MXPA00009457A - Amorphous metal transformer having a generally rectangular coil - Google Patents

Abstract

A dry-type power distribution transformer has a generally rectangular, wound amorphous metal core and a resin encapsulated, generally rectangular coil. The core has a generally rectangular core window within which is located a substantially straight section of the coil. When assembled to form a power distribution transformer, the shape of the coil's substantially strait section conforms to the shape of the core window. The transformer is inexpensive to manufacture, exhibits low resistivity and low core loss, and is light weight, compact and reliable in operation.

Description

AMORFO METAL TRANSFORMER THAT HAS A GENERALLY RECTANGULAR COIL BACKGROUND OF THE INVENTION This application claims the benefit of the provisional application of the U.S.A. No. 60 / 079,625 filed March 27, 1998. 1. Field of the Invention The present invention relates to transformers; and more particularly, to a dry type power distribution transformer, having a coiled amorphous metal core and a resin-encapsulated, generally rectangular coil. 2. Description of the Prior Art Transformers for conventional dry type energy distribution have a round or toroidal open wound coil and an amorphous or silicon steel core of the stacked or coiled variety. The transformer core typically has a rectangular shape that defines a rectangular window within which the coil is located. Frequently, the toroidal shape of the coil creates a bad coupling between the core and the coil in relation to the core window, ie the shape of the rectangular window does not correspond to the shape of the section of the coil that is located there. . This lack of correspondence or bad coupling between the core and the coil, causes that the size and cost of the transformer are significantly greater than what would be required if the transformer had more closely corresponding core and coil forms. The winding cores used in the transformers for energy distribution, whether based on silicon steel or amorphous metal, are rectangular in cross section and do not adapt to the round shape of the coil. Silicon steel transformer cores stacked on the other hand, may have a cruciform cross section that may roughly correspond to the toroidal shape of the coil. Due to the high expense of molding or cutting an amorphous metal strip in a variety of widths, it is not practical to form a stacked amorphous metal core with a cruciform cross section. For these reasons, in the manufacture of dry-type power distribution transformers having amorphous netal cores, either coiled or stacked, the cross-sectional shape of the core (ie rectangular) and the shape of the coil (i.e. round) do not correspond. The use of the coil material is not economical and the transformer sizes are too large. Transformers for energy distribution can be installed in a variety of sites and subjected to extreme environmental conditions, such as for example particulate matter (dust, dirt, etc.), moisture, caustic substances and the like, which adversely affect lifespan. and transformer performance. The open wound coils do not provide protection against the effects of harsh environments. SUMMARY OF THE INVENTION The present invention provides a transformer for dry type energy distribution, having a cored amorphous metal core and a generally rectangular resin encapsulated coil. The core has a generally rectangular cross-sectional shape, which closely corresponds to the generally rectangular shape of the resin-encapsulated coil. As the shape of the coil corresponds to the cross-section of the core, a dry-type amorphous metal energy distribution transformer is provided, which is less expensive to manufacture, less resistive and has fewer losses since less material is required to wind The coil is more compact than the transformers that have generally round or circular coils. Stated generally, the transformer for dry type energy distribution includes a rectangular coil generally encapsulated in resin having a substantially straight cross section and an amorphous metal core having a generally rectangular core window. The coil and the core are dimensioned and configured in such a way that the shape of the substantially straight section of the coil is substantially adapted to the shape of the core window. When the coil and core are assembled to form a transformer for power distribution, the substantially straight section of the coil is located inside the core window. The encapsulation of resin protects the coil against severe environmental conditions, protects the coil insulation system, improves the coil resistance under short circuit conditions and improves the cooling characteristics of the coil, by providing a smooth, uniform surface to the outside of the coil on which the air (either forced or convection) can pass uniformly and easily. Advantageously, the transformer for dry type energy distribution of the invention is durable and robust. Core and coil materials are used in a highly economical way, which significantly decreases the manufacturing cost and size of transformer. These characteristics are especially convenient in transformers for energy distribution, transformers where the size, cost and performance regulate the acceptance in the market. