Support sleeve for movable electrode of vacuum interrupter

Abstract

A support sleeve for use in a vacuum interrupter is provided. The vacuum interrupter has separable contacts including a movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode and bellows guides connected to the movable electrode and the bellows. The movable electrode and the bellows together are structured to open and close the contacts. The bellows guides are structured to support the bellows during opening and closing of the contacts. The support sleeve includes: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of venting slots formed on the cylindrical body and extending longitudinally, the venting slots each being structured to equally distribute internal pressure during the opening and closing of the contacts.

Description

SUPPORT SLEEVE FOR MOVABLE ELECTRODE OF VACUUM INTERRUPTERCROSS-REFERENCE TO RELATED APPLICATION:

[0001] This patent application claims priority to U.S. Provisional Application No. 63 / 613,826, filed on December 22, 2023, the contents of which are herein incorporated by reference.FIELD OF THE INVENTION:

[0002] The disclosed concept relates generally to a system and method of circuit protection, and in particular, to a high voltage vacuum interrupter having a support sleeve for a moving electrode therein.BACKGROUND OF THE INVENTION:

[0003] Circuit interrupters, such as for example and without limitation, circuit breakers, are typically used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition, a short circuit, or another fault condition, such as an arc fault or a ground fault. Some circuit breakers such as, for example, power circuit breakers, employ vacuum interrupters as the switching devices. Vacuum interrupters may be categorized based on their application, construction and operational characteristics and include medium voltage (MV) vacuum interrupters and high voltage (HV) vacuum interrupters. An MV vacuum interrupters are typically used in the range from, e.g., without limitation, IkV to 52kV. The MV vacuum interrupter 2 as illustrated in Figures 1-2 has the rated voltage of approximately 17kV and includes separable electrical contacts 21,22 disposed on the ends of corresponding electrodes 23,24 within an insulating housing 27 having, e.g., without limitation, a ceramic envelope 26 for insulation and vacuum containment. Typically, one 21 of the contacts is fixed relative to both the housing 27 and to an external electrical conductor, which is electrically interconnected with a power circuit associated with the vacuum interrupter 2. The other contact 22 is part of a movable contact assembly including a movable electrode 24 of circular cross-section and a contact disposed on one end of the movable electrode 24 and enclosed within a vacuum chamber 28, which further includes a shield 29 for metal vapor condensation. A driving mechanism isdisposed on the other end, external to the vacuum chamber 2. The electrodes 23,24 are typically brazed or otherwise joined together when the vacuum interrupter 2 is made. The movable electrode 24 of the movable contact assembly is structured to transfer the motion from an actuator (the driving mechanism) to the movable contact 22 within the vacuum in the vacuum chamber 28. The vacuum provides several functions, e.g., without limitation, arc extinguishing, insulation, and performance consistency.

[0004] The movable electrode 24 is connected to the movable contact 22 at one end and extends longitudinally through a set of bellows 25 disposed in the housing 27. The bellows 25 are a flexible structure made of folds or convolutions that allow for movement and are structured to maintain the vacuum seal around the moving contact assembly and prevent air or other gases from leaking into the vacuum chamber 28. Further, when the vacuum interrupter 2 opens or closes, the bellows 25 are structured to move the movable contact 22 to separate or connect to the fixed contact 21. To open the contacts 21,22, the driving mechanism applies forces to the moving contact 22 via the movable electrode 24. The bellows 25 contract, allowing this movement while maintaining the vacuum intact. To close the contacts 23,24, the driving mechanism reverses its forces, pushing the movable contact 22 to connect to the fixed contact 21. The bellows 25 are released while also maintaining the vacuum intact. The bellows 25 can directly move the movable contact 22, or be attached to an actuator that compresses or extends the bellows 25 to open or close the contacts 21,22. For a medium voltage vacuum interrupter 2, the gap between the contacts 21,22 in the open / tripped position is, e.g., without limitation, approximately 10mm. Thus, the length of the bellows 25 may be, e.g., without limitation, 30- 40mm depending on the compression ratio.

