ≤ (second curving radius) / (first radius). Particularly, the second curving radius RV is equal to or larger than the first radius R1. Optionally it is provided that RV / R1 ≤ 50, e.g. (second curving radius) / (first radius) ≤ 50, or RV / R1 ≤ 25. The second curving radius RV may be equal to up to 50 times or 25 times the first radius R1 or less than that.

[0011] It is noted that the name 'second' does not imply a necessity that there must be a corresponding feature named with 'first'.

[0012] A curving radius may be at least substantially constant along a part of the extension or along the entire extension of the respective curved segment and / or may change point by point or section by section, e.g. making the respective curved segment any arbitrary curve, e.g. an elliptic arc. For example, a curving radius may substantially and / or sectionally increase and / or decrease in the downstream direction.

[0013] The object is further solved by a circuit-breaker comprising the tulip contact, and / or by a use of the tulip contact in a circuit-breaker. The circuit-breaker may be a high voltage circuit-breaker. The circuit-breaker may have a pin contact corresponding to the tulip contact. The pin contact may have a diameter corresponding to the contact throat, e.g. the diameter measured with respect to the switching axis. The diameter of the pin contact may be equal to or larger than a diameter of the contact throat or larger than two times the first radius R1, e.g. the diameter of the pin contact being up to 1 % or 2.5% or 5% or 10% or 20% larger than the diameter of the contact throat or larger than two times the first radius R1. The circuit-breaker is particularly filled with and / or works with a quenching gas, e.g. the quenching gas may contain SF6 or may be free of SF6. SF6 is short for sulphur hexafluoride.

[0014] In other words, particularly, an arcing contact, e.g. a hollow contact, for a circuit-breaker is suggested that has a specific shape on its inside. In detail, the shape is cylindrical or conical in a front region, is bulbous or bulging (i.e. convex) in a middle region adjacent to the front region, and optionally is hollow or indented (i.e. concave) in a root region opposite the front region. The convexity of the middle region (i.e. the first curved segment) may have a certain relationship with respect to the size or diameter of the front region, wherein the radius defining the convexity is at least as large as the radius of the front region or more, and optionally up to fifty times or less than the radius of the front region. As such, the convexity may be claimed to be substantially larger, but not too large, in relation to the size / diameter of the front of the tulip (i.e. the contact throat).

[0015] For example, in the downstream direction along the switching axis, a contour line of the tulip contact or the inner contour of the tulip contact comprises a substantially straight first segment forming a throat, and e.g. forming with the switching axis an angle or being parallel thereto, with a throat radius about the switching axis defining the minimal size of the throat, and a circular arc, e.g. an upward curved segment (e.g. curved in the downstream direction substantially away from the switching axis for form an 'upward' curve), with a curving radius defining the arc, and optionally a substantially straight second segment inclined relative to the switching axis, and optionally another circular arc, e.g. a downward curved segment (e.g. curved in the downstream direction substantially towards the switching axis for form a 'downward curve), wherein 'throat radius' ≤ 'curving radius', and, preferably, 'curving radius' ≤ 50 * 'throat radius'.

[0016] The invention aims to provide an enhanced interruption performance and lifetime .

[0017] The invention is based on the idea that 'sulphur hexafluoride free', or 'SF6-free' for short, circuit-breakers provide certain technical challenges, e.g. with respect to damage or erosion to the arcing contacts, relative to circuit-breakers that include SF6 as a quenching gas. The invention may provide a tulip contact that meets technical requirements, e.g. in respect to interruption performance and lifetime, in a SF6-free circuit-breaker.

[0018] Additionally, upon developing the invention, it has been found that the tulip contact may also improve a circuit-breaker that does include SF6 as a quenching gas. It may be that the invention provides further improval to SF6-based circuit-breakers, e.g. in respect to performance, lifetime, or the like.

[0019] Thus, the invention may provide the option for a retrofit of existing circuit-breakers that may provide an improved interruption performance and / or lifetime.

[0020] Particularly, due to the invention, circuit-breakers operating with or without quenching gas comprising SF6 may be enhanced.

[0021] The tulip design according to the present invention can result in an improvement of thermal interruption capabilities of circuit-breakers, especially high voltage circuit-breaker (HVCB), that has been estimated through CFD simulations and proven with dedicated experiments. This improvement is due to the concurrence of two effects.

[0022] First, a pressure build-up of gas stored in circuit-breaker pressure volumes or gas compression arrangement can increase with the suggested contact throat. Particularly, the pressure build-up can increase with the axial length of the contact throat, especially for a cylindrical contact throat or slightly conical contact throat. This is because the longer the contact throat, the less its minimum diameter will increase from metal erosion.

[0023] Second, profiling the tulip inner contour by means of the first curved segment, which is arranged in the downstream direction, for example after the tip or the contact throat or adjacent thereto, can establish particular conditions for the supersonic flow. Namely, such a design can enhance the convective cooling of the arc and thus the thermal interruption performance of the breaker for the same given blowing pressure relative to a tulip contact known in the art that do not comprise all the features as claimed.

