Electrical switching device

Abstract

An electrical switching device comprises a first switching contact piece (2) and a second switching contact piece (3). Said switching contact pieces (2, 3) can be displaced in relation to each other. The first switching contact piece (2) is surrounded by a fluid flow guiding device (9). An enveloping contour of a flow channel (10) arranged between the fluid flow guiding device (9) and the first switching contact piece (2) is greater at its end facing the second switching contact piece (3) than the enveloping contour of the first switching contact piece (2) at its end facing the second switching contact piece (3).

Description

[0001] The invention relates to an electrical switching device comprising a first switching contact piece which is at least partially hollow and a second switching contact piece, wherein the switching contact pieces are movable relative to one another and the first switching contact piece is encompassed by a fluid flow guide device, wherein the fluid flow guide device encompasses the first switching contact piece on the casing side in such a way thatthat an envelope contour of a flow channel defined between the fluid flow guide device and the first switching contact piece is larger, at least at its end facing the second switching contact piece, than the envelope contour of the first switching contact piece at its end facing the second switching contact piece, and the first switching contact piece projects beyond the fluid flow guide device with its end facing the second switching contact piece, and in the switched-on state, contact points are present between the first switching contact piece and the second switching contact piece.

[0002] Such an electrical switching device is known, for example, from published patent application DE 31 42 183 A1. The switching device therein comprises a first switching contact piece and a second switching contact piece, which are movable relative to one another. The first switching contact piece is arranged on a support and encompassed by a fluid flow guide device. The fluid flow guide device causes the fluid to flow around the first switching contact piece and forms a constriction in front of an end face of the first switching contact piece. An arc is blown by a fluid flow in the constriction of the fluid flow guide device. Blowing the arc is considered suboptimal. In particular, there is a risk that large portions of the fluid flow will flow past the arc at a distance from it.

[0003] Documents FR 913 640 A, DE 66 03 028 U, US 2 997 564 A, and DE 10 2007 031948 A1 disclose various switching devices with switching contact pieces that can be moved relative to one another and have fluid flow devices of various shapes. The patent application DE 1 150 428 discloses a compressed air switch in which compressed air is supplied to a switching point through a movable insulator, allowing it to flow back through cooling grids in outflow channels and within a fixed contact.

[0004] The object of the invention is therefore to provide an electrical switching device which enables improved flow of an arc.

[0005] According to the invention, this object is achieved in an electrical switching device according to independent claim 1.

[0006] An electrical switching device is used to interrupt a current path. The current path can carry an electric current when live, which must also be interrupted when the electrical current path is interrupted. To interrupt a current path, switching contact pieces that are movable relative to one another can be used, between which an isolating distance is created during a switching off or opening process. The switching contact pieces can be arranged opposite one another at their ends and can be moved relative to one another along a longitudinal axis. The switching contact pieces are exposed to an electrically insulating fluid, which also flows into the isolating distance when the isolating distance is created. The switching contact pieces or the isolating distance can be specifically exposed to a fluid flow for this purpose.If the switching contacts are separated, any flowing electrical current can propagate through the isolating gap within a fluid in the form of an arc. Such an arc prevents an immediate interruption of the electrical current with galvanic separation of the switching contacts. Accordingly, such an arc is generally undesirable and should be prevented or safely extinguished if possible.

