Switchgear

Abstract

The invention relates to a switching device (1; 10; 100), in particular an earthing switch or a circuit breaker, comprising two vacuum switches arranged in series or two pairs of contacts arranged in series inside a single vacuum switch. The device also comprises an actuating mechanism to displace the contacts of the switching device between an open position and a closed position. The actuating mechanism is also designed to displace a part of the insulating housing forming the vacuum switch of the switching device relative to the contacts during opening or closing.

Description

Technical Field

[0001] The present invention relates to a switchgear, such as an earthing switch or a circuit breaker. In particular, the present invention relates to a switchgear suitable for railway applications. Background Art

[0002] A switching device such as an earthing switch or a circuit breaker usually comprises two contacts which can move between a closed position in which current can flow between the two contacts and an open position in which the two contacts are separated so that current cannot flow between the two contacts. Usually, one contact is stationary and the other contact is movable, driven by a suitable mechanism. When the contacts are in their open position, there is a distance or gap between them. Depending on the geometry of the contacts and their effective surface, the gap may be equal to or less than the clearing distance, i.e. the distance that the contacts must travel from their open position to their closed position. The contacts are preferably surrounded by a dielectric such as air, SF6 or a vacuum.

[0003] Figure 1 The breakdown voltage Ub of different insulating media including vacuum is shown as a function of the gap distance d between the contacts. Unlike the breakdown voltage in gaseous media (SF6 and air) which is almost linear as a function of the gap distance (Paschen's law), the breakdown voltage in vacuum follows a different rule and is proportional to the square root of the gap distance d (i.e. (Ub(d)∝d0.5) or even Ub(d)∝d0.6).

[0004] Generally, if the switchgear is arranged in series to form a main switchgear, the breakdown voltage of the main switchgear is the sum of all the breakdown voltages of the switchgear in the series. Therefore, considering that the gap distance between the two vacuum switchgears is 10 mm between their respective pairs of contacts, Figure 1 It is shown that in this case, the breakdown voltage of the device consisting of two vacuum switchgears arranged in series is higher than the breakdown voltage of a single vacuum switchgear with a gap distance of 20 mm. A higher breakdown voltage means higher safety and resistance of the switchgear, especially in applications such as grounding or circuit breaking.

[0005] One problem encountered when placing vacuum switchgear in series in order to withstand higher voltages is the difficulty in moving all contacts very quickly and simultaneously to their open or closed positions in order to disconnect or establish the current. When two switchgears, in particular two vacuum interrupters used as circuit breakers, are arranged in series, the safest solution is to displace both moving contacts simultaneously (connected to one end of the circuit or to each other, ensuring the series arrangement of the switchgear). Although these prerequisites are essential for certain applications (such as load or short-circuit current disconnection), they are not so important for grounding or circuit breaking applications that do not require simultaneous and rapid displacement. Summary of the invention

[0006] The object of the present invention is to provide a switchgear, such as an earthing switch or a circuit breaker, preferably for railway applications, which is safe, compact, practical and suitable for a variety of uses, in particular for earthing or circuit breaking applications.

[0007] The object of the invention is a switching device according to claim 1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Advantages and other characteristics of the invention will become more apparent from the following description of several embodiments of the invention given purely as non-limiting examples and represented in the accompanying drawings.

[0009] Figure 1 The breakdown voltage Ub of different insulating dielectrics including vacuum, air and SF6 is shown as a function of the gap distance d between the contacts for highly polished contacts.

[0010] Figure 2a A switching device comprising a single vacuum switch with a gap distance 2d between the contacts is shown, while Figure 2b A switching device is shown comprising two vacuum switches arranged in series, each vacuum switch being defined by a gap distance d between its respective contacts.

[0011] Figure 3a and 3b A first embodiment of a switching device according to the invention is shown in its closed position and in its open position, respectively.

[0012] Figure 4 yes Figure 3a A cross-sectional view of a switch device.

[0013] Figure 5 yes Figure 3b A cross-sectional view of a switch device.

[0014] Figure 6a and 6bA second embodiment of a switching device according to the invention is shown in its closed position and in its open position, respectively.

[0015] Figure 7 yes Figure 6a A cross-sectional view of a switch device.

[0016] Figure 8 yes Figure 6b A cross-sectional view of a switch device.

[0017] Fig. 9 and 10 The third embodiment of the switching device according to the invention is shown in cross-section in its closed position and in its open position, respectively.

[0018] Fig.11a and 11b FIG. 11 is a cross-sectional view of a modification of the third embodiment of the switch device according to the present invention. DETAILED DESCRIPTION

[0019] The switchgear according to the invention is designed for use as an earthing switch or as a circuit breaker, in particular for railway applications.

[0020] Each illustrated embodiment shows a switch device according to the invention used as an earthing switch, wherein one pole of the device is connected to the circuit C and the other pole is connected to ground.

[0021] Reference Figures 3a to 5 A first embodiment of a switching device according to the present invention is described.

[0022] In this first embodiment, the switchgear 1 comprises a first vacuum switch 2 and a second vacuum switch 3. The first and second vacuum switches 2, 3 are conventional and well known to those skilled in the art. In particular, they each comprise a sealed arc-extinguishing chamber 21, 31 in which a controlled low-pressure air or another dielectric fluid prevails, i.e. a vacuum. The chambers 21, 31 are defined by a tubular insulating housing 22, 32, respectively, which in the illustrated embodiment is formed by two insulating cylinders made of a suitable insulating material (such as ceramic, glass or glass ceramic) and bonded together by metallization and brazing.

