Electric field controller for vacuum interrupter, and vacuum switch

Abstract

The present invention relates to an electric field controller for a vacuum interrupter (1), the vacuum interrupter comprising an insulating support shell (2) and two conductive caps, said two conductive caps being respectively connected to the insulating support shell (2) at both axial ends of the insulating support shell (2), wherein the electric field controller is configured for being sleeved at a joint portion between the insulating support shell (2) and at least one conductive cap, and the electric field controller is configured for reducing the electric field strength at the joint portion and equalizing an electric field distribution, the electric field controller comprising a conductive inner layer (13) and an insulating outer layer (14). The present invention also relates to a vacuum switch.

Description

Technical Field

[0001] The present invention relates to an electric field controller for a vacuum interrupter, and to a vacuum switch.Background Art

[0002] As a core component of a vacuum switch, especially a medium / high voltage circuit breaker, the main function of a vacuum interrupter (also known as a vacuum circuit breaker tube) is to quickly extinguish an arc and suppress current, through the excellent insulating properties of the vacuum in the tube, when a medium / high voltage circuit connection is broken, preventing accidents and mishaps. This type of vacuum interrupter is mainly applied in power transmission and distribution control systems, and also in metallurgy, mining, petroleum, chemical engineering, railway, broadcasting, communications, industrial highfrequency heating and other power distribution systems.

[0003] There is still room for improvement in the external dielectric properties of existing vacuum interrupters.Summary of the Invention

[0004] The present invention is intended to solve the problems of the prior art.

[0005] The present invention proposes an electric field controller for a vacuum interrupter, the vacuum interrupter comprising an insulating support shell and two conductive caps, said two conductive caps being respectively connected to the insulating support shell at both axial ends of the insulating support shell, wherein the electric field controller is configured for being sleeved on a joint portion between the insulating support shell and at least one conductive cap, and the electric field controller is configured for reducing the electric field strength at the joint portion and equalizing an electric field distribution, the electric field controller comprising a conductive inner layer and an insulating outer layer.

[0006] According to a preferred embodiment, the inner layer is made of a conductive flexible material, and / or the outer layer is made of an insulating flexible material.

[0007] According to a preferred embodiment, the inner layer is made of a conductive rubber, and / or the outer layer is made of an insulating rubber.

[0008] According to a preferred embodiment, the inner layer comprises a sleeving part and a flange part, the sleeving part being configured for at least partially axially overlapping the at least one conductive cap in an installed state, and the flange part being configured for at least partially axially overlapping the insulating support shell in the installed state.

[0009] According to a preferred embodiment, the sleeving part has an inner contour that matches an outer periphery of the at least one conductive cap, the inner contour being configured for reliable contact with the outer periphery of the at least one conductive cap.

[0010] According to a preferred embodiment, the flange part of the inner layer extends further axially from a position where the flange part joins to the sleeving part, thereby axially exceeding an interface between the flange part and the sleeving part by an axial distance, the axial distance being greater than zero.

[0011] According to a preferred embodiment, the axial distance is in a range of 4 mm - 10 mm.

[0012] According to a preferred embodiment, the outer layer comprises a sleeving section that at least partially axially overlaps the sleeving part, and a flange section that at least partially axially overlaps the flange part.

[0013] According to a preferred embodiment, the sleeving section at least partially surrounds an outer circumferential surface of the sleeving part, and the flange section at least partially surrounds an outer circumferential surface and a free end of the flange part.

[0014] According to a preferred embodiment, the flange section at least partially surrounds an inner circumferential surface of the flange part.

[0015] According to a preferred embodiment, the electric field controller is constructed to have a rounded corner at a free end for mounting on the insulating support shell in a longitudinal section.

[0016] According to a preferred embodiment, the electric field controller has an anti-disengagement structure for secure contact with the joint portion.

[0017] According to a preferred embodiment, the electric field controller is at least partially configured for bonding to the joint portion.

[0018] According to a preferred embodiment, the electric field controller is constructed to have an annular shape or disc shape.

