Shielded coil assembly and method for dry-type transformer

Abstract

A shielded coil assembly (106, 108, 110) and a dry-type transformer (100) formed using the shielded coil assembly (106, 108, 110), the shielded coil assembly (106, 108, 110) comprising: a coil (114) having an outer surface (202, 218a, 220a), an inner surface (204, 218b, 220b), an upper end surface (206, 218c, 220c) and a lower end surface (208, 218d, 220d), and a shielded coil assembly (106, 108, 110) formed on the outer surface (202, 218a, 220a), the inner surface (204 , 218b, 220b), a first insulating material (216) on the upper end surface (206, 218c, 220c) and the lower end surface (208, 218d, 220d) of the coil (114); and a conductive shielding layer (210), which includes a conductive paint, which is applied along the first insulating material (216) so that the conductive paint extends on at least a portion of each of the outer surface (202, 218a, 220a), the inner surface (204, 218b, 220b), the upper end surface (206, 218c, 220c) and the lower end surface (208, 218d, 220d) of the coil (114).

Description

Technical Field

[0001] This application relates to transformers for power distribution, and more particularly to shielding of coils in dry-type transformers. Background Technology

[0002] Transformers are used to increase or decrease voltage levels during power distribution. For long-distance power transmission, transformers can be used to increase voltage and decrease the current transmitted. The reduced current level decreases the resistive losses of the cables used to transmit this power. When power is to be consumed, transformers can be used to decrease the voltage level and increase the current to the level specified by the end user.

[0003] One type of transformer that can be employed is, for example, the dry-type submersible transformer described in U.S. Patent No. 8,614,614. Such transformers can be used underground in urban areas and can be designed to withstand harsh environments that may expose the transformer to moisture, water, pollutants, etc. Improved devices, components, and methods for submersible and other dry-type transformers are desired. Summary of the Invention

[0004] In some embodiments, a shielded coil assembly is provided, comprising: (1) a coil having an outer surface, an inner surface, an upper end surface, and a lower end surface, and a first insulating material formed on the outer surface, inner surface, upper end surface, and lower end surface of the coil; and (2) a conductive shielding layer comprising a conductive coating applied along the first insulating material such that the conductive coating extends over at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil. In one or more embodiments, the shielded coil assembly can be used to form a dry-type transformer.

[0005] In some embodiments, a shielded coil assembly is provided, comprising: (1) a coil having an outer surface, an inner surface, an upper end surface, and a lower end surface, and a first insulating material formed on the outer surface, inner surface, upper end surface, and lower end surface of the coil; and (2) a conductive shielding layer having (a) a conductive mesh laid along the first insulating material such that the conductive mesh extends over at least a portion of the outer surface, inner surface, upper end surface, and lower end surface of the coil; and a semi-conductive coating formed on the conductive mesh. The conductive mesh and the semi-conductive coating form a composite structure on at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil. In one or more embodiments, the shielded coil assembly can be used to form a dry-type transformer.

[0006] In some embodiments, a method of forming a coil assembly is provided, the method comprising: (1) providing a coil having an outer surface, an inner surface, an upper end surface, and a lower end surface; (2) encapsulating the coil in a first insulating material; and (3) forming a conductive shielding layer on the coil by applying a conductive coating such that the conductive coating extends over at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil.

[0007] In some embodiments, a method of forming a coil assembly is provided, the method comprising (1) providing a coil having an outer surface, an inner surface, an upper surface, and a lower surface; (2) encapsulating the coil in a first insulating material; and (3) forming a conductive shielding layer on the coil by: (a) laying a conductive mesh along the first insulating material such that the conductive mesh extends over at least a portion of the outer surface, inner surface, upper surface, and lower surface of the coil; and (b) applying a semi-conductive coating to the conductive mesh such that the conductive mesh and the semi-conductive coating form a composite structure over at least a portion of each of the outer surface, inner surface, upper surface, and lower surface of the coil.

[0008] Other aspects, features, and advantages of this disclosure may become apparent from the following detailed description illustrated by numerous exemplary embodiments and implementations. This disclosure may also be capable of having other different implementations, and several details of this disclosure may be modified in various aspects. Therefore, the drawings and description are to be considered illustrative in nature, not restrictive. The drawings are not necessarily drawn to scale. Attached Figure Description

[0009] Figure 1A A front plan view of a submersible dry-type transformer according to an embodiment provided herein is shown.

