Medium or high voltage vacuum bulb

Abstract

A medium or high voltage vacuum interrupter (50) is proposed, comprising: - an insulator forming a receiving enclosure, the insulator being formed of two coaxial elements (1a, 1b), - two electrical contacts arranged in the insulator, configured to be moved relative to each other between a closed position and an open position, - a screen (4) radially surrounding the electrical contacts, configured to collect the metal particles emitted during the passage of an electric arc between the electrical contacts so as to protect the insulator from the emitted metal particles, the screen (4) comprising a fixing flange (5) clamped between the two elements (1a, 1b) of the insulator (1), characterized in that the vacuum interrupter (50) comprises a seal (7) made of semiconductor material surrounding the insulator, the seal (7) being in electrical contact with the screen (4).

Description

Technical field

[0001] The present invention relates to the field of medium or high voltage vacuum interrupters, also called vacuum interrupters or vacuum interrupters. Vacuum interrupters are used in medium and high voltage electrical distribution devices, i.e. voltages above 1 kV. Vacuum interrupters are associated with actuators to cut off the current in a part of the circuit. Prior art

[0002] As is well known, a vacuum interrupter has two cut-off contacts arranged opposite each other. Each contact comprises a rod for supplying the electric current, and a body secured to the rod. The contacts are arranged in an insulating envelope forming a sealed enclosure placed under vacuum. The contacts can be moved relative to each other. When the contacts are pressed against each other, the current can pass from one contact to the other. When the contacts are separated from each other, the current is interrupted.

[0003] A protective screen is arranged inside the insulating envelope and surrounds the electrical contacts. The screen prevents metal particles detaching from the contacts when an electric arc is created from being deposited on the internal surface of the insulating envelope. In order to secure the screen to the insulating envelope, it can be in two parts arranged side by side coaxially, and a portion of the screen serving as a retaining flange is clamped between the two parts of the insulating envelope. This portion of the screen serving as a retaining flange generates dielectric stresses.

[0004] It is desirable to have vacuum interrupters that can withstand higher voltages without increasing their size and, in particular, without increasing their diameter. The dielectric stresses generated by the portion of the screen serving as a retaining flange work against this objective.

[0005] There is therefore a need for a vacuum interrupter with improved dielectric strength. Summary

[0006] To this end, the invention provides a medium or high voltage vacuum bulb, comprising: an insulator forming a receiving enclosure, the insulator being formed of two coaxial elements, two electrical contacts arranged in the insulator, configured to be moved relative to each other between a closed position in which the electrical contacts are supported on each other and an open position in which the electrical contacts are spaced apart from each other, a screen radially surrounding the electrical contacts, configured to collect metal particles emitted during the passage of an electric arc between the electrical contacts so as to protect the insulator from the emitted metal particles, the screen comprising a fixing flange clamped between the two elements of the insulator, characterized in that the vacuum interrupter comprises a seal made of semi-conductor material surrounding the insulator, the seal being in electrical contact with the screen.

[0007] The presence of the gasket avoids the creation of a triple interface where the insulator, the screen and the gas surrounding the vacuum interrupter meet. Thanks to the presence of the gasket, two triple interfaces are created: a first interface between the insulator, a first portion of the gasket and the gas surrounding the vacuum interrupter, and a second interface between the screen, the insulator and a second portion of the gasket. This separation of the interfaces increases the dielectric strength of the vacuum interrupter. The semiconducting nature of the gasket material allows the gasket to be at the electrical potential of the screen in its entirety, which allows the gasket to have an electrical deflector effect reducing the electric field in this area. For the same performance, the size of the interrupter can be reduced, or for the same size, the performance of the vacuum interrupter can be improved.

[0008] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0009] The vacuum bulb is leak-proof.

[0010] The vacuum bulb is generally cylindrical in shape and extends along an axis.

[0011] The insulator, screen and electrical contacts are coaxial.

[0012] According to one aspect of the invention, the semiconducting material seal is made of butadiene-acrylonitrile copolymers.

[0013] The seal is elastically deformable.

[0014] According to one embodiment of the vacuum bulb, the seal is in mechanical contact with the screen fixing flange.

[0015] The gasket is in mechanical contact with the insulation.

[0016] According to another embodiment of the vacuum bulb, the seal is spaced from the fixing flange of the screen, and an axial surface of at least one of the two coaxial elements of the insulator comprises an electrically conductive coating, the coating being in contact with the seal and with the fixing flange.

[0017] The electrically conductive coating on the axial surface, which is in contact with the screen mounting flange on the one hand and the seal on the other, ensures electrical contact between the two parts. The seal and the screen are thus placed at the same electrical potential.