[0023] Conductive caps 23, 33 close each open end of the chambers 22, 32. The conductive caps 23, 33 are made of metal and are fixed to the tubular insulating housings 22, 32 (to their corresponding ceramic cylinders in the illustrated embodiment) in a tightly sealed manner, typically by brazing.

[0024] The chamber 21, 31 defined by the tubular insulating housing 22, 32 and the conductive cap 23, 33 comprises a pair of active contacts 4, 5 and 6, 7 respectively, which are movable relative to each other along the longitudinal axis of the vacuum switch 2, 3. Each pair of contacts 4, 5 and 6, 7 is movable between a closed position, in which the contacts 4, 5 and 6, 7 are in electrical contact and current can flow through them, and an open position, in which the contacts 4, 5 and 6, 7 are not in electrical contact and current cannot flow between them. Each contact 4, 5, 6, 7 comprises a contact pad made of a suitable material fixed to a longitudinal electrode.

[0025] Each pair of contacts 4, 5 and 6, 7 comprises a first contact 4, 6 which is firmly fixed to one of the conductive caps 23, 33, the electrode of which is coupled to one of the conductive caps, for example by welding, soldering or any other suitable type of mechanical assembly. The second contact 5, 7 of each pair of contacts is mounted with its electrode inside its respective chamber 21, 31 so as to be able to move through the other cap 23, 33. In order to maintain a controlled vacuum inside the chambers 21, 31 while allowing the second contacts 5, 7 to slide through their respective conductive caps 23, 33, sealing metal bellows 24, 34 are mounted respectively between the electrodes of their second contacts 5, 7 and the respective caps 23, 33, which sealing metal bellows may for example be welded to the electrode at one end, thereby sealing the caps 23, 33 and the openings of the chambers 21, 31.

[0026] In their open position, there is a gap d between each pair of first and second contacts 4, 5 and 6, 7. In this embodiment, in their open position, there is the same gap d between the contacts 4, 5 of the first vacuum switch 2 and the contacts 6, 7 of the second vacuum switch 3. Preferably, this gap d corresponds to the separation distance that the contacts must travel when moving from their open position to their closed position.

[0027] The vacuum switches 2, 3 are arranged in series along the same longitudinal axis. Their first contacts 4, 6 are connected and fixed together by any suitable means.

[0028] The second contact 5 of the first vacuum switch 2 corresponding to the first pole of the switchgear 1 is connected to the circuit C, while the second contact 7 of the second vacuum switch 3 corresponding to the second pole 1 of the switchgear is connected to the ground. In case the switchgear 1 is used as a circuit breaker, the two contacts 5, 7 are then connected to the circuit C.

[0029] According to the invention, the second contact 5 of the first vacuum switch 2 connected to the circuit C is fixed and does not move during opening and closing of the switching device 1. The second contact 7 of the second vacuum switch 2 is arranged to be movable relative to its first contact 6 and the integral part made of the two insulating housings 22, 32. The pair of first contacts 4, 6 is arranged to be movable relative to the fixed second contact 5 of the first vacuum switch 2.

[0030] The switch device 1 also comprises an actuating mechanism 8 designed to open and close the device. The actuating mechanism 8 is designed to displace the second contact 7 of the second vacuum switch 3 along its longitudinal axis relative to the fixed contacts 4, 6 and the insulating housing 32 of the second vacuum switch 3 (the second contact 7 slides over the conductive cap 33). The actuating mechanism 8 is also designed to move the integral part consisting of the two insulating housings 22, 32 and the pair of first contacts 4, 6 relative to the second contact 5 of the first vacuum switch 2; that is, the second contact 5 remains stationary, while the insulating housing 22 and the remaining part of the first vacuum switch 2 actuated by the actuating mechanism move.

[0031] The actuating mechanism 8 preferably comprises an electric motor which can be remotely controlled. In a variant, the actuating mechanism 8 can be manually operated.

[0032] exist Figures 3a to 5 In the illustrated first embodiment of the switchgear according to the invention, the actuating mechanism 8 comprises a flange 81 arranged between the insulating housings 22, 32 of the first and second vacuum switches 2, 3 and arranged around the connection region of the first contacts 4, 6 of the first and second vacuum switches 2, 3. The flange 81 translates integrally with the first contacts 4, 6 and the insulating housings 22, 32 of the first and second vacuum switches 2, 3. Preferably, the flange 81 is formed of a dielectric material.

[0033] The actuating mechanism 8 further comprises at least one stop rod 82. The first end of the stop rod 82 is fixed to the flange 81. The second end of the stop rod 82 is fixed to a first mechanical stop element 83, which is preferably a metal bracket. The first mechanical stop element 83 is designed to determine the displacement of the second contact 7 of the second vacuum switch 3 relative to its first contact 6 and prevent the displacement from being greater than the spacing distance between the first and second contacts 6, 7 of the second vacuum switch 3, or in this embodiment greater than the gap d, and prevent the sealing bellows 34 from being flattened. To this end, the first mechanical stop element 83 is designed to cooperate with a second mechanical stop element 84 of an actuating rod 85 firmly fixed to the actuating mechanism 8. In this embodiment, the actuating rod 85 itself is integral with the second contact 7 of the second vacuum switch 3.