[0024] Generally, the tulip contact is referred to as one of two arcing contacts of / for a circuit-breaker. The tulip contact is named as such due to its shape formed by the at least one contact section that is reminding in shape of a tulip. The tulip contact may be a contact that is configured as a tulip contact, e.g. is hollow, has a sleeve shape, and / or has a sleeve-like shape. The tulip contact is typically configured for mating with a pin contact pushed along the switching direction and in the downstream direction into the tulip contact. The at least one contact section typically relates to a part of the tulip contact that may be configured to directly contact another arcing contact of a circuit-breaker. The at least one contact section may be made of metal, e.g. a metal alloy including at least one of copper and tungsten. The at least one contact section or at least the contact throat may at least substantially consist of or be made of said metal alloy. The at least one contact section may be configured to bend or elastically deform in a radial direction, particularly such that the tip moves relative to the root in a radial direction or oblique / perpendicular to the switching axis. Bending at least one contact section may provide that the contact throat can widen when a pin contact is inserted.

[0025] The inner contour is typically shaped at least substantially symmetrically with respect to the switching axis. For example, the inner contour may have a sleeve-like and / or substantially round shape about the switching axis. The inner contour may be made by turning, e.g. two-axis turning or the like, or by milling or forming or other manufacturing processes.

[0026] The inner contour extends between the tip and the root of the at least one contact section. The tip may form a point of entry for a pin contact of a circuit-breaker while the root may form a point furthest away from the tip along the switching axis, typically within the same material. Typically, from the tip, particularly from the first curved segment or the first straight segment, if present, towards the root, particularly towards or to the second curved segment, the inner contour is shaped to widen at least substantially continuously. The inner contour has a certain design distinguishing from prior art with the premise to enhance lifetime.

[0027] The first curved segment and / or the first straight segment form / forms the contact throat at the tip. The contact throat may provide that a pin contact can get in contact with the tulip contact in terms of area. The contact throat may have a substantially cylindrical or conical shape with respect to the switching axis. In an axial view, the contact throat may have a substantially round or circular shape. In the axial view, the tulip contact may have a substantially round or circular shape, particularly on an inside and / or an outside.

[0028] The first curved segment may be arranged adjacent to the first straight segment, e.g. the first curved segment and the first straight segment transitioning with one another directly.

[0029] Optionally, there may be no first straight segment such that mainly or only the first curved segment forms the contact throat, e.g. wherein the first curved segment starts at the tip, transitions with the tip, is adjacent to the tip, or the like.

[0030] The first curved segment, or the first straight segment, if present, may exhibit the first radius in respect to the switching axis that defines the narrowest cross section of the contact throat. As such, the smallest diameter of the tulip contact in respect to the switching axis may be located close to or at the tip, e.g. adjacent to the tip, the smallest diameter of the tulip contact defined by two times the first radius. The smallest diameter furthermore affects aerodynamical resistance of the tulip for the flow of quenching gas through the tulip contact.

[0031] The first curved segment may exhibit the curving radius defining the convexity of first curved segment towards the switching axis in the longitudinal sectional view. The first curved segment is particularly convex towards the switching axis in the longitudinal sectional view. For example, the first curved segment bulges substantially towards the switching axis.

[0032] It may be provided that 1 ≤ RU / R1 or R1 ≤ RU. Particularly, the curving radius is equal to or larger than the first radius. It may be provided that RU / R1 ≤ 50 or RU ≤ 50*R1. Particularly, the curving radius is equal to or smaller than the fifty times the first radius. As such, the radius applied to a convex segment that follows in a downstream direction typically directly after the tip or the contact throat can be specified and particularly put into a relation to the minimal diameter of the contact throat. The convex segment is thus relatively round or has a large radius defining it which can be beneficial with supersonic fluids.

[0033] The second curved segment may be arranged adjacent to the root, e.g. the second curved segment and the root transitioning with one another directly or the second curved segment forming the root.

[0034] The second curved segment typically is concave towards the switching axis in the longitudinal sectional view. For example, the second curved segment bulges substantially away from the switching axis.

[0035] Particularly, the inner contour defines an inner surface of the tulip contact generated by revolving the contour around the switching axis. In an axial view, e.g. along the switching axis, the tulip contact or the inner contour forming the inner surface among one or more or all of the segments of the inner contour may have a substantially concave shape facing the switching axis; this is typically due to an annular form of the tulip contact around the switching axis.

[0036] For example, following the inner contour in a direction from the tip towards the root or in the downstream direction, the first and the second curved segment may have opposite curving directions, e.g. so that the first curved segment is convex and the second curved segment is concave towards the switching axis.

[0037] Generally, a curved segment may have a curvature. The curvature is typically defined by a radius, e.g. the first or second radius, which radius may be present across at least half of or across the entire curved segment. In respect to the switching axis, the curved segment may be monotonically, particularly strictly monotonically, decreasing or increasing. The curved segment can typically define an inwards or outwards bulging surface section inside the tulip contact.

[0038] Generally, a straight segment may follow a substantially straight line. The straight segment can typically define a cylindrical or conical surface section inside the tulip contact. A conicity of the conical surface section is typically widening in a direction from tip to root.

[0039] 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.

[0040] 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.