[0010] Figure 1B A perspective view of a coil assembly according to an embodiment provided herein is shown.

[0011] Figure 2A A perspective view of a high-voltage external coil according to the embodiments provided herein is shown.

[0012] Figure 2B A perspective view of a winding that can form part of a high-voltage external coil according to an embodiment provided herein is shown.

[0013] Figure 2C The embodiments provided herein are illustrated. Figure 2B A three-dimensional view of a winding having a first insulating material formed on the winding.

[0014] Figure 2D and Figure 2EThe embodiments provided herein are shown respectively. Figure 2C Top and bottom perspective views of a winding having a conductive shielding layer formed on a first insulating material of the winding.

[0015] Figure 3A A partial cross-sectional side view of a coil having an example embodiment of the conductive shielding layer provided herein is shown.

[0016] Figure 3B A partial cross-sectional side view of a coil having an alternative example embodiment of the conductive shielding layer provided herein is shown.

[0017] Figure 3C A partial cross-sectional side view of a coil having an alternative example embodiment of the conductive shielding layer provided herein is shown.

[0018] Figure 4 A flowchart is shown of a method for manufacturing a high-voltage external coil according to an embodiment provided herein.

[0019] Figure 5A The embodiments provided herein are illustrated. Figure 3A A partial cross-sectional side view of a portion of a conductive shielding layer, wherein the conductive shielding layers overlap themselves.

[0020] Figure 5B The embodiments provided herein are illustrated. Figure 3B A partial cross-sectional side view of a portion of a conductive shielding layer, wherein the conductive shielding layers overlap themselves.

[0021] Figure 5C The embodiments provided herein are illustrated. Figure 3C A partial cross-sectional side view of a portion of a conductive shielding layer, wherein the conductive shielding layers overlap themselves. Detailed Implementation

[0022] As mentioned above, submersible dry-type transformers can be used underground and / or in other harsh environments that may expose them to water, moisture, contaminants, etc. When exposed to moisture, humidity, or other adverse environments, transformers may be susceptible to corrosion. For proper operation and safety reasons, such transformers should be grounded to prevent dangerous voltages from being transmitted to the surrounding environment and / or personnel near the transformer. This is particularly important when the transformer is submerged.

[0023] According to one or more embodiments described herein, a shielded coil assembly for use in a dry-type transformer is provided, along with a method for forming such a shielded coil assembly. The shielded coil assembly has a groundable shield, so that the transformer using the shielded coil assembly does not generate static charge and / or there is no dangerous voltage level on the outer surface of the transformer. The shield may be embedded in a protective layer such as epoxy resin, so that the shield will not corrode when the transformer employing the shielded coil assembly is exposed to moisture or other corrosive environments.

[0024] In some embodiments, the shielded coil assembly may include an inner coil and an outer coil, and a shielding element provided at least for the outer coil of the shielded coil assembly. For example, the outer coil may have an outer surface, an inner surface, an upper surface, and a lower surface, on which an insulating material, such as epoxy resin, is formed (e.g., on all surfaces). The conductive shielding layer includes a conductive coating that may be applied to the insulated outer coil and extend over at least a portion of each of the outer, inner, upper, and lower surfaces of the outer coil. In some embodiments, gaps may be provided in the conductive coating to prevent loop current formation. A grounding lead or cable may be coupled to the conductive shielding layer, and the conductive shielding layer may be embedded within another insulating material (e.g., epoxy resin). In one or more embodiments, a semi-conductive coating may be provided beneath the conductive coating. For example, in some embodiments, the entire insulated outer coil may be coated with a semi-conductive coating before the conductive coating layer is formed. In such embodiments, the conductive coating may be formed as a continuous layer (e.g., except for gap areas for reducing / preventing loop current) or the conductive coating may be provided only in certain areas (e.g., by applying strips or grid patterns with the conductive coating). Many other implementations are provided. In some implementations, a dry-type transformer can be formed using shielded coil assemblies.

