Support bracket for transformer switch utilizing existing transformer connection points

A support bracket assembly for supporting a pair of bushing well interrupter devices provided within a transformer enclosure that encloses a transformer. The support bracket assembly includes a mounting bracket assembly rigidly secured to a parking stand on the enclosure and including a plurality of mounting bosses. The support bracket assembly further includes support brackets, a first adjustable link secured to one of the mounting bosses on the mounting assembly and a mounting boss on a support bracket, a second adjustable link secured to another one of the mounting bosses on the mounting assembly and a mounting bosses on a support bracket, and a third adjustable link secured to mounting bosses on two support bracket, where the first, second and third adjustable links form a triangular configuration.

BACKGROUND

Field

The present disclosure relates generally to a support bracket assembly for supporting a pair of switching devices provided within a transformer enclosure and, more particularly, to a support bracket assembly for supporting a pair of bushing well interrupter devices provided within a transformer enclosure for a transformer used in an underground residential power distribution network.

Discussion of the Related Art

An electrical power distribution network, often referred to as an electrical grid, typically includes power generation plants each having power generators, such as gas turbines, nuclear reactors, coal-fired generators, hydro-electric dams, etc. The power plants provide power at a variety of medium voltages that are then stepped up by transformers to a high voltage AC signal to be connected to high voltage transmission lines that deliver electrical power to substations typically located within a community, where the voltage is stepped down to a medium voltage for distribution. The substations provide the medium voltage power to three-phase feeders including three single-phase feeder lines that carry the same current but are 120° apart in phase. three-phase and single phase lateral lines are tapped off of the feeder that provide the medium voltage to various distribution transformers, where the voltage is stepped down to a low voltage and is provided to loads, such as homes, businesses, etc.

Periodically, faults occur in the distribution network as a result of various things, such as animals touching the lines, lightning strikes, tree branches falling on the lines, vehicle collisions with utility poles, etc. Faults may create a short-circuit that increases the load on the network, which may cause the current flow from the substation to significantly increase, for example, many times above the normal current, along the fault path. This amount of current causes the electrical lines to significantly heat up and possibly melt, and also could cause mechanical damage to various components in the substation and in the network. Power distribution networks of the type referred to above often include switching devices, breakers, reclosers, interrupters, etc. that control the flow of power throughout the network, and may be used to isolate faults within a faulted section of the network.

As part of its power distribution network, many utility companies employ underground single-phase lateral circuits that feed residential and commercial customers. Often times these circuits are configured in a loop and fed from both ends, where an open location, typically at a transformer, is used in the circuit to isolate the two power sources. Although providing underground power cables protects circuits from faults created by things like storms and vegetation growth, underground cables still may break or otherwise fail as a result of corrosion and other things.

For a residential loop circuit of the type referred to above having two power sources, it is usually possible to reconfigure the open location in the circuit so that loads that are affected by a failed cable are fed by the other source and service to all of the loads is maintained. However, known processes for identifying the location of a cable failure and the subsequent reconfiguration of the open location often result in long power restoration times because workers are required to physically go to the transformers to test for power and then reconfigure the transformers to change the open location.

It has been proposed to provide bushing well interrupter devices in the existing transformers for these types of loop circuits that provide automatic protection, isolation and restoration of underground residential cable loops and methods to switch cable segments without handling cable elbows. If the bushing well interrupter devices can be installed without modifying the existing transformers, it will be that much more appealing to the utility. However, the addition of the bushing well interrupter devices, which can be relatively heavy, puts added stress on the transformer bushings due to the added weight and off-center moments, which may cause the bushings to prematurely wear out and have to be replaced. Therefore, a support bracket for supporting the bushing well interrupter devices may be necessary. Such a support bracket must be flexible enough to connect to a variety of transformers that have been manufactured by different companies with limited labor and, at the same time, the support bracket must provide enough stiffness to each bushing well interrupter device so as to not allow any additional stresses at the transformer bushing well than are currently present in the existing transformers.