[0018] According to an alternative embodiment of the vacuum bulb, or in a complementary manner, a space separating the screen fixing flange and the seal comprises an electrically conductive grease.

[0019] The grease is for example a silicone grease.

[0020] According to one aspect of the proposed vacuum bulb, the seal is removable.

[0021] According to one example of use, the seal can thus be installed specifically for the conditioning procedure aimed at removing surface defects from the contact bodies of the vacuum interrupter. The seal can then be removed for use of the interrupter in an electrical appliance. According to another example of use, the seal can be retained for the entire period of use of the vacuum interrupter.

[0022] The gasket can be added to the vacuum bulb.

[0023] Once fitted, the seal can be removed from the vacuum bulb.

[0024] The insulation has the shape of a cylinder of revolution.

[0025] The two elements of the insulation have the shape of a hollow cylinder.

[0026] The two insulation elements are arranged side by side in an axial direction and are separated from each other by the screen fixing flange.

[0027] Both elements of the insulation have an identical internal diameter.

[0028] Both elements of the insulation have an identical outer diameter.

[0029] The insulation is ceramic.

[0030] The screen includes a cylindrical portion surrounding the electrical contacts.

[0031] The screen is made of copper, for example.

[0032] The shield mounting flange extends radially outward from an outer surface of the cylindrical portion of the shield.

[0033] The screen mounting flange extends in a plane transverse to the screen axis.

[0034] The screen mounting flange is annular in shape.

[0035] The screen mounting flange is made of copper.

[0036] The screen mounting flange is in contact with each of the two elements of the insulation.

[0037] The screen mounting flange is compressed in an axial direction between the two insulation elements.

[0038] The connection between the screen mounting flange and each of the two insulation elements is watertight.

[0039] An axial surface of the first element is in contact with a first face of the screen mounting flange.

[0040] An axial surface of the second element is in contact with a second face of the screen mounting flange.

[0041] An outer side surface of the fixing flange is radially recessed from an outer side surface of the first element of the insulator. Similarly, the outer side surface of the fixing flange is radially recessed from an outer side surface of the second element of the insulator.

[0042] An outside diameter of the fixing flange is greater than an average diameter of the first element and the second element.

[0043] The seal partially covers an outer side surface of the first member and an outer side surface of the second member.

[0044] The seal partially covers an axial surface of the first element and an axial surface of the second element.

[0045] According to one embodiment of the vacuum bulb, the seal is toroidal in shape when the seal is in the free state.

[0046] According to an exemplary embodiment, a diameter of a cross-section of the seal is between 5 millimeters and 40 millimeters.

[0047] According to an exemplary embodiment, an average diameter of the seal is between 50 millimeters and 200 millimeters.

[0048] Preferably, a ratio of the diameter of a cross-section of the seal to the average diameter of the seal is between 0.05 and 0.2.

[0049] This form factor allows the joint to closely match the shape of the ends of the insulation elements, while also allowing sufficient overlap of the axial end portions of the elements.

[0050] According to one embodiment of the vacuum bulb, the seal comprises in the free state: a toroidal portion, an annular portion extending radially inward, the annular portion being in contact with the first element and with the second element in an axial direction.

[0051] The annular portion allows the seal to have a shape that facilitates the establishment of mechanical contact with the screen mounting flange.

[0052] A first face of the annular portion is in contact with an axial surface of the first element of the insulator.

[0053] A second face of the annular portion, opposite the first face, is in contact with an axial surface of the second element of the insulator.

[0054] The annular portion extends toward the axis of the toroidal portion in an equatorial plane of the toroidal portion.

[0055] According to one embodiment of the vacuum bulb, the annular portion of the seal is distant from the screen fixing flange.

[0056] More specifically, the annular portion of the gasket is spaced from an outer side surface of the screen mounting flange.

[0057] A lateral surface of the annular portion of the seal is distant from the outer lateral surface of the screen fixing flange, in a radial direction.

[0058] An outer lateral surface of the fixing flange, a lateral surface of the annular portion of the seal, an axial surface of the first element and an axial surface of the second element define an annular-shaped volume.

[0059] A volume separating the annular portion of the seal and the screen mounting flange is at least partially filled with an electrically conductive grease.

[0060] The volume separating the annular portion of the seal and the screen mounting flange can be completely filled with an electrically conductive grease.

[0061] The cavity delimited by the outer lateral surface of the fixing flange, the lateral surface of the annular portion of the seal, an axial surface of the first element and an axial surface of the second element is filled, partially or totally, with an electrically conductive grease.

[0062] A ratio between the diameter of a cross-section of the toroidal part and the outer diameter of the insulator is between 0.05 and 0.2.

[0063] A ratio between the inner diameter of the toroidal part and the outer diameter of the insulator is between 0.8 and 0.95.