[0025] According to other embodiments, a conductive shielding layer can be formed by winding an insulated outer coil with a conductive mesh and applying a semiconductive coating to the conductive mesh (and / or between the conductive meshes). For example, the conductive mesh can be laid along the insulated outer coil such that it extends over at least a portion of the outer, inner, upper, and lower surfaces of the outer coil. Gap regions can be formed in the conductive mesh to reduce / prevent loop current. The semiconductive coating can help hold the conductive mesh in place during subsequent processing, such as during the encapsulation of the outer coil in a second insulating material (e.g., epoxy). Since the semiconductive coating can be applied to the conductive mesh and in any openings in the conductive mesh, the conductive mesh and semiconductive coating can form a composite structure on at least a portion of each of the outer, inner, upper, and lower surfaces of the outer coil. A grounding lead or cable can be coupled to the conductive shielding layer. In one or more embodiments, a dry-type transformer can be formed using the shielded coil assembly.

[0026] Figure 1A This is a front plan view of a dry-type transformer 100 according to the embodiments provided herein. The dry-type transformer 100 shown is a three-phase transformer, but in other embodiments, transformers with different numbers of phases (e.g., single-phase, two-phase, four-phase, five-phase, etc.) may be used. As used herein, "dry-type transformer" means a transformer comprising high-voltage and low-voltage coils that are not immersed in an oil bath or other similar fluid contained within the casing. Such dry-type transformers 100 have significant advantages: they do not use oil and can operate relatively coolly via cooling by air or water (when immersed).

[0027] As an example, a dry-type transformer 100 may include a core assembly 102 (shown in dashed lines) mounted between an upper frame portion 104U and a lower frame portion 104L. In one or more embodiments, an insulating sheet (not shown) may be provided to insulate the sides of the core assembly 102 from the respective upper frame 104U and lower frame 104L, while in other embodiments such an insulating sheet (not shown) may not be used. In some embodiments, the core assembly 102 may be formed of multiple layers of magnetic material. Example magnetic materials include iron, steel, amorphous steel or other amorphous permeable magnetic metals, silicon steel alloys, carbonyl iron, ferrite ceramics, and / or combinations of the above materials. In some embodiments, a laminated ferromagnetic metal material with a high cobalt content may be used. Other suitable magnetic materials may be used.

[0028] As shown, core assembly 102 may include multiple interconnects and may include vertical core posts or regions 102L, 102C, and 102R (each shown in dashed lines). Vertical core posts 102L, 102C, and 102R may be assembled with a top core member 102T and a bottom core member 102B (shown in dashed lines). Construction may include step-laps between the various components of core assembly 102. For example, core assembly 102 may be constructed as shown in U.S. Patent No. 8,212,645. Other constructions of core assembly 102 may be used. In some embodiments, within transformer 100, each core post 102L, 102C, and 102R may be surrounded by coil assemblies (i.e., coil assemblies 106, 108, and 110).

[0029] Figure 1B A perspective view of coil assembly 106 is shown. Coil assembly 106 is shown and described herein by way of example, and coil assemblies 108 and 110 may be identical or substantially identical to coil assembly 106. Coil assembly 106 includes a low-voltage inner coil 112 and a high-voltage outer coil 114 that may be concentric with the low-voltage inner coil 112. The low-voltage inner coil 112 may be electrically insulated from the core assembly 102 and may also be electrically insulated from the high-voltage outer coil 114. For example, the low-voltage inner coil 112 may be surrounded by an insulating material such as molding resin. Similarly, as will be fully described herein, the high-voltage outer coil 114 may include a multi-level insulating material (e.g., resin) disposed in multiple sequential molding processes. Example insulating materials may include any suitable solid insulation, such as epoxy resin, polyurethane, polyester, silicone resin, etc.

[0030] Refer again Figure 1A As described in U.S. Patent No. 8,614,614 entitled “Submersible Dry Transformer,” coil assemblies 106, 108, 110, and core assembly 102 can be separated by insulating sheets 116A to 116F and other insulating sheets (not shown). Insulating sheets 116A to 116F work together to seal the plane of the core opening or “window” between core posts 102L, 102C, and 102R of core assembly 102. As described in US 8,614,614, if core assembly 102 is immersed in a liquid, sealing the core window prevents the liquid from passing through and prevents the formation of a conductive spiral around core posts 102L, 102C, and 102R. Insulating sheets 116A to 116F can be any suitable insulating material, such as a resin with glass fibers.