[0007] An electrical switching device can be, for example, a load switch, a disconnector, an earthing switch, a circuit breaker or a similar switching device. Contact between the switching contact pieces should occur at a relative speed of approximately 3.5 m / s to approximately 5 m / s, in particular approximately 4.5 m / s. Separation of the switching contact pieces should occur at a relative speed of approximately 0.7 m / s to approximately 5 m / s, in particular approximately 1.4 m / s. A fluid flow can be directed by means of a fluid flow guide device. For example, it is possible to use the fluid flow guide device to apply particularly intensive flow to certain areas of an isolating section formed between the two switching contact pieces during a switching operation. For example, a fluid flow can flow around the sheath side of the isolating section and form a flow barrier.Suitable fluids include, for example, electrically insulating fluids in a gaseous or liquid state, such as nitrogen, carbon dioxide, sulfur hexafluoride, fluoroketones, fluoronitriles, fluorinated peroxides, or other substances with sufficient insulation strength. Preferably, the switching contact pieces can be separated from or brought closer together along a defined path with a specific movement profile. Advantageously, the fluid flow guide device can encompass the first switching contact piece. This means that the first switching contact piece is covered or overlapped by the fluid flow guide device at least in sections on an outer surface. Advantageously, the fluid flow guide device can completely enclose the first switching contact piece, for example, on the outer surface, e.g., in an annular / tubular manner. The fluid flow guide device can have closed flow surfaces.However, it can also be provided that flow surfaces are perforated so that swirling of a flowing fluid is supported. Preferably, the fluid flow guiding device can engage around the first switching contact piece in a concentric manner. For this purpose, both the first switching contact piece and the fluid flow guiding device can each be aligned or formed substantially coaxially to a longitudinal axis. The fluid flow guiding device can, for example, be tubular in shape at least in sections and aligned coaxially to a contact piece. A flow channel can, for example, be delimited on the inner casing side by the first switching contact piece and on the outer casing side by the fluid flow guiding device. An envelope contour of the flow channel can be defined by an outer cross-section of the flow channel.For a flow channel with a substantially circular cross-section, the envelope contour is defined by the outer diameter of the flow channel. The envelope contour of the first switching contact piece can be defined by the outer cross-section of the first switching contact piece.

[0008] The envelope contour of the flow channel can completely shade the envelope contour of the first switching contact piece. The flow channel can vary in cross-section by profiling the fluid flow guide device that defines it or the first switching contact piece. Profiling can cause a fluid flow to stagnate or release within the flow channel, thus influencing the fluid flow.

[0009] By designing the envelope contour of the flow channel with a larger cross-section than the envelope contour of the first switching contact piece, free access to the first switching contact piece is provided at the front end (towards the second switching contact piece). In particular, it can be provided that nozzle-like constrictions of the fluid flow guide device in front of the first switching contact piece, i.e. in front of the free end of the first switching contact piece which faces the second switching contact piece, are avoided. In this way, complete access to the front end of the first switching contact piece is possible from a direction perpendicular to the front end. As a result, there is a large area at the front end for receiving the base points of an arc, as a result of which burn-off is distributed over various points on the first switching contact piece, so that a broad flow around or flushing of an arc with a fluid is possible.Furthermore, this allows for a large-area flow of an electrically insulating fluid around the isolating gap. This allows for all-round flow of an arc in the isolating gap. The fluid flow guide device should have sufficient temperature resistance to withstand the heat generated by an arc. The fluid flow guide device can have an electrically insulating effect. The fluid flow guide device can have an electrically conductive effect. The fluid flow guide device can comprise, for example, a metal, an insulating material, e.g., PTFE, etc.

[0010] A further advantageous embodiment can provide that an outer surface of the first switching contact piece is accessible from the radial direction at its end facing the second switching contact piece.

[0011] Radial access to the first switching contact piece makes it possible to use the outer surface of the first switching contact piece to provide contact points for contacting the second switching contact piece, for example. For example, it is possible for the second switching contact piece to be pushed onto the outer surface of the first switching contact piece, and for contact to be made in the region of an outer surface of the first switching contact piece. Accordingly, with an arrangement of a flow channel according to the invention, the contact points can be widely flushed, whereby an arc can be surrounded by the fluid flow. This counteracts the breakout of the arc and causes efficient cooling of the arc. In order to achieve radial access to an outer surface of the first switching contact piece, the flow channel can, for example, widen (e.g.funnel-like cross-sectional enlargement) to enable a fanning out of a fluid flow.

[0012] A further advantageous embodiment can provide that the first switching contact piece projects beyond the fluid flow guide device with its end facing the second switching contact piece.

