EP3968350A1 - Vacuum bulb for cut-off device - Google Patents

Abstract

Vacuum interrupter (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 in an axial direction ( X) with respect to the first electrode (5) between a closed position and an open position, and- a bellows (10) arranged 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 interrupter (1) and the contact portion (8) of the second electrode (6) when the second electrode (6) is in the closed position.

Description

Technical area

The present invention relates to a vacuum interrupter of a switching device and to a switching device comprising such a vacuum interrupter.

The invention finds particular application for switches in which the vacuum interrupter is located on a branch of the main electric current line.

Prior technique

Vacuum interrupters are known in an electric circuit which make it possible to alternately cut off or restore an electric current by moving two electrodes relatively with respect to one another.

The electric current must thus flow between the electrodes of the vacuum bulb, which requires conducting the electric current from the exterior of the vacuum bulb to the interior of the vacuum bulb while allowing the movement of at least one of the two electrodes.

This is relatively difficult to implement.

Also, the invention aims to propose a switching device comprising a vacuum interrupter that is less complex, more compact and less expensive to manufacture, making it possible to conduct an electric current satisfactorily through the vacuum interrupter.

Abstract

The invention improves the situation.

• une première électrode et une seconde électrode comprenant chacune une partie de contact, la seconde électrode étant mobile selon une direction axiale par rapport à la première électrode entre une position fermée dans laquelle les parties de contact des première et seconde électrode sont en contact l'une avec l'autre pour qu'un courant électrique puisse traverser l'ampoule à vide, et une position ouverte dans laquelle les parties de contact des première et seconde électrode sont espacées l'une par rapport à l'autre de sorte qu'un courant électrique est coupé dans l'ampoule à vide, la seconde électrode comprenant une tige s'étendant selon la direction axiale et se terminant par la partie de contact, et
• un soufflet disposé autour de la tige de la seconde électrode, adapté pour assurer l'étanchéité de l'ampoule à vide tout en permettant un déplacement de la seconde électrode, le soufflet étant également adapté pour conduire un courant électrique entre l'extérieur de l'ampoule à vide et la partie de contact de la seconde électrode lorsque la seconde électrode est dans la position fermée.

A vacuum interrupter is proposed for a breaking device comprising:

• a first electrode and a second electrode each comprising a contact part, the second electrode being movable in an axial direction with respect to the first electrode between a closed position in which the contact parts of the first and second electrodes are in contact with one with each other so that an electric current can flow through the vacuum interrupter, and an open position in which the contact portions of the first and second electrodes are spaced from each other so that a current electric is cut in the vacuum interrupter, the second electrode comprising a rod extending in the axial direction and terminating in the contact part, and
• a bellows arranged around the rod of the second electrode, adapted to ensure sealing the vacuum interrupter while allowing movement of the second electrode, the bellows also being adapted to conduct an electric current between the exterior of the vacuum interrupter and the contact part of the second electrode when the second electrode is in the closed position.

According to one embodiment, the vacuum interrupter comprises an electrically conductive element adapted to conduct electric current between the exterior of the vacuum interrupter and the contact part of the second electrode when the second electrode is in the closed position, the bellows and the electrically conductive element forming two parallel electrical current passages.

According to another embodiment, the electrical conductor element is a wire or a braid.

According to another embodiment, the rod of the second electrode comprises at least one portion made of an electrically insulating material.

According to another embodiment, the portion of electrically insulating material of the rod of the second electrode is located outside the vacuum interrupter and/or is surrounded by the bellows.

According to another embodiment, the vacuum interrupter comprises a cover through which the second electrode is slidably mounted, the bellows comprising one end electrically connected to the cover and one end electrically connected to the contact part of the second electrode.

According to another embodiment, the bellows is made of stainless steel, copper and/or copper alloy.

According to another embodiment, the bellows comprises a copper coating, obtained by electrolysis, by plasma or by cold spraying.

According to another embodiment, the copper coating has a thickness greater than 0.05 millimeter, or even greater than 0.5 millimeter.

