Electrical switching device

Abstract

The present invention relates to an electrical switching device (1) comprising: a nominal contact arrangement, an arc contact arrangement defining an arc volume (6) in which an arc quenching medium resides, a discharge system (2) comprising a first discharge opening (12a) fluidly connected to a tank volume (9), and a discharge channel (7) for dissipating a high-temperature medium from the arc volume (6) into the tank volume (9), the discharge system (2) further comprising a piston (18) disposed within a compression guide (16) and defining, together with the compression guide (16), a compression chamber (20) opposite the arc volume (6). An inlet channel (30) is fluidly connected to the compression chamber (20) and extends to an inlet opening (13) fluidly connected to the tank volume (9), the inlet channel (30) and the discharge channel (7) being fluidly isolated from each other.

Description

Technical Field

[0001] The present invention is in the field of medium-voltage and high-voltage switching technology, and in particular relates to an electrical switching device according to the independent claims for use as a grounding device, a rapid operating grounding device, a circuit breaker, a generator circuit breaker, a switch-disconnector, a combined circuit breaker and a grounding switch, or a load switch in a power transmission and distribution system.

Background Art

[0002] For the purposes of the present disclosure, the term medium voltage refers to voltages from 1 kV to 72.5 kV, and the term high voltage refers to voltages above 72.5 kV.

[0003] Electrical switching devices are well known in the field of medium-voltage and high-voltage switching applications. They are used, for example, to interrupt current when an electrical fault occurs. As an example of an electrical switching device, a circuit breaker has the role of opening its contacts and keeping the contacts far apart from each other to avoid the flow of current. Similar to the circuit breaker, the rating of the electrical switching device can carry a high nominal current of 2000 A to 6300 A and switch a very high short-circuit current of 10 kA to 100 kA at a very high voltage of 110 kV to 1200 kV.

[0004] When the nominal contacts of an electrical switching device are disconnected (opened), the current flowing through the electrical switching device transfers from the nominal contacts to its arcing contacts. Similarly, when the nominal contacts are connected (closed), the arcing contacts are connected in advance. In an embodiment, the arcing contacts comprise, as a first arcing contact, an arcing contact finger arranged around the longitudinal axis of the electrical switching device within a so-called arcing finger cage, and as a second arcing contact, a rod or pin driven within the finger cage.

[0005] During the opening process of an electrical switching device, an electric arc is formed between a first arc contact and a second arc contact, which is a region called the arc volume. This arc is conductive and carries current even after the opening or physical separation of the arc contacts. To interrupt the current, the electrical switching device includes a dielectrically inert fluid that is used as a dielectric insulating medium and that extinguishes the electric arc as quickly as possible.

[0006] Extinguishing the electric arc means extracting as much energy as possible from it. As a result, a portion of the fluid located in the region where the electric arc occurs is heated quite rapidly in a very short time (up to about 20,000 °C to 30,000 °C). Due to its volume expansion, this portion of the fluid increases the pressure and is discharged from the arc volume. In this way, the electric arc is blown away near the instant when the current becomes zero. The fluid flows into one or more discharge volumes, where it is cooled and redirected by a cooling device.

[0007] During the closing process of the electrical switching device, the first arc contact moves towards the second arc contact so as to be connected to each other, bringing a low pressure into the compression volume located behind the first arc contact. To compensate for this low pressure, fluid from a discharge system or tank is sucked into the compression volume by an open refill valve. From this compression volume, the fluid flows into the arc volume at a later stage.

[0008] European Patent Application Publication No. 0087578 discloses an electrical switching device comprising at least an arc contact configuration filled with a dielectric insulating medium and having a first arc contact and a mating second arc contact. At least a first intermediate volume is provided downstream of the first arc contact and / or at least a second intermediate volume is provided downstream of the second arc contact. During the closing process of the electrical switching device, fluid is directly sucked from the discharge system into the compression volume to compensate for the low pressure.

[0009] U.S. Patent Application Publication No. 2013 / 168357 discloses a circuit breaker having a fixed main contact and a movable main contact. A fixed arc contact is provided inside the fixed main contact, and a movable arc contact is provided inside the movable main contact. The circuit breaker includes a partition provided in a fixed cylinder on the movable side of the circuit breaker to form a space inside the fixed cylinder, a mechanical buffer chamber provided adjacent to one flange of the partition, and a high-temperature gas discharge chamber provided on the same side as the other flange of the partition. The fixed cylinder has a gas inlet hole that communicates with the space inside the fixed cylinder and is formed on one side with respect to a virtual plane that bisects the fixed cylinder in the radial direction. Further, the fixed cylinder has a gas outlet hole that communicates with the space inside the fixed cylinder, a high-temperature gas discharge opening that communicates with the high-temperature gas discharge chamber, further communicates with a buffer axial flow hole, and is formed on the other side with respect to the virtual plane in the radial direction of the fixed cylinder.

[0010] According to such a configuration, since the gas inlet hole and the high-temperature gas discharge opening are arranged as far apart as possible, the risk that the high-temperature and high-pressure gas discharged from the high-temperature gas discharge opening flows into the gas inlet hole can be reduced. U.S. Patent Application Publication No. 2013 / 168357 teaches that the high-temperature gas discharge opening is arranged on the opposite side of the current conductor, that is, at the lower part of the fixed cylinder and directed downward, and the gas inlet hole is arranged at the upper part of the fixed cylinder and directed upward.

[0011] European Patent Application Publication No. 3200214 discloses a gas-insulated circuit breaker including a fixed contact, a fixed arc contact, a movable arc contact, a movable contact, a hollow operating rod, and a nozzle. The movable contact includes a fixed cylinder portion, a movable piston portion, a fixed portion, a buffer chamber, a gas inlet portion, and a gas discharge portion. The gas discharge flows into the hollow operating rod and then into the gas discharge space. The gas discharge portion is provided to connect the buffer chamber and the gas discharge space and form a flow path for allowing gas to flow between the buffer chamber and the gas discharge space.