[0013] By projecting or protruding the first switching contact piece beyond the end of the flow guide device facing the second switching contact piece, a free end of the first switching contact piece is formed, which is radially free from any overlap by the fluid flow guide device. Thus, an orifice of the flow channel is retracted behind the free end of the first switching contact piece, allowing a fluid flow to emerge from the casing side of the first switching contact piece. The orifice and the frontal free end (the end facing the second switching contact piece) of the first switching contact piece are axially spaced from one another.On the jacket side, contact points for the second switching contact piece are arranged on the first switching contact piece, so that when the contact is separated, these contact areas can be flowed from the flow channel and a hollow cylindrical (jacket-like) flushing of the isolating section with electrically insulating fluid is created between the two switching contact pieces.

[0014] A further advantageous embodiment can provide that the first switching contact piece is a bolt-shaped switching contact piece.

[0015] A bolt-shaped switching contact piece represents a mechanically robust structure with a high current-carrying capacity. In a bolt-shaped contact piece, contact points are typically arranged on the outer casing side, i.e., in the area encompassed by a fluid flow guide device. This structure makes it possible to use the outer casing surface of the first contact piece both to define a flow channel and to position contact points, thereby enabling improved flow to the contact points and thus to potential arc root points. The areas of the first switching contact piece encompassed by the fluid flow guide device and the contact points on the first switching contact piece can be arranged axially offset from one another.

[0016] Advantageously, it can further be provided that a fluid flow flowing around a bolt-shaped first switching contact piece is guided from the fluid flow guiding device to a socket-shaped second switching contact piece.

[0017] A fluid flow can advantageously be directed from the bolt-shaped first switching contact piece to a socket-shaped second contact piece. By allowing fluid to flow out, for example from the opening of a flow channel extending in an annular gap around the first switching contact piece, it is possible to enclose an isolating section from the bolt-shaped switching contact piece to the socket-shaped switching contact piece with a sheath of flowing fluid and to allow an arc to burn within this fluid-enclosed isolating section. By enclosing the arc, it can be completely cooled and blown out regardless of its position. This can counteract the displacement of fluid from a fluid flow into the edge regions of the isolating section.

[0018] A further advantageous embodiment can provide that the fluid flow guiding device and the first switching contact piece are movable.

[0019] Both the fluid flow guide device and the first switching contact piece can each be arranged so as to be movable. The fluid flow guide device and the first switching contact piece can be movable relative to one another. However, it can also be provided that the first switching contact piece and the fluid flow guide device are movable together. The mobility of the fluid flow guide device and the first switching contact piece provides a simple way of generating a fluid flow based on movement and concentrating this fluid flow in a flow channel.

[0020] A further advantageous embodiment can provide that the fluid flow guiding device is arranged at a rigid angle to the first switching contact piece.

[0021] By connecting the first switching contact piece and the fluid flow guide device at a rigid angle, the relative position of the two elements to each other is fixed. This also defines the orifice or the position of the orifice of a flow channel defined by the fluid flow guide device and the first switching contact piece. Accordingly, the fluid flow guide device can, for example, be seated on the first switching contact piece. For example, the fluid flow guide device can be seated on the outer casing side of a bolt-shaped first switching contact piece. For example, the flow guide device can be non-positively connected to the first switching contact piece. A rigid-angle connection of the first switching contact piece and the fluid flow guide device can be arranged to be movable.

[0022] One embodiment provides that the first switching contact piece is hollow at least in sections.

[0023] A hollow design of the first switching contact piece, at least in sections, makes it possible to reduce the mass of the switching contact piece. For example, a bolt-shaped switching contact piece can be formed that is hollow in at least sections. Accordingly, inefficiently used material on the first switching contact piece can be dispensed with, particularly for higher-frequency voltages or currents, where currents are displaced into the edge regions of an electrical conductor due to the skin effect. For example, it is possible to use a hollow-cylindrical first switching contact piece that interacts with a fluid flow guide device.The first switching contact piece can, for example, have a hollow design on its end face, which provides opportunities to stabilize the position of the first switching contact piece, for example, by having the end face rest against a guide element or a centering element, thus preventing vibration. Furthermore, a hollow section of the first switching contact piece can also be used to guide a fluid flow, for example the same or at least parts of the same, which is guided in the flow channel between the flow deflection device and the first switching contact piece.