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood and further advantages will be apparent when reference is made to the following detailed description and accompanying drawings, in which like reference numerals denote similar elements throughout the various views and in which: Figure 1A is a front view of the single-phase shell-type or shell-type transformer, constructed in accordance with the present invention with the coil partially exploded; Figure IB is a cross-sectional view taken on line B-B of Figure IA; Figure 2A is a front view of the single-phase core-type transformer constructed in accordance with the present invention; Figure 2B is a cross-sectional view taken on line B-B of Figure 2A; Figure 3A is a front view of a three-phase transformer constructed in accordance with the present invention; Figure 3B is a cross-sectional view taken on line B-B of Figure 3A; Figure 4 is a perspective view of a generally rectangular low voltage coil wound on a rectangular mandrel according to the present invention; Figure 5 'is a perspective view of a high voltage, generally rectangular coil wound on a rectangular mandrel according to the present invention; Figure 6 is a perspective view of an epoxy containment container, configured to encapsulate a generally rectangular coil according to the present invention; Figure 7 is a top view of the epoxy confinement vessel of Figure 6, with a generally rectangular coil contained therein; and Figure 8 is a block diagram of an encapsulation system for a coil constructed in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION With reference to Figures IA and 2A of the drawings, two variations of a first embodiment of the present invention are illustrated: an armored single phase power distribution transformer (Figure IA); and a transformer for single-phase core-type power distribution (Figure 2A). The transformer of single phase armored comprises a generally rectangular resin encapsulated coil 40 and two amorphous metal cores 20. The core-type single phase transformer 10 comprises two generally rectangular resin encapsulated coils 40 and a single amorphous metal core 20. A second embodiment of the invention is illustrated in Figure 3A. In this embodiment, the three-phase armored power distribution transformer 10 comprises three coils encapsulated in resin, generally rectangular 40 and 4 amorphous metal cores 20. While the following detailed description is directed to the single-phase armored embodiment, it will be understood by those skilled in the art that this description also applies to the single-core and three-phase armored transformer embodiments illustrated in Figures 2A, 2B, 3A and 3B. Furthermore, it will be apparent to persons of skill in the art that the present invention and its detailed description provided below, apply to various other configurations and designs of transformer for dry type energy distribution. In this way, the description given below for a single-phase armored transformer will be interpreted as illustrative and not in a limiting sense. As used herein, the terms "amorphous metal" and "amorphous metal alloys" mean a metal alloy that substantially lacks any order of great rank and is characterized by maximum X-ray diffraction intensity that are qualitatively similar to those observed. for liquids or glasses of inorganic oxide. Amorphous metal alloys are well suited for use in forming cores 20, because they have the following combination of properties: a) low hysteresis loss; b) low-loss of parasitic currents; c) low coercive force; d) high magnetic permeability; e) high saturation value; and f) minimum change in permeability with temperature. These alloys are at least 50% amorphous as determined by X-ray diffraction. Preferred amorphous metal alloys include those having the formula M60_90 T0_15 X10-25, wherein M is at least one of the elements iron, cobalt and nickel, T is at least one of the transition metal elements and X is at least one of the elements of the transition metal. minus one of the metalloid elements of phosphorus, boron and carbon. Up to 80% of the carbon, phosphorus and / or boron in X can be replaced by aluminum, antimony, beryllium, germanium, indium, silicon and tin. Used as cores of magnetic devices, these used amorphous metal alloys show generally superior properties compared to conventional polycrystalline metal alloys commonly used. Preferably, strips of these amorphous alloys are at least 80% amorphous, even more preferably at least 95% amorphous. • The amorphous alloys of the cores 20 are preferably formed by cooling a melt at a rate of approximately 106 ° C / sec. A variety of well-known techniques are available to manufacture continuously cooled amorphous metal strip. When used in magnetic cores for amorphous metal transformers, the strip material of the cores 20 typically have the • shape of a ribbon. This strip material is conveniently prepared by casting molten material directly on a cooled Ale surface or on a rapid cooling medium of some kind. These techniques of processing considerably reduce the cost of manufacturing, since intermediate procedures of wire stretching or belt formation are not required. The amorphous metal alloys of which the core 20 is preferably composed show high tensile strength, typically 14.060 to 42.180 kg / cm2 (200,000 to 600,000 psi) approximately, depending on the particular composition. This will have to be compared with the poly-crystalline alloys that are used in the annealed condition and that are usually in the range of approximately 2,182 to 5,624 kg / cm2 (40,000 to 80,000 psi).

