Expandable turntable for electrical equipment

Abstract

A rupture reduction system for a fluid-immersed electrical device, including a turntable for mounting a bushing. In response to a surge of fluid pressure in the turntable, the volume of the turntable is expandable. The expanded volume can be provided by an expandable portion of the turntable, which may include a bellows.

Description

Technical Field

[0001] The present invention generally relates to electrical equipment that is subject to pressure surges, and more particularly to an expandable turntable for such electrical equipment. Background Art

[0002] Electrical equipment can be filled with fluid to provide insulation or cooling, such as an oil-immersed transformer. Such a transformer includes windings and connections immersed in the fluid within a tank, and current is provided through conductors that are insulated by bushings mounted to a turntable of the tank.

[0003] Due to abnormal voltages, such as those caused by internal faults, lightning, or vandalism, certain operating conditions can cause internal arcing within the turntable. Other conditions can also cause internal energy surges, such as component overheating. Such internal energy surges can cause pressure surges that rupture the turntable, which can leak fluid and potentially cause a fire.

[0004] Although previous attempts have been made to address internal arcing in the turntable by attempting to reduce the occurrence of arcing, these attempts have various drawbacks, including being ineffective, expensive, and / or requiring significant modifications / additions to the components within the turntable. Accordingly, further improvements in this area are needed. Summary of the Invention

[0005] One embodiment of the present disclosure is a unique system for reducing the occurrence of rupture of the bushing turntable of a transformer tank, which is caused by pressure surges within the bushing turntable in response to internal arcing or other problems. Other embodiments include devices, systems, equipment, hardware, methods, and combinations for reducing / preventing rupture of the bushing turntable of a transformer tank. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and drawings provided herein. Brief Description of the Drawings

[0006] Figure 1 is a cross-sectional view showing a rupture reduction system for a bushing turntable of a transformer in one embodiment.

[0007] Figure 2 is a perspective view of a bushing turntable having an expandable volume in one embodiment.

[0008] Figure 3A and Figure 3B is a cross-sectional view showing a portion of a bellows for providing an expandable volume of a bushing turntable in one embodiment.

[0009] Figure 4 is a perspective view of a portion of a bushing turntable having an expandable volume in another embodiment. Detailed Description

[0010] To facilitate understanding of the principles of the present invention, reference will now be made to the embodiments shown in the accompanying drawings, and these embodiments will be described using specific language. However, it should be understood that the scope of the present invention is not limited thereby. Any changes and further modifications to the described embodiments, as well as any further applications of the principles of the present invention as described herein, are generally contemplated by those skilled in the art in the field to which the present invention pertains. Although illustrative embodiments of the present invention are described below, not all features of the actual implementation of the present invention may be described herein for the sake of clarity.

[0011] Referring Figure 1 , in an illustrative embodiment, a rupture reduction system 10 is shown, wherein a fluid-immersed electrical device 14 is disposed in a tank 12. In one embodiment, the rupture reduction system 10 is part of a transformer or shunt reactor system, and the electrical device 14 includes windings and / or other electrical devices immersed in an insulating fluid 20 such as oil or gas. In another embodiment, the tank 12 and the electrical device 14 may be a cable tank.

[0012] The system 10 may include one or more expandable turntables 50 mounted to the tank 12. Bushings 16 may be mounted to each of the turntables 50. The number of turntables and bushings mounted on the tank 12 may generally correspond, for example, to the number of phases of the electrical device 14. Further contemplated, the bushings may be mounted to each end of the turntable 50, or the bushings are mounted at a location other than one of the ends of the turntable 50. The fluid 20 may be provided within the internal space 22 of the tank 12 and within the internal volume 52 of the turntable 50. The fluid 20 surrounds an internal portion 16a of the bushing 16. The internal portion 16a extends at least into the internal volume 52 of the turntable 50, and in some embodiments, may at least partially extend into the internal space 22 of the tank 12.

[0013] Further referring Figure 2 , a turntable 50 of an embodiment is shown, which expands in volume in response to a pressure surge of the fluid 20 in the internal volume 52 of the turntable 50. Specifically, an internal arc in the turntable 50 causes a rapid pressure rise in the fluid 20 within the internal volume 52. Since the internal volume 52 is much smaller than the volume of the internal space 22 of the tank 12, the sudden pressure rise in the turntable 50 is greater than the pressure rise in the tank 12 and may cause rupture of the wall of the turntable 50. For example, the volume of the internal space 22 containing the fluid 20 may be at least twice the volume of the fluid in the internal volume 52 of the turntable 50. Thus, the internal volume 52 of the turntable 50 expands in response to an increase in the pressure of the fluid 20 therein, thereby reducing the occurrence of rupture of the turntable 50.