[0034] In the same manner, the first mechanical stop element 83 is also designed to cooperate with the third mechanical stop element 86 which is integral with the fixed frame 87 of the actuating mechanism 8 to determine the displacement of the first contact 4 of the first vacuum switch 2 relative to its second contact 5 and prevent the displacement from being greater than the spacing distance between the first and second contacts 4, 5 of the first vacuum switch 2, or greater than the gap d in this embodiment, and prevent the sealing bellows 24 from being crushed.

[0035] Figure 3a and Figure 4 The switching device 1 according to the first embodiment is shown in its closed position.

[0036] In this position 2, the first and second contacts 4, 5 of the first vacuum switch 2 are in their closed position, contacting each other as are the first and second contacts 6, 7 of the second vacuum switch 3. Thus, in this closed position of the switching device 1, the circuit C is grounded.

[0037] Starting from this closed position, the actuating mechanism 8 acts on the second contact 7 of the second vacuum switch 3 to move it along the longitudinal axis of the device in a first opening direction and to open the switching device 1 .

[0038] For better understanding and ease of description, the opening procedure will be described below as comprising two different displacements. It is clearly shown that the two displacements can be sequential or (at least partially) substantially simultaneous. Therefore, the "first" and "second" displacements below will refer to a displacement rather than a chronological position.

[0039] First, the actuating mechanism 8 acts on the second contact 7 of the second vacuum switch 3 so that the second contact 7 moves a distance d (corresponding to the gap or spacing distance of the second vacuum switch 3) relative to its first contact 6 in a first opening direction along the longitudinal axis of the device. The first mechanical stop element 83 cooperating with the second mechanical stop element 84 ensures that the second contact 7 of the second vacuum switch 3 does not move more than the distance d relative to the first contact 6 of the second vacuum switch 3.

[0040] In the second displacement of the opening procedure, the actuating mechanism 8 also acts on the second contact 7 to displace it in the first opening direction along the longitudinal axis of the device. As soon as the second mechanical stop element 84 abuts against the first mechanical stop element 83, the second contact 7 is translated integrally with the entire second vacuum switch 3 in the first opening direction, since said first mechanical stop element 83 is connected to the flange 81 via the stop rod 82. Since the pair of first contacts 4, 6 of the first and second vacuum switches 2, 3 are connected, the displacement of the entire second vacuum switch 3 also causes the displacement of the first contact 4 and the insulating housing 22 of the first vacuum switch 2. Since the second contact 5 of the first vacuum switch 2 remains stationary, fixed to the circuit C, the displacement of the insulating housing 22 and the first contact 4 of the first vacuum switch 2 thus causes the opening of said first and second contacts 4, 5 of the first vacuum switch 2. In the second displacement of the opening procedure, the second contact 7 of the second vacuum switch 3 is displaced by a distance d corresponding to the gap or spacing distance between the pair of contacts 4, 5 of the first vacuum switch 2 until the first mechanical stop element 83 abuts against the third mechanical stop element 86 of the actuating mechanism 8.

[0041] During the above-mentioned opening procedure, the first and second displacements of the second contact 7 may be substantially simultaneous or in close sequence. Therefore, "first" and "second" are used to better distinguish them rather than to indicate a strict time sequence.

[0042] During the entire opening procedure, the total displacement of the second contact 7 is equal to the sum of the gaps of the first vacuum switch 2 and the gaps of the second vacuum switch 3. Therefore, in the first embodiment shown, during the opening of the switching device 1, the second contact 7 of the second vacuum switch 3 will travel a distance of 2d. Therefore, after a complete travel 2d of the second contact 7 of the second vacuum switch 3, the two pairs of contacts 4, 5 and 6, 7 of the first and second vacuum switches 2, 3 are now in their open positions, as shown in FIG. Figure 5 As shown, the switching device 1 as a whole is in its open position.

[0043] In this first embodiment, when the switch device 1 is in its open position, the combined action of the first and third mechanical stop elements 83, 86 provides a fixed and rigid structure. Preferably, the first and third mechanical stop elements 83, 86 of the actuating mechanism 8 are also designed to keep the switch device 1 locked in its open position.

[0044] From this open position of the switching device 1 according to the first embodiment of the invention, the actuating mechanism 8 again acts on the second contact 7 of the second vacuum switch 3 to displace it along its longitudinal axis in the second closing direction and close the switching device 1 .

[0045] In the same way, the closing procedure can also be described as comprising two displacements, which can be simultaneous or sequential. The switching device 1 and the actuating mechanism 8 are designed so that the second contact 7 of the second vacuum switch 3 travels a distance d (corresponding to the gap of the second vacuum switch 3) relative to its first contact 6 in the second closing direction in the first displacement until it contacts the first contact 6.

