Vacuum bulb for cut-off device

Abstract

Vacuum bulb (1) for a switching device comprising: - a first electrode (5) and a second electrode (6) each comprising a contact part (8), the second electrode (6) being movable along an axial direction (X) relative to the first electrode (5) between a closed position and an open position, and - a bellows (10) disposed around the rod (7) of the second electrode (6), the bellows (10) being adapted to conduct an electric current between the outside of the vacuum bulb (1) and the contact part (8) of the second electrode (6) when the second electrode (6) is in the closed position.

Description

technical field

[0001] The present invention relates to a vacuum bulb of a switching device and a switching device comprising such a vacuum bulb.

[0002] The invention finds a particular application for switches in which the vacuum bulb is located on a branch of the main electric current line. Previous technique

[0003] Vacuum bulbs are known to be used in electrical circuits to alternately interrupt or restore an electric current by moving two electrodes relative to each other. A prior art vacuum bulb is described in US-A-2018308651.

[0004] The electric current must therefore flow between the electrodes of the vacuum bulb, which requires conducting the electric current from outside the vacuum bulb to inside the vacuum bulb while allowing the movement of at least one of the two electrodes.

[0005] This is relatively difficult to implement.

[0006] Also, the invention aims to provide a switching device comprising a less complex, more compact and less expensive vacuum bulb to manufacture, allowing an electric current to be conducted satisfactorily through the vacuum bulb. Summary

[0007] The invention improves the situation.

[0008] A vacuum bulb is proposed for a switching device according to claim 1.

[0009] According to another embodiment, the electrically conductive element is a wire or a braid.

[0010] According to another embodiment, the rod of the second electrode includes at least a portion made of an electrically insulating material.

[0011] According to another embodiment, the portion of electrically insulating material of the stem of the second electrode is located outside the vacuum bulb and / or is surrounded by the bellows.

[0012] According to another embodiment, the vacuum bulb includes a hood through which the second electrode is slidably mounted, the bellows comprising one end electrically connected to the hood and one end electrically connected to the contact part of the second electrode.

[0013] According to another design, the bellows is made of stainless steel, copper and / or copper alloy.

[0014] According to another embodiment, the bellows includes a copper coating, obtained by electrolysis, plasma or cold spraying.

[0015] According to another design, the copper coating has a thickness greater than 0.05 millimeters, or even greater than 0.5 millimeters.

[0016] According to another design, the bellows is made of stainless steel laminated with copper.

[0017] According to another aspect, a switching device is proposed comprising a vacuum bulb according to the invention, in particular for at least one of its electrical phases. Brief description of the drawings

[0018] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: FIG. 1 [ FIG. 1 ] is a schematic cross-sectional view of a prior art vacuum ampoule according to one embodiment. FIG. 2 [ FIG. 2 ] is a schematic cross-sectional view of a prior art vacuum ampoule according to another embodiment. FIG. 3 [ FIG. 3] is a schematic cross-sectional view of a vacuum bulb according to the invention in one embodiment. FIG. 4 [ FIG. 4 ] is a schematic cross-sectional view of a vacuum bulb according to the invention in another embodiment. FIG. 5 [ FIG. 5 ] is a schematic cross-sectional view of a vacuum bulb according to the invention in another embodiment. Description of the implementation methods

[0019] The drawings and description below contain, for the most part, elements of a definite nature. They may therefore not only serve to better explain this disclosure, but also contribute to its definition, if necessary. In particular, the figures are cross-sectional views. It is understood, however, that many elements, such as the casing, the covers, the bellows, or the vacuum tube electrodes, have rotational symmetry about a central axis.

[0020] In what follows, the terms "upper" and "lower" are used solely to indicate the relative positions of elements of the vacuum tube as shown in the figures. However, it is understood that the vacuum tube may be installed in a switching device in any orientation.

[0021] There [ FIG. 3 [ ] illustrates a schematic example of a vacuum bulb 1 according to the invention in one embodiment. The vacuum bulb 1 is intended for use in a switching device to interrupt an electric current in an electrical circuit, in particular medium and / or high voltage.