A high tensile strength is an important consideration in applications where high centrifugal forces are present as higher resistance alloys prolong the service life of the transformer. In addition, the amorphous metal alloys used to form the core 20, show a high electrical resistivity, in the range of approximately 160 to 180 microhm-cm at 25 ° C, depending on the particular composition. Typical materials of the prior art have resistivities of about 45 to 160 microhm-cm. The high resistivity presented by the amorphous metal alloys defined above is useful in AC applications, to minimize the losses of paracitic currents which in turn are a factor in reducing core loss. An additional advantage of using amorphous metal alloys to form the core 20 is that lower coercive forces are obtained than with the prior art compositions, substantially with the same metallic content, thus allowing more iron to be used, which is relatively economic in the core 20, compared to a higher proportion of nickel, which is more expensive. Each of the cores 20 is formed by winding successive turns on a mandrel (not shown) keeping the strip material under tension to effect a closed or tight formation. The number of turns is chosen depending on the desired size of each core 20. The thickness of the strip material of the cores 20 is preferably in the range of .0254 to .0508 mm (1 to 2 mils). Due to the high relative tensile strength of the amorphous metal alloy employed herein, the strip material having a thickness of .0254 to .0508 mm (1-2 mils) can be used without fear of rupture. It will be appreciated that maintaining the relatively thin strip material increases the effective resistivity since there are many boundaries per unit of radial length that the parasitic currents must pass. With continued reference to Figures IA and IB, a simple-phase, armored-type dry-type power distribution transformer 10 includes a core / coil structure 12 consisting of two amorphous metal cores 20 and a generally rectangular encapsulated coil 40. The transformer 10 also includes a bottom frame 30 and an upper frame 34 having bottom and top coil supports 32, 36, respectively and within which the core / coil structure 12 is mounted in a sustained manner. core 20 is preferably coiled from a plurality of amorphous metal layers or strips 28 having a generally rectangular cross-sectional shape (see Figure IB). Each nucleus 20 -? it has two long sides 24 and two short sides 26 which collectively define a generally rectangular core window 22, within which a middle section • substantially straight 52 of the generally rectangular coil 40 of the present invention, is located. The dimension ratio, ie the ratio between the short and long sides 24, 26 of the core 20, is here defined as the ratio of the window height (ie long side 24) to the window width (ie short side 26). ) and of The preference is between about 3.5 to l and 4.5 to l.

• This construction of. The preferred core minimizes the number of amorphous metal emboiled layers or strips 28 required to construct the core 20, which in turn produces lower temperature gradients in the coil 40. Coats of Epoxy (not shown) are applied on the long sides 24 to support the height of the core 20. The initial epoxy layer, preferably is generally yielding and penetrates between the amorphous metal layers or strips 28 comprising the core 20. Layers subsequent epoxies, in general they are more rigid to impart the desired strength to the long sides 24 of the core 20. The core 20 is preferably constructed from amorphous metal tape having a nominal chemistry this tape is sold by AlliedSignal Inc. under the trade designation METGLASMR alloy SA-1.

The desired shape of the coil 40 of the present invention is generally rectangular. However, other geometric shapes are also considered within the scope of the present invention, provided, however, that these other geometric shapes include a substantially straight midsection 52 that is dimensioned and configured to fit within the generally rectangular 22nd of the core 20. For example, coil 40 may have rounded end sections 54 that are not located within core window 22, and a generally straight mid section 52 that passes through and locates within the core window, is say for example an oval with generally straight middle sections. As illustrated more clearly in Figure IB, the generally rectangular coil 40 of the present invention comprises a plurality of coil windings 42, windings together with an insulating material 44 and with selectively placed cooling duct spacers 46 (see Figures 4 and 4). 