[0046] In the second displacement of the closing sequence, the actuating mechanism 8 displaces the second contact 7 of the second vacuum switch 3 in the same second closing direction. At the same time, the pressure difference between the air outside the switching device 1 and the vacuum inside the first vacuum switch 2 tends to displace the integral unit constituted by the insulating parts 22, 32 and the fixed contacts 4, 6 of the first and second vacuum switches 2, 3 in the same second closing direction. After coming into contact with the first contact 6, the second contact 7 pushes against the first contact 6 of the second vacuum switch 3, acting on the first contact 6 of the second vacuum switch 3, but also on the first contact 4 and on the insulating housing 22 of the first vacuum switch 2. The first contact 4 of the first vacuum switch 2 is thus moved relative to the second contact 5 of the first vacuum switch 2, which remains stationary and fixed to the circuit C, until the first contact 4 comes into contact with the second contact 5. At this point, the entire switching device 1 is in its closed position.

[0047] Preferably, the switchgear 1 further comprises a guide mechanism 9 designed to guide the displacement of an integral assembly formed by the two insulating housings 22, 32 of the first and second vacuum switches 2, 3 and the two first contacts 4, 6 during an opening or closing procedure of the switchgear 1.

[0048] In a first embodiment of the invention, the guide mechanism 9 is firmly fixed to the fixed frame 87 of the actuating mechanism 8 and comprises at least one, but preferably two or three, guide rods 91. Said guide rods 91 are fixed at one end to the fixed frame 87 of the actuating mechanism 8. They pass through the flange 81 and are fixed at their other end to a guide flange 92. The guide flange 92 itself is fixed to the second contact 5 of the first vacuum switch 2 and therefore remains immobile during the opening or closing procedure of the switching device 1. Therefore, during the opening and closing of the switching device 1, the flange 81 slides along the guide rods 91, ensuring the proper translation of the moving parts of the device 1 without the risk of deviation and breakage.

[0049] Now refer to Figures 6a to 8 A second embodiment of a switching device according to the invention is described.Components and elements already described in relation to the first embodiment will retain the same reference numerals.

[0050] In this second embodiment, the switch device 10 further includes a first vacuum switch 2 and a second vacuum switch 3 which are similar in every point to those described in the first embodiment.

[0051] As mentioned before, there is a gap d between each pair of first and second contacts 4, 5 and 6, 7 in their open position. In this embodiment, there is the same gap d between the contacts 4, 5 of the first vacuum switch 2 and the contacts 6, 7 of the second vacuum switch 3 in their open position. Preferably, the gap d corresponds to the separation distance that the contacts must travel when moving from their open position to their closed position.

[0052] The vacuum switches 2, 3 are arranged in series along their longitudinal axes. Their first contacts 4, 6 are connected and fixed together by any suitable means.

[0053] The second contact 5 of the first vacuum switch 2 corresponding to the first pole of the switching device 10 is connected to the circuit C, and the second contact 7 of the second vacuum switch 3 corresponding to the second pole of the switching device 10 is connected to the ground. In the case where the switching device 10 is used as a circuit breaker, the two movable contacts 5, 7 are then connected to the circuit C.

[0054] The second contact 5 of the first vacuum switch 2 connected to the circuit is fixed and does not move during the opening and closing of the switching device 10, while the second contact 7 of the second vacuum switch 3 is arranged to be movable relative to its first contact 6 and the integral part composed of the two insulating housings 22, 32, and the pair of first contacts 4, 6 is arranged to be movable relative to the fixed second contact 5 of the first vacuum switch 2.

[0055] In this second embodiment, the actuating mechanism 80 comprises a first mechanical stop element 83 which is fixedly secured in a suitable manner to the conductive cap 33 of the second vacuum switch 3, through which the second contact 7 passes. The first mechanical stop element 83 is designed to cooperate with a second mechanical stop element 84 which is fixedly secured to an actuating rod 85 of the actuating mechanism 80. The actuating rod 85 itself is integral with the second contact 7 of the second vacuum switch 3. In the second embodiment, the first mechanical stop element 83 has, for example, the shape of a tubular sleeve through which the second contact 7 of the second vacuum switch 3 and the second mechanical stop 84 can slide. The second mechanical stop 84 is a connecting conductive element fixed between the second contact 7 and the actuating rod 85 of the actuating mechanism 80.

[0056] The first and second stop elements 83, 84 are designed to limit the displacement of the second contact 7 of the second vacuum switch 3 relative to its first contact 6 to prevent the second contact 7 from moving a distance greater than the gap d relative to the first contact 6 during the opening procedure of the switching device 10 and to prevent the sealing bellows 34 from being crushed.

[0057] Figure 6a and Figure 7 A switching device 10 according to a second embodiment of the invention is shown in its closed position.

[0058] In this position, the first and second contacts 4 , 5 of the first vacuum switch 2 are in their closed position, as are the first and second contacts 6 , 7 of the second vacuum switch 3 , which are in contact with one another.

[0059] Starting from this closed position, the actuating mechanism 80 acts on the second contact 7 of the second vacuum switch 3 to displace it along its longitudinal axis in a first opening direction and to open the switching device 10 .

[0060] As mentioned above, the opening procedure can be described as comprising two displacements substantially simultaneously or sequentially. The switching device 10 and the actuating mechanism 80 are designed so that the second contact 7 of the second vacuum switch 3 travels a distance d (corresponding to the gap of the second vacuum switch 3) relative to its first contact 6. During this first displacement of the opening procedure, the actuating mechanism 80 acts on the connecting rod 85 to move the second contact 7 along its longitudinal axis in the first opening direction. The second contact 7 of the second vacuum switch 3 slides over its conductive cap 33 and passes through the first mechanical stop element 83.