[0022] In what follows, the terms "medium voltage" and "high voltage" are used in their usual sense, namely that the term "medium voltage" refers to a voltage that is greater than 1,000 volts AC and 1,500 volts DC but does not exceed 52,000 volts AC and 75,000 volts DC, while the term "high voltage" refers to a voltage that is strictly greater than 52,000 volts AC and 75,000 volts DC.

[0023] In what follows, the term "switching device" is used to refer to an electrical device for interrupting the current, such as a contactor, switch, fuse, or recloser. Other types of switching devices using a vacuum bulb are also possible.

[0024] The vacuum bulb 1 can in particular be used in a switch as described in document EP2182536, in particular in which the vacuum bulb is located on a branch of a main electric current line.

[0025] The vacuum bulb 1 comprises a substantially cylindrical casing 2 made of electrically insulating material, preferably ceramic. The casing 2 is sealed by two end caps, in particular an upper cap 3 and a lower cap 4. The casing 2 and the upper and lower caps 3, 4 define an internal cutoff chamber in which a vacuum can be created.

[0026] In what follows, the cut-off chamber refers to the inside of the vacuum bulb 1, while what is not located in the cut-off chamber constitutes the outside of the vacuum bulb 1.

[0027] The vacuum bulb 1 comprises a first electrode 5 and a second electrode 6 housed at least partly inside the vacuum bulb 1. The first electrode 5 is fixed, in particular attached to the lower cover 4, while the second electrode 6 is movable, in particular mounted to slide along an axial direction X inside the vacuum bulb 1 through the upper cover 3.

[0028] Each of the first and second electrodes 5, 6 comprises a rod 7 extending along the axial direction X towards a contact end 8. The rod 7 of the second electrode 6 is thus located both inside and outside the vacuum bulb 1. The contact end 8 can have various shapes and sizes, including a contact disc or sphere with a greater or lesser radius of curvature.

[0029] As is known, the sliding of the second electrode 6 can be driven by an actuation mechanism not shown in the figures. The second electrode 6 can thus be moved between a closed and an open position. In the figures, only the open position is shown. In the closed position, the contact portion 8 of the first electrode 5 and the contact portion 8 of the second electrode 6 are in contact with each other so that an electric current can flow through the vacuum bulb 1. In the open position, the contact portion 8 of the first electrode 5 and the contact portion 8 of the second electrode 6 are separated from each other so that the electric current is interrupted in the vacuum bulb 1.

[0030] The vacuum bulb 1 also includes a bellows 10. The bellows 10 consists of a deformable tubular element. The bellows 10 is arranged around, or surrounds at least a portion of, the rod 7 of the second electrode 6, in particular the portion of the rod 7 of the second electrode 6 located inside the vacuum bulb 1. The bellows 10 thus comprises one end electrically connected to the upper cover 3 and one end electrically connected to, or near, the contact portion 8 of the second electrode 6. The bellows 10 is attached to the upper cover 3 and to the second electrode 6, for example, by brazing.

[0031] The bellows 10, also called the sealing bellows, is adapted to ensure the gas tightness of the vacuum bulb against the outside (in particular to maintain the vacuum in the vacuum bulb 1), while allowing the sliding of the second electrode 6.

[0032] The vacuum bulb 1 may also include a dielectric screen 11 placed around the contact parts 8 of the first and second electrodes 5, 6. Other screens not shown are also conceivable, such as for example a secondary screen around the bellows 10.

[0033] On the [ FIG. 1 ] And [ FIG. 2 Representing the prior art, an electric current is conducted between the first electrode 5 and the second electrode 6 by the rods in the closed position, as illustrated by arrows C (showing the flow of electric current when the second electrode is in the closed position). The rods of the first and second electrodes are thus made of an electrically conductive material.

[0034] According to the representation of the [ FIG. 1The electric current flows from an electrical current inlet 12 located outside the vacuum tube. The electric current is then conducted to the rod of the second electrode by flexible electrically conductive strips or wires 12, for example made of copper. The conductive wires thus allow the electric current to be carried while allowing the rod of the second electrode to slide within the vacuum tube.