[0005] However, an HV vacuum interrupter 3 requires the gap between the contacts 31,32 to be, e.g., without limitation, 40mm. Since the HV vacuum interrupters and the MV vacuum interrupters have similar components, overlapping description is omitted for the sake of brevity. This gap is much larger (e.g., without limitation, 4x) than the gap required for the MV vacuum interrupter contacts 21,22. This is because while the dielectric strength of the vacuum in the HV vacuum interrupter 3 is extremely high, the electric field intensity increases as the voltage increases. The larger gap thus helps with distributing the electric field over a greater distance, thereby reducing the possibility of an electrical breakdown or arc reignition. In short, the dielectric strength required to prevent an electrical breakdown increases with voltage,requiring a larger gap at higher voltages. In order to move the movable contact 32 by the amount of the gap required, the lengths of the movable electrode 34 and the bellows 35 need to be sufficiently longer (as shown in Figures 3-6). Further, the bellows 35 are sectionalized in equal length segments and supported by bellows guides 36. Sectionalizing the bellows 35 allows for longer strokes, and the bellows guides 36 support the bellows 35 and reduce buckling, squirming or collapse of the bellows 35 due to external pressures or internal vacuum forces. Nevertheless, the bellows 35 of HV vacuum interrupters 3 are prone to buckling or squirming. For example, when an HV vacuum interrupter 3 is used as a circuit breaker in a GIS (gas-insulated switchgear), any pressure differential between the vacuum chamber and the pressurized GIS chamber may stress the bellows 35, causing the bellows 35 to squirm or buckle. Figure 5 illustrates the squirmed bellows 35 ’ and bellows guides 36’ , which are no longer usable. The squirmed bellows 35’ and bellows guides 36’ may further cause damages to the movable electrode 34 of the movable contact assembly. Figure 6 illustrates the movable electrodes 34’ that have been scratched by the squirmed bellows 35 and bellows guides 36’, and thus their performance has been compromised. For example, the scratches may affect the dielectric strength of the vacuum interrupter 3 by creating paths for electrical breakdown, or lead to misalignment of the movable electrodes 34, preventing the contacts 31 ,32 from closing properly or causing uneven mechanical stress during the operation.

[0006] There is room for improvement in electrical switching devices, and in particular in high voltage vacuum interrupters.SUMMARY OF THE INVENTION:

[0007] These needs, and others, are met by a support sleeve for use in a vacuum interrupter. The vacuum interrupter has separable contacts including a movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode and bellows guides connected to the movable electrode and the bellows. The movable electrode and the bellows together are structured to open and close the contacts. The bellows guides are structured to support the bellows during opening and closing of the contacts. The support sleeve includes: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of venting slots formed on the cylindrical body and extending longitudinally, the venting slots each beingstructured to equally distribute internal pressure during the opening and closing of the contacts.

[0008] Another example embodiment includes a support sleeve for use in a vacuum interrupter. The vacuum interrupter has separable contacts including a movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode and bellows guides connected to the movable electrode and the bellows. The movable electrode and the bellows together are structured to open and close the contacts. The bellows guides are structured to support the bellows during opening and closing of the contacts. The support sleeve includes: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of longitudinal corrugations formed on external surface of the cylindrical body, the corrugations being structured to equally distribute internal pressure during the opening and closing of the contacts.

[0009] Yet another example embodiment includes a vacuum interrupter including: separable contacts including a movable contact; a movable contact assembly including the movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode, and bellows guides connected to the movable electrode and the bellows, the movable electrode and the bellows together structured to open and close the contacts, the bellows guides structured to support the bellows during opening and closing of the contacts; and a support sleeve. The support sleeve includes: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of venting slots formed on the cylindrical body and extending longitudinally, the venting slots each being structured to equally distribute internal pressure during the opening and closing of the contacts.BRIEF DESCRIPTION OF THE DRAWINGS:

[0010] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

[0011] Figures 1-2 illustrate a medium voltage vacuum interrupter;

[0012] Figures 3-4 illustrate a high voltage (HV) vacuum interrupter;

[0013] Figure 5 illustrates bellows and bellows guides of the HV vacuum interrupter ofFigures 3-4. The bellows and bellows guides are squirmed due to the pressure differential between a vacuum chamber and a GIS chamber;

[0014] Figure 6 illustrates movable electrodes of a movable contact assembly of the HV vacuum interrupter of Figures 3-4. The movable electrodes are damaged by the squirmed bellows and bellows guides of Figure 5 ;

[0015] Figures 7-9 illustrate an exemplary support sleeve structured to be disposed between the bellows guides and the movable electrode of the movable contact assembly of a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept;

[0016] Figures 10-11 illustrate the exemplary support sleeve of Figure 7 disposed between the bellows guides and the movable electrode of the movable contact assembly of the HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept;