5) . The generally rectangular shape of the coil 40 is obtained by winding the coil components (eg windings 42 and insulating material 44) with respect to a rectangular winding mandrel 60 (see Figures 4 and 5), alternatively winding coil windings 42 and material insulator 44 in a plurality of concentric layers. In a preferred embodiment, the insulating material 44 comprises the innermost and outermost layers of the wound coil 40 and further provides electrical insulation between the adjacent coil windings 42. A substantially rectangular coil channel 56 is defined longitudinally through the coil 40 when removing the rectangular winding mandrel 60. Since the coil winding material is typically supplied on a reel, the material can retain an elbow radius after the coil 40 is wound, causing the coil 40 to bend or acquire a generally oval shape due to the memory of the winding material. This disadvantageously increases the construction dimensions of the coil, especially in the middle section 52, which is preferably substantially straight, and can result in coils that are too large to fit in the cores 20. In this way it is necessary to ensure that the windings coil 42 (and coil 40) retains its generally rectangular shape, then removes it from winding mandrel 60. A solution that is provided by the present invention, involves using kraft paper with epoxy dots as the insulating material 44 between the coil windings 42 The epoxy adheres to the coil windings 42 and when curing imparts rigidity to the windings 42 which counteract the tendency to bend the winding material. Alternatively, a winding shape 62 (see Figures 4 and 5) may include corners of. metal 64 forming corners in coil windings 42 and coil 40 is wound on mandrel 60. A third solution involves shaping the generally rectangular structure of coil 40 as the winding material is coiled in mandrel 60, such as for example using a block of wood and nylon hammer. Still another solution involves leaving the coil 40 in the winding mandrel 60 and pressing the long legs of the winding 40 between clamps, then • that the coil 40 has been completely wound and before encapsulation. In addition to providing the generally rectangular shape to the spool 40, this latter solution serves to further compress the legs of the coil 40, in this way minimizing the accumulation between the windings 42 and the insulation material 44 in the sections where the accumulation should be minimized, ie the middle sections F substantially straight 52. 20 To further minimize the size of the finished coil 40, the cooling duct spacers 46 are not placed (and the cooling cores 58 are not located) in the substantially straight middle sections 52 of the coil. This provides a distinct advantage over round or toroidal coils that require continuous cooling ducts circumferentially. In this manner, a circumferentially discontinuous cooling duct that is defined by the selective placement of the spacers 46, is provided only in the end sections 54 of the substantially rectangular coil 40. The insulating material 44 is sandwiched between adjacent layers of the coil windings 42, to provide electrical insulation between them and form the innermost and outermost layers of the coil 40 (not considering the epoxy encapsulation described below). In a preferred embodiment, the insulating material 44 comprises a sheet or sheets of aramid paper such as Nomex ™ brand from Dupont. It will be apparent to those skilled in the art that various other insulating materials can be provided without departing from the spirit or intent of the present invention. The innermost and outermost sheets of the insulating material 44 are preferably sized to extend approximately 12mm beyond the longitudinal ends of the coil 40. In addition, the insulating material 44 located on each side of the cooling duct spacers 46 also it extends approximately 12 mm beyond the ends of the spool 40. These sheets of extended insulation material 44 are sealed with a coarse epoxy such as for example that made by Magnolia Co., part number 3126, A / B. The epoxied expanded sheets of insulating material 44 then serve to contain any uncured epoxy during the encapsulation process (described in more detail below) of coil 40. Cooling for dry type energy distribution transformers can be either convection or forced air. Cooling ducts 58 of this way are necessary between coil windings • to allow the passage of air. The cooling duct spacers 46 can be inserted between coil windings 42, as the coil 40 is rewound and removed after the coil 40 has been encapsulated (as shown in FIG. describes in more detail below). Since it is convenient to control the winding dimensions of the coil 40 to ensure that it fits within the core window 22 of the core 20, the duct spacers of the • Cooling 46 are advantageously inserted only in those sections of the coil 40 that are not located within the core window 22 (i.e. at the longitudinally distant ends of the coil 40, as clearly illustrated in Figure IB in the assembled transformer 10. In this way, the dimension of coil 40 it controls in the section that will be located within the ? core window 22 in this way providing smaller (ie narrower 40) coils which in turn produce smaller energy distribution transformers. The generally rectangular shape of the coil of the present invention allows the use of cooling ducts 58 that are not continuous with respect to the circumference of the rectangular coil. The convenience of selective localization of the cooling ducts 58 and of providing circumferentially non-continuous cooling ducts 58 is clear consideration of the fact that the cooling ducts 58 increase the size of the coil-- which is especially undesirable in the substantially mid-section 52 of the coil 40 The generally rectangular shape of the coil 40 of the present invention provides 4 clearly delineated sides (which the round