[0035] According to the representation of the [ FIG. 2 ], the electric current flows from an electric current input 12 and is conducted to the rod of the second electrode by an electrically conductive joint 15. The joint 15 thus allows the electric current to be conducted while allowing the rod of the second electrode to slide in the vacuum bulb.

[0036] However, these representations are not entirely satisfactory because they require the use of additional parts between the power supply and the vacuum tube, particularly to allow the electric current to flow through the second electrode. These parts can be a source of malfunction, especially if the conductive wires or the seal are damaged or worn.

[0037] Thus, according to the invention more particularly illustrated on the [ FIG. 3 ], [ FIG. 4 ] And [ FIG. 5 ], the bellows 10 is also adapted to conduct electric current between an electric current inlet 12 located outside the vacuum bulb 1 and the contact part 8 of the second electrode 6.

[0038] The bellows 10 is thus made of an electrically conductive material, for example, a metal, particularly stainless steel. To ensure higher electrical conductivity, especially with stainless steel, the bellows 10 may include a coating of another material, for example, copper, obtained notably by electrolysis, plasma, or cold spray. The coating may advantageously have a thickness greater than 0.05 millimeters, or even greater than 0.5 millimeters.

[0039] In another example, bellows 10 is made of stainless steel laminated with copper. Such a bellows 10 is, for example, manufactured by co-lamination.

[0040] Other constructions of the bellows 10 are conceivable to ensure satisfactory electrical conductivity, for example made of copper or a copper alloy, such as, but not limited to, bronze, phosphor bronze, copper beryllium (CuBe), or bronze (CuSn8P or CuSn9P). Other alloys are also possible.

[0041] Depending on the method of implementation of the [ FIG. 3 ], the electric current is conducted entirely or almost entirely through the bellows 10 to the contact part 8 of the second electrode 6, as illustrated by the arrows C (showing the flow of electric current when the second electrode is in the closed position).

[0042] According to this embodiment, the electric current supply 12 is for example electrically connected to the upper cover 3 of the vacuum bulb 1. The electric current can then flow from the electric current supply 12, through the upper cover 3, through the bellows 10, through the contact part 8 of the second electrode 6, through the first electrode 5 and then through an electric current outlet 14. The electric current outlet 14 is located outside the vacuum bulb 1, for example electrically connected to the first electrode 5 of the vacuum bulb 1.

[0043] According to another embodiment, more particularly illustrated in the [ FIG. 4 ] And [ FIG. 5 ], the vacuum bulb 1 may also include an additional electrically conductive element 16 adapted to conduct the electric current between the electric current inlet 12 located outside the vacuum bulb 1 and the contact part 8 of the second electrode 6.

[0044] The conductive element 16 can, for example, be a flexible wire or metal braid made of copper. However, these examples are not exhaustive and other designs are possible.

[0045] According to one embodiment, the conductive element 16 can be arranged in the cutting chamber between the bellows 10 and the casing 2, as illustrated in the [ FIG. 4 ]. According to another embodiment, the conducting element 16 can be arranged between the rod 7 of the second electrode 6 and the bellows 10, as illustrated in the [ FIG. 5 ], which also helps to limit the local disturbance of the electric field.

[0046] The conductive element 16 includes one end electrically connected to the upper cover 3 or to the power supply 12. The conductive element 16 also includes one end electrically connected to, or near, the contact portion 8 of the second electrode 6, in particular by brazing or welding. The bellows 10 and the conductive element 16 thus form two parallel paths of electrical current between the exterior of the vacuum tube and the contact portion 8 of the second electrode 6.

[0047] According to the achievements of[ FIG. 4 ] And [ FIG. 5 ], the electric current is conducted simultaneously through the conducting element 16 and the bellows 10, as illustrated by the arrows C (showing the flow of electric current when the second electrode is in the closed position).

[0048] By "the current is conducted simultaneously by the conducting element 16 and the bellows 10," we mean that the electric current is distributed between them in varying proportions as it passes through the vacuum bulb 1, depending on their local resistivities. At least 5%, possibly 10%, or even 20% of the electric current flows through the bellows 10.