[0014] In the illustrated embodiment, the turntable 50 includes a fixed-length portion 54 and an expandable portion 56 that provides an expanded volume of the turntable 50. It is contemplated that the expandable portion 56 can expand in width and / or length to provide the expanded volume. The expandable volume can be provided by the bellows 66 shown or other suitable structures of expandable volume. In one embodiment, the expandable portion 56 is made of a material that is more ductile than the material of the fixed-length portion 54. For example, the expandable portion 56 can be made of stainless steel material, and the fixed-length portion 54 can be made of standard structural steel or any other suitable material. The expandable portion 56 can also be made of high-strength structural steel material and / or standard structural steel.

[0015] The fixed-length portion 54 includes a cylindrical tube or pipe 60 that extends between a first turntable flange 62 at its first end and a second turntable flange 64 at its opposite second end. In the illustrated embodiment, the turntable 50 includes a circular cross-sectional shape, but other cross-sectional shapes are also contemplated. The combination of the fixed-length portion 54 and the expandable portion 56 should include structural properties sufficient to support the load of the sleeve 16 on the box 12 and sufficient to maintain that support during the long-term operation of the electrical device 14.

[0016] Further reference Figure 3A and 3B , the expandable portion 56 of one embodiment includes a bellows 66 having a corrugated sidewall 68 that extends between a first end flange 70 and a second end flange 72. The first end flange 70 and the second end flange 72 are circular and include holes for receiving bolts to secure the end flanges 70, 72 to adjacent structures. Other embodiments can contemplate other shapes and / or other fastening arrangements for the bellows 66 and / or the end flanges 70, 72.

[0017] The sidewall 68 of the bellows 66 can include a plurality of V-shaped or U-shaped wall segments that can collapse by folding against each other when the bellows 66 is in a compressed state, as shown by the sidewall 68 in Figure 3A . In the compressed state, the bellows 66 includes a length L1 between the end flanges 70, 72. When the bellows 66 expands, the sidewall 68 can unfold or separate, as shown by the sidewall 68' in Figure 3B . In the expanded state, the volume of the bellows 66 is increased by the length extending from the length L1 to a greater length L2. The magnitude of the difference between the length L2 and the length L1 is adjusted such that the volume provided by the expandable portion 56 can accommodate an expected pressure surge in the fluid 20 in response to, for example, an internal arc in the turntable 50.

[0018] In Figure 2 , Figure 3A and Figure 3BIn it, the second end flange 72 of the bellows 66 is mounted to the first turntable flange 62 with a fastener 76. As Figure 1 shown, the second turntable flange 64 is mounted to the top wall 24 of the box 12, or to an intermediate structure attached to the box 12. In other embodiments, the turntable 50 and / or the bellows 66 may be mounted to one of the side walls of the box 12, such as the side wall 26.

[0019] Additionally, the first end flange 70 of the bellows 66 may be mounted to the sleeve flange 74 of the sleeve 16. When the bellows 66 expands, the sleeve 16 vertically displaces with the vertical movement of the bellows 66. The flexible connection provided by the conductor 18 and the electrical device 14 provides sufficient slack to allow the sleeve 16 to displace in response to bellows expansion without disconnecting the conductor 18.

[0020] In one embodiment, one or more guide rods 80 are provided that extend along the expandable portion 56 and guide the expandable portion 56 in displacement between the compressed state and the expanded state. The guide rods 80 are equally spaced around the perimeter of the bellows 66. In Figure 2 it, four guide rods 80 are shown, but other embodiments may contemplate fewer than four or more than four guide rods 80. The guide rods 80 may also assist in keeping the sleeve 16 and the fixed length portion 54 of the turntable 50 aligned during normal operation and / or during and after the movement of the bellows 66 in response to a pressure surge event, resisting lateral bending or flexure of the bellows 66.

[0021] Each guide rod 80 is fixed to one of the flanges 62, 74. For example, in Figure 3A and Figure 3B it, the guide rod 80 is fixed to a first bump 86 extending from the first turntable flange 62. The guide rod 80 axially extends along the bellows 66 through a second bump 88 extending from the sleeve flange 74. In other embodiments, the guide rod 80 may be fixed to the sleeve flange 74 and may move along the first turntable flange 62. In other embodiments, the guide rod 80 may be connected to one or both of the bellows end flanges 70, 72.