[0019] The present invention further proposes a vacuum switch, which comprises a vacuum interrupter, the vacuum interrupter having the electric field controller as described above. Vacuum switches should be understood to include circuit breakers, contactors and vacuum load switches.Brief Description of the Drawings

[0020] Fig. 1 shows a schematic longitudinal cutaway view of a vacuum interrupter without an electric field control apparatus. Fig. 2 shows a partial equipotential contour plot of a vacuum interrupter without an electric field control apparatus. Fig. 3 shows a partial contour plot of electric field strengthof a vacuum interrupter without an electric field control apparatus. Fig. 4 shows a schematic longitudinal cutaway view of a vacuum interrupter with an electric field control apparatus. Fig. 5 shows a top view of a first embodiment of an electric field controller. Fig. 6 shows a cutaway view along section line "A-A" of Fig. 5. Fig. 7 shows an enlarged view of part B of Fig. 6. Fig. 8 shows a partial equipotential contour plot of a vacuum interrupter with an electric field controller. Fig. 9 shows a partial contour plot of electric field strength of a vacuum interrupter with an electric field controller. Fig. 10 shows an axonometric view of a second embodiment of an electric field controller. Fig. 11 shows a longitudinal cutaway view of the second embodiment of the electric field controller. Fig. 12 shows an enlarged view of part C of Fig. 11. Fig. 13 shows a top view of a third embodiment of an electric field controller. Fig. 14 shows a cutaway view along section line "D-D" of Fig. 13. Fig. 15 shows an enlarged view of part E of Fig. 14. Detailed Description of the Invention

[0021] Hereinafter, specific technical means of the present invention will be described by way of specific embodiments with reference to the accompanying drawings. However, the present invention may be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, the provision of these embodiments makes the present invention comprehensive and complete, and comprehensively conveys the concept of the exemplary embodiments to those skilled in the art.

[0022] In the following description, the orientational terms used, such as "axial", "radial", "circumferential", "inner" and "outer", are defined with reference to a central axis of symmetry of the vacuum interrupter 1 or a central axis of symmetry of the electric field controller that is coaxial with the vacuum interrupter in an installed state.

[0023] As shown in Fig. 1, the vacuum interrupter 1 has a housing for forming a vacuum chamber. The housing mainly comprises an insulating support shell 2, a movable end cap 3, a stationary end cap 4 and bellows 16. A contact system is arranged in the chamber that is defined by the insulating support shell 2, the movable end cap 3, the stationary end cap 4 and the bellows 16. The contact system is configured for switching a circuit on and off. The contact system comprises a movable end conductive rod 5 with a movable end contact 7, and a stationary end conductive rod 6 with a stationary end contact 8. Optionally, a guide member 9 may be provided for the movable end conductive rod 5. In addition, an operating mechanism (not shown) is provided for moving the movable end conductive rod 5, wherein the operating mechanism moves the movable end conductive rod 5 axially to bring the movable end contact 7 into contact with and out of contact with the stationary end contact 8, thereby switching the circuit on and off. For example, the vacuum interrupter 1 may further comprise a shielding tube 10, for shielding metal vapour and spatter generated during the switching operation.

[0024] For the type of vacuum interrupter shown in Fig. 1, a joint portion is formed between the stationary end cap 4 and the insulating support shell 2; the joint portion is understood to be a portion with a certain axial dimension, the portion comprising an axial section of the corresponding stationary end cap 4 and an axial section of the insulating support shell 2. The "interface between the stationary end cap 4 and the insulating support shell 2" refers to the exact boundary between the stationary end cap 4 and the insulating support shell 2. The same applies to the joint portion and interface between the movable end cap 3 and the insulating support shell 2.