[0024] One embodiment provides that a fluid flow is guided both inside and outside the first switching contact piece.

[0025] A fluid flow can extend both inside and outside the first switching contact piece. Provision can be made for the fluid flow to be directed from the interior of the first switching contact piece into the flow channel on an outer surface of the first switching contact piece, so that the first switching contact piece is exposed to a flow both from the inside and from the outside, at least in sections. This allows the fluid flow to not only flow to an arc but also to cool the first switching contact piece. For example, a first switching contact piece that is hollow at least in sections can utilize a cavity located within its interior to conduct a fluid flow.

[0026] One embodiment provides that the fluid flow crosses a wall of the first switching contact piece.

[0027] A wall can, for example, have a communication opening to allow a fluid flow from the interior of the first switching contact piece into a flow channel between the fluid flow guiding device and the first switching contact piece. This allows the flow channel to be fed from the interior of the first switching contact piece. Advantageously, an axial offset of a fluid flow guided on the inside and outside of the first switching contact piece can be provided. This makes it possible, for example, to guide fluid compressed in a compression device inside the first switching contact piece in the direction of the separating section and to direct the fluid flow outwards on the jacket side through a communication opening. There, a laminar flow can be generated on the outer jacket side of the first switching contact piece by means of the fluid flow guiding device.After the fluid has escaped from the flow channel, the separation section can be enclosed on the shell side.

[0028] A further advantageous embodiment can provide that a flow channel with a substantially circular cross-section is delimited by the first switching contact piece and the fluid flow guiding device.

[0029] The flow channel between the first switching contact piece and the fluid flow deflection device can have a substantially circular cross-section. The circular cross-section can be constant, at least in sections. Particularly in the area of ​​the outlet opening, the cross-section of the flow channel should be constant, so that the flowing fluid is calmed and laminarized before exiting through the outlet opening of the flow channel. In this area, the flow channel should have a substantially hollow-cylindrical shape with a constant cross-section.However, it can also be provided that, for example, to create access to the casing side of the first switching contact piece at its end facing the second switching contact piece, the cross-section of the flow channel is enlarged, creating, for example, a funnel-like diffuser effect, which increases the dispersion of the fluid flow in the area of ​​the orifice and reduces the flow velocity. In this area, it is then additionally possible to access the casing-side area of ​​the free end of the first switching contact piece from the radial direction.

[0030] A further advantageous embodiment can provide that in the contacted state of the switching contact pieces, an opening in a shielding cap of the second switching contact piece is sealed by means of the fluid flow guiding device.

[0031] The second switching contact piece can be surrounded by a shielding cap for the purpose of dielectric shielding, with the second switching contact piece being accessible via an opening in the shielding cap. The fluid flow guide device makes it possible to seal off the opening in the shielding cap when switched on, i.e., when the first and second switching contact pieces are in contact. On the one hand, mechanical sealing is possible by preventing undesired fluid flows from passing through the shielding cap. On the other hand, dielectric sealing of the opening in the shielding cap can also be achieved by homogenizing electric fields with a dielectric "closure." If required, the fluid flow guide device can comprise an electrically insulating material and / or an electrically conductive material.It can be provided that at least some sections of the fluid flow guide device have an electrically insulating effect, while other sections are designed to be electrically conductive. For example, surface areas can be made electrically conductive by means of a coating, or an electrically insulating material can be doped with electrically conductive additives.

[0032] Advantageously, it can further be provided that an erosion-resistant region of the first switching contact piece is free from radial overlap by the fluid flow guiding device.

