Expandable turret for electrical equipment

A rupture reduction system for fluid-immersed electrical equipment includes a turret for mounting of a bushing. The turret is expandable in volume in response to a surge in pressure of the fluid in the turret. The expansion volume can be provided by an expandable section of the turret, which may include a bellows.

TECHNICAL FIELD

The present invention generally relates to electrical equipment subject to pressure surges, and more particularly, to an expandable turret for such electrical equipment.

BACKGROUND

Electrical equipment may be filled with a fluid to provide insulation or cooling, such as oil-immersed transformers. Such transformers include windings and connections that are submerged in the fluid in a tank, and provide electrical current through conductors insulated by a bushing mounted to a turret of the tank.

Certain operating conditions may create internal arcing in the turret due to an abnormal voltage from, for example, an internal fault, lightening, or vandalism. Other conditions may also create an internal surge in energy, such as overheating of components. This internal surge in energy may create a pressure surge that ruptures the turret, which leaks the fluid and may result in a fire.

While prior attempts have been made to address internal arcing in the turret by attempting to reduce the occurrence of arcing, these attempts suffer from various drawbacks, including being ineffective, costly, and/or requiring substantial modifications and additions to the components internal to the turret. Therefore, further improvements in this area are needed.

SUMMARY

One embodiment of the present disclosure is a unique system for reducing the occurrence of a rupture of a bushing turret for a transformer tank in response to a pressure surge in the bushing turret due to internal arcing or other issue. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for transformer tank bushing turret rupture reduction/prevention. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. While illustrative embodiments of the invention are described below, in the interest of clarity, not all features of an actual implementation of the invention may be described herein.

Referring toFIG. 1, in the illustrative embodiment, a rupture reduction system10is shown in which fluid-immersed electrical equipment14is provided in a tank12. In one embodiment, the rupture reduction system10is part of a transformer or shunt reactor system, and the electrical equipment14includes windings and/or other electrical equipment that is immersed in an insulating fluid20, such as oil or gas. In another embodiment, the tank12and electrical equipment14could be a cable box.

System10may include one or more expandable turrets50mounted to tank12. A bushing16may be mounted to each of the turrets50. The number of turrets and bushings mounted to tank12may, for example, generally corresponding with the number of phases of the electrical equipment14. It is further contemplated that a bushing may be mounted to each end of the turret50, or that the bushing is mounted at a location other than one of the ends of the turret50. Fluid20may be provided in an internal space22of tank12and in an internal volume52of turret50. Fluid20surrounds the internal part16aof bushing16. Internal part16aextends at least into internal volume52of turret50and, in some embodiments, may extend at least partially into internal space22of tank12.

Referring further toFIG. 2, one embodiment of turret50is shown which is expandable in volume in response to a pressure surge in fluid20in internal volume52of turret50. In particular, internal arcing in turret50creates a rapid pressure rise in the fluid20in the internal volume52. Since the internal volume52is substantially smaller than the volume of internal space22of tank12, the sudden pressure rise is greater in turret50than in tank12, and can cause rupture of the wall of turret50. For example, the internal space22may contain a volume of fluid20that is at least twice as great as the volume of fluid in internal volume52of turret50. Therefore, the internal volume52of turret50is expandable in response to the pressure rise of fluid20therein to reduce the occurrence of ruptures of turret50.

In the illustrated embodiment, turret50includes a fixed length section54and an expandable section56that provides the expansion volume of turret50. It is contemplated that expandable section56may expand in width and/or length to provide the expansion volume. The expandable volume can be provided by a bellows66as illustrated, or other suitable expandable volume type of structure. In one embodiment, the expandable section56is made from a material that is more ductile than the material to fixed length section54. For example, expandable section56can be made from a stainless steel material, and fixed length section54can be made from standard structural steel or any other suitable material. Expandable section56may also be made from high strength structural steel material and/or standard structural steel.

Fixed length section54includes a cylindrical tube or pipe60extending between a first turret flange62at a first end thereof and a second turret flange64at an opposite second end thereof. In the illustrated embodiment, the turret50includes a circular cross-sectional shape, but other cross-sectional shapes are also contemplated. The combination of the fixed length section54and the expandable section56should include structural properties that are sufficient to support the load of bushing16on tank12and to maintain that support during long-term operation of the electrical equipment14.

Referring further toFIGS. 3A and 3B, one embodiment of the expandable section56includes bellows66having a corrugated sidewall68extending between a first end flange70and a second end flange72. The first and second end flanges70,72are circular in shape and include holes to receive bolts76to secure the end flanges70,72to adjacent structures. Other embodiments contemplate other shapes and/or fastening arrangements for the bellows66and/or end flanges70,72.

The sidewall68of bellows66may include a number of V-shaped or U-shape wall segments that can collapse of fold against one another with bellows66in the compressed condition, as shown by sidewall68inFIG. 3A. In the compressed condition, bellows66includes a length L1between end flanges70,72. Sidewall68can unfold or separate as bellows66is expanded, as shown by sidewall68′ inFIG. 3B. In the expanded condition, the volume of bellows66is increased by the length being extended from length L1to a greater length L2. The difference between length L2and length L1can be sized so that the volume provided by the expandable section56can accommodate the anticipated pressure surge in fluid20in response to, for example, internal arcing in turret50.