According to another embodiment, the bellows is made of stainless steel laminated with copper.

According to another aspect, there is proposed a switching device comprising a vacuum interrupter according to the invention, in particular for at least one of its electrical phases.

Brief description of the drawings

• FIG. 1
  [FIG. 1] est une vue en coupe schématique d'une ampoule à vide de l'art antérieur selon une réalisation.
• FIG. 2
  [FIG. 2] est une vue en coupe schématique d'une ampoule à vide de l'art antérieur selon une autre réalisation.
• FIG. 3
  [FIG. 3] est une vue en coupe schématique d'une ampoule à vide selon l'invention selon une réalisation.
• FIG. 4
  [FIG. 4] est une vue en coupe schématique d'une ampoule à vide selon l'invention selon une autre réalisation.
• FIG. 5
  [FIG. 5] est une vue en coupe schématique d'une ampoule à vide selon l'invention selon une autre réalisation.

Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the appended drawings, in which:

• FIG. 1
  [ FIG. 1 ] is a schematic sectional view of a prior art vacuum interrupter according to one embodiment.
• FIG. 2
  [ FIG. 2 ] is a schematic sectional view of a vacuum interrupter of the prior art according to another embodiment.
• FIG. 3
  [ FIG. 3 ] is a schematic sectional view of a vacuum interrupter according to the invention according to one embodiment.
• FIG. 4
  [ FIG. 4 ] is a schematic sectional view of a vacuum interrupter according to the invention according to another embodiment.
• FIG. 5
  [ FIG. 5 ] is a schematic sectional view of a vacuum interrupter according to the invention according to another embodiment.

Description of embodiments

The drawings and the description below contain, for the most part, certain elements. They may therefore not only serve to better understand this disclosure, but also contribute to its definition, where applicable. In particular, the figures are sectional views. It is however understood that many elements, such as the casing, the covers, the bellows or the electrodes of the vacuum interrupter have a symmetry of revolution around a central axis.

In the following, the terms "upper" and "lower" are used only to indicate the relative positions of elements of the vacuum interrupter as shown in the figures. However, it is understood that the vacuum interrupter can be installed in a switchgear according to any orientation.

The [ FIG. 3 ] illustrates a schematic example of a vacuum interrupter 1 according to the invention according to one embodiment. The vacuum interrupter 1 is intended to be used in a switching device for cutting off an electric current in an electric circuit, in particular medium and/or high voltage.

In the following, the terms "medium voltage" and "high voltage" are used in their usual sense, namely that the term "medium voltage" means a voltage which is greater than 1,000 volts in alternating current and 1,500 volts in direct current but which does not exceed 52,000 volts in alternating current and 75,000 volts in direct current, while the term "high voltage" designates a voltage which is strictly greater than 52,000 volts in alternating current and 75,000 volts in direct current.

In the following, the term “breaking device” is used to designate an electrical device for breaking the current, such as a contactor, a switch, a fuse switch or a recloser. Other types of breaking devices using a vacuum interrupter are also possible.

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

The vacuum interrupter 1 comprises a substantially cylindrical casing 2 made of electrically insulating material, preferably ceramic. The envelope 2 is closed off by two end covers, in particular an upper cover 3 and a lower cover 4. The envelope 2 and the upper and lower covers 3, 4 delimit an internal arcing chamber in which it is possible to to empty.

In what follows, the interrupting chamber designates the interior of the vacuum interrupter 1 while what is not located in the interrupting chamber constitutes the exterior of the vacuum interrupter 1.

The vacuum bottle 1 comprises a first electrode 5 and a second electrode 6 housed at least partly inside the vacuum bottle 1. The first electrode 5 is fixed, in particular secured to the lower cover 4, while the second electrode 6 is movable, in particular slidably mounted in an axial direction X inside the vacuum interrupter 1 through the upper cover 3.

