Patent Publication Number: US-2018047499-A1

Title: Distribution transformer and integrated power conditioning device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a non-provisional of, and claims priority to, U.S. Provisional Patent Application Ser. No. 62/373,687, filed Aug. 11, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Embodiments of the present invention relate generally to power distribution transformers, and, more particularly, to a distribution transformer having a power conditioning device integrated therewith. 
     Transformers, and similar devices, come in many different shapes and sizes for many different applications and uses. Fundamentally, all of these devices include at least one primary winding(s) with at least one core path(s) and at least one secondary winding(s) wrapped around the core(s). When a varying current (input) is passed through the primary winding a magnetic field is created which induces a varying magnetic flux in the core. The core is typically a highly magnetically permeable material which provides a path for this magnetic flux to pass through the secondary winding thereby inducing a voltage on the secondary (output) of the device. 
     Transformers are employed within distribution systems in order to transform voltage to a desired level and are sized by the current requirements of their connected load. If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit, through the transformer, to the load. Transformers are designated by their power rating, typically in kVA, which describes the amount of energy per second that they can transfer and also by their primary and secondary operating voltages, typically in kV. 
     Transformers as described above can be connected to associated power electronics—with the power electronics being connected to the secondary to receive electrical energy therefrom and provide power conditioning thereto, such as controlling voltage, power factor and harmonics, for example. At present, such power electronics are provided separately from the transformer, with each of the power transformer and the power electronics being provided in its own dedicated housing and often being mounted on its own pad. Connections between the transformer and the power electronics are then made via the use of external cables that are close-coupled or separate to the transformer. For example, the external cables are often provided as underground connections that run between the transformer and the power electronics. 
     While the above described arrangement and connection of transformers and associated power electronics—within separate enclosures and on separate pads, being connected via external/underground cables—is sufficient for achieving a desired power transfer and power conditioning, it is recognized that such an arrangement/connection has drawbacks associated therewith. For example, it is recognized that the underground cables connecting the transformers and power electronics present an increased level of complexity and added cost to the low voltage connections of the distribution transformer front plate, with additional cables and low voltage terminals being required that crowd the connection compartment of the transformer. Additionally, the above described arrangement and connection of transformers and associated power electronics requires the purchase and installation (on separate pads) of separate pieces of equipment, with the non-standard installation of underground cables adding further to the cost/complexity of the installation. 
     Therefore, it would be desirable to provide a distribution transformer having a power conditioning device integrated therewith. Such an integrated unit would simplify the low voltage connections of the distribution transformer front plate and reduce the cost and complexity of purchase and installation of the transformer and its associated power electronics. 
     BRIEF DESCRIPTION 
     In accordance with one aspect of the present invention, a power system comprises a transformer including a fluid enclosure having a front plate, a rear plate, and side surfaces, the fluid enclosure configured to hold a transformer fluid therein, and a core and coil assembly positioned within the fluid enclosure so as to be immersed in the transformer fluid, the core and coil assembly including a transformer core and a plurality of windings wound about the transformer core. The power system also comprises a power conditioning device integrated with the transformer and connected thereto to receive an output power from the transformer, the power conditioning device including an electrical enclosure and a power conditioning circuit housed within the electrical enclosure and configured to perform power conversion and conditioning on the output power from the transformer. The power system further comprises a first set of electrical conductors coupled between the core and coil assembly and the power conditioning circuit to transfer the output power from the transformer to the power conditioning circuit and a second set of electrical conductors coupled between the power conditioning circuit and electrical connections on the front plate of the fluid enclosure, the second set of electrical conductors being routed through the fluid enclosure of the transformer. 
     In accordance with another aspect of the present invention, an enclosure unit for an integrated transformer—power conditioning system includes a fluid tank configured to house a core and coil assembly of a transformer therein, with the fluid tank further including a front panel having electrical fittings thereon, a pair of side panels, and a rear panel, wherein one of the front panel, the side panels, and the rear panel comprises a plurality of openings formed therein. The enclosure unit also includes an electrical enclosure configured to house a power conditioning circuit therein, the electrical enclosure comprising a mounting panel having a plurality of openings formed therein, the mounting panel of the electrical enclosure mounted to the one of the front panel, the side panels, and the rear panel of the fluid tank having the plurality of openings formed therein. The enclosure unit further includes a plurality of electrical connectors positioned in the plurality of openings formed in the mounting panel of the electrical enclosure and in the plurality of openings formed in the one of the front panel, the side panels, and the rear panel of the fluid tank, the plurality of electrical connectors providing for a first set of electrical conductors to pass out from the fluid tank into the electrical enclosure and a second set of electrical conductors to pass out from the electrical enclosure back into the fluid tank. 