[0064] A portion of the first element in contact with the seal comprises a chamfer.

[0065] Similarly, a portion of the second element in contact with the seal comprises a chamfer.

[0066] The invention also relates to a method of conditioning a vacuum ampoule.

[0067] The process involves the following steps: (i) providing a vacuum interrupter comprising: an insulator forming a receiving enclosure, the insulator being formed of two coaxial elements, a pair of electrical contacts disposed in the insulator, comprising a movable contact and a fixed contact, a screen radially surrounding the electrical contacts, configured to collect the metal particles emitted when an electric arc passes between the electrical contacts so as to protect the insulator from the emitted metal particles, the screen comprising a fixing flange clamped between the two elements of the insulator, (ii) providing a seal, (iii) equipping the vacuum interrupter with a seal surrounding the insulator, the seal being in electrical contact with the screen, (iv) separating the contacts of the vacuum interrupter and increasing an electrical voltage between the electrical contacts until an electric arc is created between the contacts,(v) iterate the step of creating an electric arc so as to condition the surfaces of the electrical contacts, (vi) dismantle the seal of the vacuum bulb.

[0068] The addition of the seal for the vacuum interrupter conditioning phase allows the voltage between the electrical contacts to be increased without creating a discharge between the vacuum interrupter insulation and the external environment. Electric arcs can be created in a preferential manner between the electrical contacts, which allows for faster vacuum interrupter conditioning. Step (vi) is optional.

[0069] According to a variant of the proposed packaging method, the seal can remain mounted on the vacuum interrupter for the entire duration of use of the vacuum interrupter. In this case, the interrupter is mounted in an electrical device equipped with its seal. The presence of the seal makes it possible to improve the dielectric strength of the vacuum interrupter in service.

[0070] Step (vi) of dismantling the seal is thus replaced by a step: (vi') maintaining the seal on the vacuum bulb until the vacuum bulb is mounted in an electrical device. Brief description of the drawings

[0071] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: There Figure 1 is a schematic side view of a vacuum bulb, The Figure 2 is a side view, in section, of a vacuum bulb, The Figure 3 is a side view of a vacuum bulb according to one embodiment of the invention, The Figure 4 is a partial side and sectional view of the vacuum bulb of the Figure 3 , not equipped with its seal, The Figure 5 is a partial side and sectional view of the vacuum bulb of the Figure 3 , There Figure 6is a partial side and sectional view of an alternative embodiment of the vacuum bulb of the Figure 3 , There Figure 7 represents a seal equipping a vacuum bulb according to one embodiment, The figure 8 represents a seal equipping a vacuum bulb according to another embodiment, The figure 9 is a block diagram of a method for conditioning a vacuum bulb according to the invention. Description of the embodiments:

[0072] To facilitate reading the figures, the different elements are not necessarily represented to scale. In these figures, identical elements bear the same references. Some elements or parameters may be indexed, i.e. designated for example by first element or second element, or first parameter and second parameter, etc. This indexing is intended to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names may be interchanged. When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in this subsystem. Similarly, when it is specified that a subsystem includes a given element, it is understood that the subsystem includes at least this element.

[0073] In the different figures, the X, Y, Z axes designate the three directions of space in order to identify the viewing angle of each figure.

[0074] It has been represented on the Figure 1 as well as on the Figure 2 a 50 medium or high voltage vacuum bulb.

[0075] The 50 vacuum bulb includes: a first electrical cut-off contact 2, a second electrical cut-off contact 3.

[0076] At least one of the first contact 2 and the second contact 3 is configured to be moved along an axis D between a so-called open position O in which the electrical contacts 2, 3 are spaced apart from each other, and a so-called closed position F in which the electrical contacts 2, 3 are supported on each other so as to allow a passage of electric current between the first contact 2 and the second contact 3.

[0077] The 50 vacuum interrupter is part of a medium voltage cut-off device, such as a circuit breaker or a disconnector.

[0078] On part A of the Figure 1 , the electrical cut-off contacts 2, 3 are in contact with each other, and an electric current can flow. On part A of the Figure 1 , the sign C represents the passage of electric current.

[0079] When the contacts 2, 3 are moved apart from each other, the flow of electric current is interrupted, generally after a transient period during which an electric arc is present between the two electrical contacts 2, 3.

[0080] On part B of the Figure 1 , the electrical contacts are separated by a distance represented by the sign g, and the flow of electric current from one contact to the other is interrupted.