SUMMARY

The following discussion discloses and describes a support bracket assembly for supporting a pair of bushing well interrupter devices provided within a transformer enclosure that encloses a transformer. The support bracket assembly includes a mounting bracket assembly rigidly secured to the enclosure and including a plurality of mounting bosses. The support bracket assembly further includes a first support bracket secured to one of the interrupter devices, a second support bracket secured to the other interrupter device, a third support bracket secured to the first support bracket, where the third support bracket includes a plurality of mounting bosses, and a fourth support bracket secured to the second support bracket, where the fourth support bracket includes a plurality of mounting bosses. The support bracket assembly also includes a first adjustable link secured to one of the mounting bosses on the mounting assembly and one of the mounting bosses on the third support bracket, a second adjustable link secured to another one of the mounting bosses on the mounting assembly and one of the mounting bosses on the fourth support bracket, and a third adjustable link secured to another one of the mounting bosses on the third support bracket and another one of the mounting bosses on the fourth support bracket, where the first, second and third adjustable links form a triangular configuration.

Additional features of the disclosure will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the disclosure directed to a support bracket assembly for supporting a pair of bushing well interrupter devices provided within a transformer enclosure is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses. For example, the support bracket assembly discussed herein has particular application for use with transformers employed in underground residential loop circuits. However, the support bracket assembly may have other applications.

FIG.1is an isometric view andFIG.2is a front view of a transformer10of the type that is mounted on a pad12that may be employed in an underground single-phase lateral loop circuit that feeds residential and commercial customers. The transformer10includes an enclosure14that houses the transformer primary and secondary coils (not shown) and other electrical components (not shown) of the transformer10. A cover of the enclosure14has been removed to expose a panel16in the enclosure14. A connector bushing20positioned within and coupled to a bushing well18extends through the panel16that accepts a bushing well interrupter device22that connects a power line24having an elbow connector26to one side of the primary coil and a connector bushing30positioned within and coupled to a bushing well28extends through the panel16that accepts a bushing well interrupter device32that connects a power line34having an elbow connector36to the other side of the primary coil, where the bushing well interrupter devices22and32are configured to provide automatic protection, isolation and power restoration of a lateral loop circuit without handling cable elbows. It is noted that the devices22and32are mirror images of each other to accommodate spacing for the existing features on the transformer10. The devices22and32each include an outer enclosure40, a load-break interface42, a transformer interface46and a manual handle48. A 120 V positive connector50is coupled to the secondary coil through a connector bushing52in the panel16, a 120 V negative connector54is coupled to the secondary coil through a connector bushing56in the panel16, and a neutral connector58is coupled to the secondary coil through a connector bushing60in the panel16. Distribution lines62are connected to the connectors50,54and58to deliver low voltage power to the desired number of loads (not shown). In this example, the lines24,34and62run underground.

As will be discussed in detail below, a support bracket assembly76(seeFIGS.4and5) is added to the transformer10to support the bushing well interrupter devices22and32on the panel16. To begin this discussion,FIG.3shows the transformer10with the bushing well interrupter devices22and32and other components removed, which illustrates a parking stand78that is welded to the panel16between the bushing connectors20and30, where the parking stand78includes a raised panel80having a cut-out section82. The parking stand78is an existing fixture that allows one of the elbow connectors26or36to be supported thereto when it is disconnected from the bushing connector20or30to provide a break in the loop circuit prior to the bushing well interrupter devices22and32being employed in the transformer10, which will be used to support the bracket assembly76referred to above. More particularly, when the elbow connector26or36is removed from the bushing20or30, it is inserted in the cut-out section82so that part of it locks between the panels16and80. The bushing well interrupter devices22and32are an added feature to existing transformers of the type shown and described above already operating in the field, and are configured to be usable in the space provided in the enclosure14including providing access to the parking stand78.