[0061] Once the second contact 7 has travelled the distance d relative to its first contact 6 , the second mechanical stop element 84 abuts the first mechanical stop element 83 .

[0062] In the second displacement of the opening procedure, the actuating mechanism 80 also acts on the connecting rod 85 to displace the second contact 7 in the first opening direction along the longitudinal axis of the device. As soon as the second mechanical stop element 84 abuts the first mechanical stop element 83, the second contact 7 is translated integrally with the insulating housing 32 of the second vacuum switch 3, to which the first mechanical stop element 83 is fixed. The actuating mechanism 80 thus also acts firmly on the integral assembly consisting of the two insulating housings 22, 32 of the first and second vacuum switches and the pair of first contacts 4, 6. Since the second contact 5 of the first vacuum switch 2 remains immobile and fixed to the circuit C, the displacement of the insulating housing 22 and the first contact 4 of the first vacuum switch 2 thus results in the opening of the first and second contacts 4, 5 of the first vacuum switch 2.

[0063] As in the first embodiment, during the second displacement of the opening procedure, the second contact 7 of the second vacuum switch 3 is displaced a distance d corresponding to the gap or spacing distance between the pair of contacts 4, 5 of the first vacuum switch 2. As in the first embodiment, this second displacement is limited by the cooperation of the third mechanical stop element 86 and the fourth mechanical stop element 88. In this second embodiment, the third mechanical stop element 86 is fixed to the second contact 5 of the first vacuum switch 2, while the fourth mechanical stop is integral with the insulating housing 22 of the first vacuum switch 2. During the opening procedure, the total displacement of the second contact 7 is equal to the sum of the gap of the first vacuum switch 2 and the gap of the second vacuum switch 3. Therefore, in the second embodiment, during the opening of the switching device 10, the second contact 7 of the second vacuum switch 3 will also travel a distance 2d. Therefore, after a complete stroke 2d of the second contact 7 of the second vacuum switch 3, the two pairs of contacts 4, 5 and 6, 7 of the first and second vacuum switches 2, 3 are now in their open position, as shown in FIG. Figure 5 As shown, the switching device 10 as a whole is in its open position.

[0064] Starting from this open position of the switching device 10 according to the second embodiment of the invention, the actuating mechanism 80 again acts on the second contact 7 of the second vacuum switch 3 to displace it in the second closing direction along its longitudinal axis and close the switching device 10. The closing procedure in this second embodiment is the same as that disclosed above for the first embodiment.

[0065] In this second embodiment, the guide mechanism 90 comprises a guide tube 93 accommodating the first and second vacuum switches 2, 3. A guide flange 94 is fixed to each of the first and second vacuum switches 2, 3 and is designed to slide along the inner wall of the guide tube 93. Thus, during the opening and closing of the switching device 10, the guide flange 94 slides inside the guide tube 93, ensuring proper translation of the moving parts of the device 10 without risk of deviation and breakage. Preferably, the guide tube is made of composite fiberglass or glass ceramic, and the guide flange 94 is made of a dielectric low-friction material such as Teflon (registered trademark, polytetrafluoroethylene or PTFE) so as not to hinder the displacement of the vacuum switches 2, 3 inside the guide tube 93 during the opening and closing procedures.

[0066] Now refer to Figures 9 to 11b A third embodiment of the switching device according to the present invention is described.

[0067] In this third embodiment, the switchgear 100 comprises a single vacuum switch 200. The single vacuum switch 200 comprises a sealed arc-extinguishing chamber 210, in which controlled low-pressure air or another dielectric fluid prevails, i.e., a vacuum. The chamber 210 is defined by a tubular insulating housing 220, which in the illustrated embodiment is formed by two insulating cylinders 221, 222, which are made of a suitable insulating material (such as ceramic or glass ceramic) and are bonded together by metallization and brazing.

[0068] In particular, in the third embodiment, two insulating cylinders 221, 222 are brazed to the metal plate 250. The metal plate 250 supports the center electrode 260, and the ends of the center electrode respectively have contact pads constituting the first and second center contacts 400, 600. The first and second center contacts 400, 600 cannot move relative to the insulating cylinders 221, 222.

[0069] The single vacuum switch 200 further includes a fixed contact 500 connected to the circuit C and a movable contact 700 connected to the ground. The first center contact 400 and the fixed contact 500 form a first pair of contacts that can move relative to each other along the longitudinal axis of the single vacuum switch 200. The second center contact 600 and the movable contact 700 form a second pair of contacts that can move relative to each other along the longitudinal axis of the single vacuum switch 200.

[0070] Each pair of contacts 400, 500 and 600, 700 is movable between a closed position in which the contacts 400, 500 and 600, 700 are in electrical contact and current can flow through them, and an open position in which the contacts 400, 500 and 600, 700 are not in electrical contact and current cannot flow between them.

[0071] Conductive caps 230, 231 close each open end of the chamber 220. The conductive caps 230, 231 are made of metal and are fixed to the tubular insulating housing 220 (fixed to their corresponding insulating cylinders 221, 222 in the illustrated embodiment) in a tightly sealed manner, usually by brazing. The conductive caps 230, 231 are arranged so that the fixed and movable contacts 500, 700 can pass through them respectively. In order to maintain a controlled vacuum inside the chamber 210 while allowing the fixed contact 500 and the movable contact 700 to slide through their respective conductive caps 230, 231, two sealing metal bellows 240, 241 are respectively assembled between the electrodes of their fixed and movable contacts 500, 700, and the two sealing metal bellows can be welded or brazed to the electrodes, for example, at one end thereof, and the corresponding caps 230, 231 thereby seal the caps 230, 231 and the opening of the chamber 210.