or toroidal coils do not) that allow selective location of the cooling ducts 58 in the end sections 54 of the coil 40. For coils Low voltage, such as those typically employed as the secondary winding of a power distribution transformer, the winding winding 42 comprises a sheet or sheets of aluminum or copper (see Figure 4). For high voltage coils, such as those typically employed as the primary winding of an energy distribution transformer, the coil winding 42 comprises a circular or rectangular copper wire of cross section (see Figure 5). For both high and low voltage coils, the coil 40 is wound on a rectangular mandrel 60, preferably in conjunction with a winding shape 62 having metal corners 64 with a predefined angular configuration. The substantially rectangular coil 40 of the present invention may comprise only one high voltage or low voltage coil or in alternating form, it may comprise both low and high voltage coils. The wound coil 40 is completely contained in and encapsulated by an epoxy resin layer 50 as described in more detail below. Now with . Referring to Figures 4 and 5, there is illustrated a generally rectangular coil 40 configured in accordance with the present invention, for low voltage and high voltage applications, respectively. The low voltage coil 40 shown in Figure 4 is formed by winding a coil winding 42 such as for example a copper or aluminum foil, with respect to a generally rectangular winding mandrel 60. To electrically isolate adjacent layers of windings 42, an insulating material 44 is inserted between them. The insulating material 44 comprises the innermost and outermost layers of the wound coil coil 40. • Cooling ducts 58 are provided in the wound coil 40 when inserting cooling duct spacers 46 between the coil windings 42 as the coil 40 reel The spacers 46 are removed after the coil 40 is encapsulated and the cooling ducts 58, thus defined by the cavity created by the removed spacer 46. The high voltage coil 40 illustrated in Figure 5 is formed in a similar manner. to the low voltage coil 40 of Figure 4, except that the coil winding 42 comprises a rectangular or round copper wire that is spirally wound or disk relative to the rectangular mandrel 60. The coil 40 of the present invention is encapsulates in an epoxy resin layer 50 using a confining container 70, as illustrated in Figure 6. The container 70 comprises a container shell 72 having first and second halves 72a, 72b, a container core 74 and a bottom of container 76. Receptacle core 74 may also comprise first and second halves 74a, 74b or alternatively the container core 74 may comprise the rectangular winding mandrel 60 at which the generally rectangular coil 40 of the present invention is wound and formed. Clamps 78 provided in the first and second container halves 72a, 72b, may be used for to hold the two halves together during the encapsulation process. The encapsulation process will now be described in detail and with reference to Figures 6, 7 and 8. The wound coil 40 is placed in the confinement vessel 70 which preferably extends beyond the top of the coil 40 at about 100 mm, to allow any shrinkage in the epoxy after curing. The container 70 and the coil 40 are then loaded into the vacuum chamber 80 which is connected to a vacuum source 82 and. an epoxy source 84. The chamber 80 is then evacuated through the vacuum source 82 to approximately 150 torr. A low viscosity epoxy such as Bisphenol A epoxy resin, of the type sold by Magnolia Co., as part number 111-047, is introduced into and completely fills the confinement vessel 70. When the container 70 is filled to the upper part with epoxy, the vacuum chamber 80 is additionally evacuated to approximately 20 torr. Additional epoxy is fed to the confining vessel 70. If the epoxy level drops during the above described pressure changes inside the chamber 80. Once the confining vessel 70 is completely filled with epoxy and the epoxy level is stabilized inside of the container 70, the epoxy is cured to produce a layer of epoxy resin 50, which completely encloses and encapsulates the coil 40. After the epoxy has cured, the coil 40 is removed from the confinement vessel 70 and the cooling duct spacers 46. they are removed from coil 40. The coil. resin encapsulated, generally rectangular 40, may now be employed in conjunction with a coiled amorphous metal core 20, having a generally rectangular section and a generally rectangular core window 22. The substantially straight section 52 of the coil 40 is located within the core window 22 and substantially corresponds to the size and shape of the window 22. In this manner, the present invention provides a transformer for dry type energy distribution, having a cored amorphous metal core with a generally rectangular cross-sectional shape and a coil encapsulated in resin, generally rectangular. The encapsulation protects the coil against severe environmental conditions, protects the coil insulation system, improves the coil resistance under short circuit conditions and improves the cooling characteristics of the coil, by providing a uniform surface. and smooth with respect to the outside of the coil on which air (either forced or convection) can pass uniformly and easily.