[0049] The electric current can then flow from the electric current inlet 12, through the upper cover 3, then simultaneously through the bellows 10 and the conductive element 16, through the contact part 8 of the second electrode 6, through the first electrode 5 and then through the electric current outlet 14.

[0050] According to the invention, the electric current does not flow through the rod 7 of the second electrode 6 or through only a portion of the rod 7 of the second electrode 6. In this way, it is not necessary for all or part of the rod 7, illustrated in hatching on the [ FIG. 3], [ FIG. 4 ] And [ FIG. 5 ], or in an electrically conductive material. A portion of the rod 7 can therefore be made of a relatively less expensive electrically insulating material, thus avoiding the dielectric constraints associated with the use of conductive materials that could locally influence the electric field inside the vacuum bulb. The portion made of an insulating material is advantageously surrounded by the bellows 10, and its length can vary depending on the size of the bellows 10 used in the axial direction X.

[0051] Furthermore, thanks to the invention, it is not necessary to use additional parts, such as the wires or conductive joints illustrated in the [ FIG. 1 ] And [ FIG. 2 ] of the prior art. This results in a technical solution comprising fewer parts, therefore more compact and less expensive to manufacture.

Claims

1. Vacuum bottle (1) for a switching device comprising: - a first electrode (5) and a second electrode (6) each comprising a contact portion (8), the second electrode being mobile in an axial direction (X) with respect to the first electrode (5) between a closed position in which the contact portions (8) of the first and second electrodes (5, 6) are in contact with each other so that an electric current may flow through the vacuum bottle (1), and an open position in which the contact portions (8) of the first and second electrodes (5, 6) are spaced apart with respect to each other such that an electric current is interrupted in the vacuum bottle (1), the second electrode (6) comprising a rod (7) extending in the axial direction (X) and terminating in the contact portion (8), and - a bellows seal (10) positioned around the rod (7) of the second electrode (6), suitable for ensuring that the vacuum bottle is sealed while allowing the second electrode to be moved, the bellows seal (10) being also suitable for conducting an electric current between the outside of the vacuum bottle (1) and the contact portion (8) of the second electrode (6) when the second electrode (6) is in the closed position, characterized in that the vacuum bottle (1) comprising an electrically conductive element (16) suitable for conducting the electric current between the outside of the vacuum bottle (1) and the contact portion (8) of the second electrode (6) when the second electrode (6) is in the closed position, the bellows seal (10) and the electrically conductive element (16) forming two paths for the electric current which are parallel to each other, the conductive element (16) being positioned between the rod (7) of the second electrode (6) and the bellows seal (10).

2. Vacuum bottle (1) according to Claim 2, wherein the electrically conductive element (16) is a wire or a braided conductor.

3. Vacuum bottle (1) according to any one of the preceding claims, wherein the rod (7) of the second electrode (6) comprises at least one segment made of an electrically insulating material.

4. Vacuum bottle (1) according to Claim 3, wherein the segment made of electrically insulating material of the rod (7) of the second electrode (6) is located on the outside of the vacuum bottle (1) and / or is surrounded by the bellows seal (10).

5. Vacuum bottle (1) according to any one of the preceding claims, comprising a cover (3) through which the second electrode (6) is slidably mounted, the bellows seal (10) comprising an end which is electrically connected to the cover (3) and an end which is electrically connected to the contact portion (8) of the second electrode (6).

6. Vacuum bottle (1) according to any one of the preceding claims, wherein the bellows seal (10) is made of stainless steel, of copper and / or of a copper alloy.

7. Vacuum bottle (1) according to any one of the preceding claims, wherein the bellows seal (10) comprises a coating, notably made of copper, obtained by electrolysis, by plasma spraying or by cold spraying.

8. Vacuum bottle (1) according to Claim 7, wherein the coating has a thickness greater than 0.05 millimetres, or even greater than 0.5 millimetres.

9. Vacuum bottle (1) according to any one of the preceding claims, wherein the bellows seal (10) is made of copper-clad stainless steel.

10. Switching device comprising a vacuum bottle (1) according to any one of the preceding claims.

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