[0012] Japanese Patent Application Laid-Open No. 1-313827 discloses a gas-insulated circuit breaker including a fixed contact, a fixed arc contact, a movable arc contact, a drive rod, a movable contact, and a nozzle. The circuit breaker also includes a cylinder portion having a partition wall defining a buffer chamber and a high-temperature gas chamber, and a movable piston portion. The partition wall is provided with a plurality of communication holes and check valves such that the insulating gas flows only from the buffer chamber to the high-temperature gas chamber, and the insulating gas is introduced into the buffer chamber through an intake chamber having a gas inlet.

[0013] Normally, the fluid from the discharge volume, i.e., the exhaust gas, is not clean and contains arc dust as well as the generated particles that later enter the compression volume. It remains in the compression volume, and at a stage after the current is zero, the intermediate valve between the compression volume and the heating volume opens. The heating volume is fluidly connected to the arc volume, and as a result, the potentially contaminated fluid is led into the arc volume. This can cause a flashover or a post-strike that adversely affects the dielectric strength within the arc volume.

[0014] In certain embodiments of an electrical switching device such as a high-voltage circuit breaker (HVCB) surrounded by metal, the HVCB must be able to perform the O-0.3s-CO operation normally under various levels of short-circuit current stress for test duty. During the closing operation, a low pressure is generated within the compression volume to suck the arc extinguishing medium from the discharge system into the compression volume, and a post-strike may be observed.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] An object of the present invention is to provide an improved design having a new arc extinguishing medium that can be utilized to refill the compression volume within an electrical switching device.

MEANS FOR SOLVING THE PROBLEMS

[0016] This object is achieved by the subject matter of the independent claims. Embodiments are disclosed in the description together with the dependent claims, any combination of those claims, and the drawings.

[0017] The switching device means an electrical switching device and can include, for example, a high-voltage circuit breaker, a generator circuit breaker, a circuit breaker, a hybrid circuit breaker and an earthing switch, a load-breaking switch, an earthing device, or a rapid-acting earthing device.

[0018] An electrical switching device having a longitudinal axis and defining a tank volume is disclosed. The electrical switching device comprises a nominal contact configuration having a first nominal contact and a mating second nominal contact, preferably centered on the longitudinal axis, which are movable relative to each other parallel to the longitudinal axis and cooperate with each other to switch between the closed state and the open state of the switching device.

[0019] The electrical switching device also comprises an arc contact configuration having a first arc contact associated with the first nominal contact and a mating second arc contact, preferably centered on the longitudinal axis, associated with the second nominal contact, which are movable relative to each other parallel to the longitudinal axis and cooperate with each other to switch between the closed state and the open state.

[0020] The first arc contact and the second arc contact generate an arc during the switching between the closed state and the open state and define an arc volume in which an arc extinction medium is present. The arc extinction medium is used as a dielectric insulating medium and is a dielectrically inert fluid for extinguishing the electrical arc as quickly as possible.

[0021] Furthermore, the electrical switching device comprises an exhaust system surrounding the arc volume and separating the arc volume from the tank volume. The exhaust system comprises an exhaust channel designed to fluidly connect the arc volume to the tank volume and dissipate the hot arc extinction medium from the arc volume to the tank volume. This hot arc extinction medium is also referred to as exhaust gas in the present disclosure.

[0022] The discharge channel comprises an arc end opening into the arc volume and a first discharge opening opening into the tank volume. The first discharge opening is defined as the interface between the discharge system and the tank volume and represents the transition surface across which the discharge gas moves from the discharge system into the tank volume.

[0023] The discharge channel can comprise a plurality of elements fluidly connected to one another directly or via one or more intermediate volumes, which are commonly considered for optimizing the discharge gas flow and discharge gas cooling. The discharge channel can preferably be in the form of a discharge pipe centered on a longitudinal axis and can comprise a first channel element fluidly connecting the arc volume of the arc end opening and the first discharge volume on the discharge side of the discharge pipe, the first discharge volume being connected to and opening into the tank volume of the first discharge opening.

[0024] The discharge system further comprises a longitudinally extending compression guide and a piston preferably arranged slidably within the compression guide in an airtight manner. The piston can be at least partially formed by a first nominal contact. The piston has an open side facing the arc volume and, together with the compression guide on the side facing the arc volume, defines a heating chamber fluidly connected to the arc volume. The volume within the compression guide between the piston and the compression guide defines a compression chamber. The compression chamber is designed to be compressed in a compression stage by relative movement of the first arc contact and the second arc contact from a closed state to an open state when the piston and the first nominal contact move in a direction facing the arc region. Further, the compression chamber is designed to expand in an expansion stage by relative movement of the first arc contact and the second arc contact from an open state to a closed state when the piston and the first nominal contact move in the direction of the arc region.

[0025] The first nominal contact and the first arc contact are electrically connected to a first current conductor. The second nominal contact and the second arc contact are electrically connected to a second current conductor.

[0026] In an embodiment, the first nominal contact and the first arc contact are movable along the longitudinal axis, and the second nominal contact and the second arc contact are fixed. In this case, the first nominal contact and the first arc contact are connected to a first current conductor which is a movable-side current conductor. The second nominal contact and the second arc contact are electrically connected to a second current conductor which is a fixed-side current conductor.

[0027] In another embodiment, the first nominal contact and the first arc contact are fixed, and the second nominal contact and the second arc contact are movable along the longitudinal axis.

[0028] When viewed along the longitudinal axis, the first discharge opening is arranged on the side of the arc volume having a compression chamber. The discharge system can further comprise a second discharge opening arranged on the side of the arc volume facing the compression chamber. The first discharge opening is formed axially symmetrically with respect to the longitudinal axis, extends across the circumference of the discharge system, and can form a continuous slit in the discharge system. A similar arrangement is possible for the second discharge opening.