[0081] The first electrical contact 2 comprises a cylindrical rod 22 and a disc-shaped contact body 21. The contact body 21 is integral with the rod 22 and extends transversely to the cylindrical rod 22. Similarly, the second electrical contact 3 comprises a cylindrical rod 32 and a disc-shaped contact body 31, integral with the cylindrical rod 32 and extending transversely to the cylindrical rod 32. Each contact body 21, 31 is fixed respectively to the cylindrical rod 22, 32, for example by soldering. When the electrical contacts 2, 3 are in contact, the contact body 21 and the contact body 31 bear against each other. In the closed position, a spring, not shown, maintains a preload between the contact bodies 21, 31. In other words, a contact pressure is applied in the closed position between the contact bodies 21, 31, this contact pressure being determined by the force applied by the spring.The preload spring is part of the control mechanism of the vacuum interrupter 50. The electrical contacts 2, 3 are arranged in an insulating envelope, also called insulator 1. A protective screen 4 is arranged inside the insulator 1, radially arranged between the electrical contacts 2, 3 and the inner wall of the insulator 1. The protective screen 4 prevents metal particles detaching from the contacts 2, 3 when electric arcs are created from being deposited on the inner surface of the insulator 1.

[0082] There Figure 3 is an exterior view of the proposed 50 vacuum bulb.

[0083] The 50 medium or high voltage vacuum bulb includes: an insulator 1 forming a receiving enclosure, the insulator 1 being formed of two coaxial elements 1a, 1b, two electrical contacts 2, 3 arranged in the insulator 1, configured to be moved relative to each other between a closed position F in which the electrical contacts 2, 3 are supported on each other and an open position O in which the electrical contacts 2, 3 are spaced apart from each other, a screen 4 radially surrounding the electrical contacts 2, 3, configured to collect metal particles emitted during the passage of an electric arc between the electrical contacts 2, 3 so as to protect the insulator 1 from the emitted metal particles.

[0084] The screen 4 comprises a fixing flange 5 clamped between the two elements 1a, 1b of the insulator 1.

[0085] The vacuum bulb 50 comprises a seal 7 made of semiconducting material surrounding the insulator 1, the seal 7 being in electrical contact with the screen 4.

[0086] The presence of the seal 7 avoids the creation of a triple interface where the insulator 1, the screen 4 and the gas surrounding the vacuum bottle 50 would meet. Thanks to the presence of the seal 7, two distinct triple interfaces are created: a first triple interface between the insulator 1, a first portion of the seal 7 and the gas surrounding the vacuum bottle 50, and a second triple interface between the screen 4, the insulator 1 and a second portion of the seal 7.

[0087] This separation of the triple interfaces makes it possible to increase the dielectric strength of the vacuum interrupter 50. The semiconducting nature of the material of the seal 7 makes it possible to ensure that the seal 7 is at the electrical potential of the screen 4 in its entirety, which allows the seal 7 to have an electrical deflector effect reducing the electric field in this area. For the same performance, the size of the bulb can be reduced, or for the same size the performance of the vacuum interrupter can be improved.

[0088] The vacuum bulb 50 is generally cylindrical in shape and extends along an axis D.

[0089] Insulator 1 has the shape of a cylinder of revolution.

[0090] The two elements 1a, 1b of the insulator 1 have the shape of a hollow cylinder. The two elements 1a, 1b of the insulator 1 are arranged side by side in an axial direction and are separated from each other by the fixing flange 5 of the screen 4. The insulator 1, the screen 4 and the electrical contacts 2, 3 are coaxial. The axis D is the common axis of the first element 1a of the insulator 1, the second element 1b of the second element 1b of the insulator 1, the screen 4, the first electrical contact 2 and the second electrical contact 3.

[0091] There Figure 4 represents a vacuum bulb 50 in which the seal 7 is not fitted.

[0092] The two elements 1a, 1b of the insulator 1 have an identical internal diameter. This internal diameter is designated by the sign Di-1 on the Figure 4 .

[0093] The two elements 1a, 1b of the insulator 1 have an identical external diameter. This external diameter is designated by the sign De-1 on the Figure 4 .

[0094] Insulator 1 is ceramic.

[0095] Insulator 1 is for example made of alumina. (chemical formula Al 2 O 3 )

[0096] More precisely, each element 1a, 1b is made of ceramic, for example alumina.

[0097] The screen 4 comprises a cylindrical portion 6 surrounding the electrical contacts 2, 3.

[0098] The cylindrical portion 6 extends along the rods 22, 32 and is opposite the contact bodies 21, 31.

[0099] Screen 4 is for example made of copper.

[0100] The fixing flange 5 of the screen 4 extends radially outwards from an outer surface 6e of the cylindrical portion 6 of the screen 4.

[0101] The fixing flange 5 of the screen 4 extends in a plane P transverse to the axis D of the screen 4.

[0102] The fixing flange 5 of the screen 4 is annular in shape.

[0103] The fixing flange 5 of the screen 4 is made of copper.