     In accordance with yet another aspect of the present invention, an integrated transformer-voltage conversion system includes a transformer comprising a fluid tank comprising a front plate, a rear plate and side panels, a core and coil assembly positioned within the tank and including a transformer core and a plurality of windings wound about the transformer core, and a transformer fluid contained within the fluid tank and immersing the core and coil assembly. The system also includes a power conditioning device mounted on one of the front plate, the rear plate, or a respective side panel of the fluid tank, the power conditioning device electrically connected to the transformer to receive an output power therefrom and perform a power conditioning and conversion on the output power. The system further includes a first set of electrical conductors coupled between the transformer and the power conditioning device to transfer the output power from the transformer to the power conditioning device and a second set of electrical conductors coupled between the power conditioning device and electrical connections on the front plate of the fluid tank, wherein the second set of electrical conductors is routed through the fluid enclosure of the transformer so as to be immersed in the transformer fluid. 
     Various other features and advantages will be made apparent from the following detailed description and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate preferred embodiments presently contemplated for carrying out the invention. 
       In the drawings: 
         FIG. 1  is a perspective view of a power system that includes a power conditioning device incorporated with a transformer, according to an embodiment of the invention. 
         FIG. 2  is a cross-sectional view of the power system of  FIG. 1  taken along line  2 - 2 , according to an embodiment of the invention. 
         FIG. 3  is a cross-sectional view of the power system of  FIG. 1  taken along line  3 - 3 , according to an embodiment of the invention. 
         FIG. 4  is a schematic view of a rear plate of the transformer of  FIG. 1 , according to an embodiment of the invention. 
         FIG. 5  is a schematic view of a front plate of the transformer of  FIG. 1 , according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention are directed to a power system that includes a distribution transformer and a power conditioning device integrated therewith. Power conditioning electronics are provided on a back panel of the transformer, outside of the main transformer fluid enclosure in which insulating fluid is contained, with low voltage connections being routed through the fluid enclosure from the power conditioning electronics to connections on a front plate of the enclosure. 
     While an operating environment of an exemplary embodiment of such a power system is described below with respect to the system including a three-phase liquid-filled transformer, it is recognized that embodiments of the invention are not limited to such an implementation. That is, it is recognized that embodiments of the invention are not to be limited to the specific transformer configurations set forth in detail below and that all single-phase and three-phase transformers, voltage regulators, and distribution equipment are recognized to fall within the scope of the invention. According to additional embodiments, power conditioning electronics may be incorporated with medium transformers as well as large power, substation, solar power, generator step-up, auxiliary, auto, and grounding transformers, for example. 
     Referring to  FIG. 1 , an exemplary power system  10  is shown according to an embodiment of the invention. The system  10  includes a distribution transformer  12  and a low voltage power conditioning device  14  that is incorporated with the transformer  12  to provide for output of a conditioned low voltage power that is suitable to drive a load or loads that are connected to the system  10 . The transformer  12  includes a fluid enclosure or tank  16  having a front plate  18 , sides  20 , and a rear plate  22  that generally define a volume that houses a core and coil assembly and that provides a volume in which cooling fluid is contained/stored to immerse the core and coil assembly, as will be explained in greater detail below, with it being understood that the term “cooling fluid” as used herein is not meant to be limited to a liquid insulating medium, but may encompass any type of appropriate cooling fluid medium (gas, liquid, etc.). 
     Extending from the bottom of side edges of the enclosure  16  is a sill or risers  24  that includes sides and a front. Sill  24  is typically formed from a single piece of metal that is bent into the desired shape. Fluid enclosure  16  and riser  24  typically rest on a transformer pad  26  and are affixed thereto by bolts or the like. A cabinet door or other protective cover  28  may, in one embodiment, be pivotally attached to an upper edge of front plate  18  by means of hinges or the like and be configured to complement the space defined by riser  24  and front plate  18 , so that when door  28  is closed, it rests on riser  24  and forms an interface with the fluid enclosure  16  and riser  24  and encloses electrical components extending through front plate  18 . While the door or cover  28  is described above as being attached to an upper edge of front plate  18  and interacting with riser  24  to enclose the electrical components extending through front plate  18 , it is recognized that the door or cover  28  may be provided in an alternative form. For example, door or cover  28  may be provided as a pair of doors that rotate outward on hinges located on side edges of front plate  18  or may be provided in other suitable forms or constructions that function to properly enclose the electrical components extending through front plate  18 , with or without the use of a riser  24 . 