[0041] The invention is based on the principle that in a circuit-breaker, typically, a high energy gas (e.g. with high pressure and / or temperature) can be blown onto an arc temporarily formed between arcing contacts, or '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 an arc zone that typically separates the arcing contacts or the contacts in an insulating manner. During contact separation, a part of the gas may fill an upstream volume, e.g. of a 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 between (the) upstream and downstream regions of the circuit-breaker that can sustain highspeed, ideally transonic, flows. High temperatures, especially above a certain temperature limit, are detrimental to the cooling effectiveness of the gas flow.

[0042] The circuit-breaker is preferably configured for medium and / or high voltage switching applications, e.g. configured as a medium voltage or high voltage circuit-breaker. 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 / or switching very high short-circuit currents of 31.5 kA to 80 kA particularly 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.

[0043] High or medium voltage 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. Circuit-breakers may have the task of opening contacts, quenching an arc, and keeping the 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.

[0044] 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. Especially in case of a self-blast circuit-breaker, an intermediate volume, e.g. heating volume, may be arranged between a gas compression arrangement, e.g. compression volume, and an 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.

[0045] One or two of the contacts of the circuit-breaker may be arranged movable, especially movable along the switching axis. The contacts referred to herein may particularly include arcing contacts. The tulip contact may be one of two arcing contacts, e.g. with the other contact of the two arcing contacts being a pin contact. The circuit-breaker may 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.

[0046] 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.

[0047] 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, particularly partially through the tulip contact, and / or away from the arc zone. The circuit-breaker may have a / 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.

[0048] Typically, the tulip contact is or has an arcing contact. The circuit-breaker may have another arcing contact corresponding to the tulip contact, e.g. a pin contact. Additionally, the circuit-breaker may have a / the nominal contact(s). The arcing contacts are meant for withstanding arcs during opening or closing of the circuit-breaker and are typically arranged at least sectionally inside a / the nozzle of the circuit-breaker. The nominal contacts are typically meant for nominal current conduction when the circuit-breaker is closed. 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.

[0049] 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.

[0050] The arc zone is typically surrounded by a / the nozzle or insulating nozzle of the circuit-breaker. The nozzle typically also serves for guiding a stream of the quenching gas for extinguishing or blowing off the arc, especially via an / the inflow channel. Particularly, the nozzle provides the inflow channel or heating channel. The nozzle may as well provide an outlet or outlets for the quenching gas to exit the arcing zone. 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 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 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.

[0051] 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 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. Specifically, the quenching gas used can be 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.

[0052] The quenching gas may comprise or at least substantially consist of SF6, or alternatively may be at least substantially free of SF6 or not contain it. The quenching gas may or may not comprise CO2, O2, N2, C4FN, SF6 and / or CF4, particularly mixtures thereof, and / or may or may not comprise 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). Alternatively or additionally, the 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.

[0053] The gas compression arrangement the circuit-breaker typically has, particularly a 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.

[0054] The nozzle of the circuit-breaker typically is, 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.

[0055] The nozzle may provide an / 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.

[0056] Typically, the arc zone is arranged directly adjacent to the tulip contact along the switching axis. The arc zone is typically configured for surrounding the pin contact and / or the pin contact can be inserted into the arc zone. For example, the arc zone surrounds the pin contact upon closing or opening the circuit-breaker, especially with the pin contact located inside the nozzle, especially inside an auxiliary nozzle and / or a main nozzle thereof.

[0057] The nozzle may radially restrict the arc zone between the tulip contact and the pin contact, particularly when said 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.

[0058] The tulip contact typically comprises a central opening corresponding in shape to a pin contact of the circuit-breaker for mating therewith. The tulip contact may have a tulip shape with the central opening. The pin contact can be inserted into the central opening and make electrical contact therewith, e.g. by means of the contact throat.

[0059] The tulip contact may comprise a base at the root. The base may have a ring-like shape or annular shape extending about the switching axis. The at least one contact section may include four or more contact sections with the inner contour. The four or more contact sections may extend from the base. The four or more contact sections may extend along the switching axis at least substantially in parallel to one another. The four or more contact sections may be distributed about the switching axis to form axially extending slits between one another. Thereby, the tulip contact may have the contact sections as contact arms, e.g. the contact arms forming the tulip shape and / or surrounding the central opening. It may be that the tulip contact comprises the slits for provision of an elastic movement of the tulip contact, e.g. of (the) contact arms of the tulip contact, when mating or unmating with the pin contact. For example, the pin contact may push away the contact sections or contact arms in a radial direction when being pushed into the central opening or contact throat.

[0060] Typically, the nozzle has a nozzle throat that is axially in front of the tip of the tulip contact. It may be provided that the nozzle comprises a main nozzle and an auxiliary nozzle, particularly 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 nozzle, particularly the main nozzle throat and / or the auxiliary nozzle throat, may be larger in diameter than the contact throat, the diameter considered with respect to the switching axis. For example, the nozzle or its nozzle throat, e.g. main nozzle and / or auxiliary nozzle, 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 contact throat may have a smaller diameter, e.g. two times the first radius, than the nozzle throat, e.g. by at least 1 % or more smaller than the nozzle throat.