[0104] The fixing flange 5 of the screen 4 is fixed to the cylindrical portion 6 surrounding the electrical contacts 2, 3 by soldering.

[0105] The fixing flange 5 and the cylindrical part 6 of the screen 4 are thus at the same electrical potential.

[0106] The fixing flange 5 of the screen 4 is in contact with each of the two elements 1a, 1b of the insulator 1.

[0107] The fixing flange 5 of the screen 4 is compressed in an axial direction between the two elements 1a, 1b of the insulator 1.

[0108] The connection between the fixing flange 5 of the screen 4 and each of the two elements 1a, 1b of the insulation is watertight.

[0109] An axial surface 10a of the first element 1a is in contact with a first face 15 of the fixing flange 5 of the screen 4.

[0110] An axial surface 10b of the second element 1b is in contact with a second face 16 of the fixing flange 5 of the screen 4.

[0111] The 50 vacuum bulb is leak-proof.

[0112] The pressure inside the vacuum bulb 50 is for example less than 10 -4< millibar.

[0113] The gaseous medium in which the vacuum bottle 50 is arranged is for example ambient air. The ambient air in which the vacuum bottle is placed is represented diagrammatically by the signs A on the figures 4, 5 , 6 .

[0114] An outer lateral surface 17 of the fixing flange 5 is radially set back from an outer lateral surface 11a of the first element 1a of the insulator 1. In the same way, the outer lateral surface 17 of the fixing flange 5 is radially set back from an outer lateral surface 11b of the second element 1b of the insulator 1.

[0115] An outer diameter De-5 of the fixing flange 5 is greater than an average diameter Dm-1 of the first element 1a and of the second element 1b.

[0116] The average diameter Dm-1 of the first element 1a is the average between the internal diameter Di-1 and the external diameter De-1.

[0117] There Figure 5 and the Figure 6 are views of the area designated by the sign F on the Figure 4 .

[0118] In these figures, the vacuum bulb 50 is equipped with a seal 7.

[0119] The seal 7 made of semiconducting material is made of butadiene-acrylonitrile copolymers.

[0120] This material is also called nitrile rubber, and is commonly referred to by the English acronym NBR for “nitrile butadiene rubber”.

[0121] The seal 7 is elastically deformable.

[0122] The seal 7 is in the example illustrated a single piece.

[0123] The seal 7 is for example obtained by molding.

[0124] According to an embodiment of the vacuum bulb 50 illustrated in the Figure 5, the seal 7 is in mechanical contact with the fixing flange 5 of the screen 4.

[0125] The electrical contact between the seal 7 and the fixing flange 5 of the screen 4 is then obtained by establishing direct mechanical contact between the two parts.

[0126] The seal 7 is in mechanical contact with the insulator 1.

[0127] More precisely, the seal 7 is in mechanical contact with the first element 1a of the insulator 1. The seal 7 is also in mechanical contact with the second element 1b of the insulator 1.

[0128] The seal 7 surrounds the insulator 1 and partly covers the outer surface 11a of the first element 1a of the insulator 1, as well as the outer surface 11b of the second element 1b.

[0129] The seal 7 partially covers an outer lateral surface 11a of the first element 1a and an outer lateral surface 11b of the second element 1b.

[0130] The seal 7 partially covers an axial surface 10a of the first element 1a and an axial surface 10b of the second element 1b.

[0131] There Figure 6 illustrates an embodiment of the vacuum bulb 50 in which the seal 7 is distant from the fixing flange 5 of the screen 4.

[0132] A space designated by the sign V radially separates the fixing flange 5 and the screen 4. The seal 7 is not in mechanical contact with the fixing flange 5 of the screen 4.

[0133] An axial surface 10a, 10b of at least one of the two coaxial elements 1a, 1b of the insulator 1 comprises an electrically conductive coating 14, the coating 14 being in contact with the seal 7 and with the fixing flange 5.

[0134] The electrically conductive coating 14 is present on an axial surface of at least one element 1a, 1b, this axial surface being in contact on the one hand with the fixing flange 5 of the screen 4 and on the other hand with the seal 7. The coating 14 makes it possible to ensure electrical continuity between the seal 7 and the fixing flange 5. The seal 7 and the screen 4 are thus placed at the same electrical potential.

[0135] The coating 14 is for example a metallic layer deposited on the axial end of an element of the insulator 1.

[0136] According to the example of the Figure 6 , only the first element 1a of the insulator 1 comprises the electrically conductive coating 14.

[0137] According to an example not shown, the first element 1a and the second element 1b each comprise an electrically conductive coating deposited on their respective axial end.

[0138] A space V separating the fixing flange 5 from the screen 4 and the seal 7 comprises an electrically conductive grease.