[0033] The first switching contact piece can be designed as a so-called power contact piece and serve to guide an arc. In order to provide sufficient resistance to the arc, at least sections of the first switching contact piece must be made of an erosion-resistant material so that an erosion-resistant area is created on the first switching contact piece. The erosion-resistant area of ​​the first switching contact piece should be free of radial coverage by a fluid flow guide device. This makes it possible to allow the base points of a burning arc to migrate across the erosion-resistant area and thus distribute its erosive energy over a large surface area and, in doing so, to ensure suitable flow by means of a fluid flow guide device. In particular, the arc can also be based on the outer sheath side on an area of ​​the first switching contact piece that is not radially covered.This reduces thermal stress on the fluid flow guide device. Furthermore, the erosion-resistant area can be exposed to a fluid flow, allowing the arc to be constricted and compacted within the isolating gap by the fluid flow. The erosion-resistant area can define a isolating gap.

[0034] A further advantageous embodiment can provide that the switching contact pieces are displaceable relative to one another while facing one another.

[0035] Switching contact pieces can face each other end-on. In particular, switching contact pieces facing each other end-on can be arranged so as to be axially displaceable relative to each other, so that a linear relative movement can be induced between the two switching contact pieces to create a separating distance. For example, the switching contact pieces can be designed as a bolt and an opposing socket, so that a bolt can be moved in or out of a socket by means of a linear movement. A linear movement also promotes the formation of a flow jacket around the separating distance, since a flow in the form of a jacket can be continuously generated around the separating distance, parallel to the relative movement of the two switching contact pieces. Deflecting or transversely directing a freely flowing fluid flow is therefore not necessary.This further supports the containment and constriction of an arc within an isolating gap.

[0036] An advantageous embodiment can provide that the socket-shaped second switching contact piece has a centering pin in a socket opening.

[0037] A centering pin in a socket opening makes it possible to support the insertion or removal of a bolt into or from a socket. Oscillation or swinging of the bolt can be prevented by the bolt running onto the centering pin. For this purpose, the bolt can be hollow on the front, for example, so that the centering pin can protrude into the bolt. This type of centering can support precise contacting or separation of the switching contact pieces. In particular, elastically deformable contact elements of the first or second switching contact piece are protected from excessive mechanical stress caused by twisting or other deflections. It can be provided that the centering pin does not come into contact during normal operation. For this purpose, a corresponding fit with play can be provided between the centering pin and the first switching contact piece.Thus, vibration is permissible within the limits of the fit. Only larger vibrations are limited. The centering pin can be designed as part of the contact system. However, it can also be designed for the centering pin to perform only a mechanical function and not be involved in any electrical function of the contact system.

[0038] In the following, an embodiment of the invention is shown schematically in a drawing and described in more detail. Figure 1 an electrical switching contact arrangement in the switched-on state, Figure 2 which is made of the Figure 1 known electrical switching contact arrangement for the beginning of a switching-off movement, Figure 3, which consists of the Figures 1 and 2 known electrical switching contact arrangement at an advanced point in time of a switching-off movement and Figure 4 which consists of the Figures 1 to 3known electrical switching contact arrangement in the switched off state.

[0039] In the Figure 1 A cross-section through an electrical switching device is shown. Figure 1 The basic structure of the electrical switching device is first described.

[0040] The Figure 1The electrical switching device shown is a so-called earthing switch, with the aid of which a busbar section used for power transmission can be subjected to earth potential. The electrical switching device is designed as a pressure-fluid-insulated switching device. For this purpose, the electrical switching device has a housing 1. The housing 1 is designed as a fluid-tight encapsulation so that an electrically insulating fluid can be enclosed inside. The housing 1 prevents the electrically insulating fluid from evaporating. The housing 1 is designed, for example, as a metallic housing 1 conducting earth potential, wherein the electrically insulating fluid enclosed inside the housing 1 is pressurized. This further improves the electrical insulation strength of the electrically insulating fluid.The busbar section that can be grounded by means of the electrical switching device is also arranged within the housing 1. However, it can also be provided that the groundable busbar section is arranged outside the housing 1 or in an adjacent housing in a separate fluid chamber, wherein only an electrical contact with the electrical switching device is provided.