[0072] In their open position, there is a gap d between each pair of contacts 400, 500 and 600, 700. In this embodiment, in their open position, there is the same gap d between the first center contact 400 and the fixed contact 500 and between the second center contact 600 and the movable contact 700. Preferably, this gap d corresponds to the separation distance that the contacts must travel when moving from their closed position to their open position.

[0073] As in the previous embodiment, the switch device 100 according to the third embodiment includes an actuating mechanism 800 designed to move the movable contact 700 and the insulating housing 220 of the vacuum switch 200 along the longitudinal axis thereof. In this third embodiment, the first mechanical stop element is a conductive cap 231 through which the movable contact 700 passes, and the second mechanical stop element 840 has a sleeve shape firmly fixed to the electrode of the movable contact 700 inside the chamber 210 of the vacuum switch 200. In particular, in the illustrated embodiment, the second stop element 840 surrounds the sealing bellows 241 of the movable contact 700. In the same way, the third mechanical stop element is a conductive cap 230 through which the fixed contact passes, and the third mechanical stop element 860 has a sleeve shape firmly fixed to the electrode of the fixed contact 500 inside the chamber 210 of the single vacuum switch 200. In particular, in the illustrated embodiment, the third stopper element 860 surrounds the sealing bellows 240 of the stationary contact 500 .

[0074] The conductive cap 231 and the second stop element 840 are designed to limit the displacement of the movable contact 700 relative to the second center contact 600 to prevent the movable contact 700 from moving a distance greater than the gap d relative to the second center contact 6 during the opening procedure of the switching device 100 and prevent the sealing bellows 241 from being crushed.

[0075] Fig. 9 A switching device 100 according to a third embodiment of the invention is shown in its closed position.

[0076] In this position, the first center contact 400 and the fixed contact 500 are in their closed positions, as are the second center contact 600 and the movable contact 700 in contact with each other.

[0077] Starting from this closed position, the actuating mechanism 800 acts on the movable contact 700 to displace it along its longitudinal axis in a first opening direction and to open the switching device 100 .

[0078] As previously mentioned, the opening procedure comprises two displacements of the movable contact 700, either substantially simultaneously or sequentially. The switch device 100 and the actuating mechanism 800 are designed so that the movable contact 700 travels a distance d (corresponding to the gap between the movable contact 700 and the second center contact 600) relative to the second center contact 600. During this first displacement, the actuating mechanism 800 acts on the movable contact 700 to move it along its longitudinal axis in a first opening direction. The movable contact 700 slides over its conductive cap 231 until the second stop element 840 inside the chamber 210 abuts against the inner surface of the conductive cap 231. This abutting position corresponds to the open position of the movable contact 700 and the second center contact 600.

[0079] During the second displacement, the actuating mechanism 800 moves the movable contact 700 along its longitudinal axis in the first opening direction, and the second stop element 840 fixed to the second contact 700 abuts the conductive cap 231, the movable contact 700 being translated integrally with the insulating housing 220. Therefore, in this case, any displacement of the movable contact 700 in the opening direction results in a displacement of the insulating housing 220 and the first and second center contacts 400, 600. Since the fixed contact 500 remains stationary, fixed to the circuit C, the displacement of the insulating housing 220 and the first center contact 400 thus results in the opening of the first center contact 400 and the fixed contact 500. The insulating housing 220 and the first center contact 400 are limited by the third mechanical stop element 860 abutting against the conductive cap 230 of the fixed contact 500. Like the switching device 100, the vacuum switch 200 is now in its open position.

[0080] As in the previous embodiment, during the entire opening procedure, the total displacement of the movable contact 700 is equal to the sum of the gaps between the first center contact 400 and the fixed contact 500 and between the second center contact 600 and the movable contact 700. Therefore, in the third embodiment, the movable contact 700 will travel a distance of 2d during the opening of the switch device 100. Therefore, after the entire travel 2d of the movable contact 7, the switch device 100 is in its open position.

[0081] Starting from this open position of the switch device 100 according to the third embodiment of the present invention, the actuating mechanism 800 acts again on the movable contact 700 to displace it in the second closing direction along its longitudinal axis and close the switch device 100. The closing procedure in this third embodiment is the same as that disclosed above for the first and second embodiments. The entire closing stroke of the movable contact 700 is also 2d, while the rest of the vacuum switch 200 (except the fixed contact 500) is displaced by a distance d.

[0082] The guide mechanism of the switch device 100 according to the third embodiment is similar to that disclosed above for the second embodiment. In this case, the guide flange 94 is respectively fixed to one of the insulating cylinders 221, 222 forming the insulating housing 220. Alternatively, the guide flange 94 may be fixed to each of the conductive caps 230, 231.