[0139] The electrical contact between the seal 7 and the fixing flange 5 of the screen 4 can be obtained, or completed, thanks to the electrical conduction of the grease interposed between the seal 7 and the fixing flange 5 of the screen 4.

[0140] In addition, the grease placed in the annular space V between the seal 7 and the fixing flange 5 of the screen 4 makes it possible to avoid the presence of air bubbles in this space separating the two parts.

[0141] The grease is for example a silicone grease.

[0142] Seal 7 is removable.

[0143] According to an example of use, the seal 7 can thus be put in place specifically for the packaging procedure carried out during the manufacture of the vacuum bulb 50.

[0144] This conditioning procedure aims to remove surface defects from the contact bodies 21, 31 of the vacuum bottle 50.

[0145] To do this, electric arcs are created between the contacts, and these electric arcs allow the surface defects forming angular singularities on the surface of the new contact bodies to melt and disappear.

[0146] The seal 7 can then be removed once the procedure for conditioning the vacuum bottle 50 is complete. The seal 7 is thus absent from the vacuum bottle 50 when using the vacuum bottle 50 in an electrical appliance.

[0147] According to another example of use, the seal 7 can be kept for the entire duration of use of the vacuum bulb 50.

[0148] For example, seal 7 is installed before the packaging procedure and is then left in place.

[0149] Gasket 7 can be added to vacuum bulb 50.

[0150] Once fitted, the seal 7 can be removed from the vacuum bulb 50.

[0151] Multiple successive assemblies and disassemblies can be carried out without damaging the seal 7.

[0152] The seal 7 can for example be dismantled to facilitate the installation of the vacuum bulb 50 in an electrical device.

[0153] According to one embodiment of the vacuum bulb 50, the seal 7 is toroidal in shape when the seal 7 is in the free state.

[0154] In other words, the seal has the shape of a torus in the absence of mechanical stress likely to deform the seal.

[0155] There Figure 7 represents the seal 7 in the free state, that is to say not mounted on the vacuum bulb 50.

[0156] According to an exemplary embodiment, a diameter Dt-7 of a cross-section of the seal 7 is between 5 millimeters and 40 millimeters.

[0157] The diameter Dt-7 of a cross-section of the seal 7 is the diameter in the free state, i.e. without deformation. It is therefore the dimension when the seal 7 is not mounted on the vacuum bulb 50.

[0158] The diameter Dt-7 is also called the torus diameter.

[0159] According to an exemplary embodiment, an average diameter Dm-7 of the seal 7 is between 50 millimeters and 200 millimeters.

[0160] The average diameter of the torus is understood to be the average between the internal diameter Di-7 of the torus and the external diameter De-7 of the torus.

[0161] As before, the average diameter Dm-7 of joint 7 is the diameter in the free state, i.e. without deformation.

[0162] The inner diameter Di-7 and the outer diameter De-7 are measured parallel to the equatorial plane P7 of joint 7.

[0163] Preferably, a ratio of the diameter Dt-7 of a cross-section of the seal 7 and the average diameter Dm-7 of the seal 7 is between 0.05 and 0.2.

[0164] This form factor allows the seal 7 to closely match the shape of the ends of the lateral surface of the elements 1a, 1b of the insulator 1, while also allowing sufficient coverage of the axial end portions 10a, 10b of the elements 1a, 1b.

[0165] According to the embodiments illustrated on the figures 5 And 6 , joint 7 comprises in the free state: a toroidal portion 8, an annular portion 9 extending radially inwards, the annular portion 9 being in contact with the first element 1a and with the second element 1b in an axial direction.

[0166] The annular part 9 allows the seal 7 to have a shape facilitating the establishment of mechanical contact with the fixing flange 5 of the screen 4.

[0167] A first face 19 of the annular portion 9 is in contact with an axial surface 10a of the first element 1a of the insulator 1.

[0168] A second face 20 of the annular portion 9, opposite the first face 19, is in contact with an axial surface of the second element 1b of the insulator 1.

[0169] The annular portion 9 extends towards the axis D of the toroidal portion 8 in an equatorial plane P8 of the toroidal portion 8.

[0170] The thickness of the annular part 9 is smaller than the diameter of the toroidal part 8. The annular part 9 can therefore be easily inserted into the space separating the axial surface 10a of the first element 1a from the axial surface 10b of the second element 1b.

[0171] On the Figure 5 and on the Figure 6 , the toroidal part 8 is represented by taking into account, schematically, the deformation undergone in contact with the external surface 11a, 11b of the insulator 1.

[0172] Depending on the method of implementation of the Figure 6 , the annular portion 9 of the seal 7 is distant from the fixing flange 5 of the screen 4.