[0061] The main nozzle and / or the auxiliary nozzle may surround the tulip contact and / or have an annular shape. The auxiliary nozzle may be inserted into the main nozzle, particularly along the switching axis. 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 auxiliary nozzle, if present, may be arranged directly in front of the tulip contact. The main nozzle may be arranged in front of the tulip contact, e.g. with the auxiliary nozzle in between the main nozzle and the tulip contact.

[0062] It may be provided that the quenching gas is at least substantially free of SF6. This gas composition provides an environmentally friendly alternative to SF6 while aiming to maintain effective arc-quenching performance.

[0063] Alternatively, it may be provided that the quenching gas comprises SF6. The idea is that the tulip contact may improve known circuit-breakers e.g. in respect to lifetime, which circuit-breakers need to operate with SF6 and cannot operate as an SF6-free circuit-breaker.

[0064] The quenching gas may be understood to be a part of the circuit-breaker, e.g. may be comprised by the circuit-breaker. The invention may as well be directed to a use of the circuit-breaker, wherein the circuit breaker is configured to be used or is used for making or breaking in combination or filled with quenching gas, e.g. which quenching gas does contain SF6 or which quenching gas 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, e.g. which quenching gas does contain SF6 or which quenching gas does not contain SF6, and especially wherein is the circuit-breaker is being operated afterwards.

[0065] The relationship between the curving radius RU of the first curved segment and the first radius R1 may be further specified. It may be provided that 3 ≤ RU / R1 or 4 ≤ RU / R1 or 5 ≤ RU / R1 or 6 ≤ RU / R1. It may be provided that RU / R1 ≤ 40 or RU / R1 ≤ 30 or RU / R1 ≤ 25. Particularly, the following may be provided: 4 ≤ (curving radius) / (first radius) ≤ 25. Particularly, the curving radius is equal to or larger than four or 4 times the first radius. Particularly, the curving radius is equal to up to twenty five or 25 or twenty four or 24 times the first radius or less than that. Narrowing down the relationship between RU and R1 to this particular range, further improvements in lifetime can be possible. Hot gas can smoothly pass the contact throat.

[0066] As described, the inner contour may have the second curved segment. The first curved segment and the second curved segment, if present, may be arranged adjacent to one another. Alternatively or additionally, the inner contour may comprise a second straight segment between the first curved segment and the root, particularly between the first curved segment and the second curved segment. The second straight segment may provide that the tulip contact can be designed sufficiently long along the switching axis and that the manufacture is easier. The second straight segment may transition continuously on one side into the first curved segment and / or on another side or second side into the second curved segment. The second straight segment may transition on one or on both sides continuously or steplessly for efficient and smooth aerodynamics.

[0067] The second straight segment may be arranged at an angle of at least 1 ° or at least 2° or at least 3° or at least 4° or at least 5° and / or up to 30° or up to 25° or up to 20° or up to 18° or up to 16° with respect to the switching axis. The second straight segment may provide that the tulip contact, at least sectionally or in this segment, continuously widens in a downstream direction. The second straight segment may provide a conical section of the tulip contact that is between the root and the tip, for example configured as a diffusor.

[0068] The first straight segment may be arranged at an angle of at least 0° and / or up to 20° with respect to the switching axis, e.g. for the contact throat to be cylindrical or conical in shape. The first straight segment may optionally provide, i.e. in case of the angle be above 0° and below 90°, that the tulip contact continuously widens in a downstream direction. It can particularly be beneficial that the angle is below 20°. Thus, lifetime may be enhanced.

[0069] The first straight segment may transition continuously on one side into the first curved segment and / or on another side into a tip curved segment, particularly which tip curved segment is convex towards the switching axis in the longitudinal sectional view. The first straight segment may transition on one or on both sides continuously or steplessly for efficient and smooth aerodynamics.

[0070] The first curved segment may transition continuously on one side into one of the second straight segment or the second curved segment and / or on another side into one of the first straight segment or a / the tip curved segment, particularly which tip curved segment is convex towards the switching axis in the longitudinal sectional view. The first curved segment may transition on one or on both sides continuously or steplessly for efficient and smooth aerodynamics.

[0071] A point of transition between the first straight segment and the first curved segment may exhibit a second radius R2 in respect to the switching axis. The second curved segment may exhibit at the root a third radius R3 in respect to the switching axis. It may be provided that 0.5 ≤ R2 / R1 or 1 ≤ R2 / R1 or 1.5 ≤ R2 / R1. It may be provided that 0.1 ≤ R3 / R1 or 0.25 ≤ R3 / R1 or 0.5 ≤ R3 / R1 or 1 ≤ R3 / R1. It may be provided that R3 / R1 ≤ 5 or R3 / R1 ≤ 4 or R3 / R1 ≤ 3.3 or R3 / R1 ≤ 3 or R3 / R1 ≤ 2.5. Particularly, the second radius may be equal to or larger than the first radius. Particularly, the third radius may be equal to or larger than the first radius. Particularly, the third radius may be equal to up to 3.3 times the first radius or less than that. Narrowing down the relationship between the first radius and the second radius can provide a certain design of the contact throat widely applicable to different quenching gases and aiming to provide a long lifetime.