[0022] In the collapsed state of the bellows 66, the guide rod 80 includes a first stop member 82 that contacts a first bottom or lower side 90 of the sleeve flange 74. The first stop member 82 prevents settlement during normal operation to maintain a constant minimum volume of the turntable 50. In the expanded state, the guide rod 80 includes a second stop member 84 that contacts a second top or upper side 92 of the sleeve flange 74. The second stop member 84 prevents the bellows 66 from overexpanding in response to a pressure surge event in the fluid 20.

[0023] As Figure 4As shown, a turntable of another embodiment is provided and denoted by 50'. The turntable 50' is similar to the turntable 50, except that the expandable portion 56' is mounted to the box 12, and the fixed-length portion 54 extends between and connects the expandable portion 56' and the sleeve 16. Other arrangements may also be considered. For example, the turntable may be provided with more than one expandable portion. In another example, the turntable may include fixed-length portions mounted to the box and the sleeve, and one or more expandable portions between these fixed-length portions.

[0024] Consider various aspects of the present disclosure. According to one aspect, a device includes a turntable. The turntable includes: a first end that can be mounted to a box for an electrical device; a second end that can be mounted to a sleeve that insulates at least one conductor connecting the electrical device; a volume between the first end and the second end for accommodating a fluid; and at least one portion between the first end and the second end of the turntable that expands in volume in response to a pressure surge in the fluid within the turntable to reduce the occurrence of turntable rupture.

[0025] Various embodiments of the device may also be considered. For example, the device may include one or more of the following features. At least one portion of the turntable may include a bellows that expands in length in response to a pressure surge. The turntable may include a fixed-length portion extending between a first turntable flange and a second turntable flange, the bellows may include a corrugated sidewall extending between a first end flange and a second end flange, and one of the first end flange and the second end flange may be mounted to one of the first turntable flange and the second turntable flange.

[0026] The bellows may include at least one guide rod extending along the corrugated sidewall that guides the bellows from a compressed state to an expanded state. The at least one guide rod may include a first stop member and a second stop member, the first stop member contacting a first side of the flange connected to the bellows in the compressed state of the bellows, and the second stop member contacting a second side of the flange in the expanded state of the bellows. The at least one guide rod may be fixed to the second flange connecting the bellows. The at least one guide rod may include a plurality of guide rods spaced equidistantly around the bellows.

[0027] The sleeve may extend into the volume of the turntable. The turntable may be made of a first material, and at least one expandable portion may be made of a second material that is more ductile than the first material. In another embodiment, the turntable and the expandable portion are made of the same material.

[0028] According to another aspect, a transformer system includes: a tank including an internal space for accommodating one or more electrical components, and a turntable mounted to the tank. The transformer system further includes bushings mounted to the turntable that insulate one or more conductors that receive current from the one or more electrical components. Fluid is provided in the tank and the turntable, and in response to a pressure surge in the fluid within the turntable, the volume of the turntable is expandable.

[0029] Various embodiments of the system are also contemplated. For example, the system may include one or more of the following features. The turntable may include a first portion of fixed length and a second portion of expandable length in response to a pressure surge.

[0030] The turntable may include a bellows that expands in response to a pressure surge. The bellows may include a corrugated sidewall extending between a first end flange of the bellows and a second end flange of the bellows.

[0031] The first end flange of the bellows may be connected to a bushing flange, and the second end flange of the bellows may be connected to a first turntable flange of the turntable. The turntable may include a second turntable flange opposite the first turntable flange, and the second turntable flange may be mounted to the tank.

[0032] The first end flange of the bellows may be connected to the first turntable flange of the turntable, and the second end flange of the bellows may be connected to the tank.

[0033] The bellows may include at least one guide rod extending along the bellows that guides the movement of the bellows from a compressed state to an expanded state. The at least one guide rod may include a first stop member and a second stop member, the first stop member contacting a first side of a first flange connected to the bellows in the compressed state, the second stop member contacting a second side of the flange in the expanded state. The at least one guide rod may be fixed to a second flange connected to the bellows. The at least one guide rod may include a plurality of guide rods spaced equidistantly around the bellows.

[0034] The turntable may be mounted to the top wall of the tank. The turntable may include a first portion made of a first material and a second portion made of a second material that is more ductile than the first material and expands in volume in response to a pressure surge. The turntable may include a first volume for accommodating fluid, the tank may include a second volume for accommodating fluid, and the second volume may be much larger than the first volume.

[0035] Although the present invention has been described and illustrated in detail in the accompanying drawings and the foregoing description, it is to be regarded as illustrative rather than restrictive. It should be understood that only the preferred embodiments have been shown and described, and all changes and modifications consistent with the spirit of the present invention are desired to be protected. It should be understood that words such as "preferred", "preferably", "preferable" or "more preferably" used in the foregoing description indicate that the features so described may be more desirable, but they may not be essential, and embodiments lacking such words may be considered within the scope of the present invention, which is defined by the claims that follow.