[0083] In this third embodiment, when the switch device 100 is in its open position, each gap between the fixed contact 500 and the first center contact 400 and between the second center contact 600 and the movable contact 700 represents a capacitance C1 and C2, respectively. The voltage distribution between the two gaps depends on the capacitance C1, C2 in each gap. In the case where the switch device 100 is used as a grounding switch, one pole (700) is grounded and the other pole (500) is connected to the high voltage of the circuit C, the voltage distribution between the two gaps will depend on the stray capacitance Cs relative to the bottom surface. In particular, even if the two gaps are identical so as to assume that their capacitances are equal (C1=C2), the voltage distribution between the two gaps is not equal. In fact, the actual equivalent capacitance C2r in the gap between the second center contact 600 and the movable contact 700 will be higher than the actual equivalent capacitance C1r in the gap between the fixed contact 500 and the first center contact 400.

[0084] The magnitude of the stray capacitance Cs is often comparable to the individual capacitances C1, C2 in the gap. Therefore, its influence on the voltage distribution cannot be ignored. In some cases, the voltage in the first gap between the fixed contact 500 and the first center contact 400 may exceed two-thirds of the voltage applied in the entire switch device 100.

[0085] When the switch device 100 is used as an earthing switch, the earthing side is known; therefore the individual capacitances C1, C2 of each gap can be influenced. To increase or decrease the capacitance, the effective contact surface of a pair of contacts can be changed or the gap distance of one of the gaps can be changed. Fig.11a A first alternative is shown in which the gap distances d between the fixed contact 500 and the first center contact 400 and between the second center contact 600 and the movable contact 700 are the same, but the active contact surfaces of the fixed contact 500 and the first center contact 400 are different. Fig.11b A second alternative is shown, in which the active contact surfaces of the contacts 400 , 500 , 600 , 700 are identical, but the gap distance d′ between the fixed contact 500 and the first center contact 400 is different from the gap distance d between the second center contact 600 and the movable contact 700 .

[0086] As described above, the mechanical stop element prevents the movable contact or the second contact of the second vacuum switch displaced by the actuating mechanism from moving a distance farther than the gap between the contacts, and its corresponding contact can be positioned on the outside of the vacuum switch (stop rod 82, first mechanical stop element 83 and second mechanical stop element 84), or can be positioned on the inside of the vacuum switch (second and third mechanical stop elements 840, 860 and conductive caps 230, 231). With the first alternative, two standard vacuum switches already available on the market can be used, while with the second alternative, a suitable vacuum switch including these stop elements must be constructed.

[0087] In the first and second embodiments, similar mechanical stop elements (840, 230) used in the third embodiment may be applied to each end of the individual vacuum switches 2 and 3 instead of the external mechanical stop elements 83, 84, 86.

[0088] In the first and second embodiments described above, the first and second vacuum switches 2, 3 are identical. In a variant, they may be different (different geometries of the active surfaces of the contacts, different gaps between the contacts, different spacing distances, different external creepage distances, other structural differences ...).

[0089] In fact, two vacuum switches arranged in series can withstand high voltage (HV) tests better than a single vacuum switch with an equivalent total contact gap of two vacuum switches. With two vacuum switches, vacuum redundancy along the insulation path is established. Under rated voltage conditions during the service life of the equipment, the probability of simultaneous breakdown in two vacuum switches or a single vacuum switch with two pairs of contacts in series is much lower than in a device with a single gap.

Claims

1. Switching device (1; 10; 100), comprising: at least two pairs of contacts (4, 5, 6, 7; 400, 500, 600, 700), each pair being enclosed in a vacuum chamber (21, 31; 210) defined by an insulating housing (22, 32; 220), the insulating housing being closed at each end by a conductive cap (23, 33; 230); a first pair of contacts (4, 5; 400, 500) comprising a first contact and a second contact movable relative to each other between a closed position and an open position, the closed position and the open position of which are The distance between the first contact and the second contact (5, 500) is a first spacing distance (d), and the second contact (5, 500) forms a first pole of the switching device (1; 10; 100); the second pair of contacts (6, 7; 600, 700) includes a first contact and a second contact movable relative to each other between a closed position and an open position, and the distance between their closed position and the open position is the second spacing distance (d), and the second contact (700) forms a second pole of the switching device (1; 10; 100); the first contact (4; 400) of the first pair of contacts is fixed to the first contact (400) of the second pair of contacts a contact (6; 600) such that the first pair of contacts and the second pair of contacts are arranged in series; an actuating mechanism (8; 80; 800) designed to open or close the switching device (1; 10; 100) by displacing the second contact (7; 700) of the second pair of contacts, characterised in that the actuating mechanism (8; 80; 800) is also designed to displace the insulating housing (22, 32; 220) relative to the second contact (5; 500) of the first pair of contacts (4, 5; 400, 600) during opening and closing of the switching device; The actuating mechanism (8; 80; 800) comprises a first mechanical stop element (83, 231) fixed to the insulating housing (22, 32; 220) and designed to cooperate with a second mechanical stop element (84, 840), wherein the second mechanical stop element is fixed to a second contact (7; 700) of the second pair of contacts to prevent the second contact (7; 700) of the second pair of contacts from moving a distance greater than a second spacing distance relative to the first contact (6; 600) of the second pair of contacts and relative to the insulating housing (22, 32; 220).