     In one embodiment, one or more banks of corrugate  30  are provided on and as part of the enclosure  16 —such that the enclosure  16  may be described as a “corrugated enclosure”—to provide for enhanced cooling of the cooling fluid therein. That is, a bank of corrugate  30  may be formed on one or more of sides  20  of enclosure  16 , with each bank of corrugate  30  being formed of a plurality of cooling fins  32  that are welded to a wall of the enclosure  16  and spaced apart from one another a desired distance, with each of the cooling fins  32  having a hollow or semi-hollow construction, such that cooling fluid can be circulated therethrough from the enclosure  16 . 
     As shown in  FIG. 1 , the power conditioning device  14  is integrated into system  10  and is secured to the transformer  12  on fluid enclosure  16 . While  FIG. 1  illustrates the power conditioning device  14  being secured onto the rear plate  22  of fluid enclosure  16 , in other embodiments of the invention the power conditioning device  14  may instead be secured onto one of the side panels  20  or the front plate  18  of the fluid enclosure  16 , or may instead be secured onto one of the top or bottom of the enclosure, or any other part thereof, or on cabinetry associated therewith, e.g., door or sill. In still another embodiment, the power conditioning device  14  can be a free-standing device placed within an enclosure and positioned on transformer pad  26 , without mechanical attachment to the fluid enclosure  16 , with the dimensions and the weight of the power conditioning device  14  being such that it would not allow any random movement thereof. Thus, while described here below as being secured onto the rear plate  22  of fluid enclosure  16 , the scope of the invention is not to be limited to the specifically illustrated embodiment. 
     As shown in  FIG. 1 , according to one embodiment, the power conditioning device  14  includes an enclosure  34  that houses a power conditioning circuit  36  configured to receive a power output from transformer  12  and perform a conditioning or conversion of the received power in a desired fashion, as will be explained in greater detail below. The enclosure  34  may be constructed similar to cabinet door  28 , such that it may be pivotally attached to an upper edge of rear plate  22  by means of hinges (not shown) and rotated upwardly to provide access to the power conditioning circuit  36 . Alternatively, the enclosure  34  may include a pair of doors (not shown) that rotate on hinges and swing outwardly to provide access to the power conditioning circuit  36 , or may have another suitable construction that provides for protection of and access to the power conditioning circuit  36 . Standard fasteners of a known type may be used to secure enclosure  34  to the rear plate  22  of transformer fluid enclosure  16 , with the fasteners coupling a back panel  38  of enclosure  34  to the rear plate  22  of transformer fluid enclosure  16 . In an exemplary embodiment, the enclosure  34  is mounted to transformer  12  such that an air gap  40  is present between the enclosure  34  of power conditioning device  14  and the fluid enclosure  16  of transformer  12 . The gap  40  may be in the form of a pair of channels formed on rear plate  22  or may be a continuous gap between the rear plate  22  and enclosure  34 . This air gap  40  provides for efficient cooling of the power conditioning device  14  by providing for air flow (e.g., forced air flow) against the rear plate  22  and power conditioning circuit enclosure  34  and by providing additional surface area for convective heat transfer between the power conditioning device  14  and the ambient environment. In addition or alternative to the air gap  40 , natural convection and/or liquid cooling systems may be employed to provide cooling to the power conditioning device  14 . Additionally, in one embodiment, louvers  41  are formed on at least one wall/surface of the enclosure  34  (e.g., a side wall) to provide enhanced cooling to the power conditioning circuit  36 . 
     Referring now to  FIG. 2 , which is a cross-section view of the fluid enclosure  16  taken along line  2 - 2 , an interior of the transformer  12  is shown to more fully illustrate and describe the transformer. As shown in  FIG. 2 , the fluid enclosure  16  houses a core and coil assembly  42  formed of a magnetic core  44  with windings  46  there-around. According to an embodiment of the invention, magnetic core and coil assembly  42  includes a single phase magnetic core  44 . Magnetic core  44  can be formed of a plurality of stacks of magnetic, metallic laminations (not shown), such as grain-oriented silicon steel, for example. While transformer  12  is shown as including a single phase magnetic core  44 , it is recognized that transformer  12  could also be configured as a three phase transformer or a voltage regulator. 