[0036] In reading the claims, it is intended that when words such as "a", "an", "at least one" or "at least a portion" are used, the claim is not intended to be limited to only one item unless there is a clear contrary indication in the claim. When the language "at least a portion" and / or "a portion" is used, the item may include a portion and / or the whole item unless there is a clear contrary indication. Unless otherwise specified or limited, the terms "mounted", "connected", "supported" and "coupled" and their variants are used broadly and include both direct and indirect mounting, connecting, supporting and coupling. Further, "connected" and "coupled" are not limited to physical or mechanical connection or coupling.

Claims

1. An apparatus for an electrical device, comprising: a turntable that can be mounted to a box for an electrical device and can also be mounted to at least one bushing for insulating at least one conductor connected to the electrical device, a volume for containing fluid between a first end and a second end of the turntable, and at least one portion between the first end and the second end of the turntable that expands in volume in response to a pressure surge in the fluid within the turntable to reduce the occurrence of rupture of the turntable; characterized in that a plurality of guide rods are provided, which extend along the expandable portion and guide the expandable portion to displace between a compressed state and an expanded state.

2. The apparatus according to claim 1, wherein, the at least one portion includes a bellows that expands in length in response to the pressure surge.

3. The apparatus according to claim 2, wherein, the turntable includes a fixed-length portion extending between a first turntable flange and a second turntable flange, the bellows includes a corrugated sidewall extending between a first end flange and a second end flange, and one of the first end flange and the second end flange is mounted to one of the first turntable flange and the second turntable flange.

4. The apparatus according to claim 2, wherein, each of the guide rods includes a first stop member and a second stop member, the first stop member contacts a first side of the flange connected to the bellows in the compressed state of the bellows, and the second stop member contacts a second side of the flange in the expanded state of the bellows.

5. The apparatus according to claim 4, wherein, each of the guide rods is fixed to the second end flange connected to the bellows.

6. The apparatus according to claim 2, wherein, the guide rods among the plurality of guide rods are equally spaced around the bellows.

7. The apparatus according to claim 1, wherein, the bushing extends into the volume of the turntable.

8. The apparatus according to claim 1, wherein, the turntable is made of a first material, and the at least one portion is made of a second material that is more ductile than the first material.

9. The apparatus according to claim 1, wherein, the first end of the turntable can be mounted to the box, and the second end of the turntable can be mounted to the at least one bushing.

10. A transformer system, comprising: a box including an internal space for accommodating one or more electrical components; a turntable mounted to the box; at least one bushing mounted to the turntable to insulate one or more conductors receiving current from the one or more electrical components; and fluid in the box and the turntable, wherein, in response to a pressure surge in the fluid within the turntable, the volume of the turntable is expandable, wherein the turntable includes a first portion with a fixed length and a second portion with a length that is expandable in response to the pressure surge, characterized in that a plurality of guide rods are provided, which extend along the expandable portion and guide the expandable portion to displace between a compressed state and an expanded state.

11. The system according to claim 10, wherein, the turntable includes a bellows that expands in response to the pressure surge.

12. The system according to claim 11, wherein, the bellows includes a corrugated sidewall extending between a first end flange and a second end flange of the bellows.

13. The system according to claim 12, wherein, the first end flange of the bellows is connected to a sleeve flange, and the second end flange of the bellows is connected to a first turntable flange of the turntable.

14. The system according to claim 13, wherein, the turntable includes a second turntable flange opposite to the first turntable flange, and the second turntable flange is mounted to the box.

15. The system according to claim 12, wherein, the first end flange of the bellows is connected to the first turntable flange of the turntable, and the second end flange of the bellows is connected to the box.

16. The system according to claim 11, wherein, the at least one guide rod includes a first stop member and a second stop member, the first stop member contacts a first side of a first flange connected to the bellows in the compressed state, and the second stop member contacts a second side of the flange in the expanded state.

17. The system according to claim 16, wherein, each of the guide rods is fixed to a second end flange connected to the bellows.

18. The system according to claim 11, wherein, the guide rods among the plurality of guide rods are spaced apart at equal intervals around the bellows.

19. The system according to claim 10, wherein, the turntable is mounted to the top wall of the box.

20. The system according to claim 10, wherein, the turntable includes the first part made of a first material and the second part made of a second material that is more ductile than the first material and expands in volume in response to a pressure surge.

21. The system according to claim 10, wherein, the turntable includes a first volume for accommodating the fluid, the box includes a second volume for accommodating the fluid, and the second volume is much larger than the first volume.

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