2. The switch device according to claim 1, characterized in that: The actuating mechanism (8; 80; 800) is designed to open and close the switching device (1; 10; 100) by displacing the second contact (7; 700) of the second pair of contacts by a first predetermined distance corresponding to the second spacing distance in the opening direction and the closing direction respectively relative to the first contact (6; 600) of the second pair of contacts and the insulating housing (22, 32; 220), and by displacing the second contact (7; 700) of the second pair of contacts together with the first contact (4; 6; 400, 600) of the first and second pairs of contacts and the insulating housing (22, 32; 220) by a second predetermined distance corresponding to the first spacing distance in the opening direction and the closing direction respectively.

3. The switch device according to claim 1 or 2, characterized in that: The first spacing distance and the second spacing distance are equal.

4. The switch device according to claim 1 or 2, characterized in that: The first separation distance and the second separation distance correspond to gap distances between the first pair of contacts and between the second pair of contacts in their respective open positions.

5. The switch device according to claim 1 or 2, characterized in that: The vacuum chamber is formed by a first vacuum chamber (21) and a second vacuum chamber (31), wherein the first vacuum chamber is defined by a first tubular insulating shell (22) closed by two first conductive caps (23), and the second vacuum chamber is defined by a second tubular insulating shell (32) closed by two second conductive caps (33), the first vacuum chamber accommodates a first pair of contacts, and the second vacuum chamber accommodates a second pair of contacts, the first contact (4) of the first pair of contacts is fixed relative to the first tubular insulating shell (22), and the first contact (6) of the second pair of contacts is fixed relative to the second tubular insulating shell (32).

6. The switch device according to claim 1 or 2, characterized in that: The vacuum chamber (210) is defined by a single tubular insulating housing (210) closed by two conductive caps (230, 231).

7. The switch device according to claim 1 or 2, characterized in that: A first mechanical stop element (83) is fixed to one end of a stop rod (82), which is firmly fixed to the insulating housing (22, 32; 220) via a flange (81).

8. The switch device according to claim 1 or 2, characterized in that: The first mechanical stop element is part of one of the conductive caps (230, 231).

9. The switch device according to claim 8, characterized in that: A second mechanical stop element (84, 840) is fixed inside the vacuum chamber (21, 31; 210) to the second contact (7; 700) of the second pair of contacts or to a part thereof.

10. The switch device according to claim 1 or 2, characterized in that: The switch device also includes a third mechanical stop element (86; 860), which is designed to cooperate with the first mechanical stop element (83) or the fourth mechanical stop element (88, 231) to prevent the insulating housing (22, 32; 220) and the first contact (4, 6; 400, 600) of the first and second pairs of contacts from moving relative to the second contact (5; 500) of the first pair of contacts by a distance greater than the first spacing distance.

11. The switch device according to claim 10, characterized in that: The third mechanical stop element (86) is fixed to a fixed frame (87) of the actuating mechanism (8).

12. The switch device according to claim 10, characterized in that The third mechanical stop element (860) is fixed to the second contact (5; 500) of the first pair of contacts or to a part thereof inside or outside the vacuum chamber (21, 31; 210).

13. The switch device according to claim 1 or 2, characterized in that: The switching device also comprises a guide mechanism (9; 90) designed to guide the displacement of the insulating housing (22, 32; 220) during opening and closing of the device.

14. The switch device according to claim 13, characterized in that The guide mechanism (9) comprises at least one guide rod (91), and a flange (81) fixed to the insulating housing is capable of sliding along the at least one guide rod.

15. The switch device according to claim 13, characterized in that The guide mechanism (9) comprises a guide tube (93) accommodating an insulating housing (22, 32; 220) and at least one guide flange (94) fixed to the insulating housing (22, 32; 220) and designed to be able to slide along the inner wall of the guide tube (93).

16. The switch device according to claim 1, characterized in that The switch device is an earthing switch or a circuit breaker.

17. Switching device (1; 10; 100), comprising: · at least two pairs of contacts (4, 5, 6, 7; 400, 500, 600, 700), each pair being enclosed in a vacuum chamber (21, 31; 210) defined by an insulating housing (22, 32; 220), the insulating housing being closed at each end by a conductive cap (23, 33; 230); · a first pair of contacts (4, 5; 400, 500) comprising a first contact and a second contact movable relative to each other between a closed position and an open position, the distance between their closed position and the open position being a first spacing distance (d), the second contact (5, 500) forming a first pole of the switching device (1; 10; 100); · a second pair of contacts (6, 7; 600, 700) comprising a first contact and a second contact movable relative to each other between a closed position and an open position, the distance between their closed position and the open position being a second spacing distance ( d), the second contact (700) forms the second pole of the switching device (1; 10; 100), the first contact (4; 400) of the first pair of contacts is fixed to the first contact (6; 600) of the second pair of contacts, so that the first pair of contacts and the second pair of contacts are arranged in series; an actuating mechanism (8; 80; 800) designed to open or close the switching device (1; 10; 100) by displacing the second contact (7; 700) of the second pair of contacts, characterized in that the actuating mechanism (8; 80; 800) is also designed to displace the insulating housing (22, 32; 220) relative to the second contact (5; 500) of the first pair of contacts (4, 5; 400, 600) during opening and closing of the switching device; the switching device also includes a guiding mechanism (9; 90) designed to guide the displacement of the insulating housing (22, 32; 220) during opening and closing of the device.

18. The switch device according to claim 17, characterized in that The switch device is an earthing switch or a circuit breaker.

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