[0173] More precisely, the annular portion 9 of the seal 7 is distant from an external lateral surface 17 of the fixing flange 5 of the screen 4.

[0174] A lateral surface 18 of the annular portion 9 of the seal 7 is thus distant from the external lateral surface 17 of the fixing flange 5 of the screen 4, in a radial direction.

[0175] In other words, a radial clearance is present between the annular portion 9 of the seal 7 and the fixing flange 5 of the screen 4.

[0176] An outer lateral surface 17 of the fixing flange 5, a lateral surface 18 of the annular portion 9 of the seal 7, an axial surface 10a of the first element 1a and an axial surface 10b of the second element 1b define a volume V of annular shape.

[0177] The volume V separating the annular portion 9 of the seal 7 and the fixing flange 5 of the screen 4 is filled at least partially with an electrically conductive grease.

[0178] The volume V separating the annular portion 9 of the seal 7 and the fixing flange 5 of the screen 4 can be completely filled with an electrically conductive grease.

[0179] The cavity delimited by the outer lateral surface 17 of the fixing flange 5, the lateral surface 18 of the annular portion 9 of the seal 7, an axial surface 10a of the first element 1a and an axial surface 10b of the second element 1b is filled, partially or totally, with an electrically conductive grease.

[0180] A ratio between the diameter of a cross-section of the toroidal part 8 and the outer diameter De-1 of the insulator 1 is between 0.05 and 0.2.

[0181] A ratio between the inner diameter of the toroidal part 8 and the outer diameter De-1 of the insulator 1 is between 0.8 and 0.95.

[0182] A portion of the first element 1a in contact with the seal 7 comprises a chamfer 14a.

[0183] Likewise, a portion of the second element 1b in contact with the seal 7 comprises a chamfer 14b.

[0184] The chamfer 14a of the first element 1a connects a portion of the axial surface 10a of the first element 1a and a portion of the outer lateral surface 11a of the first element 1a.

[0185] The same applies to chamfer 14b of the second element 1b.

[0186] The chamfers 14a, 14b facilitate the insertion of the seal 7 between the axial surfaces 10a, 10b of the first element 1a and the second element 1b.

[0187] A conditioning process can be applied to a vacuum bulb. This conditioning is applied when the bulb is new, before it is installed in an electrical appliance.

[0188] The invention also relates to a method of packaging a vacuum ampoule 50.

[0189] The process for packaging a vacuum ampoule 50 comprises the steps: (i) providing a vacuum interrupter 50 comprising: -- an insulator 1 forming a receiving enclosure, the insulator 1 being formed of two coaxial elements 1a, 1b, -- a pair of electrical contacts 2, 3 arranged in the insulator 1, comprising a movable contact 2 and a fixed contact 3, -- a screen 4 radially surrounding the electrical contacts 2, 3, configured to collect the metal particles emitted during the passage of an electric arc between the electrical contacts 2, 3 so as to protect the insulator 1 from the emitted metal particles, the screen 4 comprising a fixing flange 5 clamped between the two elements 1a, 1b of the insulator 1, (ii) providing a seal 7, (iii) equipping the vacuum interrupter 50 with a seal 7 surrounding the insulator 1, the seal 7 being in electrical contact with the screen 4, (iv) separating the contacts of the vacuum interrupter 50 and increasing a voltage electrical between the electrical contacts 2, 3 until an electric arc is created between the contacts 2, 3,(v) repeat step (iv) of creating an electric arc so as to condition the surfaces of the electrical contacts 2, 3, (vi) remove the seal 7 from the vacuum bulb 50.,

[0190] The addition of the seal 7 for the conditioning phase of the vacuum interrupter 50 makes it possible to increase the voltage between the electrical contacts 2, 3 without creating a discharge between the insulation of the vacuum interrupter 50 and the external environment.

[0191] Electric arcs can be created in a preferential manner between the electrical contacts 2, 3, which makes it possible to increase the voltage at which the conditioning is carried out. The duration of the conditioning phase of the vacuum interrupter 50 can thus be shortened. Step (vi) is optional.

[0192] According to a variant of the proposed packaging method, the seal 7 can remain mounted on the vacuum bulb 50 for the entire duration of use of the vacuum bulb 50.

[0193] The bulb is thus mounted in an electrical device equipped with its seal 7.

[0194] The presence of the seal 7 makes it possible to improve the dielectric strength in service of the vacuum interrupter 50, and also to accelerate the conditioning phase.

[0195] Step (vi) of dismantling the seal 7 is thus replaced by a step: (vi') holding the seal 7 on the vacuum bulb 50 until the vacuum bulb 50 is mounted in an electrical device.

[0196] The electrical device can be, for example, a circuit breaker.