     The windings  46  disposed about magnetic core  44  are composed of a set of primary and secondary windings, with the sets of primary and secondary windings being connected in a known type of configuration. The windings  46  are formed from strips of electrically conductive material such as copper or aluminum and can be rectangular or round in shape, for example, although other materials and shapes may also be suitable. Individual turns of windings  46  are electrically insulated from each other by cellulose insulating paper (i.e., “Kraft paper”) to ensure that current travels throughout every winding turn and to protect the windings  46  from the high electrical and physical stresses present in the transformer. 
     As shown in  FIG. 2 , transformer  12  is configured as a liquid-filled transformer in that the core  44  and windings  46  are immersed in a bath of transformer fluid  66  (i.e., cooling fluid) that both cools and electrically insulates the windings  46 . That is, cooling fluid  66  is a dielectric fluid that also exhibits desirable cooling properties. According to an exemplary embodiment, the cooling fluid  66  is in the form of an oil-based fluid having a high fire point (i.e., a less-flammable fluid). The cooling fluid  66  could be in form of a seed-, vegetable-, bio-, or natural ester-based oil or a silicone-based oil or synthetic hydrocarbon, that remains stable at transformer operating temperature conditions and provides superior heat transfer capabilities. It is also recognized, however, that other dielectric fluids could be utilized having suitable insulating and cooling properties, such as fluorinated hydrocarbons, for example, or any other dielectric fluid that exhibits desirable stability and heat transfer capabilities. The fluid enclosure  16  of transformer  12  is filled to a level  68  with the cooling fluid  66  to immerse the core  44  and windings  46 . 
     Referring now to  FIG. 3 , which is a cross-section view of the system taken along line  3 - 3 , a low voltage wiring scheme for electrically connecting the transformer  12  to the power conditioning device  14  is illustrated, according to an exemplary embodiment. As seen in  FIG. 3 , a first set of electrical conductors  72  are provided off of a secondary (output) of the core and coil assembly  42  and are routed to a first pair of electrical connectors  74  included on the rear plate  22  of fluid enclosure  16  and back panel  38  of enclosure  34  of power conditioning device  14  (i.e., positioned in openings  75  formed in rear plate  22  and back panel  38 ) that provide electrical insulation and allow the electrical conductors  72  to pass through the plates/panels  22 ,  38 . In an exemplary embodiment, the electrical connectors  74  are in the form of bushings (i.e., low voltage bushings) having a known construction. Thus, while not shown in  FIG. 3 , it is recognized that the bushings  74  may thus be formed out of an insulating material such as epoxy, for example, with cavities being formed in a mounting flange and a channel being formed through the center of the bushing to receive the conductor, and a threaded receptacle and threaded stud for coupling to the conductor and an external voltage lead/terminal. One or more gaskets may be used in combination with the bushing  74  to create a leak resistant seal between the bushing (i.e., annular mounting flange(s)) and the rear plates/panels, with the gasket(s) being formed of a non-conductive material such as rubber, for example. 
     The electrical conductors  72  connect to/through bushings  74  and are routed to an input  76  of the power conditioning circuit  36  of power conditioning device  14 . The power conditioning circuit  36  may operate according to known techniques to dynamically (or according to other known, controlled techniques) control and condition power received from the transformer  12  for output to a load or loads connected to system  10 . The power conditioning circuit  36  may thus dynamically control voltage, power factor and harmonics to more effectively increase energy efficiency, manage peak demand, support sensitive customer equipment, and increase overall system reliability. The power conditioning circuit  36  may therefore provide functionality including, but not limited to: load voltage regulation, such as by directly boosting and bucking voltage across a wide range during forward and reverse power flow; sag/swell mitigation to protect sensitive loads from voltage sags and swells caused by disturbances on the grid; reactive power compensation to regulate power factor by dynamically injecting or absorbing reactive power; and harmonic cancellation to correct source current and load voltage harmonic distortion and reduce overall total harmonic distortion (THD). 