[0025] Considering the manufacturing process of the vacuum interrupter, the cap and the insulating support shell 2 are usually joined together by welding, etc., such as brazing or argon arc welding. During a welding process, solder melts, and tends to form sharp points or triple points at the joint portion between the stationary end cap 4 and the insulating support shell 2. Medium voltage (MV) and high voltage (HV) devices typically use a combination of conductive materials and a variety of insulating gases and / or solid insulating materials, which may have different dielectric constants. At the place where the three types of different material are combined together, that is, the so-called triple point, a strong increase in dielectric stress can be seen. For example, when the dielectric constant of a solid insulator is higher than that of the surrounding air, such a sharp point or triple point is formed at the position where a conductor is connected to the solid insulator surrounded by air. Due to the presence of the sharp points, a strong dielectric stress is formed near the joint portion, which can even lead to the external insulation failure of the vacuum interrupter. The same applies to the joint portion between the movable end cap 3 and the insulating support shell 2.

[0026] An equipotential contour plot and a contour plot of electric field strength of the vacuum interrupter of Fig. 1 in a region near the joint portion between the stationary end cap 4 and the insulating support shell 2 are shown in Figs. 2 and 3, respectively. The equipotential contour plot and the contour plot of electric field strength correspond to an electric field distribution and an electric potential gradient when the vacuum interrupter is in an opened position. As shown in the figures, at the joint portion between the stationary end cap 4 and the insulating support shell 2, there is a problem of a significant concentration of potential lines and enhancement of electric field strength, thereby inevitably causing a problem of concentrated dielectric stress, and insulation may even fail.

[0027] In order to solve the above problem, that is, to avoid the formation of strong dielectric stress in the vicinity of the joint portion, the present invention envisages the addition of a dedicated electric field control apparatus for the vacuum interrupter. A vacuum interrupter with an electric field control apparatus is shown in Fig. 4. In this embodiment, the electric field control apparatus may comprise a stationary end electric field controller 12 and / or a movable end electric field controller 11. Hereinafter, the stationary end electric field controller 12 and the movable end electric field controller 11 are sometimes also referred to collectively as the "electric field controller", and the movable end cap 3 and the stationary end cap 4 are referred to collectively as the "cap". The stationary end electric field controller 12 circumferentially surrounds a joint portion between the stationary end cap 4 and the insulating support shell 2 on an outer side, and the movable end electric field controller 11 circumferentially surrounds a joint portion between the movable end cap 3 and the insulating support shell 2 on an outer side.

[0028] It should be noted here that it is possible to only provide a movable end electric field controller, or to only provide a stationary end electric field controller, or both the movable end electric field controller and the stationary end electric field controller may be concurrently provided as shown in Fig. 4. These solutions are all within the scope of the present invention.

[0029] The following describes the specific construction of an electric field controller, taking the stationary end field controller 12 as an example.

[0030] As shown in Fig. 4, the stationary end electric field controller 12 annularly surrounds the joint portion between the stationary end cap 4 and the insulating support shell 2. In a first embodiment shown in Figs. 5-7, the stationary end electric field controller 12 has an overall annular construction and comprises a conductive inner layer 13 and an insulating outer layer 14.

[0031] The inner layer 13 of the stationary end electric field controller 12 is preferably made of a conductive flexible material, such as a conductive rubber. The conductive rubber may be selected from materials known from the prior art according to specific conditions of use, such as, but not limited to, nickel-plated graphite filled silicone rubber, silver filled silicone rubber extruded liner, silver-plated aluminium filled silicone rubber, silver-plated nickel filled silicone rubber, silver-plated copper filled silicone rubber, graphite filled silicone rubber, pure silver filled silicone rubber and other such materials.

[0032] The inner layer 13 consists mainly of a sleeving part 131 that axially overlaps the stationary end cap 4, and a flange part 132 that axially overlaps the insulating support shell 2. The installed state shown is the ideal installed state, i.e. the interface between the sleeving part 131 and the flange part 132 coincides with the interface between the stationary end cap 4 and the insulating support shell 2. However, there may also be a non-ideal installed state, i.e. the interface between the sleeving part 131 and the flange part 132 does not coincide with the interface between the stationary end cap 4 and the insulating support shell 2. Preferably, the distance between the two end faces in the installed state does not exceed a deviation threshold. The deviation threshold is, for example, between 0 and H to prevent a shielding effect from diminishing or disappearing.