[0072] An extension of the first straight segment along the switching axis may exhibit a first length L1. The length L1 may be zero or more than zero. It may be provided that 0 ≤ L1 / R1 and / or R1 ≤ L1, particularly 0.01 ≤ L1 / R1 or 0.1 ≤ L1 / R1 or 0.5 ≤ L1 / R1 or 1 ≤ L1 / R1 or 1.5 ≤ L1 / R1. It may be provided that L1 / R1 ≤ 4 or L1 / R1 ≤ 3 or L1 / R1 ≤ 2.5 or L1 / R1 ≤ 1.8. Particularly, the first length may be equal to or larger than zero, particularly larger than 0.1 mm and / or a fraction of the first radius. Particularly, the first length may be equal to up four times the first radius or less than that. Narrowing down the relationship between the first length and the first radius can provide that supersonic flow of quenching gas is optimized while enhancing lifetime.

[0073] A summarized extension of the first curved segment and optionally the second curved segment and optionally the second straight segment may exhibit a second length L2. It may be provided that 0.5 ≤ L2 / R1 or 1 ≤ L2 / R1 or 2 ≤ L2 / R1 or 3 ≤ L2 / R1 or 4 ≤ L2 / R1. It may be provided that L2 / R1 ≤ 20 or L2 / R1 ≤ 15 or L2 / R1 ≤ 12 or L2 / R1 ≤ 10. Particularly, the second length may be equal to or larger than twice the first radius. Particularly, the second length may be equal to up to twelve times the first radius or less than that. Narrowing down the relationship between the second length and the first radius can provide that supersonic flow of quenching gas is optimized while enhancing lifetime.

[0074] The inner contour may extend along the switching axis between the tip and the root as a total extension L3. It may be provided that 0.01 ≤ L1 / L3 or 0.05 ≤ L1 / L3 or 0.1 ≤ L1 / L3 or 0.2 ≤ L1 / L3 or 0.3 ≤ L1 / L3. It may be provided that L1 / L3 ≤ 0.9 or L1 / L3 ≤ 0.75 or L1 / L3 ≤ 0.5 or L1 / L3 ≤ 0.3 or L1 / L3 ≤ 0.25. L1 / L3 may be 0.2. i.e. L1 may be 20% of L3. Particularly, the first length may be equal to or larger than 0.1 times the total extension. Particularly, the first length may be equal to up to 0.5 times the total extension or less than that.

[0075] A minimal thickness T1 and a maximal thickness T2 of the at least one contact section in a radial direction may be located at least substantially between the tip and the root. It may be provided that 1.1 ≤ T2 / T1 or 1.5 ≤ T2 / T1 or 2 ≤ T2 / T1 or 2.5 ≤ T2 / T1. It may be provided that T2 / T1 ≤ 6.0 or T2 / T1 ≤ 5.0 or T2 / T1 ≤ 4.0 or T2 / T1 ≤ 3.5 or T2 / T1 ≤ 3. T2 / T1 may be 2.75 ± 0.25 or 3 ± 0.25. Particularly, the maximal thickness may be equal to or larger than twice the minimal thickness. Particularly, the maximal thickness may be equal to up to 3.5 times the minimal thickness or less than that. Narrowing down the relationship between the minimal thickness and the maximal thickness can provide that material can be spared where not necessary while providing flexibility of the at least one contact section.

[0076] 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

[0077] These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.

[0078] In the drawing: Fig. 1 shows parts of a circuit-breaker in a schematic half-section, particularly in a longitudinal sectional view.Description of implementations

[0079] The description may contain 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.

[0080] Fig. 1 shows parts of a gas-insulated circuit-breaker 1 with a tulip contact 10. The tulip contact 10 is configured for the circuit-breaker 1, e.g. is configured as an arcing contact for the circuit-breaker 1.

[0081] The circuit-breaker 1 is configured as a high-voltage circuit-breaker 1. The circuit-breaker 1 has a pin contact 40 as an arcing contact and that corresponds to the tulip contact 10. At least one of the contacts 10, 40 is movable along a switching axis X for making or breaking an electrical connection. Particularly, the contacts 10, 40 are movable relative to one another. The contacts 10, 40 are made of metal, e.g. in each case a metal alloy including at least one of tungsten and copper.

[0082] Not shown are nominal contacts of the circuit-breaker 1, which nominal contacts are typically arranged radially outside the arcing contacts.

[0083] The contacts 10, 40 are arranged inside an annular nozzle 2 of the circuit-breaker 1. The nozzle 2 restricts an arc zone in which an arc is formed when the electrical connection is interrupted between the contacts 10, 40. The nozzle 2 provides an inflow channel 4 originating from a gas compression arrangement 3 of the circuit-breaker 1. The inflow channel 4 connects the arrangement 3 with the arc zone.

[0084] Through the inflow channel 4, quenching gas can be blown into the arc zone and onto the arc in order to extinguish the arc. The quenching gas can leave the arc zone by flowing through the tulip contact 10 along the switching axis X, e.g. towards an exhaust of the circuit-breaker 1. Also, the quenching gas can leave the arc zone on a side opposite the tulip contact 10, e.g. by passing around the pin contact 40.