[0017] Figures 12-14 illustrates an exemplary two-slotted support sleeve structured to be disposed between the bellows guides and the movable electrode of the movable contact assembly of a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept;

[0018] Figures 15-16 illustrate other exemplary two-slotted support sleeves structured to be disposed between the bellows guides and the movable electrode of the movable contact assembly of a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept;

[0019] Figures 17-22 illustrate other exemplary multi-slotted support sleeves structured to be disposed between the bellows guides and the movable electrode of the movable contact assembly of a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept; and

[0020] Figures 23-24 illustrate exemplary dimensionally variable slotted support sleeves structured to be disposed between the bellows guides and the movable electrode of the movable contact assembly of a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept; and

[0021] Figures 25-27 illustrate an exemplary corrugated support sleeve structured to be disposed between the bellows guides and the movable electrode of the movable contact assemblyof a HV vacuum interrupter in accordance with a non-limiting, example embodiment of the disclosed concept.DETAILED DESCRIPTION OF THE INVENTION:

[0022] Directional phrases used herein, such as, for example, left, right, front, back, top, bottom and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.

[0023] As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.

[0024] Figures 7-9 illustrate an exemplary support sleeve 100 for use in a high voltage (HV) vacuum interrupter 1 in accordance with a non-limiting, example embodiment of the disclosed concept. The HV vacuum interrupter 1 may be applied to a high-pressure gas chamber of a gas-insulated switchgear (not shown) with dry and / or compressed air up to 8 bars (i.e., air that has been pressurized to a level where the pressure is 8x the atmospheric pressure at sea level). Hence, the bellows 35 may experience buckling (squirming), and push the bellows guides 36 closer to the movable electrode 35. Such buckling and resultant repositioning of the bellows guides 36 closer to the movable electrode 35 may damage the bellows 35 and / or the bellows guides 36, leading to electrical breakdown or failure. As mentioned previously, GIS type systems for, e.g., without limitation, 72kV high voltage application require the contact gaps to be large, e.g., without limitation, approximately 40mm at full opening. The support sleeve 100 provides a crucial role in preventing the damages to the movable electrode 24, the bellows 35 and the bellows guides 36, and thus any failure of the vacuum interrupter 3.

[0025] The support sleeve 100 is cylindrical in shape and structured to fit around the movable electrode 35. It may have a height 107 of, e.g., without limitation, 4.302 inches, an inner diameter 109 of, e.g., without limitation, 1.509 inches, and an outer diameter 108 of, e.g., without limitation, 1.638 inches. The support sleeve 100 is thus disposed between the bellows guides 36 and the movable electrode 34 of the movable contact assembly of the HV vacuum interrupter 1 as shown in Figure 10-11. That is, the support sleeve 100 is precisely and tightly fitted to the movable electrode 34. The support sleeve 100 is structured to provide support to the movable electrode 34 and prevent the bellows 35 and the bellows guides 36 from bindingwith the movable electrode 34.

[0026] The support sleeve 100 includes a plurality of venting slots 104 structured to eliminate unequally distributed motion of the bellows guides 36 and convolutions (corrugations or folds) in the bellows 35. Thus, the venting slots 104 allow equal distribution of internal pressure during the cycling operations of the HV vacuum interrupter 1. The cycling operations refer to the number of times the HV vacuum interrupter 1 can be opened and closed, thereby interrupting and reestablishing the electrical circuit therein over the interrupter’s operational life. Further, the venging slots 104 provide relief from high pressure gas (e.g., without limitation, sulfur hexafluoride (SF6)) used as dielectric insulation by eliminating the risk of the bellows guides 36 to create a pinch point that could restrict the gas flow. The venting slots 104 may have a width of, e.g., without limitation, .25 inches and extends substantially over the height of the support sleeve 100. The top of the venting slots 104 begins at a distance 110 of 0.177 inches from the top of the support sleeve 100 and the bottom of the venting slots 104 terminates at a distance 111 of 0.375 inches from the bottom of the support sleeve 100. It will be noted that the dimensions of the support sleeve 100 and the venting slots 104 are for illustrative purposes only, and thus may vary depending of the application and manufacturer’s preferences.