[0029] The compression chamber is fluidly connected to the tank volume by a fluid connection designed to allow passage of the arc extinguishing medium from the tank volume to the compression chamber during the expansion phase and from the compression chamber to the tank volume during the compression phase.

[0030] The inlet channel is fluidly connected to the compression chamber and extends to an inlet opening fluidly connected to the tank volume, and the inlet channel and the discharge channel are fluidly separated from each other. During the expansion phase, the arc extinguishing medium sucked through the inlet opening can replenish the tank volume from the compression volume. As a result, the separation of the inlet channel and the discharge channel prevents the compression volume from being replenished by the arc extinguishing medium containing arc dust coming from the discharge system. As a result, the clean and cold arc extinguishing medium replenished in the compression volume enters the arc volume at a later stage. Consequently, this helps to reduce the possibility of late restrikes and increase the dielectric strength by the cleaner arc extinguishing medium reaching the arc volume.

[0031] During the compression stage, instead of being mixed with the exhaust gas in the exhaust system, the arc extinguishing medium is released directly from the compression volume into the volume tank.

[0032] The separation of the inlet channel and the discharge channel should be understood such that, except for leakage between the assembled parts of the electrical switching device, the arc extinguishing medium flowing in or through the discharge channel can reach the inlet channel only when it first flows through the volume tank.

[0033] The clean arc extinguishing medium should be understood as the arc extinguishing medium from the tank volume, in contrast to the arc extinguishing medium present in the exhaust system, i.e., the exhaust gas containing arc dust. The exhaust gas reaches the tank volume at one point after the separation of the arc contacts. However, the arc dust separates from the exhaust gas in the tank volume and accumulates in the wall region of the tank volume. As a result, the arc extinguishing medium in the tank volume gradually decreases in arc dust content over time.

[0034] According to the present invention, the inlet channel is directed downward at the use position of the electrical switching device. This arrangement reduces the amount of arc dust that may accumulate on the inner wall of the inlet channel. The inner wall of the inlet channel is defined as the wall that contacts the arc extinguishing medium flowing between the compression chamber and the tank volume. As a result, this arrangement further reduces the amount of arc dust that can enter the compression chamber at a later stage. This helps to further reduce the possibility of late restrikes and contributes to an increase in dielectric strength due to the cleaner arc extinguishing medium reaching the arc volume.

[0035] The use position of the electrical switching device corresponds to its mounting position for on-site use. When the use position corresponds to a longitudinal axis extending in the horizontal direction, it should be understood that the downward direction extends in the direction of gravity. At the use position, a first conductor that can be a moving-side current conductor and a second conductor that can be a fixed-side current conductor are arranged on the side opposite to the direction of gravity of the electrical switching device.

[0036] Furthermore, according to the present invention, the inlet opening is arranged behind the first discharge opening when viewed in the direction facing the arc region along the longitudinal axis (z). With this arrangement, in the region where the inlet opening is adjacent to the first discharge opening, the exhaust gas flowing from the exhaust system into the inlet channel is reduced. In this region, the exhaust gas can flow into the tank volume and then flow into the inlet channel through the adjacent inlet opening. Preferably, the inlet opening and the first discharge opening have no overlapping region in order to minimize the above-described interaction.

[0037] In a preferred embodiment, the inlet channel can be directly fluid-connected to the compression chamber and can extend from the compression chamber to the inlet opening. In an embodiment, the inlet channel can be fluid-connected to a connection chamber, extend from the connection chamber to the inlet opening, and the connection chamber is fluid-connected to the compression chamber. This subsequent arrangement has the advantage that the interface geometry between the compression chamber and the connection chamber can be designed independently of the geometry of the inlet channel, providing more flexibility in the design of the electrical switching device.

[0038] In a preferred embodiment, the inlet channel can be formed as a hollow spoke to keep the design simple.

[0039] In a preferred embodiment, the inlet channel extends inclined with respect to the longitudinal axis radially outward when viewed in the direction facing the arc region. In other words, the inlet channel axis of the inlet channel extends such that the distance from the longitudinal axis increases as viewed in the direction of the arc extinguishing medium flowing out of the compression chamber in the compression stage. This embodiment has the advantage that fresh cryogenic arc extinguishing medium is guided into the inlet channel in an improved manner.

[0040] "Inclined" in the present disclosure also includes a direction "perpendicular to the longitudinal axis". For this purpose, the inclination angle of the inlet channel axis with respect to the longitudinal axis can be in the range of 5° to 85°, preferably in the range of 30° to 60°, more preferably about 45°. These ranges result in an efficient guidance of the fresh cryogenic arc extinguishing medium, but in the range of 30° to 60°, an improved result has been found that the vicinity of 45° is optimal.

[0041] Also, embodiments are conceivable in which the inlet channel is oriented upward at the use position of the electrical switching device. Since the arc dust separates and accumulates under the influence of gravity on the lower inner wall of the tank volume, i.e., the bottom, the upward orientation of the inlet channel has the advantage of further increasing the distance from the inlet opening to the accumulated arc dust.

[0042] The choice of the upward or downward direction of the inlet channel may depend on the structure of the tank volume and the discharge system that affect the accumulation site of the arc dust. For the same reason, embodiments are also conceivable in which the inlet channel is oriented downward and a further inlet channel is oriented upward.

[0043] In a preferred embodiment, without increasing the size of each inlet opening, a plurality of inlet channels each having an inlet opening that together form the plurality of inlet openings can be provided to increase the amount of arc extinguishing medium flowing between the tank volume and the compression chamber. As a result, more arc extinguishing medium can flow, but the amount of arc dust sucked in does not increase much. Preferably, the inlet opening is formed as a hollow spoke for simplicity of design.