Further, by adjusting the "prma" of the coil to that of the cross-section of the core, the present invention provides a transformer for dry type amorphous metal energy distribution that is less expensive to manufacture, less resistive and thus has less losses, (less coil material is required to wind it), and it is more compact than the prior art transformers that have generally round or circular coils. The present invention thus provides a transformer for energy distribution of dry, durable and robust type, which uses the transformer materials in a more economical way in this way reducing manufacturing costs and total transformer size. Having thus described the invention rather in full detail, it will be understood that said detail need not be strictly satisfied, but that various changes and modifications may be suggested to a person skilled in the art, all falling within the scope of the invention. , as defined by the appended claims. &

Claims (39)

1. CLAIMS 1. A dry type energy distribution transformer, characterized in that it comprises: a generally rectangular coil encapsulated in resin having a substantially straight section; and an amorphous metal core having a generally rectangular core window there defined; the coil and the core are dimensioned and configured in such a way that the shape of the substantially straight section of the coil, 10 substantially adapts to the shape of the window of • core, the substantially straight section of the coil is located inside the core window, when the coil and core are assembled to form the power distribution transformer.
2. 2. The transformer for dry type energy distribution according to claim 1, characterized in that the coil further includes: a plurality of generally rectangular concentric layers. • comprising a coil winding and a 20 insulating material that provides electrical insulation between adjacent concentric layers of the coil and a layer of resin encapsulating the coil.
3. 3. A dry type power distribution transformer according to claim 2, Characterized in that the coil further comprises a plurality of cooling ducts defined between adjacent ones of the plurality of concentric layers, the cooling ducts are circumferentially non-continuous with respect to the generally rectangular coil and are located in part of the coil that does not comprises the substantially straight section.
4. 4. A dry type power distribution transformer according to claim 2, characterized in that the coil winding is constructed from 10 a material selected from the group of materials that • consist of aluminum and copper.
5. 5. A dry type energy distribution transformer according to claim 2, characterized by a resin layer comprising a resin 15 low viscosity epoxy.
6. 6. A dry type energy distribution transformer according to claim 5, characterized in that the low viscosity resin is a • bisphenol A epoxy resin.
7. 7. A dry type energy distribution transformer according to claim 1, characterized in that the core is a coiled core.
8. 8. A dry type power distribution transformer according to claim 1, Characterized in that the core is made of an amorphous metal alloy having the formula M60_90 T0_15 X_o-25 / where M is at least one of the elements iron, cobalt and nickel, T is at least one of the elements of transition metal and X is at least one of the elements metalloids phosphorus, boron and carbon, and where up to 80 percent of the content of carbon, phosphorus and boron can be replaced by aluminum, antimony, beryllium, germanium, indium, silicon and tin.
9. 9. A dry type power distribution transformer according to claim 1, characterized in that the core window defines a dimension ratio greater than about 3.5 to 1.
10. 10. A dry type power distribution transformer in accordance with the claim 1, characterized in that the core window defines a ratio of dimensions between approximately 3.5 to 1 and 4.5 to 1.
11. 11. A dry type energy distribution transformer according to claim 1, characterized in that the coil is a low voltage coil.
12. 12. A dry type power distribution transformer according to claim 1, characterized in that the coil is a high voltage coil. fis
13. 13. A dry type power distribution transformer according to claim 1, characterized in that the coil comprises a low voltage coil and a high voltage coil.
14. 14. A power distribution transformer of type, characterized in that it comprises: a generally rectangular coil encapsulated in resin, having a substantially straight section and formed by winding in an alternating form of a conductive material and an insulating material in a form of rectangular winding to form a plurality of generally rectangular concentric layers of insulating and conductive material and thus forming an encapsulating resin layer of the coil; a generally rectangular amorphous metal core having a generally rectangular core window there defined; the coil and the core are dimensioned and configured in such a way that the shape of the substantially straight section of the coil is substantially adapted to the shape of the core window, the substantially straight section of the coil being located within the core window, when the coil and core are assembled to form the power distribution transformer.
15. 15. A dry type power distribution transformer according to claim 14, characterized in that the conductive material is chosen from a group of materials consisting of aluminum and copper.
16. 16. A dry type power distribution transformer according to claim 14, characterized in that the coil further comprises a plurality of cooling ducts defined between adjacent ones of the plurality of concentric layers, the cooling ducts are circumferentially non-continuous with respect to the generally rectangular coil and are located in a part of the coil that does not comprise the substantially straight section disposed within the core window when the coil
17. 17. A dry type energy distribution transformer according to claim 14, characterized in that the resin layer comprises a low viscosity epoxy resin.
18. 18. A dry type energy distribution transformer according to claim 17, characterized in that the low viscosity resin is an epoxy bisphenol A resin.