[0041] The electrical switching device has a first switching contact piece 2 and a second switching contact piece 3. The first switching contact piece 2 is designed as a bolt-shaped switching contact piece 2. The second switching contact piece 3 is designed as a socket-shaped switching contact piece 3. The second switching contact piece 3 is mounted on the housing 1 and is electrically contacted therewith, such that the ground potential of the housing 1 is also transferred to the second switching contact piece 3. To form a socket, the second switching contact piece 3 has a plurality of contact fingers arranged radially distributed around a longitudinal axis 4, such that a socket opening 5 is delimited. A centering pin 6 is arranged centrally in the socket opening 5. The centering pin 6 carries the same electrical potential as the contact fingers delimiting the socket opening 5. In the direction of the longitudinal axis 4, the centering pin 6 projects beyond the contact fingers delimiting the socket opening 5.At its end, which projects beyond the socket opening 5, the centering pin 6 is equipped with an erosion-resistant tip. The centering pin 6 is rigidly connected to the housing 1 via a base of the second switching contact piece 3 and is electrically connected to it.

[0042] The second contact piece 3 is arranged in the shield shadow of a shielding cap 7. In this case, the shielding cap 7 is essentially dome-shaped and made of an electrically conductive material. The shielding cap 7 carries the same electrical potential as the housing 1. The shielding cap 7 is mounted on the housing 1 together with the second switching contact piece 3. The shielding cap 7 has an opening 8. The opening 8 provides access to the socket opening 5 of the second switching contact piece 3.

[0043] The drivable and thus movable first switching contact piece 2 is arranged on the end face opposite the socket opening 5. The first switching contact piece 2 is essentially hollow-cylindrical in shape. A fluid flow guide device 9 sits on the outer shell side of the first switching contact piece 2. The fluid flow guide device 9 is connected to the first switching contact piece 2 in a rigid angle. The fluid flow guide device 9 further has an inner shell surface, which is positioned at a distance from an outer shell surface of the first switching contact piece 2, so that a flow channel 10 is formed between the outer shell surface of the first switching contact piece 2 and the inner shell surface of the fluid flow guide device 9.The flow channel 10 has a substantially circular cross-section, which has a substantially constant cross-section over its extent, so that the flow channel 10, which is delimited by the outer circumferential surface of the first switching contact piece 2 and the inner circumferential surface of the fluid flow guide device 9, has a substantially hollow-cylindrical structure. The flow channel 10 has an opening 11 at the free end of the first switching contact piece 2 or at the end facing the second switching contact piece 3. The opening 11, in turn, has a circular cross-section, which has a cross-section substantially identical to the course of the flow channel 10.The essentially cylindrical fluid flow guide device 9 is positioned on the first switching contact piece 2 in such a way that the first switching contact piece 2 projects beyond the fluid flow guide device 9 in the direction of the second switching contact piece 3 (with its free end). As a result, the free end of the first switching contact piece 2, which faces the first switching contact piece 3, is free from radial overlap by the fluid flow guide device 9. Accordingly, radial access to the free end, i.e., to the end of the first switching contact piece 2 facing the second switching contact piece 3, is possible. Accordingly, contact points 12 are arranged on the outer jacket side of the first switching contact piece 2, against which contact points the contact fingers of the second switching contact piece 3, which delimit the socket opening 5, can come into contact.The front side of the first switching contact piece 2 is formed by an erosion-resistant tip, which, as an erosion-resistant region of the first switching contact piece 2, is free from radial overlap by the fluid flow guide device 9.