[0044] In a preferred embodiment, the plurality of inlet channels and the corresponding plurality of inlet openings are circumferentially distributed axially symmetrically with respect to the longitudinal axis. This arrangement provides efficient guidance of the fresh cryogenic arc extinguishing medium.

[0045] However, if the structure of the discharge system, for example, does not allow a symmetric arrangement, it is also possible to arrange the plurality of inlet channels asymmetrically.

[0046] In a preferred embodiment, the plurality of inlet channels and the corresponding plurality of inlet openings are symmetrically distributed circumferentially with respect to the longitudinal axis and symmetrically with respect to the longitudinal symmetry plane. This arrangement allows for a simple design.

[0047] In a preferred embodiment, the plurality of inlet openings are directed downward at the use position of the electrical switching device. The advantages of this arrangement have already been described in detail above. This orientation reduces the amount of arc dust that may enter and accumulate on the inner wall of the inlet channel. This helps to reduce the likelihood of late restrikes and increases the dielectric strength by allowing a cleaner arc extinguishing medium to reach the arc volume.

[0048] As a result, in a preferred embodiment, the same number of inlet channels are arranged on both sides of the central inlet channel. This arrangement allows for a simple design, and the advantages have been described above.

[0049] In a preferred embodiment, the longitudinal symmetry plane can be oriented vertically. In this arrangement, the arc dust is uniformly segregated on both sides of the longitudinal symmetry plane under the influence of gravity. Further, in an embodiment where the longitudinal symmetry plane extends through the central inlet channel of the plurality of inlet channels, the central channel and its corresponding inlet opening are arranged at the lowest position with respect to the plurality of inlet channels and inlet openings. Therefore, the intrusion of arc dust is minimized.

[0050] In a preferred embodiment, the plurality of channel openings are circumferentially distributed with respect to the longitudinal axis within a circular sector having a central angle α in the range of 5° to 180° as measured in a plane perpendicular to the longitudinal axis. The circular sector defines an angular opening within which the plurality of channel openings are circumferentially distributed. These angular sectors minimize the arc dust entering the inlet channels. At a preferred angle α in the range of 60° to 120°, a further reduction in the arc dust entering the inlet channels can be shown while still presenting the necessary mechanical stability near the inlet channels. The range of 45° to 90° for the angle α is more preferred to further optimize this aspect.

[0051] In embodiments having a longitudinal symmetry plane, the circular sector consequently extends equally on both sides of the longitudinal symmetry plane. In this case, an angular sector of 60° means that the plurality of channel openings are circumferentially distributed over 30° on each side of the longitudinal symmetry plane.

[0052] In a preferred embodiment, the plurality of channel openings can be circumferentially distributed, and at least one of the channel openings is axially offset with respect to the other channel openings. This arrangement allows the channel openings to be arranged within a narrow circular sector of 60° to 30° without reducing the circumferential distance between successive inlet openings so that the structure supporting the inlet openings is not weakened and the mechanical stability is improved.

[0053] In a preferred embodiment, the inlet opening and the plurality of inlet openings are each fluidly connected to a replenishment valve designed to allow the arc quenching medium to pass from the tank volume to the compression chamber and an overpressure valve designed to allow the arc quenching medium to pass from the compression chamber to the tank volume.

[0054] In a preferred embodiment, the electric switching device comprises a channel element adjacent to the compression chamber on the side opposite the arc volume, in which the inlet opening and the plurality of inlet openings are respectively formed.

[0055] In a preferred embodiment, the channel element is formed as a hollow conduit, preferably formed cylindrically, which defines a connection chamber having side walls. The connection chamber is designed to be fluidly connected to the compression chamber at the conduit end. The opposite end is hermetically closed so as not to be in fluid communication with the discharge system. The side walls have a plurality of windows from which each time one inlet channel extends radially outwards to form a plurality of inlet channels. Each inlet channel extends through the side wall to a corresponding inlet opening to form a plurality of inlet openings. It is also possible to design the inlet channels to extend downwards and outwards in the use position of the electric switching device. Providing the channel element has the advantage that the design of the electric switching device can be easily adapted to different discharge configurations by adjusting only the geometric shape of the channel element.

[0056] In a preferred embodiment, the arc quenching medium is a dielectric insulating medium containing an organic fluorine compound selected from the group consisting of SF6 and / or CO2 and / or fluoroethers, oxiranes, fluoroamines, fluoroketones, fluoroolefins, fluoronitriles, and mixtures and / or decomposition products thereof.

[0057] For the purposes of the present disclosure, the arc quenching medium used in an electrical switching device may be SF6 gas or any other dielectric insulating medium, which may be gaseous and / or liquid, in particular a dielectric insulating gas or an arc quenching gas. Such a dielectric insulating medium may include, for example, a medium containing an organic fluorine compound, and such an organic fluorine compound is selected from the group consisting of fluoroethers, oxiranes, fluoroamines, fluoroketones, fluoroolefins and mixtures and / or decomposition products thereof. As used herein, the terms "fluoroether", "oxirane", "fluoroamine", "fluoroketone" and "fluoroolefin" refer to at least partially fluorinated compounds. In particular, the term "fluoroether" includes both hydrofluoroethers and perfluoroethers, the term "oxirane" includes both hydrofluorooxiranes and perfluorooxiranes, the term "fluoroamine" includes both hydrofluoroamines and perfluoroamines, the term "fluoroketone" includes both hydrofluoroketones and perfluoroketones, and the term "fluoroolefin" includes both hydrofluoroolefins and perfluoroolefins. Thereby, fluoroethers, oxiranes, fluoroamines and fluoroketones may preferably be fully fluorinated, i.e., perfluorinated.

[0058] In high-voltage or medium-voltage switching devices, the arc quenching medium may decompose when heated above a certain level, which may be encountered under certain operating conditions. This decomposition is undesirable as it reduces the insulating properties of the arc quenching medium. SF6 has the property that when cooled, it recombines, thereby substantially restoring its full dielectric properties and having a positive effect on the performance of the electrical switching device.