[0085] The nozzle 2 has a nozzle throat axially in front of the tulip contact 10. In detail, the nozzle 2 includes an auxiliary nozzle 5 with an auxiliary nozzle throat directly in front of the tulip contact 10. The nozzle 2 furthermore includes a main nozzle 6 with a main nozzle throat in front of the tulip contact 10. The auxiliary nozzle throat is substantially between the main nozzle throat and the tulip contact 10. The inflow channel 4 is formed between the auxiliary nozzle 5 and the main nozzle 6. The nozzle 2 is made of an electrically insulating material, e.g. a polymer compound, e.g. including PTFE.

[0086] The tulip contact 10 comprises at least one contact section 12 having an inner contour 18 extending along a switching axis X between a tip 14 and a root 16 of the tulip contact 10.

[0087] The tulip contact 10 and the nozzle 2 are substantially annular and / or symmetrically shaped about the switching axis X. Particularly, the inner contour 18 defines an inner surface of the tulip contact 10 generated by revolving the contour 18 around the switching axis X.

[0088] The tulip contact 10 comprises a base 11 at the root 16, the base 11 having a ring-like shape or annular shape, said shape extending about the switching axis X. The at least one contact section 12 extends from the base 11.

[0089] Particularly, the at least one contact section 12 includes several contact sections 12 with the inner contour 18. The contact sections 12 extend from the base 11.

[0090] The base 11 may be formed by means of the nozzle 2 or may be connected to the nozzle 2 and / or to any metallic part that may hold the nozzle 2. The base 11 may be made of metal, e.g. a metal alloy including at least one of tungsten and copper.

[0091] The contact sections 12 extend along the switching axis X at least substantially in parallel to one another and are distributed about the switching axis X to form axially extending slits between one another. The slits are thus present in the inner surface.

[0092] From the tip 14 to the root 16 or in a downstream direction, the thickness T1, T2 of the at least one contact section 12 reduces at least substantially and particularly at least sectionally monotonically.

[0093] The thickness T1, T2 may overall decrease from tip 14 to root 16, but in general not necessarily monotonically in all locations; there can be portions of the at least one contact section 12 in which the thickness T1, T2 may increase in the downstream direction

[0094] The downstream direction can be seen from the right to the left or from the tip 14 to the root 16 in Fig. 1 or away from the pin contact 40 along the switching axis X. 'Downstream' relates to the typical flow of the quenching gas during operation.

[0095] The inner contour 18 is formed such that the cross-sectional area of a fluid duct delimited by it increases downstream along the switching axis X between the tip 14 and the root 16 and / or between a contact throat and the root 16.

[0096] The inner contour 18 forms the contact throat at or close to the tip 14.

[0097] The contact throat exhibits a first radius R1 in respect to the switching axis X. The first radius R1 defines a narrowest cross section of the contact throat.

[0098] The inner contour 18 comprises a first straight segment S1 and a first curved segment C1 adjacent to the first straight segment S1. At least one of the first curved segment C1 and the first straight segment S1 forms the contact throat. Particularly, the first straight segment S1 forms the contact throat.

[0099] The first curved segment C1 exhibits a curving radius RU defining a convexity of first curved segment C1 towards the switching axis X in a longitudinal sectional view, which view is shown. The curving radius RU is present from point of transition P1 to point of transition P2 as shown in Fig. 1 and / or along the switching direction X substantially along the entire length of the first curved segment C1.

[0100] A relationship between the curving radius RU and the first radius R1 may be predefined or limited, e.g. within a range. Particularly, it is provided that at least one of the following equations is true: 2 ≤ RU / R1 and RU / R1 ≤ 50, and especially 4 ≤ RU / R1 and RU / R1 ≤ 25.

[0101] The first straight segment S1 is arranged at an angle A1 between 0° and 20° with respect to the switching axis X for the contact throat to be conical in shape or to comprise a conicity, e.g. along the switching axis X. Here, the angle A1 is 3° ± 2°.

[0102] The inner contour 18 comprises a second curved segment C2 adjacent to the root 16. The second curved segment C2 is concave towards the switching axis X in the longitudinal sectional view. The second curved segment C2 transitions into the base 11, particularly continuously.

[0103] Here, the second curved segment C2 exhibits a second curving radius RV defining the concavity of the second curved segment towards the switching axis X in the longitudinal sectional view. It may be provided that the following equation is true: 1 ≤ RV / R1 .

[0104] The curvature or curving radius RU or RV of the curved segment C1 or C2 may be at least sectionally and / or at least substantially constant along the switching axis X.

[0105] The curving radius RU or RV may be at least substantially constant along the extension of the curved segment C1 or C2 or may change in some embodiments point by point, typically making C1 or C2 any arbitrary curve, e.g. an elliptic arc.

[0106] The inner contour 18 comprises a second straight segment S2 between the first curved segment C1 and the second curved segment C2. The second straight segment S2 transitions continuously on one side, namely at a point of transition P2, into the first curved segment C1 and transitions continuously on another side, namely at a point of transition P3, into the second curved segment C2.