[0027] In operation, between temperature and electrode compaction, the frictional force between the support sleeve 100 and the movable electrode 34 will increase, allowing the support sleeve 100 to tightly fit to the movable electrode 34. Further, the radial compressive forces on the non-slotted portion of the venging slots 104 also allow the support sleeve 100 to tightly fit to the movable electrode 34. Thus, the support sleeve 100 prevents collision with the bellows guides 36 or the top or bottom end of the bellows 35. Further, the support sleeve 100 prevents any damages to the bellows 35 and / or the bellows guides 36 by precluding the bellows 35 and the bellows guides 36 from buckling, squirming or deforming under high pressure. By preventing such collision and deformation, the support sleeve 100 thus plays an essential role in ensuring the HV vacuum interrupter 1 to perform effectively and reliably, and reach its maximum cycle operations over its expected life.

[0028] Figures 12-27 illustrate various exemplary support sleeves in accordance with non-limiting, example embodiments of the disclosed concept. The support sleeves operate in the same manner as the support sleeve 100 of Figures 7-11, and thus overlapping description is omitted for the sake of brevity. Figures 12-14 show an exemplary two-slotted support sleeve120 with a height 127 of, e.g., without limitation, 4.5 inches and an external diameter 129 of, e.g., without limitation 1.650±0.20 inches. The two venting slots 124 are disposed diametrically opposite to each other. Each venting slot 124 has a rectangular shape with rounded top and bottom. Figure 15 shows another exemplary two-slotted support sleeve 130 having venting slots 134 formed in rectangular shape. The two rectangular- shaped venting slots 134 are disposed diametrically opposite to each other. Figure 16 depicts a support sleeve 140 having two sets of venting slots 144, each set disposed diametrically opposite the other set. Each set includes two venting slots 144 having the same shape. Each venting slot 144 has substantially rectangular shape with rounded top and bottom. Each venting slot 144 extends longitudinally and substantially one half of the height of the support sleeve 140.

[0029] Figures 17-18 illustrate an exemplary four-slotted support sleeve 150. Each venting slot 154 extends longitudinally over the length of the support sleeve 150 and has rounded top and bottom. The top and bottom of each venting slot 154 are recessed 155 from the external surface of the support sleeve 150 as shown in Figure 18. Figure 19 shows a support sleeve 160 having four sets of venting slots 164. Each venting slot 164 has the same rectangular shape with rounded top and bottom. Each venting slot 164 has substantially rectangular shape with rounded top and bottom. Each venting slot 164 extends longitudinally and substantially one half of the height of the support sleeve 160. Figure 20 illustrates an exemplary support sleeve 170 having two sets of three longitudinally spaced-apart venting slots 174. The two sets are disposed diametrically opposite to each other. Each venting slot 174 has a rectangular shape. Figures 21 and 22 illustrate a support sleeve 180 having four sets of three longitudinally spaced-apart venting slots 184. Each venting slot 184 has a rectangular shape. The top and bottom of each venting slot 184 are recessed 185 from the external surface of the support sleeve 180 as shown in Figure 22.

[0030] Figures 23 and 24 illustrate support sleeves 190,200 having multi-sets of dimensionally variable venting slots 194,204. Figure 23 shows a support sleeve 190 having a plurality of sets of venting slots 194. Each set includes three venting slots 194 having rectangular shape with varying heights with the top venting slot 194 having the smallest height to the bottom venging slot 194 having the largest height. Figure 24 illustrates a support sleeve 200 having multi-sets of longitudinally spaced-apart venting slots 204. Each set includes venting slots 204 that not only have variable-dimensions, but also are staggered, i.e., misaligned from one another.Figures 25-27 show a corrugated support sleeve 210. The support sleeve 210 has corrugations that extend longitudinally on the external surface thereof. While the support sleeve 210 includes no venting slots, the corrugations perform similarly as the venting slots do, i.e., equally distribute the internal pressure within the vacuum interrupter 1 during opening and closing of the contacts 31,32. It is noted that the numbers, shapes, sizes and alignments of the venting slots 104,124,134,144,154,164,174,184,194,204, are for illustrative purposes only, and thus may be varied depending on the application and manufacturer preferences. Further, regardless of the variations in numbers, shapes, dimensions and alignments of the venting slots 104,124,134,144,154,164,174,184,194,204, each and every support sleeve 100,120,130,140,150,160,170,180,190,200,210 effectively and efficiently prevents the collision between the movable electrode 34 and the bellows guides 36 and the buckling or other deformation of the bellows 35 and the bellows guides 36 due to the high pressure.