[0059] In an embodiment, the arc extinction medium is selected from the group consisting of one (or several) hydrofluoroethers, one (or several) perfluoroketones, one (or several) hydrofluoroolefins, and mixtures thereof.

[0060] In particular, the term "fluoroketone" as used in the context of the present invention should be construed broadly and shall include both fluoromono-ketones and fluorodiketones or generally fluoropolyketones. Explicitly, one or more carbonyl groups adjacent to a carbon atom may be present in the molecule. The term shall also include both saturated and unsaturated compounds containing double and / or triple bonds between carbon atoms. The at least partially fluorinated alkyl chain of the fluoroketone may be linear or branched and may optionally form a ring.

[0061] In an embodiment, the arc extinction medium is a fluoromono-ketone and / or comprises at least one compound containing at least one heteroatom incorporated into the carbon skeleton of the molecule, such as a nitrogen atom, an oxygen atom, and a sulfur atom replacing one or more carbon atoms. More preferably, the fluoromono-ketone, in particular the perfluoroketone, can have 3 to 15 or 4 to 12 carbon atoms, especially 5 to 9 carbon atoms. Most preferably, it may contain exactly 5 carbon atoms and / or exactly 6 carbon atoms and / or exactly 7 carbon atoms and / or exactly 8 carbon atoms.

[0062] In an embodiment, the arc extinction medium comprises at least one compound that is a fluoroolefin selected from the group consisting of hydrofluoroolefins (HFOs) containing at least 3 carbon atoms, hydrofluoroolefins (HFOs) containing exactly 3 carbon atoms, trans-1,3,3,3-tetrafluoro-1-propene (HFO-1234ze), 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), and mixtures thereof.

[0063] The dielectric insulating medium can further contain a background gas or carrier gas different from the organic fluorine compound (in particular, different from fluoroethers, oxiranes, fluoroamines, fluoroketones, and fluoroolefins), and in embodiments, can be selected from the group consisting of air, N2, O2, CO2, noble gases, H2; NO2, NO, N2, O; fluorocarbons, in particular perfluorocarbons such as CF4; CF3I, SF6; and mixtures thereof.

[0064] In a preferred embodiment, the organic fluorine compound is selected from the group consisting of perfluoroethers, hydrofluoroethers, perfluoroamines, perfluoroketones, perfluoroolefins, hydrofluoroolefins, perfluoronitriles, and mixtures thereof, and in particular, in a mixture with a background gas, more specifically, in a mixture with a background gas compound selected from the group consisting of air, air components, nitrogen, oxygen, carbon dioxide, and nitrogen oxides.

[0065] In a preferred embodiment, the organic fluorine compound is a fluoroketone having 4 to 15 carbon atoms, and in particular, the fluoroketone is selected from the group consisting of a fluoroketone having exactly 5 carbon atoms, a fluoroketone having exactly 6 carbon atoms, a fluoroketone having exactly 7 carbon atoms, and a fluoroketone having exactly 8 carbon atoms, and such a fluoroketone having at least one of the above carbon atoms is replaced by a heteroatom, in particular by nitrogen and / or oxygen and / or sulfur, and mixtures thereof, and / or the perfluoronitrile is a perfluoronitrile containing 2, 3, or 4 carbon atoms, and in particular, a perfluoroalkyl nitrile, specifically, perfluoroacetonitrile, perfluoropropionitrile (C2F5CN) and / or perfluorobutyronitrile (C3F7CN), and more specifically, perfluoroisobutyronitrile according to the formula (CF3)2CFCN and / or perfluoro-2-methoxypropanenitrile according to the formula CF3CF(OCF3)CN.

[0066] In an embodiment, the fluoronitrile is in a mixture with an organofluorine compound selected from the group consisting of fluoroethers, oxiranes, fluoroamines, fluoroketones, fluoroolefins, and mixtures and / or decomposition products thereof, and in particular, the fluoronitrile is in a mixture with a background gas, and more specifically, in a mixture with a background gas compound selected from the group consisting of air, air components, nitrogen, oxygen, carbon dioxide, and nitrogen oxides.

[0067] Sulfur hexafluoride (SF6) is a well-established insulating gas due to its excellent dielectric properties and its chemical inertness. Despite these properties, efforts to find alternative insulating gases are being intensified, considering alternatives having a lower global warming potential (GWP) than that of SF6 in particular.

[0068] Considering providing non-SF6 alternatives, it has been proposed to use organofluorine compounds as dielectric insulating media. Specifically, WO 2010 / 142346 pamphlet proposes a dielectric insulating medium containing a fluoroketone containing 4 to 12 carbon atoms.

[0069] Fluoroketones have been shown to have a high dielectric strength. At the same time, they have a very low global warming potential (GWP) and a very low toxicity. This combination of features makes fluoroketones a viable alternative to SF6.

[0070] A further development in this regard is reflected in WO 2012 / 080246 pamphlet, which suggests a dielectric insulating gas containing a fluoroketone containing exactly 5 carbon atoms, in particular 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-butan-2-one, in a mixture with a carrier gas, in particular air or air components, and this fluoroketone, together with the fluoroketone, results in a non-linear increase in the dielectric strength of the insulating medium with respect to the sum of the dielectric strengths of the gas components of the insulating medium.

[0071] Further attempts to find another "non-SF6" insulating medium are reflected in WO 2013 / 151741 pamphlet, which suggests using heptafluoroisobutyronitrile, (CF3)2CFCN, or 2,3,3,3-tetrafluoro-2-(trifluoromethoxy) propanenitrile (CF3CF(OCF3)CN) as the dielectric fluid.

[0072] WO 2015 / 040069 specification describes a medium voltage or high voltage electrical device comprising a housing containing a gaseous medium comprising heptafluoroisobutyronitrile, carbon dioxide and oxygen.