     As can be seen in  FIG. 3 , upon performing a desired conditioning/converting of the power received from transformer  12 , power is output from power conditioning circuit  36  to a second set of electrical conductors  78  coupled to outputs  80  of the power conditioning circuit  36 . The electrical conductors  78  coupled to outputs  80  are then routed back into transformer  12  via a second pair of bushings  82  provided on the rear plate  22  of fluid enclosure  16  and back panel  38  of enclosure  34  of power conditioning device  14 , with the bushings  82  providing electrical insulation and allowing the set of electrical conductors  78  to pass through the plates/panels  22 ,  38 . The second pair of bushings  82  may have a known construction as described previously with respect to the first pair of bushings  74 . 
     Upon being routed back into transformer  12 , the second set of electrical conductors  78  is passed through the fluid enclosure  16  and through the electrically insulating transformer fluid  66  (i.e., immersed in the fluid  66 ). The electrical conductors  78  are routed through fluid enclosure  16  along a path that maintains an adequate separation between the conductors  78  and the core and coil assembly  42  (as well as any other components/devices within the enclosure, such as coolant circulation devices, for example), so as to ensure that no damage is done to the conductors  78 . The electrical conductors  78  are then connected to a third pair of bushings  84  provided on the front plate  18  of fluid enclosure  16 , with the bushings  84  providing electrical insulation and allowing the electrical conductors  78  to pass through the front plate  18 . The bushings  84  on front plate  18  thus serve as electrical connections to the power system  10  and provide a conditioned, low voltage output that may be directly connected to a load or loads that receive power from the power system  10 . 
     While the embodiment of  FIG. 3  is shown and described as including electrical bushings  74 ,  82 ,  84 ,  88  for passing electrical conductors  72 ,  78  through the plates/panels  18 ,  22 ,  38  of enclosures  16 ,  34 , it is recognized that other suitable connectors could alternatively be used. That is, connectors of different types and constructions from the bushing construction described above could instead by used to pass the electrical conductors  72 ,  78  through the plates/panels  18 ,  22 ,  38  of enclosures  16 ,  34 , as long as such connectors provide the required electrical insulation and leak resistant sealing, and such connectors are considered to be within the scope of the invention. Additionally, it is recognized that alternate methods of connecting the power conditioning device  14  to any type of core and coil assembly  42  may be employed, and that embodiments of the invention are not meant to be limited only to the transformer schematic/construction illustrated in  FIG. 3 . 
       FIGS. 4 and 5  provide more detailed views of the rear plate  22  and front plate  18  of the fluid enclosure  16 , respectively, according to an embodiment. Referring first to  FIG. 4 , the rear plate  22  of fluid enclosure  16  includes the first pair of bushings  74  and second pair of bushings  82  thereon that provide for routing of the first set of electrical conductors  72  out from transformer  12  (out from fluid enclosure  16 ) to the power conditioning device  14  and for routing of the second set of electrical conductors  78  from the power conditioning device  34  back to the transformer  12  (back into fluid enclosure  16 ). In an exemplary embodiment, rear plate  22  is constructed to include mounting channels  86  that are formed therein or welded thereto. The mounting channels  86  provide for the enclosure  34  of power conditioning device to be fastened and secured to fluid enclosure  16  and also additionally provide a path for air flow against the rear plate  22  and power conditioning circuit enclosure  34 . As it is recognized that a substantial amount of heat may be generated by power conditioning circuit  36  during operation, the channels  86  help to ensure that sufficient cooling is provided to the power conditioning circuit. While a pair of mounting channels  86  is shown in  FIG. 4 , it is recognized that other suitable features could instead be employed for assisting with mounting of enclosure  34  and/or providing a path for air flow against the rear plate  22  and power conditioning circuit enclosure  34 , and thus embodiments of the invention are not meant to be limited to the above described mounting channels. It is further recognized that the low voltage connections  74 ,  82  (e.g., bushings) can be mounted anywhere in any configuration on the said rear plate  22 , and that these connections can be flush mounted to the plate, recessed, or fully exposed. 
     Referring now to  FIG. 5 , the front plate  18  of fluid enclosure  16  includes the third pair of bushings  84  thereon that provide for routing of the second set of electrical conductors  78  out through the front plate  18 . An additional bushing  88  is also provided on front plate  18  and serves as a ground for the transformer  12  via an electrical conductor  89  connected from the core and coil assembly  42  to the bushing  88  (as also shown in  FIG. 3 ), with bushing  88  allowing for connection of a ground clamp (not shown) thereto. Front plate  18  further includes various electrical fittings and components  90  connected to the transformer  12  and that extend through the front plate  18 , with such fittings/components  90  including, for example, high voltage connections that may receive an input power from the grid for providing to the core and coil assembly  14 . 