[0044] Due to the hollow cylindrical design of the first switching contact piece 2, the end of the first switching contact piece 2 facing the second switching contact piece 3 is provided with a central recess into which the centering pin 6 projects when switched on. Thus, the centering pin 6 can stabilize a linear displacement of the first switching contact piece 2 relative to the second switching contact piece 3, particularly when inserted into the socket opening 5 of the second switching contact piece 3. The central recess within the first switching contact piece 2 is sealed with a barrier 13, which limits the insertion depth of the centering pin 6. On the side of the barrier 13 facing away from the second switching contact piece 3, communication openings 14 penetrate a wall of the first switching contact piece 2 in the peripheral area.The communication openings 14 in the wall of the hollow-cylindrical first switching contact piece 2 enable communication between a cavity inside the first switching contact piece 2 and the flow channel 10. A piston 15 is arranged inside the first switching contact piece 2 and is movable relative to the first switching contact piece 2. For example, the piston 15 can be arranged stationary relative to the housing 1, whereas the first switching contact piece 2 can be arranged movable relative to the housing 1 and thus movable relative to the piston 15. By means of a drive device, the electrical switching device can be switched on or off by driving the first switching contact piece 2. The piston 15 sits in a complementary shape in the recess of the hollow first switching contact piece 2.

[0045] Based on the Figures 1 , 2 , 3 and 4A switching-off process, ie a breaking of an earth connection to the busbar section, is to be described. Figure 1First, the switched-on state of the first and second switching contact pieces 2, 3 is shown. This means that the first switching contact piece 2 is initially galvanically connected to the second switching contact piece 3, so that the earth potential of the housing 1 is transferred via the second switching contact piece 3 to the first switching contact piece 2 and from there to the earthed busbar section. During a switching-off process, a movement is coupled to the first switching contact piece 2. This linear movement of the first switching contact piece 2 occurs in such a way that the first switching contact piece 2 moves away from the second switching contact piece 3. This results in a reduction in the volume of the recess present between the piston 15 and the barrier 13 in the interior of the first switching contact piece 2, whereby an overpressure is created in the electrically insulating fluid located inside the first switching contact piece 2.Driven by the excess pressure, electrically insulating fluid, which was previously located inside the first switching contact piece 2, overflows via the communication openings 14 into the flow channel 10. Galvanic separation of the first switching contact piece 2 from the contact fingers that define the socket opening 5 can result in the occurrence of an arc. This can be caused, for example, by charging phenomena on the first switching contact piece 2 or on the busbar current section. In this case, the centering pin 6 is dimensioned such that electrical contact is not established through a direct connection between the centering pin 6 and the second switching contact piece 2, and its position is only secured in the event of significant oscillation or swinging of the first switching contact piece 2.Accordingly, an arc initially extends between the erosion-resistant section of the first switching contact piece 2 and one or more contact fingers defining the socket opening. However, it can also be provided that an arc is ignited between the first switching contact piece 2 and the centering pin 6, particularly at their erosion-resistant sections. Due to the contact overlap of the first and second switching contact pieces 2, 3 (see position of the contact points 12) on the outer surface of the first switching contact piece 2, compression of electrically insulating fluid due to the relative movement of piston 15 and first switching contact piece 2 begins even before galvanic separation. For compression to begin, galvanic contact between the first and second switching contact pieces 2, 3 still exists. Only the position of the contact points 12 on the first switching contact piece 2 shifts.As a result, a continuous flow of fluid flowing out of the flow channel 10 is already present at the time of galvanic separation of the first and second switching contact pieces 2, 3. Galvanic separation of the first and second switching contact pieces 2, 3 may result in the occurrence of an arc (see . Figure 2 ). At this point in time, fluid has already begun to flow through the isolating gap between the first and second switching contact pieces 2, 3, so that an igniting arc is surrounded by an already flowing fluid. With increasing distance between the first switching contact piece 2 and the second switching contact piece 3 (cf. Figure 3) there is an increasing scattering of the fluid emerging from the outlet opening 11 of the flow channel 10. This occurs in particular because the fluid flow is subject to a decreasing directivity with increasing distance between the first switching contact piece 2 and the second switching contact piece 3, and thus also with increasing distance between the outlet opening 11 and the second switching contact piece 3. As the distance between the first and second switching contact pieces 2, 3 increases, the distance that has to be bridged by an arc is increased. In addition to this increasing distance, the arc is blown out and thus cooled, and combustion products are removed from the isolating distance. The conditions for the burning of the arc become increasingly worse. Furthermore, particularly when used in disconnectors or earthing switches, the arc-driving charges are dissipated via the arc. The arc is extinguished.When the arc is extinguished, the first switching contact piece 2 can be moved further away from the second switching contact piece 3. When the end positions are reached (see . Fig. 4 ) from the first and second switching contact piece 2, 3, ie the first and second switching contact piece 2, 3 are at rest, the arc is extinguished.