[0073] Description of the Drawings Embodiments, advantages, and uses of the present invention are obtained from the dependent claims, combinations of claims, as well as the following description and drawings. The drawings are as follows.

Brief Description of the Drawings

[0074]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0075] FIG. 1 shows a cross-sectional view of an embodiment of a high voltage circuit breaker 1 in an open configuration. The high voltage circuit breaker 1 shown is an exemplary embodiment of an electrical switching device according to the present invention. Elements of the circuit breaker related to the present invention will be described, but a detailed description of the operating principle of the circuit breaker 1 will be omitted.

[0076] The electrical switching device 1 can be essentially rotationally symmetric with respect to the longitudinal axis z. A purely exemplary high-voltage circuit breaker 1 is usually cylindrical and is arranged around the longitudinal axis z and is surrounded by an external enclosure 5 that defines a volume tank 9. The electrical switching device 1 includes a nominal contact configuration 3a, 3b having a first nominal contact with a plurality of contact fingers 3a, and only two of the fingers are shown here for clarity. The nominal contact fingers 3a are formed as a finger cage around the longitudinal axis z. The nominal contact configuration further includes a second mating nominal contact 3b that is coaxially arranged around the nominal contact fingers 3a and the longitudinal axis z and is usually a metal tube. The shield 5a can be arranged around the first and second nominal contacts 3a, 3b.

[0077] The switching device 1 further includes an arc contact configuration 4a, 4b having a first arc contact 4a and a second arc contact 4b coaxially arranged around the first arc contact 4a and the longitudinal axis z. Similar to the first nominal contact 3a, the first arc contact 4a also includes a plurality of fingers 4a arranged in the finger cage. The second arc contact 4b is usually rod-shaped.

[0078] The contact fingers 3a, 4a are movable relative to the contacts 3b, 4b from a closed configuration in which they are in electrical contact with each other to an open configuration shown in FIG. 1 in which they are separated from each other and vice versa.

[0079] For the purpose of explaining the present invention, it is assumed that only the first nominal contact 3a and the first arc contact 4a are movable along the longitudinal axis z, and the second nominal contact 3b and the second arc contact 4b are stationary. However, the present invention is not limited to this configuration.

[0080] The first nominal contact 3a and the first arc contact 4a are connected to the movable-side current conductor 15. The second nominal contact 3b and the second arc contact 4b are electrically connected to the fixed-side current conductor 14.

[0081] As used herein, "closed configuration" means that the nominal contacts and / or arc contacts of the electrical switching device 1 are closed, i.e., in contact with each other. Thus, as used herein, "open configuration" means that the nominal contacts and / or arc contacts of the electrical switching device 1 are open, i.e., separated.

[0082] As described above, the electrical switching device 1 is shown in FIG. 1 during the opening process at the moment when the electrical arc 3 still exists between the arc contacts 4a and 4b because the distance between the arc contacts 4a and 4b is still very small. In the present disclosure, the volume around the electrical arc 3 is referred to as the arc volume 6.

[0083] Furthermore, the switching contact 1 is coaxially arranged around the longitudinal axis z and includes a nozzle 6a surrounding the arc volume 6 such that when the switching device 1 is closed, the contact positions of the arc contacts 4a and 4b are arranged within the nozzle 6a.

[0084] The first arc contact 4a is attached to a discharge pipe 7a that is fluidly connected to the arc-side arc volume 6 of the discharge pipe 7 and the discharge side of the discharge pipe 7, i.e., the first discharge volume 7' on the side of the switching device 1 having the first arc contact 4a and opposite to the arc volume 6 of the discharge pipe.

[0085] Thus, the first discharge volume 7' is arranged downstream of the arc volume 6 when viewed in the direction of the discharge gas flowing out of the arc volume 6 on the first side of the switching device 1 having the first arc contact 4a. The first discharge volume 7' is surrounded by a first wall 7b and includes a first discharge gas passage 11a for receiving the discharge gas coming from the discharge pipe 7 and a first discharge opening 12a for discharging the discharge gas in the tank volume 9 defined by the enclosure 5.

[0086] The second discharge volume 8' is arranged downstream of the arc volume 6 when viewed in the direction of the discharge gas flowing out of the arc volume 6 on the second side of the switching device 1 having the second arc contact 4b. The second discharge volume 8' is surrounded by a second wall 8b and includes a second discharge gas passage 11b for receiving the discharge gas coming from the arc region 6. The second discharge volume 8' has a second discharge opening 12b fluidly connected to the tank volume 9.

[0087] In this embodiment, the second discharge volume 8' includes an intermediate volume 8 surrounded by an intermediate wall 8a fluidly connected to the second discharge gas passage 11b and the second discharge opening 12b.

[0088] The discharge pipe 7, the first discharge volume 7', the second discharge volume 8', and the intermediate volume 8 form a discharge system surrounding the arc volume 6. The discharge pipe 7a and the first discharge volume 7' form a discharge channel 7 fluidly connecting the arc volume 6 to the first discharge opening 12a.

[0089] The enclosure 5 and the tank volume 9 at least partially, or in this case completely, surround the discharge system.

[0090] The discharge system further includes a longitudinally extending compression guide 16 and a piston 18 slidably disposed within the compression guide 16 in an airtight manner. The piston is at least partially formed by the first nominal contact 3a. The piston 18 has an open side facing the arc volume 6, and together with the compression guide 16 on the side facing the arc volume 6, defines a heating chamber 10 fluidly connected to the arc volume 6. The volume within the compression guide 16 between the piston 18 and the compression guide 16 defines a compression chamber 20. The heating chamber 10 is fluidly connected to the compression chamber 20 by a separation valve 22.

[0091] In FIG. 1, the second arc contact 4b no longer mates with the first arc contact 4a at least partially formed by the discharge pipe 7. Thus, the arc extinguishing medium can flow from the heating chamber 10 through the nozzle 6a and the discharge pipe 7a in the direction of the tank volume 9.