[0031] Each of the coil assemblies 106, 108, and 110 of the transformer 100 may be provided with a high-voltage terminal 118. In one embodiment, the high-voltage terminal 118 may be placed at the top front of the respective coil assembly 106, 108, or 110. The low-voltage terminal 119 of the low-voltage internal coil 112 may be provided with a high-voltage terminal 118. Figure 1B It is disposed on the back side of coil assembly 106, coil assembly 108, or coil assembly 110, or in some other suitable location. For example, such as Figure 1B As shown, the high-voltage terminal 118 can be located at the top front of the columnar front extension 126E of the high-voltage outer coil 114, and the low-voltage terminal 119 can be located at the rear of the low-voltage inner coil 112. However, the high-voltage terminal 118 and the low-voltage terminal 119 can be located elsewhere. The high-voltage terminal 118 provides an electrical connection to the high-voltage outer coil 114 of the respective coil assemblies 106, 108, 110. Connectors (not shown) (e.g., sealed plug-in connectors) can be provided to facilitate a sealed connection between the high-voltage terminal 118 and a cable (not shown). A delta or Y-connection (not shown) can be achieved with the low-voltage terminal 119. Other suitable sealed connections are also possible.

[0032] Transformer 100 may also include delta connections 120A, delta connection 120B, and delta connection 120C between the respective high-voltage external coils 114 of coil assemblies 106, 108, and 110. Figure 1A For example, delta connections 120A, 120B, and 120C may include shielded cables. As shown, the upper terminal 122 and lower terminal 124 of the high-voltage external coil 114 of each of coil assemblies 106, 108, and 110 can be connected to realize each of delta connections 120A, 120B, and 120C. In some embodiments, the electrical connection may be a sealed connection. The upper terminal 122 and lower terminal 124 may extend horizontally from the columnar front extension 126E of the high-voltage external coil 114 (e.g., Figure 1B (As shown). For example, in some embodiments, the upper terminal 122 and the lower terminal 124 may extend outward from the front end 126F of the columnar front extension 126E.

[0033] Each of the high-voltage external coils 114 may include a tap changer assembly 132. For example, the tap changer assembly 132 may be provided as an extension from the front of the high-voltage external coil 114. More particularly, in some embodiments, the tap changer assembly 132 may be as follows: Figure 1B The extension shown is from the columnar front extension 126E, and its shape can be conical.

[0034] The high-voltage external coil 114 of each of the coil assemblies 106, 108, and 110 may include a grounding terminal 128. For example, a grounding conductor 129 such as a braided cable ( Figure 1A A common grounding strip 130 can be attached to the lower frame 104L and can provide grounding. The high-voltage external coil 114 of each of coil assemblies 106, 108, and 110 includes a conductive shielding layer that will be fully described herein.

[0035] Figure 2A A perspective view of a high-voltage external coil 114 according to an embodiment provided herein is shown. As described above, each coil assembly 106, 108, and 110 includes a high-voltage external coil 114. The high-voltage external coil 114 includes an outer surface 202, an inner surface 204, an upper end surface 206, and a lower end surface 208 (e.g., each external coil 114 of each coil assembly 106, 108, and 110 has an outer surface, an inner surface, an upper end surface, and a lower end surface).

[0036] A conductive shielding layer 210 (shown in dashed lines) can provide shielding for each surface of the high-voltage external coil 114 (described further below). The conductive shielding layer 210 can be highly conductive, thereby providing a low-resistance path to ground for static charges and / or high voltage levels on the outer surface of the high-voltage external coil 114. A grounding terminal 128 is connected to the conductive shielding layer 210, thereby providing means for electrically grounding the outer surface of the high-voltage external coil 114.

[0037] The conductive shielding layer 210 on each surface of the high-voltage outer coil 114, on which the conductive shielding layer 210 is formed, may include a loop separation region 212. As shown, the loop separation region 212 is formed as an interruption of the conductive shielding layer 210 (below each of the outer surface 202, inner surface 204, upper end surface 206, and lower end surface 208 of the high-voltage outer coil 114). The loop separation region 212 forms a continuous loop (e.g., an open loop) without conductive material. Including the loop separation region 212 in the conductive shielding layer 210 helps prevent loop currents from being generated on the surface of the high-voltage outer coil 114.

[0038] In terms of broad applicability to transformers, an improved conductive shielding layer 210 is provided for each surface of the high-voltage external coil 114.