[0033] The sleeving part 131 has an inner contour, for example that is cylindrical, that matches an outer periphery of the stationary end cap 4. The inner contour is configured for sleeving over the stationary end cap 4 and contacting the stationary end cap 4. In particular, the cylindrical inner contour of the sleeving part 131 reliably contacts the cylindrical outer periphery of the stationary end cap 4, thereby ensuring that the inner layer 13 is at the same electric potential as the stationary end cap 4. The cylindrical outer contour of the sleeving part 131 matches the outer layer 14 and closely contacts the inner contour of the outer layer 14, and in particular is connected thereto.

[0034] The flange part 132 of the inner layer 13 is connected to the sleeving part 131. As shown in the figures, corresponding to the joint portion, the flange part 132 expands radially outward from the sleeving part 131 and further extends axially. That is, the flange part 132 as a whole has a larger diameter than the sleeving part 131, and the flange part 132 has an axial range of extension away from the sleeving part 131. Therefore, from the interface between the sleeving part 131 and the flange part 132, the flange part 132 extends further axially by an axial distance H. In the installed state, the flange part 132 of the inner layer 13 extends radially and axially beyond the interface between the stationary end cap 4 and the insulating support shell 2, and extends away from the stationary end cap 4. Here, the axial distance H, by which the flange part 132 axially extends beyond the interface between the sleeving part 131 and the flange part 132, should be greater than zero, thereby ensuring electric field shielding performance. The axial distance H is, for example, 2 mm - 15 mm, preferably 4 mm - 10 mm. As shown in the figures, a free end of the flange part 132 facing the insulating support shell 2 has a rounded corner construction in a longitudinal section. The radius of the rounded corner is, for example, 1 - 10mm, preferably 1.5mm - 5mm. The radius of the rounded corner can be adjusted according to the dimensions of the interrupter.

[0035] By providing the flange part 132, a conductive material shields the sharp point or triple point of the interface between the interrupter cap and the insulating shell, improving the uniformity of the electric field distribution.

[0036] The outer layer 14 of the stationary end electric field controller 12 is likewise preferably made of an insulating flexible material, such as an insulating rubber. The insulating rubber may be chosen from materials known from the prior art according to specific conditions of use, such as, but not limited to, synthetic natural rubber, styrene-butadiene rubber, polybutadiene rubber (BR), Polychloroprene Rubber (CR), etc. For example, that outer layer 14 and the inner layer 13 are fixedly connected to each other, such as by vulcanization, bonding, etc. Alternatively, the stationary end electric field controller 12 containing the outer layer 14 and the inner layer 13 may be manufactured in one process, such as by two-component injection moulding or multi-component injection moulding.

[0037] As shown in the figures, the inner layer 13 is encapsulated on an outer side (particularly a radial outer side) by the material of the outer layer 14. For example, the sleeving part 131 of the inner layer 13 is encapsulated on the radial outer side by the material of a sleeving section 141 of the outer layer 14. That is, the material of the sleeving section 141 completely or partially surrounds an outer circumferential surface of the sleeving part 131. Of course, a construction different from that illustrated is also conceivable; for example, the free end of the sleeving part 131 of the inner layer facing away from the flange part 132 may also be partially covered by the outer layer material.

[0038] The flange part 132 of the inner layer 13 is wholly or partially covered by the material of the flange section 142 of the outer layer 14 at the radial inner side, the radial outer side and free end. That is, the material of the flange section 142 continuously surrounds the inner circumferential surface, the free end and the outer circumferential surface of the flange part 132. Of course, other embodiments are also conceivable; for example, the material of the flange section 142 continuously covers the free end and the outer circumferential surface of the flange part 132, but not the inner circumferential surface of the flange part 132.

[0039] The flange section 142 may be configured to be adapted to the flange part 132 and also be formed to have a rounded corner construction in the longitudinal section at the region of the free end, the radius of the end rounded corner being, for example, 1 mm - 10 mm, preferably 1.5 mm - 5 mm.

[0040] As shown in the figures, in this example, the entire outer layer 14 is in contact only with the insulating support shell 2 and not with a charged component (i.e. the stationary end cap 4). By providing the insulating outer layer 14, an initial discharge voltage can be increased, further improving the external insulation performance of the interrupter.