     Beneficially, embodiments of the invention thus provide a power system that includes a transformer and a power conditioning device integrated therewith. Power conditioning electronics are provided on a plate/panel of the transformer (e.g., rear panel), outside of the main transformer fluid enclosure in which insulating fluid is contained, with connections being routed through the fluid enclosure from the power conditioning electronics to the front plate of the enclosure. The power conditioning device is mounted on a transformer plate/panel that is similar to the front plate used for the high voltage and low voltage connections of the transformer, with the plate/panel replacing a blank panel presently used on the existing transformer fluid enclosures, and with connections routed through the fluid enclosure. The incorporation of the power conditioning electronics with the transformer provides a conditioned output that may be directly connected to a load or loads that receive power from the power system, with no additional hardware/connections being required on the low voltage bushings of the transformer front plate and eliminate. The incorporation of the power conditioning electronics with the transformer also allows for the elimination of addition low voltage cabling in the transformer connection compartment that is typically required when the power conditioning device is separate and/or remote from the transformer, while also providing enhanced power quality, such as by compensating for sags, swells, and harmonics to prevent tripping of sensitive customer equipment and extend customer and utility asset life. 
     Therefore, according to an embodiment of the invention, a power system comprises a transformer including a fluid enclosure configured to hold a transformer fluid therein and having a front plate, a rear plate, and side surfaces, the fluid enclosure configured to hold a transformer fluid therein, and a core and coil assembly positioned within the fluid enclosure so as to be immersed in the transformer fluid, the core and coil assembly including a transformer core and a plurality of windings wound about the transformer core. The power system also comprises a power conditioning device integrated with the transformer and connected thereto to receive an output power from the transformer, the power conditioning device including an electrical enclosure and a power conditioning circuit housed within the electrical enclosure and configured to perform power conversion and conditioning on the output power from the transformer. The power system further comprises a first set of electrical conductors coupled between the core and coil assembly and the power conditioning circuit to transfer the output power from the transformer to the power conditioning circuit and a second set of electrical conductors coupled between the power conditioning circuit and electrical connections on the front plate of the fluid enclosure, the second set of electrical conductors being routed through the fluid enclosure of the transformer. 
     According to another embodiment of the invention, an enclosure unit for an integrated transformer—power conditioning system includes a fluid tank configured to house a core and coil assembly of a transformer therein, with the fluid tank further including a front panel having electrical fittings thereon, a pair of side panels, and a rear panel, wherein one of the front panel, the side panels, and the rear panel comprises a plurality of openings formed therein. The enclosure unit also includes an electrical enclosure configured to house a power conditioning circuit therein, the electrical enclosure comprising a mounting panel having a plurality of openings formed therein, the mounting panel of the electrical enclosure mounted to the one of the front panel, the side panels, and the rear panel of the fluid tank having the plurality of openings formed therein. The enclosure unit further includes a plurality of electrical connectors positioned in the plurality of openings formed in the mounting panel of the electrical enclosure and in the plurality of openings formed in the one of the front panel, the side panels, and the rear panel of the fluid tank, the plurality of electrical connectors providing for a first set of electrical conductors to pass out from the fluid tank into the electrical enclosure and a second set of electrical conductors to pass out from the electrical enclosure back into the fluid tank. 
     According to yet another embodiment of the invention, an integrated transformer-voltage conversion system includes a transformer comprising a fluid tank comprising a front plate, a rear plate and side panels, a core and coil assembly positioned within the tank and including a transformer core and a plurality of windings wound about the transformer core, and a transformer fluid contained within the fluid tank and immersing the core and coil assembly. The system also includes a power conditioning device mounted on one of the front plate, the rear plate, or a respective side panel of the fluid tank, the power conditioning device electrically connected to the transformer to receive an output power therefrom and perform a power conditioning and conversion on the output power. The system further includes a first set of electrical conductors coupled between the transformer and the power conditioning device to transfer the output power from the transformer to the power conditioning device and a second set of electrical conductors coupled between the power conditioning device and electrical connections on the front plate of the fluid tank, wherein the second set of electrical conductors is routed through the fluid enclosure of the transformer so as to be immersed in the transformer fluid. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.