[0107] At the points of transition P2, P3, the second straight segment S2 and the first curved segment C1 or the second curved segment C2, respectively, have substantially a same inclination with respect to the switching axis X so as to have the continuous transition. Generally this may be the case in certain or all points of transition, e.g. P1, P2, P3 or another, for adjacent segments, e.g. C3, S1, C1, S2, C2, C3, or another.

[0108] The second straight segment S2 is arranged at a further angle A2 between 3° and 18° with respect to the switching axis X. Here, the angle A2 is 13° ± 4°.

[0109] The first straight segment S1 transitions continuously on one side, namely at a point of transition P1, into the first curved segment C1 and on another side into a third curved segment or tip curved segment C3. The tip curved segment C3 is convex towards the switching axis X in the longitudinal sectional view. The tip curved segment C3 forms an entrance to the contact throat for the pin contact 40.

[0110] At the point of transition P1, the first straight segment S1 and the first curved segment C1 have substantially a same inclination with respect to the switching axis X so as to have the continuous transition.

[0111] The first straight segment S1 exhibits at the tip 14 the first radius R1 in respect to the switching axis X.

[0112] The point of transition P1 between the first straight segment S1 and the first curved segment C1 exhibits a second radius R2 in respect to the switching axis X.

[0113] The second curved segment C2 exhibits at the root 16 a third radius R3 in respect to the switching axis X.

[0114] Particularly, it is provided that the following equation is true: 1 ≤ R2 / R1, and especially 1.05 ≤ R2 / R1, and especially 1.1 ≤ R2 / R1.

[0115] Particularly, it is provided that at least one of the following equations is true: 1 ≤ R3 / R1 and R3 / R1 ≤ 4, and especially 1.25 ≤ R3 / R1 and R3 / R1 ≤ 3.3, and especially 1.5 ≤ R3 / R1 and / or R3 / R1 ≤ 2.5.

[0116] An extension of the first straight segment S1 along the switching axis X exhibits a first length L1.

[0117] Particularly, it is provided that at least one of the following equations is true: 0 ≤ L1 / R1 and L1 / R1 ≤ 2, and especially 0.01 ≤ L1 / R1 and / or L1 / R1 ≤ 1.8, and especially 0.5 ≤ L1 / R1 and / or L1 / R1 ≤ 1.5.

[0118] A summarized extension of the first curved segment C1 and optionally the second straight segment S2 and optionally the second curved segment C2 exhibits a second length L2.

[0119] Particularly, it is provided that at least one of the following equations is true: 1.5 ≤ L2 / R1 and L2 / R1 ≤ 15, and especially 2 ≤ L2 / R1 and / or L2 / R1 ≤ 12, and especially 3 ≤ L2 / R1 and / or L2 / R1 ≤ 7.

[0120] The inner contour 18 extends along the switching axis X between the tip 14 and the root 16 as a total extension L3. Here, the first length L1 is 20% ± 10% of the total extension L3.

[0121] Particularly, it is provided that at least one of the following equations is true: 0.01 ≤ L1 / L3 and L1 / L3 ≤ 0.75, and especially 0.5 ≤ L1 / L3 and / or L1 / L3 ≤ 0.3.

[0122] Furthermore, it may be provided that the second length L2 fulfils some criterion to be adequately designed for supersonic fluid flow. Particularly, it is provided that at least one of the following equations is true: 0.2 ≤ L2 / L3 and L2 / L3 ≤ 0.95, and especially 0.4 ≤ L2 / L3 and / or L2 / L3 ≤ 0.9, and especially 0.7 ≤ L2 / L3 and / or L2 / L3 ≤ 0.85.

[0123] A minimal thickness T1 and a maximal thickness T2 of the at least one contact section 12 in a radial direction Y are located between the tip 14 and the root 16.

[0124] The maximal thickness T2 can be at least 1.1 times and / or can be up to 4 times or up to 6 times larger than the minimal thickness T1.

[0125] Particularly, it is provided that at least one of the following equations is true: 1.1 ≤ T2 / T1 and T2 / T1 ≤ 6, and especially 2 ≤ T2 / T1 and T2 / T1 ≤ 3.5.

[0126] The pin contact 40 of the circuit-breaker 1 has a diameter corresponding to the contact throat, e.g. the diameter of the pin contact 40 being by up to 20% or up to 15% or up to 10% or up to 5% or less larger than two times or twice the first radius R1 as a diameter of the contact throat.

[0127] The circuit-breaker 1 is filled with a quenching gas. The quenching gas is free of SF6. Alternatively, the quenching gas may comprise SF6.