19. 19. A dry type energy distribution transformer according to claim 14, characterized in that the core is a coiled core.
20. 20. A dry type energy distribution transformer according to claim 14, characterized in that the core is made of an amorphous metal alloy having the formula M60_90 T0_15 X10-25 / where M is at least one of the elements iron, cobalt and nickel, T is at least one of the elements of transition metal and X is at least one of the metalloid elements phosphorus, boron and carbon, and where up to 80 percent of the content of carbon, phosphorus and boron can replaced by aluminum, antimony, beryllium, germanium, indium, silicon and tin.
21. 21. A dry type power distribution transformer according to claim 14, characterized in that the core window defines a dimension ratio greater than about 3.5 to 1.
22. 22. A dry type power distribution transformer in accordance with claim 14, characterized in that the core window defines a dimension ratio of between about 3.5 to 1 and 4.5 to 1.
23. 23. A dry type power distribution transformer according to claim 14, characterized in that the coil is a low voltage coil.
24. 24. A dry type power distribution transformer according to claim 14, characterized in that the coil is a high voltage coil.
25. 25. A dry type power distribution transformer according to claim 14, characterized in that the coil comprises a high voltage coil and a low voltage coil.
26. 26. A dry type energy distribution transformer according to claim 14, characterized by a generally rectangular resin encapsulated coil having a substantially straight section, the coil being characterized in that it comprises: a plurality of generally rectangular concentric layers, which they comprise a conductive coil winding and an insulating material that provides electrical insulation between adjacent concentric layers of the coil; and a resin layer that encapsulates the coil.
27. 27. A resin encapsulated coil, generally rectangular, according to claim 26, characterized in that the coil further comprises a plurality of cooling ducts defined between adjacent of the plurality of concentric layers., the cooling ducts are circumferentially non-continuous with respect to the generally rectangular coil and are located in part of the coil that does not comprise the substantially straight section.
28. 28. A coil encapsulated in resin, generally rectangular, according to claim 26, characterized in that the coil winding is chosen from a group of materials consisting of aluminum and copper.
29. 29. A resin encapsulated coil, generally rectangular, according to claim 26, characterized in that the resin layer comprises a low viscosity epoxy resin.
30. 30. A resin encapsulated coil, generally rectangular, according to claim 29, characterized in that the low viscosity resin is an epoxy resin of bisphenol A.
31. 31. A coil encapsulated in resin, generally rectangular, according to claim 26 , characterized in that the coil is a low voltage coil.
32. 32. A coil encapsulated in resin, generally rectangular, according to claim 26, characterized in that the coil is a high voltage coil.
33. 33. A resin encapsulated coil, generally rectangular, according to claim 26, characterized in that the coil comprises a low voltage coil and a high voltage coil.
34. 34. A method for producing a dry type energy distribution transformer, characterized in that it comprises the steps of: a) forming a generally rectangular coil having a substantially straight section; b) encapsulating the coil in an epoxy resin; c) forming a core from amorphous metal, the core having a substantially rectangular window there defined; and d) assembling a dry type energy distribution transformer from the encapsulation coil and the amorphous metal core, such that the substantially straight section of the coil is located within the core window and wherein the shape of the substantially straight section of the coil, substantially conforms to the shape of the core window.
35. 35. A method for producing a dry type energy distribution transformer, according to claim 34, characterized in that step a) further comprises: e) alternately winding a conductive material and an insulating material in a form of rectangular winding to constitute a plurality of concentric layers of insulating and conductive material, the insulating material provides electrical insulation between adjacent concentric layers of the conductive material.
36. 36. A method for producing a transformer for dry type energy distribution according to claim 34, characterized in that step b) further comprises: f) placing the coil in a containment container; g) place the confinement container in an empty chamber; h) evacuating the vacuum chamber to a predetermined pressure; i) filling the confinement vessel with an epoxy resin; and j) curing the epoxy resin to form an epoxy resin layer that encapsulates the coil.
37. 37. A method for producing a transformer for dry type energy distribution according to claim 36, characterized in that the predetermined pressure of step h) is about 150 torr.
38. 38. A dry type energy distribution transformer according to claim 8, characterized in that the core is made from an amorphous metal alloy having the formula Fe80 B11Si9.
39. 39. A dry type energy distribution transformer according to claim 20, characterized in that the core is made from an amorphous metal alloy having the formula Fe80 B1: LSi9.