Claims

1. Medium or high voltage vacuum interrupter (50), comprising: - an insulator (1) forming a receiving enclosure, the insulator (1) being formed of two coaxial elements (1a, 1b), - two electrical contacts (2, 3) arranged in the insulator (1), configured to be moved relative to each other between a closed position (F) in which the electrical contacts (2, 3) are supported on each other and an open position (O) in which the electrical contacts (2, 3) are spaced apart from each other, - a screen (4) radially surrounding the electrical contacts (2, 3), configured to collect metal particles emitted during the passage of an electric arc between the electrical contacts (2, 3) so as to protect the insulator (1) from the emitted metal particles, the screen (4) comprising a fixing flange (5) clamped between the two elements (1a, 1b) of the insulator (1), characterized in thatthe vacuum bulb (50) comprises a removable seal (7) made of semiconducting material surrounding the insulator (1), the seal (7) being in electrical contact with the screen (4).

2. Vacuum bulb (50) according to claim 1, in which the seal (7) made of semiconducting material is made of butadiene-acrylonitrile copolymers.

3. Vacuum bulb (50) according to claim 1 or 2, wherein the seal (7) is in mechanical contact with the fixing flange (5) of the screen (4).

4. Vacuum cartridge (50) according to claim 1 or 2, wherein the seal (7) is distant from the fixing flange (5) of the screen (4), and wherein an axial surface (10a, 10b) of at least one of the two coaxial elements (1a, 1b) of the insulator (1) comprises an electrically conductive coating (14), the coating (14) being in contact with the seal (7) and with the fixing flange (5).

5. Vacuum bulb (50) according to one of the preceding claims, in which a space (V) separating the fixing flange (5) from the screen (4) and the seal (7) comprises an electrically conductive grease.

6. Vacuum cartridge (50) according to one of the preceding claims, wherein: - the seal (7) partly covers an outer lateral surface (11a) of the first element (1a) and an outer lateral surface (11b) of the second element (1b), and - the seal (7) partly covers an axial surface (10a) of the first element (1a) and an axial surface (10b) of the second element (1b).

7. Vacuum bulb (50) according to one of claims 1 to 6, wherein the seal (7) is toroidal in shape when the seal (7) is in the free state.

8. Vacuum bulb (50) according to one of the preceding claims, wherein a ratio of a diameter (Dt-7) of a cross-section of the seal (7) and an average diameter (Dm-7) of the seal (7) is between 0.05 and 0.

2.

9. Vacuum cartridge (50) according to one of claims 1 to 6, in which the seal (7) comprises in the free state: - a toroidal portion (8), - an annular portion (9) extending radially inwards, the annular portion (9) being in contact with the first element (1a) and with the second element (1b) in an axial direction.

10. Vacuum bulb (50) according to the preceding claim, wherein the annular portion (9) extends towards the axis of the toroidal portion (8) in an equatorial plane (P8) of the toroidal portion (8).

11. A vacuum bulb (50) according to claim 9 or 10, wherein a ratio between a diameter (Dt-8) of a cross-section of the toroidal portion (8) and an outer diameter (De-1) of the insulator (1) is between 0.05 and 0.

2.

12. Vacuum bulb (50) according to one of claims 9 to 11, in which a ratio between an inner diameter (Di-8) of the toroidal part (8) and an outer diameter (De-1) of the insulator (1) is between 0.8 and 0.

95.

13. Vacuum cartridge (50) according to one of the preceding claims, wherein: - a portion of the first element (1a) in contact with the seal (7) comprises a chamfer (14a), and - a portion of the second element (1b) in contact with the seal (7) comprises a chamfer (14b).

14. A method of packaging a vacuum interrupter, comprising the steps of: (i) providing a vacuum interrupter (50) comprising: - an insulator (1) forming a receiving enclosure, the insulator (1) being formed of two coaxial elements (1a, 1b), - a pair of electrical contacts (2, 3) arranged in the insulator (1), comprising a movable contact (2) and a fixed contact (3), - a screen (4) radially surrounding the electrical contacts (2, 3), configured to collect the metal particles emitted during the passage of an electric arc between the electrical contacts (2, 3) so as to protect the insulator (1) from the emitted metal particles, the screen (4) comprising a fixing flange (5) clamped between the two elements (1a, 1b) of the insulator (1), (ii) providing a seal (7), (iii) equipping the vacuum interrupter (50) with a seal (7) surrounding the insulator (1), the seal (7) being in electrical contact with the screen (4),(iv) moving the contacts of the vacuum bulb (50) apart and increasing an electrical voltage between the electrical contacts (2, 3) until an electric arc is created between the contacts (2, 3), (v) iterating the step of creating an electric arc so as to condition the surfaces of the electrical contacts.,

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