[0046] During a switching-on process, the second switching contact piece 3 is moved closer to the first switching contact piece 2. When the first and second switching contact pieces 2, 3 reach the switching-on position (cf. Figure 1 ) the recess located inside the first switching contact piece 2 for receiving a fluid is filled with a quantity of fluid, so that switching off can be carried out again by means of an electrically insulating fluid while flowing through an arc which may be ignited.

Claims

1. Electrical switching device having a first switching contact piece (2), which is of hollow design at least in sections, and a second switching contact piece (3), wherein the switching contact pieces (2, 3) can be moved relative to one another and the first switching contact piece (2) is surrounded by a fluid flow guiding device (9), wherein the fluid flow guiding device (9) surrounds the lateral surface side of the first switching contact piece (2) in such a way that an enveloping contour of a flow duct (10) which is delimited between the fluid flow guiding device (9) and the first switching contact piece (2), at least at its end which faces the second switching contact piece (3), is larger than the enveloping contour of the first switching contact piece (2) at its end which faces the second switching contact piece (3), and the first switching contact piece (2), by way of its end which faces the second switching contact piece (3), protrudes beyond the fluid flow guiding device (9) and, in the connected state, the end of the fluid flow guiding device (9) which faces the second switching contact piece (3) is kept free of contact-making points with the second switching contact piece (3), characterized in that, in the connected state between the first switching contact piece (2) and the second switching contact piece (3), contact-making points (12) are present on the lateral surface side, and in that a wall of the first switching contact piece (2) has a communication opening (14) in order to allow a fluid flow to pass from the interior of the first switching contact piece (2) into the flow duct (10) between the fluid flow guiding device (9) and the first switching contact piece (2) during a disconnection movement, so that the fluid flow is guided both inside and outside the first switching contact piece (2) in a manner traversing the wall of the first switching contact piece (2).

2. Electrical switching device according to Claim 1, characterized in that an outer lateral surface of the first switching contact piece (2), at its end which faces the second switching contact piece (3), is accessible from the radial direction.

3. Electrical switching device according to Claim 1 or 2, characterized in that the first switching contact piece (2) is a bolt-like switching contact piece.

4. Electrical switching device according to any of Claims 1 to 3, characterized in that a fluid flow which flows around a bolt-like first switching contact piece (2) is guided by the fluid flow guiding device (9) to a bushing-like second switching contact piece (3).

5. Electrical switching device according to any of Claims 1 to 4, characterized in that the fluid flow guiding device (9) and the first switching contact piece (2) are movable.

6. Electrical switching device according to any of Claims 1 to 5, characterized in that the fluid flow guiding device (9) is arranged at a fixed angle in relation to the first switching contact piece (2).

7. Electrical switching contact arrangement according to any of Claims 1 to 6, characterized in that a flow duct (10) with a substantially ring-like cross section is delimited by the first switching contact piece (2) and the fluid flow guiding device (9).

8. Electrical switching contact arrangement according to any of Claims 1 to 7, characterized in that an opening in a shielding hood (7) of the second switching contact piece (3) is blocked by means of the fluid flow guiding device (9) in the state in which the switching contact pieces (2, 3) are contact-connected.

9. Electrical switching contact arrangement according to any of Claims 1 to 8, characterized in that an erosion-resistant region of the first switching contact piece (2) is free of radial overlapping by the fluid flow guiding device (9).

10. Electrical switching contact arrangement according to any of Claims 1 to 9, characterized in that the switching contact pieces (2, 3) can be displaced relative to one another with their end sides situated opposite one another.

11. Electrical switching contact arrangement according to any of Claims 4 to 10, characterized in that the bushing-like second switching contact piece (3) has a centring pin (6) in a bushing opening (5).

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