FIG.4is a broken-away front view andFIG.5is a broken-away side view of the transformer10illustrating the support bracket assembly76andFIGS.6-9are broken-away views of the transformer10illustrating the support bracket assembly76is various stages of assembly. Before the bushing well interrupter devices22and32are secured to the connector bushings20and30, respectively, a support bracket84having opposing flanges86is bolted to the interface of the device22and a support bracket88having opposing flanges90is bolted to the interface of the device32. The assembly76is secured to the parking stand78using a parking stand bracket92and an anchor bracket94, whereFIG.10shows the parking stand bracket92separated from the assembly76andFIG.11shows the anchor bracket94positioned relative to the parking stand78. The bracket92includes a top wall102having wings104and106, a cut-out section108and an oval window110, side walls112and114and a lower flange116having a pair of J-shaped slots118and120that can be seen through the window110. The bracket92has the general configuration of the parking stand78to allow it to be used as a parking stand for the elbow connectors26and36when the parking stand78is being used to secure the bracket assembly76. The anchor bracket94includes a base portion122to which are secured raised bolts124and126and an anchor portion128to which are secured tapered bosses130and132. The anchor portion122is slid between the panels16and80and the bolts124and126are extended through the cut-out section82. The bracket92is positioned so that the bolts124and126are inserted and locked in the J-shaped slots118and120, respectively. The bolts124and126are then tightened to secure the brackets92and94to the parking stand78.

The assembly76also includes a support bracket140having an L-shaped body142with a short portion144and a long portion146. A tab148extends from the long portion146, a tapered boss150including a threaded opening extends from the side of the long portion146and a tapered boss152including a threaded opening extends from the short portion144. A threaded rod154is threaded into the tab148, where the rod154includes a support156mounted thereto opposite to the tab148. The short portion144is bolted to the flanges90by bolts158and the threaded rod154is adjusted by threading through the tab148so that the support156pushes against the panel16with the desired force to prevent downward sagging of the device32. The assembly76also includes a support bracket170having a T-shaped body172. One end of the body172includes tapered bosses174and176having threaded openings extending therefrom and an opposite end of the body portion172is bolted to the flanges86by bolts178.

The assembly76also includes an adjustable link180having a cylindrical portion182and a threaded portion184threaded into the cylindrical portion182.FIG.12is a front view of the link180separated from the bracket assembly76. The cylindrical portion182includes a ball joint186at an end opposite to the threaded portion184, where the ball joint186includes a ring188and a ball190having an opening192rotatably mounted within the ring188. The threaded portion184includes a ball joint194at an end opposite to the cylindrical portion182, where the ball joint194includes a ring196and a ball198having an opening200rotatably mounted within the ring196. The ball190is slid onto the boss130and secured thereto by a bolt202threaded into the opening192. The threaded portion184is threaded so that the ball joint194aligns with the boss150. The ball198is slid onto the boss150and secured thereto by a bolt204threaded into the opening200.

The assembly76also includes an adjustable link210having a cylindrical portion212and a threaded portion214threaded into the cylindrical portion212, where the link210is identical to the link180. The cylindrical portion212includes a ball joint216at an end opposite to the threaded portion214and the threaded portion214includes a ball joint218opposite to the cylindrical portion212. The ball joint216is mounted to the boss132and secured thereto by a bolt220threaded into the opening of the boss132. The threaded portion214is threaded so that the ball joint218aligns with the boss176. The threaded portion is then retracted a predetermined amount and the device22is lifted against sagging so that the ball joint218again aligns with the boss176. The ball joint218is then mounted to the boss176and secured thereto by a bolt222threaded into the opening of the boss176.

The assembly76also includes an adjustable link230having a cylindrical portion232and a threaded portion234threaded into the cylindrical portion232, where the link230is identical to the link180. The cylindrical portion232includes a ball joint236at an end opposite to the threaded portion234and the threaded portion234includes a ball joint238opposite to the cylindrical portion232. The ball joint236is mounted to the boss152and secured thereto by a bolt240threaded into the opening of the boss152. The threaded portion234is threaded so that the ball joint238aligns with the boss174. The ball joint238is then mounted to the boss174and secured thereto by a bolt242threaded into the opening of the boss174. Thus, the combination of the adjustable links180,210and230form a triangular configuration.