Each of the first and second electrodes 5, 6 comprises a rod 7 extending along the axial direction X towards one end 8 forming the contact part. The rod 7 of the second electrode 6 is thus located both inside and outside the vacuum interrupter 1. The end 8 forming the contact part can have various shapes and sizes, in particular in the form of a pad or a contact ball having a greater or lesser radius of curvature.

In known manner, 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 position and an open position. In the figures, only the open position is shown. In the closed position, the contact part 8 of the first electrode 5 and the contact part 8 of the second electrode 6 are in contact with each other so that an electric current can pass through the vacuum interrupter 1 In the open position, the contact part 8 of the first electrode 5 and the contact part 8 of the second electrode 6 are spaced from each other so that the electric current is cut off in the bulb. empty 1.

The vacuum interrupter 1 also comprises a bellows 10. The bellows 10 consists of a deformable tubular element. The bellows 10 is arranged around, or surrounds at least a part of the rod 7 of the second electrode 6, in particular the part of the rod 7 of the second electrode 6 located inside the vacuum interrupter 1. The bellows 10 thus comprises one end electrically connected to the upper cover 3 and one end electrically connected to, or close to the contact part 8 of the second electrode 6. The attachment of the bellows 10 to the upper cover 3 and to the second electrode 6 is for example made by brazing.

The bellows 10, also called sealing bellows, is adapted to ensure the gas tightness of the vacuum interrupter vis-à-vis the outside (in particular to maintain the vacuum in the vacuum interrupter 1) , while allowing the sliding of the second electrode 6.

The vacuum interrupter 1 can also include a dielectric screen 11 placed around the contact parts 8 of the first and second electrodes 5, 6. Other screens, not shown, can also be envisaged, such as for example a secondary screen around the bellows 10.

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 the arrows C (showing the flow of electric current when the second electrode is in position closed). The rods of the first and second electrodes are thus made of an electrically conductive material.

According to the representation of the [ FIG. 1 ], the electric current flows from an electric current inlet 12 located outside the vacuum interrupter. The electric current is then conducted to the rod of the second electrode by strips or flexible electrical conductor wires 12, for example made of copper. Conductive wires allow thus to conduct the electric current while allowing the rod of the second electrode to slide in the vacuum interrupter.

According to the representation of the [ FIG. 2 ], the electric current flows from an electric current inlet 12 and is conducted to the rod of the second electrode by an electrically conductive joint 15. The joint 15 thus makes it possible to conduct the electric current while allowing the rod of the second electrode to slide in the vacuum interrupter.

However, these representations are not entirely satisfactory in that they require the use of additional parts between the electric current inlet and the vacuum interrupter, in particular to cause the electric current to flow in the second electrode. However, these parts can be the source of malfunction, in particular if the conductive wires or if the seal are damaged or worn.

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

The bellows 10 is thus made of an electrically conductive material, for example metal, in particular stainless steel. In order to ensure higher electrical conductivity, in particular with stainless steel, the bellows 10 may comprise a coating of another material, for example copper, obtained in particular by electrolysis, by plasma or by cold spraying (“ cold spray” in English). The coating may have a thickness advantageously greater than 0.05 millimeter, or even greater than 0.5 millimeter.

According to another example, the bellows 10 is made of stainless steel laminated with copper. Such a bellows 10 is for example produced by co-rolling.

Other embodiments of the bellows 10 can be envisaged to ensure satisfactory electrical conductivity, for example made of copper or a copper alloy, such as, without limitation, bronze, phosphor bronze, beryllium copper (CuBe), or bronze (CuSn8P or CuSn9P). Other alloys are also possible.

According to the embodiment of the [ FIG. 3 ], the electric current is conducted entirely or almost entirely by 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).

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

According to another embodiment, more particularly illustrated in [ FIG. 4 ] and [ FIG. 5 ], the vacuum interrupter 1 can also comprise an additional electrical conductor element 16 adapted to conduct the electric current between the electric current inlet 12 located outside the vacuum interrupter 1 and the contact part 8 of the second electrode 6.