[0031] By allowing the equal distribution of internal pressure during cycling operations, the support sleeve 100,120,130,140,150,160,170,180,190,200,210 prevents deformation of the bellows 35 and the bellows guides 36, thereby preempting any collision or bonding between deformed bellows and bellows guides and the movable electrodes. Such preemption of component deformation and collision during high pressure situations is not provided by the existing HV vacuum interrupters, nor are they capable of such. Therefore, unlike the movable contact assembly of the existing HV vacuum interrupters, the support sleeve 100,120,130,140,150,160,170,180,190,200,210 ensures that the movable contact assembly and the HV vacuum interrupter 1 are operating properly, effectively and reliably by preventing component deformation and collision during high pressure conditions.

[0032] While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.

Claims

What is claimed is:

1. A support sleeve for use in a vacuum interrupter having separable contacts including a movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode and bellows guides connected to the movable electrode and the bellows, the movable electrode and the bellows together structured to open and close the contacts, the bellows guides structured to support the bellows during opening and closing of the contacts, the support sleeve comprising: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of venting slots formed on the cylindrical body and extending longitudinally, the venting slots each being structured to equally distribute internal pressure during the opening and closing of the contacts.

2. The support sleeve of claim 1 , wherein frictional force between the support sleeve and the movable electrode increases based on temperature and electrode compaction during the opening and closing of the contacts.

3. The support sleeve of claim 2, wherein the increase in the frictional force allows the support sleeve to tightly fit around the movable electrode.

4. The support sleeve of claim 2, wherein radial compressive forces on the support sleeve allow the support sleeve to tightly fit around the movable electrode.

5. The support sleeve of claim 1, wherein the support sleeve is structured to prevent collision or bonding between the bellows guides and the movable electrode.

6. The support sleeve of claim 1 , wherein the support sleeve is structured to prevent collision or bonding between the bellows and the movable electrode.

7. The support sleeve of claim 1, wherein the support sleeve is structured to prevent deformation of the bellows and the bellows guides during opening and closing of the contacts, the deformation including buckling, squirming or collapsing.

8. The support sleeve of claim 1, wherein the venting slots comprise two venting slots disposed diametrically opposite to each other and having rounded top and bottom.

9. The support sleeve of claim 1, wherein the venting slots comprise two rectangular-shaped venting slots disposed diametrically opposite each other.

10. The support sleeve of claim 1, wherein the venting slots comprise a plurality of sets of venting slots, each set comprising a plurality of longitudinally spaced-apart venting slots.

11. The support sleeve of claim 10, wherein the venging slots have same dimensions.

12. The support sleeve of claim 10, wherein the venting slots in each set have different dimensions.

13. The support sleeve of claim 10, wherein the venting slots are staggered or misaligned from one another.

14. The support sleeve of claim 1, wherein the venting slots are recessed from external surface of the cylindrical body.

15. A support sleeve for use in a vacuum interrupter having separable contacts including a movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode and bellows guides connected to the movable electrode and the bellows, the movable electrode and the bellows together structured to open and close the contacts, the bellows guides structured to support the bellows during opening and closing of the contacts, the support sleeve comprising: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; and a plurality of longitudinal corrugations formed on external surface of the cylindrical body, the corrugations being structured to equally distribute internal pressure during the opening and closing of the contacts.

16. A vacuum interrupter, comprising: separable contacts including a movable contact; a movable contact assembly including the movable contact, a movable electrode connected to the movable contact, bellows connected to the movable electrode, and bellows guides connected to the movable electrode and the bellows, the movable electrode and the bellows together structured to open and close the contacts, the bellows guides structured to support the bellows during opening and closing of the contacts; and a support sleeve including: a cylindrical body structured to fit around the movable electrode and disposed between the movable electrode and the bellows guides; anda plurality of venting slots formed on the cylindrical body and extending longitudinally, the venting slots each being structured to equally distribute internal pressure during the opening and closing of the contacts.

17. The vacuum interrupter of claim 16, wherein the vacuum interrupter is a high voltage vacuum interrupter.

18. The vacuum interrupt of claim 16, wherein the bellows are sectionalized in equal parts and each section is supported by respective bellows guide attached to the support sleeve.

19. The vacuum interrupter of claim 16, wherein the support sleeve is structured to prevent collision and / or bonding between the bellows and the movable electrode and collision and / or bonding between the bellows guides and the movable electrode.

20. The vacuum interrupter of claim 16, wherein the support sleeve is structured to prevent deformation of the bellows and the bellows guides during opening and closing of the contacts, the deformation including buckling, squirming or collapsing.

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