InFIGS. 2, 3A and 3B, second end flange72of bellows66is mounted to first turret flange62with fasteners76. Second turret flange64is mounted to a top wall24of tank12as shown inFIG. 1, or to an intervening structure attached to tank12. In other embodiments, turret50and/or bellows66may be mounted to one of the sidewalls of tank12, such as sidewall26.

In addition, first end flange70of bellows66can be mounted to a bushing flange74of bushing16. As bellows66expands, the bushing16is displaced vertically with the vertical movement of bellows66. The flexible connection provided by conductors18with electrical equipment14provides sufficient slack to allow displacement of bushing16in response to the bellows expansion without disconnecting the conductors18.

In one embodiment, one or more guide rods80are provided that extend along and guide the displacement of expandable section56between the compressed and expanded conditions. Guide rods80may be positioned at equally spaced intervals about the perimeter of bellows66. InFIG. 2, there are shown four guide rods80, but other embodiments contemplate fewer than four guide rods80, or more than four guide rods80. Guides rods80may also assist in maintaining the alignment of bushing16with the fixed length section54of turret50during normal operation and/or during and after movement of the bellows66in response to a pressure surge event, resisting lateral bending or flexing of the bellows66.

Each of the guides rods80is fixed to one of the flanges62,74. For example, inFIGS. 3A and 3B, the guide rod80is fixed to a first tab86extending from first turret flange62. Guide rod80extends axially along bellows66through a second tab88extending from bushing flange74. In other embodiments, the guide rod80could be fixed to bushing flange74and movable along first turret flange62. In other embodiments, the guide rods80could be connected to one or both of the bellows end flanges70,72.

In the collapsed condition of bellows66, the guide rod80includes a first stop member82that contacts a first, bottom or lower side90of bushing flange74. The first stop member82prevents settling during normal operation to maintain a constant minimum volume for turret50. In the expanded condition, the guide rod80includes a second stop member84that contacts a second, top or upper side92of bushing flange74. The second stop member84prevents over-expansion of bellows66in response to the pressure surge event in fluid20.

As shown inFIG. 4, another embodiment turret is provided and designated at50′. Turret50′ is similar to turret50, except expandable section56′ is mounted to the tank12, and the fixed length section54extends between and connects the expandable section56′ and bushing16. Other arrangements are also contemplated. For example, the turret may be provided with more than one expandable section. In another example, the turret may include fixed length sections mounted to the tank and the bushing, and one or more expandable sections between these fixed length sections.

Various aspects of the present disclosure are contemplated. According to one aspect, an apparatus includes a turret. The turret includes a first end mountable to a tank for electrical equipment, a second end mountable to a bushing for insulating at least one conductor connected to the electrical equipment, a volume between the first and second ends for containing a fluid, and at least one section between the first and second ends of the turret that expands in volume in response to a pressure surge in the fluid within the turret to reduce occurrences of ruptures of the turret

Various embodiments of the apparatus are also contemplated. For example, the apparatus may include one or more of the following features. The at least one section of the turret may include a bellows that expands in length in response to the pressure surge. The turret may include a fixed length section extending between a first turret flange and a second turret flange, and the bellows may include a corrugated sidewall extending between a first end flange and a second end flange, and one of the first and second end flanges may be mounted to one of the first and second turret flanges.

The bellows may include at least one guide rod extending along the corrugated sidewalls that guide movement of the bellows from a compressed condition to an expanded condition. The at least one guide rod may include a first stop member that contacts a first side of a flange connected to the bellows in the compressed condition of the bellows and a second stop member that contacts a second side of the flange in the expanded condition of the bellows. 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 at equal intervals about the bellows.

The bushing may extend into the volume of the turret. The turret may be made from a first material and the at least one expandable section may be made from a second material that is more ductile than the first material. In another embodiment, the turret and expandable section are made from the same material.

According to another aspect, a transformer system includes a tank including an internal space for housing one or more electrical components and a turret mounted to the tank. The transformer system also includes a bushing mounted to the turret to insulate one or more conductors that receive electrical current from the one or more electrical components. A fluid is provided in the tank and the turret, and the turret is expandable in volume in response to a pressure surge in the fluid in the turret.

Various embodiments of the system are also contemplated. For example, the system may include one or more of the following features. The turret may include a first section that is fixed in length and a second section that is expandable in length in response to the pressure surge.

The turret may include a bellows that expands in response to the 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.

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 turret flange of the turret. The turret may include a second turret flange opposite the first turret flange, and the second turret flange may be mounted to the tank.

The first end flange of the bellows may be connected to a first turret flange of the turret and the second end flange of the bellows may be connected to the tank.

The bellows may include at least one guide rod extending along the bellows that guides movement of the bellows from a compressed condition to an expanded condition. The at least one guide rod may include a first stop member that contacts a first side of a first flange connected to the bellows in the compressed condition and a second stop member that contacts a second side of the flange in the expanded condition. 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 at equal intervals about the bellows.

The turret may be mounted to a top wall of the tank. The turret may include a first section made from a first material and a second section made from a second material that is more ductile than the first material and expands in volume in response to the pressure surge. The turret may include a first volume for housing the fluid, the tank may include a second volume for housing the fluid, and the second volume may be substantially greater than the first volume.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow.

In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.