[0128] Shown and described is a use of a tulip contact 10 a circuit-breaker 1 that has a pin contact 40 with a diameter corresponding to the contact throat, , e.g. the diameter of the pin contact 40 being by up to 20% or up to 15% or up to 10% or up to 5% or less larger than two times or twice the first radius R1 as a diameter of the contact throat. The circuit-breaker 1 may be filled with a quenching gas that may be free of SF6 or may contain SF6.Reference signs list

[0129] 1circuit-breaker 2nozzle 3gas compression arrangement 4inflow channel 5auxiliary nozzle 6main nozzle 10tulip contact 11base 12contact section 14tip 16root 18inner contour 40pin contact A1-A2angle C1first curved segment C2second curved segment C3tip curved segment L1first length L2second length L3total extension P1point of transition R1first radius R2second radius R3third radius RUcurving radius RVsecond curving radius S1first straight segment S2second straight segment T1minimal thickness T2maximal thickness Xswitching axis Yradial direction

Claims

1. Tulip contact (10) for a gas-insulated circuit-breaker (1), comprising at least one contact section (12) having an inner contour (18) extending along a switching axis (X) between a tip (14) and a root (16), wherein the inner contour (18) forms a contact throat at the tip (14) and exhibits a first radius (R1) in respect to the switching axis (X) that defines a narrowest cross section of the contact throat; the inner contour (18) comprises a first curved segment (C1) and, optionally, adjacent to the first curved segment (C1) a first straight segment (S1), at least one of the first curved segment (C1) and the first straight segment (S1) form the contact throat; the first curved segment (C1) exhibits a curving radius (RU) defining a convexity of first curved segment (C1) towards the switching axis (X) in a longitudinal sectional view; and 1 ≤ RU / R1 and, optionally, RU / R1 ≤ 50.

2. Tulip contact (10) according to the preceding claim, wherein 2 ≤ RU / R1 or 4 ≤ RU / R1 and, optionally, RU / R1 ≤ 25.

3. Tulip contact (10) according to any one of the preceding claims, wherein the first straight segment (S1) is arranged at an angle (A1) of at least 0° and up to 20° with respect to the switching axis (X) for the contact throat to be cylindrical or conical in shape.

4. Tulip contact (10) according to any one of the preceding claims, wherein the inner contour (18) comprises a second curved segment (C2) adjacent to the root (16), the second curved segment (C2) being concave towards the switching axis (X) in the longitudinal sectional view.

5. Tulip contact (10) according to the preceding claim, a second straight segment (S2) between the first curved segment (C1) and the second curved segment (C2), wherein the second straight segment (S2) transitions continuously on one side into the first curved segment (C1) and on another side into the second curved segment (C2).

6. Tulip contact (10) according to any one of the preceding claims, wherein the second straight segment (S2) is arranged at a further angle (A2) of at least 3° and up to 18° with respect to the switching axis (X).

7. Tulip contact (10) according to any one of the preceding claims, wherein the first straight segment (S1) transitions continuously on one side into the first curved segment (C1) and on another side into a tip curved segment (C3) that is convex towards the switching axis (X) in the longitudinal sectional view.

8. Tulip contact (10) according to any one of claims 4 to 7, wherein a point of transition (P1) between the first straight segment (S1) and the first curved segment (C1) exhibits a second radius (R2) in respect to the switching axis, the second curved segment (C2) exhibits at the root (16) a third radius (R3) in respect to the switching axis (X), 1 ≤ R2 / R1, and 1 ≤ R3 / R1 and, optionally, R3 / R1 ≤ 4.

9. Tulip contact (10) according to any one of the preceding claims, wherein an extension of the first straight segment (S1) along the switching axis (X) exhibits a first length (L1), and 0 ≤ L1 / R1 and, optionally, L1 / R1 ≤ 2.

10. Tulip contact (10) according to any one of the preceding claims, wherein a summarized extension of the first curved segment (C1) and the second curved segment (C2) and optionally the second straight segment (S2) exhibits a second length (L2), and 1.5 ≤ L2 / R1 and, optionally, L2 / R1 ≤ 1511. Tulip contact (10) according to any one of the preceding claims, wherein an extension of the first straight segment (S1) along the switching axis (X) exhibits a / the first length (L1), the inner contour (18) extends along the switching axis (X) between the tip (14) and the root (16) as a total extension (L3), and 0 ≤ L1 / L3 and, optionally, L1 / L3 ≤ 0.75.

12. Tulip contact (10) according to any one of the preceding claims, wherein a minimal thickness (T1) and a maximal thickness (T2) of the at least one contact section (12) in a radial direction (Y) are located between the tip (14) and the root (16), and 1.1 ≤ T2 / T1 and, optionally, T2 / T1 ≤ 6.

13. Tulip contact (10) according to any one of the preceding claims, the tulip contact (10) comprising a base (11) at the root (16), the base (11) having a ring-like shape extending about the switching axis (X), the at least one contact section (12) including four or more contact sections (12) with the inner contour (18) and that extend from the base (11), the four or more contact sections (12) extending along the switching axis (X) at least substantially in parallel to one another and distributed about the switching axis (X) to form axially extending slits between one another.

14. Circuit-breaker (1) comprising a tulip contact (10) according to any one of the preceding claims and a pin contact (40) with a diameter corresponding to the contact throat, particularly the diameter of the pin contact (40) being equal to or larger than two times the first radius (R1), particularly wherein the circuit-breaker (1) is filled with a quenching gas that is free of SF6 or that includes SF6.

15. Use of a tulip contact (10) according to any one of claims 1 to 13 in a circuit-breaker (1) that has a pin contact (40) with a diameter corresponding to the contact throat, particularly the diameter of the pin contact (40) being equal to or larger than two times the first radius (R1), particularly wherein the circuit-breaker (1) is filled with a quenching gas that is free of SF6 or that includes SF6.

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