[0092] In this embodiment, the discharge pipe 7a extends longitudinally about the longitudinal axis z through the piston bottom wall, and the discharge pipe 7a is airtightly and firmly connected. The discharge pipe 7a further extends slidably in an airtight manner through the bottom wall 70 of the compression chamber and opens into the first discharge volume 7'.

[0093] A plurality of inlet channels 30 in the form of hollow spokes are fluidly connected to the compression chamber 20, each extending from the compression chamber 20 to the inlet openings 13 and forming a plurality of inlet openings 13 fluidly connected to the tank volume 9. As seen in FIG. 1, only one inlet channel 30 and one inlet opening 13 are shown. The inlet channel 30 and the discharge channel 7 are fluidly separated from each other. In the expansion phase, the arc extinguishing medium sucked through the inlet opening 13 can replenish the compression volume 20 from the tank volume 9.

[0094] The inlet channel 30 is directed downward in the use position of the electric switching device 1. This orientation reduces the amount of arc dust that can accumulate on the inner wall of the inlet channel 30. As a result, the amount of arc dust that can enter the compression chamber 20 at a later stage is further reduced.

[0095] The use position of the electric switching device 1 corresponds to the mounting position of the electric switching device 1 for on-site use. In this case, the use position corresponds to the longitudinal axis z extending horizontally, and the downward direction should be understood to extend in the direction of gravity. In the use position, the moving-side current conductor 15 and the fixed-side current conductor 14 are arranged on the side opposite to the direction of gravity of the electric switching device 1. The inlet opening 13 is arranged behind the first discharge opening 12a when viewed in the direction facing the arc region 6 along the longitudinal axis (z). This arrangement reduces the discharge gas flowing from the discharge system into the inlet channel 30 in the region where the inlet opening 13 is adjacent to the first discharge opening 12a.

[0096] Specifically, the compression chamber 20 is fluidly connected to the plurality of inlet openings 13 via a replenishment valve 24 and an overpressure valve 26 arranged on the bottom wall 70 of the compression chamber. The replenishment valve 24 is designed to allow the passage of the arc extinguishing medium from the tank volume 9 into the compression chamber 20, and the overpressure valve 26 is provided to allow the passage of the arc extinguishing medium from the compression chamber 20 into the tank volume 9.

[0097] The electrical switching device 1 comprises a channel element 23 adjacent to the compression guide 16 on the side opposite to the arc volume 6, in which the plurality of inlet openings 13 are formed so as to have no fluid connection with the discharge channel 7. The channel element 23 is arranged between the compression guide 16 and the discharge end of a discharge pipe 7a which extends through the channel element 23 in a gastight and slidable manner.

[0098] Referring to FIG. 2, an exemplary embodiment of the channel element 23 disassembled from the electrical switching device 1 according to the invention is shown. The channel element 23 has a substantially cylindrical symmetry with respect to the longitudinal axis z of the switching device 1. This is formed as a hollow cylindrical conduit 60 defining a connection chamber 66 having a side wall 60a.

[0099] The channel element 23 comprises a first flange 62 arranged at the end of the conduit on the side opposite to the arc volume 6 for fixing the channel element 23 to the support structure of the electrical switching device 1. In this embodiment, the support structure includes the wall 68 shown in FIG. 1 and forms a separation between the connection chamber 66 and the discharge system 2, here specifically the first discharge volume 7'. It also comprises a second flange 64 arranged at the end of the conduit facing the arc volume 6 for fixing the channel element 23 to the compression guide 16 and enabling the fluid connection of the connection chamber 66 to the compression chamber 20.

[0100] The end of the conduit facing the arc volume 6 allows the passage of the discharge pipe 7a and the displacement of the discharge pipe 7a along the longitudinal axis z together with the piston 18. In the mounted state of the channel element 23, the discharge pipe 7a has no fluid connection with the connection chamber 66. In other words, the fluid flowing through the discharge pipe 7a, for example the exhaust gas, cannot flow into the connection chamber 66.

[0101] Furthermore, the conduit end facing the arc volume 6 is designed to enable fluid connection of the connection chamber 66 to the compression chamber 20, as described above. The fluid connection can be effected by means of a replenishment valve 24 and an overpressure valve 26 provided in the compression chamber bottom wall 70.

[0102] The inside of the side wall 60a has a plurality of windows 72a, 72b and 72c, from each of which one inlet channel 30 extends radially outwards in each case, forming a plurality of inlet channels 30. Each inlet channel 30 extends through the side wall 60a to a corresponding inlet opening 13, forming a plurality of inlet openings 13. The inlet channels 30 are formed as hollow spokes fluidly connecting the internal volume of the channel element 23 to the tank volume 9, each projecting radially outwards from the side wall 60a from the windows 72a, 72b and 72c.

[0103] The embodiment shown in FIG. 2 has three essentially rectangular windows extending along the longitudinal axis z, arranged symmetrically with respect to the longitudinal symmetry plane extending through the central window 72a of the plurality of windows. The plurality of windows are arranged symmetrically with respect to the symmetry plane in an angular sector α (alpha) of approximately 90°. Measured circumferentially, the transparent opening of each window can be in the range of an angle β (beta) of 5° to 10°. Currently, the windows 72a, 72b, and 72c are identically formed and are spaced equidistantly from each other by an angular sector γ (gamma) of approximately 45°. The corresponding inlet openings 13, not visible in the perspective view of FIG. 2, are in this embodiment distributed in the same geometric shape at the other end of each inlet channel on the outside of the side wall 60a, i.e. on the side of the side wall 60a facing the tank volume 9.