[0039] Figures 2B to 2E The formation of the conductive shielding layer 210 of the high-voltage external coil 114 is shown. Figure 2B A perspective view of a winding 214 that can form part of a high-voltage external coil 114 is shown. Figure 2CA perspective view of a winding 214 having a first insulating material 216 formed on the winding 214 is shown. Figure 2D and Figure 2E Top and bottom perspective views of a winding 214 having a conductive shielding layer 210 formed on a first insulating material 216 are shown respectively.

[0040] Reference Figures 2B to 2C In some embodiments, in order to form a high-voltage external coil 114 ( Figure 2A ), can be used with the first insulating material 216 (in Figure 2C (as shown in the diagram) Covering winding 214 (in) Figure 2B The outer surface 218a, inner surface 218b, upper surface 218c, and lower surface 218d (shown in the diagram) can be used. A conductive shielding layer 210 (in...) Figure 2D and 2E (as shown in the diagram) covering the first insulating material 216 (in) Figure 2C The conductive shielding layer 210 includes an outer surface 220a, an inner surface 220b, an upper surface 220c, and a lower surface 220d (shown in the diagram). A loop separation region 212 may be included across each surface including the high-voltage outer coil 114 in the conductive shielding layer 210. As shown, the loop separation region 212 is formed as an interruption of the conductive shielding layer 210 along each of the outer surface 220a, inner surface 220b, upper surface 220c, and lower surface 220d of the first insulating material 216 of the winding 214 of the high-voltage outer coil 114. The loop separation region 212 forms a continuous loop along each surface including the first insulating material 216 of the high-voltage outer coil 114, and the continuous loop does not contain conductive material. Including the loop separation region 212 in the conductive shielding layer 210 helps prevent loop currents from being generated on the surface of the high-voltage outer coil 114.

[0041] The following reference Figures 3A to 3C An example conductive shielding layer is described for use with a high-voltage external coil 114. For convenience, Figures 3A to 3C Only a portion of winding 214 is shown. It should be understood that in some embodiments, the conductive shielding layer may provide shielding for most, if not all, of the surface of the high-voltage outer coil 114.

[0042] Figure 3A A partial cross-sectional side view of a portion of a high-voltage external coil 114 with a conductive shielding layer according to an embodiment provided herein is shown. (Refer to...) Figure 3A The winding 214 of the high-voltage external coil 114 is covered by a first insulating material 216. For example, the winding 214 can be wound into a cylindrical shape, forming a... Figure 2B The winding structure shown has an outer surface 218a, an inner surface 218b, an upper end surface 218c, and a lower end surface 218d. For example... Figure 2C As shown, the first insulating material 216 can completely cover these surfaces. The first insulating material 216 can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can be used. Example resins include those available from Huntsman Quimica Ltda., São Paulo, Brazil. HY 926CH and / or CY 5948. In some embodiments, the resin may be glass fiber reinforced. The thickness of the first insulating material 216 layer may be between 6 mm and 7 mm, but other suitable thickness ranges may also be used.

[0043] A conductive shielding layer 210 is formed on a first insulating material 216. Specifically, the conductive shielding layer 210 is formed on the insulating material 216, which includes at least a portion of each surface of the high-voltage external coil 114. For example, as... Figures 2C to 2E As shown, the conductive shielding layer 210 can be formed on at least a portion of the first insulating material 216 of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high voltage outer coil 114.

[0044] In some embodiments, the conductive shielding layer 210 may be a conductive coating applied to the first insulating material 216. The conductive coating may include a conductive metal, including one or more of copper, nickel, silver-plated copper, nickel-silver, and silver. Other suitable conductive coatings may be used. In some embodiments, the resistivity of the applied conductive coating may be between about 0.01 ohms / sq in / mil and 1 ohm / sq in / mil, and / or the thickness may be between about 30 micrometers and 500 micrometers, and in some embodiments, the thickness may be between about 30 micrometers and 150 micrometers, but other suitable resistivity and / or thickness ranges may also be used (where "sq in" is an abbreviation for "square inch" and "mil" is 0.001 inch). The conductive coating may be applied by any suitable process such as brushing, rolling, spraying, and dip coating. Furthermore, patterns can be formed on the first insulating material 216 using a template or mask, including grid patterns, strip patterns, or any other suitable patterns. In some embodiments, the application of the conductive shielding layer 210 can be carried out in a manner that ensures electrical continuity across each surface of the high-voltage outer coil 114 (e.g., each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114).