[0041] Since the inner layer 13 and outer layer 14 of the stationary end electric field controller 12 are both made of flexible material, the stationary end electric field controller 12 can be deformed. Therefore, an interference fit structure can be simply configured between the joint portion and the stationary end electric field controller 12. That is, the inner diameter of the stationary end electric field controller 12 in an uninstalled state is slightly smaller than the outer diameter of the joint portion, so that the stationary end electric field controller 12 is sleeved on the joint portion, being deformed in the installed state. Here, for example, a compression ratio of the material of the inner layer 13 is greater than a compression threshold. This compression ratio is obtained, for example, by dividing the absolute value of the difference, which is a difference between the inner diameter of the inner layer in the uninstalled state and the inner diameter of the inner layer in the installed state, by the inner diameter in the uninstalled state. This compression threshold is, for example, 2% - 10%, preferably 5%. In this way, reliable contact of the inner layer 13 with the stationary end cap 4 is ensured, thereby ensuring a proper electrical connection between the conductive inner layer of the electric field controller and the interrupter cap.

[0042] Here, the self-shrinking properties of the flexible material of the stationary end electric field controller 12 can be utilized as a fixing means, without the need for an additional fixing means. Therefore, the mounting steps are simplified and costs are saved. It is also possible to simply add a stationary end electric field controller 12 to an existing vacuum interrupter that has already been manufactured. Of course, for more reliable fixing, it is also conceivable to adhere the inner layer 13 of the stationary end electric field controller 12 to the outer circumferential surface of the stationary end cap 4 with a conductive adhesive, and / or, for example, adhere the outer layer 14 of the stationary end electric field controller 12 to the insulating support shell 2 with an insulating adhesive.

[0043] Figs. 8 and 9 show a partial equipotential contour plot and contour plot of electric field strength of a vacuum interrupter with an electric field controller. Figs. 8 and 9 correspond to Figs. 3 and 4, respectively. As shown in the figures, in the case where a stationary end electric field controller is provided, at the joint portion between the stationary end cap 4 and the insulating support shell 2, the distribution of the electric potential lines is significantly more dispersed, and the electric field strength is also correspondingly reduced. By providing the stationary end electric field controller, a problem of insulation failure caused by high local electric field strength is solved.

[0044] Figs. 10-12 show a second embodiment of a stationary end electric field controller. The second embodiment differs from the first embodiment mainly in that an anti-disengagement structure is provided on the inner circumferential surface of the stationary end electric field controller 12 in contact with the stationary end cap 4. By providing the anti-disengagement structure 15, in one aspect, the stationary end electric field controller 12 can be fixed more reliably, and the stationary end electric field controller 12 can be prevented from falling off during use. In another aspect, a contact pressure can be further increased to ensure conductive performance.

[0045] As can be better seen from Figs. 11 and 12, in the present embodiment, the anti-disengagement structure 15 is constructed as a threaded structure on an inner circumferential surface of an inner layer 13 of the stationary end electric field controller 12. Of course, other anti-disengagement structures 15 are also conceivable, such as, but not limited to, hook-back structures, snap-ring structures, flanged structures, etc.

[0046] Fig. 13 shows a third embodiment of a stationary end electric field controller. The third embodiment differs from the first embodiment mainly in that the stationary end electric field controller therein is constructed to have a disc shape, rather than an annular shape as in the first embodiment. In this embodiment, an inner layer 13 of the stationary end electric field controller further comprises a flanged part 133, this flanged part 133 being joined to a sleeving part 131 and extending radially inward. An outer layer 14 comprises a flanged section 143, this flanged section 143 being joined to the sleeving section 141 and extending radially inward.

[0047] The construction and arrangement of a movable end electric field controller 11 may be the same as or similar to the stationary end electric field controller 12; see the above description regarding this.

[0048] In general, the present invention improves the external insulation performance of the vacuum interrupter by providing an electric field control apparatus. This electric field control apparatus is easy to assemble and has no additional parts, and is therefore inexpensive.