The conductive element 16 can for example be a wire or a flexible metal braid, made of copper. However, these examples are not limiting and other embodiments are possible.

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

The conductive element 16 comprises one end electrically connected to the upper cover 3 or to the electric current supply 12. The conductive element 16 also comprises one end electrically connected to, or close to the contact part 8 of the second electrode 6, in particular by brazing or welding. The bellows 10 and the conductive element 16 thus form two electrical current passages between the outside of the vacuum interrupter and the contact part 8 of the second electrode 6 in parallel to each other.

According to the achievements of[ FIG. 4 ] and [ FIG. 5 ], the electric current is conducted simultaneously by the conductive 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).

By "the current is conducted simultaneously by the conductive element 16 and the bellows 10", it is meant that the electric current is distributed between them in variable proportions during its passage through the vacuum interrupter 1, depending on their resistivities. local. At least 5%, even 10%, even 20% of the electric current flows through the bellows 10.

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

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 that all or part of the rod 7, shown hatched in 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 electrical insulating material and makes it possible to overcome the dielectric constraints linked to the use of conductive materials capable of locally influencing the electric field inside the vacuum bulb. The portion made of an insulating material is advantageously surrounded by the bellows 10, and can be longer or shorter depending on the size of the bellows 10 used in the axial direction X.

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

Obviously, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that a person skilled in the art may consider in the context of the present invention and in particular all combinations of the various modes of operation described previously, which may be taken separately or in combination.

Claims (11)

Vacuum interrupter (1) for a breaking device comprising: - a first electrode (5) and a second electrode (6) each comprising a contact part (8), the second electrode (6) being movable in an axial direction (X) relative 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 can flow through the vacuum interrupter (1), and a open position in which the contact portions (8) of the first and second electrodes (5, 6) are spaced apart from each other so that an electric current is interrupted in the vacuum interrupter (1) , the second electrode (6) comprising a rod (7) extending in the axial direction (X) and ending in the contact part (8), and - a bellows (10) arranged around the rod (7) of the second electrode (6), adapted to seal the vacuum interrupter while allowing movement of the second electrode,
characterized in that the bellows (10) is also adapted to conduct an electric current between the exterior of the vacuum interrupter (1) and the contact part (8) of the second electrode (6) when the second electrode ( 6) is in the closed position. A vacuum interrupter (1) according to claim 1, comprising an electrically conductive element (16) adapted to conduct electric current between the exterior of the vacuum interrupter (1) and the contact part (8) of the second electrode (6) when the second electrode (6) is in the closed position, the bellows (10) and the electric conductor element (16) forming two passages of the electric current parallel to each other. A vacuum interrupter (1) according to claim 2, wherein the electrically conductive element (16) is a wire or a braid. Vacuum interrupter (1) according to any one of the preceding claims, in which the rod (7) of the second electrode (6) comprises at least a portion made of an electrically insulating material. Vacuum interrupter (1) according to Claim 4, in which the portion made of electrically insulating material of the rod (7) of the second electrode (6) is located outside the vacuum interrupter (1) and/or is surrounded by the bellows (10). Vacuum interrupter (1) according to any one of the preceding claims, comprising a cover (3) through which the second electrode (6) is slidably mounted, the bellows (10) comprising one end electrically connected to the cover (3) and one end electrically connected to the contact part (8) of the second electrode (6). Vacuum interrupter (1) according to any one of the preceding claims, in which the bellows (10) is made of stainless steel, copper and/or a copper alloy. Vacuum bulb (1) according to any one of the preceding claims, in which the bellows (10) comprises a coating, in particular of copper, obtained by electrolysis, by plasma or by cold spraying. Vacuum interrupter (1) according to Claim 8, in which the coating has a thickness greater than 0.05 millimeters, or even greater than 0.5 millimeters. A vacuum interrupter (1) according to any preceding claim, wherein the bellows (10) is made of stainless steel laminated with copper. Switching apparatus comprising a vacuum interrupter (1) according to any one of the preceding claims.

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