Description of the reference signs

[0104] List of reference signs 1 Circuit breaker 2 Discharge system 3 Electric arc 3a Contact finger of the first nominal contact 3b Second nominal contact 4a First arc contact 4b Second arc contact 5 Enclosure 5a Shield 6 Arc volume 7’ First discharge volume 7 Discharge channel 7a Discharge pipe 7b Wall of the first discharge volume 8 Second intermediate volume 8’ Second discharge volume 8a Wall of the second intermediate volume 8b Wall of the second discharge volume 9 Tank volume 10 Heating chamber 11a First discharge passage 11b Second discharge passage 12a First discharge opening 12b Second discharge opening 13 Inlet opening 14 Fixed-side current conductor 15 Moving-side current conductor 16 Compression guide 18 Piston 20 Compression chamber 22 Separation valve 23 Channel element 24 Supplementary valve 26 Overpressure valve 30 Inlet channel, spoke 60 Cylindrical conduit 60a Side wall 62 First flange 64 Second flange 66 Connection chamber 70 Compression chamber bottom wall 72a, 72b, 72c Windows in side wall 60a

Claims

1. An electrical switching device (1) having a longitudinal axis (z) and defining a tank volume (9), A nominal contact configuration having a first nominal contact (3a) and a mating second nominal contact (3b) that are movable relative to each other parallel to the longitudinal axis (z) and cooperate with each other to switch between the closed and open states of the switching device (1); An arc contact configuration having a first arc contact (4a) associated with the first nominal contact (3a) and a mating second arc contact (4b) associated with the second nominal contact (3b) that are movable relative to each other parallel to the longitudinal axis and cooperate with each other to switch between the closed and open states, wherein the first arc contact (4a) and the second arc contact (4b) define an arc volume (6) in which an arc (3) occurs during switching between the closed and open states and in which an arc extinguishing medium is present; An exhaust system (2) surrounding the arc volume (6), A first discharge opening (12a) fluidly connected to the tank volume (9), An exhaust channel (7) extending from the arc volume (6) to the first discharge opening (12a), The exhaust channel (7) is designed to dissipate a hot arc extinguishing medium from the arc volume (6) through the first discharge opening (12a) into the tank volume (9), The exhaust system (2) includes A compression guide (16) extending along the longitudinal axis (z), A piston (18) slidably disposed within the compression guide (16) that, together with the compression guide (16), defines a heating chamber (10) fluidly connected to the arc volume (6) on the side facing the arc volume (6) and a compression chamber (20) fluidly connected to the tank volume (9) on the side opposite the arc volume (6). An inlet channel (30) fluidly connected to the compression chamber (20) and extending to an inlet opening (13) fluidly connected to the tank volume (9), wherein the inlet channel (30) and the discharge channel (7) are fluidly separated from each other, the inlet channel (30) extends radially outward in a direction facing the arc volume (6) and is inclined with respect to the longitudinal axis (z), and the inlet channel (30) is directed downward in the use position of the electric switching device (1), the use position corresponding to the longitudinal axis (z) extending horizontally, the downward direction being defined as the direction extending in the direction of gravity, characterized in that, when viewed in the direction facing the arc volume (6) along the longitudinal axis (z), the inlet opening (13) is arranged behind the first discharge opening (12a), further comprising an inlet channel (30). An electric switching device (1) comprising a discharge system (2). Claim 2 The electric switching device (1) according to claim 1, characterized in that the inlet opening (13) is arranged behind the first discharge opening (12a) without overlapping regions with each other. Claim 3 The electric switching device (1) according to claim 1 or 2, characterized by a plurality of inlet channels (30) formed as hollow spokes. Claim 4 The electric switching device (1) according to claim 3, characterized in that the plurality of inlet channels (30) are distributed circumferentially in an axisymmetric manner with respect to the longitudinal axis (z). Claim 5 The electric switching device (1) according to claim 3, characterized in that the plurality of inlet channels (30) are distributed symmetrically in the circumferential direction with respect to the longitudinal axis (z) with respect to a longitudinal symmetry plane extending through the central inlet channel (30) of the plurality of inlet channels (30), and the plurality of inlet channels (30) have corresponding plurality of inlet openings (13). Claim 6 The electric switching device (1) according to claim 5, characterized in that the plurality of inlet openings (13) are directed downward in the use position of the electric switching device (1). Claim 7 The plurality of inlet channels (30) are circumferentially distributed with respect to the longitudinal axis (z) within a circular sector having a central angle α in the range of 5° to 180° as measured in a plane perpendicular to the longitudinal axis (z), the electrical switching device (1) according to claim 5 or 6.

8. The inlet opening (13) and the inlet channel (30) are each fluidly connected to a replenishment valve (24) designed to allow the arc quenching medium to pass from the tank volume (9) to the compression chamber (20), and an overpressure valve (26) designed to allow the arc quenching medium to pass from the compression chamber (20) to the tank volume (9), the electrical switching device (1) according to any one of claims 1 to 7.

9. A channel element (23) adjacent to the compression chamber (20) on the side opposite to the arc volume (6), wherein the inlet opening (13) and the inlet channel (30) are each formed therein, the electrical switching device (1) according to any one of claims 1 to 8.

10. The arc extinguishing medium is SF ６ , and / or CO ２ and / or a dielectric insulating medium containing an organic fluorine compound selected from the group consisting of fluoroethers, fluoroamines, fluoroketones, fluoroolefins, fluoronitriles, and mixtures and / or decomposition products thereof, characterized in that it is an electric switching device (1) according to any one of claims 1 to 9.

11. The organic fluorine compound is selected from the group consisting of perfluoroethers, hydrofluoroethers, perfluoroamines, perfluoroketones, perfluoroolefins, hydrofluoroolefins, perfluoronitriles, and mixtures thereof, the electrical switching device (1) according to claim 10.

12. The organic fluorine compound is a fluoroketone having 4 to 15 carbon atoms, the electrical switching device (1) according to claim 10 or 11.

13. The dielectric insulating medium can further include a background gas different from the organic fluorine compound, the electrical switching device (1) according to any one of claims 10 to 12.

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