[0049] The present invention also relates to a vacuum switch having the vacuum interrupter as described above.

[0050] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the disclosed content of the above embodiments. The present application is intended to cover any variation, use or adaptive change of the present invention, wherein these variations, uses or adaptive changes follow the general principles of the present invention and comprise common general knowledge or customary technical means in the art not disclosed by the present invention. The Description and the embodiments are only to be considered as exemplary.List of reference signs

[0051] 1vacuum interrupter 2insulating support shell 3movable end cap 4stationary end cap 5movable end conductive rod 6stationary end conductive rod 7movable end contact 8stationary end contact 9guide member for movable end conductive rod 10shielding tube 11movable end electric field controller 12stationary end electric field controller 13inner layer 14outer layer 131inner layer sleeving part 132inner layer flange part 141sleeving section of outer layer 142flange section of outer layer 15anti-disengagement structure 133flanged part of inner layer 143flanged section of outer layer 16bellows

Claims

1. Electric field controller for a vacuum interrupter (1), the vacuum interrupter comprising an insulating support shell (2) and two conductive caps, said two conductive caps being respectively connected to the insulating support shell (2) at both axial ends of the insulating support shell (2), wherein the electric field controller is configured for being sleeved at a joint portion between the insulating support shell (2) and at least one conductive cap, and the electric field controller is configured for reducing the electric field strength at the joint portion and equalizing an electric field distribution, the electric field controller comprising a conductive inner layer (13) and an insulating outer layer (14).

2. Electric field controller according to Claim 1, characterized in that the inner layer (13) is made of a conductive flexible material, and / or the outer layer (14) is made of an insulating flexible material.

3. Electric field controller according to Claim 1 or 2, characterized in that the inner layer (13) is made of a conductive rubber, and / or the outer layer (14) is made of an insulating rubber.

4. Electric field controller according to any one of Claims 1-3, characterized in that the inner layer (13) comprises a sleeving part (131) and a flange part (132), the sleeving part (131) being configured for at least partially axially overlapping the at least one conductive cap in an installed state, and the flange part (132) being configured for at least partially axially overlapping the insulating support shell (2) in the installed state.

5. Electric field controller according to Claim 4, characterized in that the sleeving part (131) has an inner contour that matches an outer periphery of the at least one conductive cap, the inner contour being configured for reliable contact with the outer periphery of the at least one conductive cap.

6. Electric field controller according to Claim 4 or 5, characterized in that the flange part (132) of the inner layer (13) extends further axially from a position where the flange part joins to the sleeving part (131), thereby axially exceeding an interface between the flange part (132) and the sleeving part (131) by an axial distance (H), the axial distance (H) being greater than zero.

7. Electric field controller according to Claim 6, characterized in that the axial distance (H) is in a range of 4 mm to 10 mm.

8. Electric field controller according to any of Claims 4-7, characterized in that the outer layer (14) comprises a sleeving section (141) that at least partially axially overlaps the sleeving part (131), and a flange section (142) that at least partially axially overlaps the flange part (132).

9. Electric field controller according to Claim 8, characterized in that the sleeving section (141) at least partially surrounds an outer circumferential surface of the sleeving part (131), and the flange section (142) at least partially surrounds an outer circumferential surface and a free end of the flange part (132).

10. Electric field controller according to Claim 8 or 9, characterized in that the flange section (142) at least partially surrounds an inner circumferential surface of the flange part (132).

11. Electric field controller according to any one of Claims 1-10, characterized in that the electric field controller is constructed to have a rounded corner at a free end for mounting on the insulating support shell (2) in a longitudinal section.

12. Electric field controller according to any one of Claims 1-11, characterized in that the electric field controller has an anti-disengagement structure for secure contact with the joint portion.

13. Electric field controller according to any one of Claims 1-12, characterized in that the electric field controller is at least partially configured for bonding to the joint portion.

14. Electric field controller according to Claim 1-13, characterized in that the electric field controller is constructed to have an annular shape or disc shape.

15. Vacuum switch, comprising a vacuum interrupter, the vacuum interrupter having the electric field controller according to any one of Claims 1-14.

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