[0045] In some embodiments, the conductive shielding layer 210 may include a loop separation region 212. The loop separation region 212 may be formed by interruptions in the conductive shielding layer 210 on each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114. Figures 2C to 2E In some embodiments, the width of the interruption can be between 4 mm and 6 mm, but other suitable width ranges may also be used. The loop separation region 212 forms a continuous loop (e.g., an open loop) without any conductive coating across all surfaces including the high-voltage outer coil 114 (extending across each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114). Figures 2C to 2E Whether the conductive coating is applied as a continuous sheet or a pattern, loop separation regions 212 can be provided in one form or another.

[0046] In some embodiments, the grounding connector 310 may be coupled to the conductive shielding layer 210. For example, in some embodiments, the grounding connector 310 may be a metal plate in direct contact with the conductive shielding layer 210 or a conductive strip formed on or under the conductive shielding layer 210. For example, if the conductive shielding layer 210 includes a conductive coating, at least a portion of the grounding connector 310 may be disposed on top of or under the conductive coating. Other grounding connectors may be used. A grounding terminal 312 may be attached to the grounding connector 310, and an external grounding lead or cable may be attached to the grounding terminal 312. The grounding connector 310 and / or the grounding terminal 312 may be formed of any suitable material such as copper, brass, aluminum, etc. In some embodiments, one or more of the high-voltage terminal 118, the upper terminal 122, the lower terminal 124, the grounding terminal 128, and / or the tap changer assembly 132 may be shielded during the application of the conductive shielding layer 210.

[0047] A second insulating material 314 can be applied to the conductive shielding layer 210 and the grounding connector 310. Similar to the first insulating material 216, the insulating material can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can also be used. Regardless of the insulating material used, the second insulating material 314 can protect the conductive shielding layer 210 from moisture, water, contamination, etc.

[0048] Figure 3B A partial cross-sectional side view of a coil having an alternative example embodiment of the conductive shielding layer provided herein is shown. (Refer to...) Figure 3BThe winding 214 of the high-voltage external coil 114 is covered by a first insulating material 216. For example, a continuous layer of the first insulating material 216 can completely cover the winding 214. The first insulating material 216 can cover the outer surface 218a, inner surface 218b, upper end surface 218c, and lower end surface 218d of the winding 214 of the high-voltage external coil 114. Figures 2B to 2C The first insulating material 216 can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can be used. Example resins include those available from Huntsman Quimica Ltda., São Paulo, Brazil. HY 926CH and / or CY 5948. In some embodiments, the resin may be glass fiber reinforced. The thickness of the first insulating material 216 may be between 6 mm and 7 mm, but other suitable thickness ranges may also be used.

[0049] exist Figure 3B In this embodiment, the conductive shielding layer 210 is formed of a semi-conductive coating layer 316 and a conductive coating layer 317. For example, the semi-conductive coating layer 316 may be formed on the first insulating material 216. The semi-conductive coating 316 may be applied to the first insulating material 216, including all surfaces of the high-voltage external coil 114. For example, the semi-conductive coating 316 may be applied to the first insulating material 216 of the high-voltage external coil 114. Figure 2C The insulating material 216 is applied to each of the outer surface 220a, inner surface 220b, upper surface 220c, and lower surface 220d of the high-voltage outer coil 114. A layer of semi-conductive coating 316 can be applied across the high-voltage outer coil 114. Figure 2A The outer surface 202, inner surface 204, upper surface 206 and lower surface 208 provide a uniform electric field and / or voltage potential.

[0050] Semiconducting coating 316 may be similar in composition to conductive coating 317. Semiconducting coating 316 may include a conductive metal, including one or more of copper, nickel, silver-plated copper, nickel-silver, and silver. Other suitable types of semiconducting coatings may be used. The difference between semiconducting coating 316 and conductive coating 317 is that semiconducting coating 316 typically covers a higher resistance range. In some embodiments, the resistance of the applied semiconducting coating 316 may be between about 1 kilo-ohm / sq in / mil and 10 kilo-ohm / sq in / mil, and / or the thickness may be between about 10 micrometers and 500 micrometers, and in some embodiments, the thickness may be between about 10 micrometers and 50 micrometers, but other suitable resistance and / or thickness ranges may also be used.

[0051] After the semiconductive coating 316 layer is formed, a conductive coating 317 is formed on the semiconductive coating 316 layer. For example, the conductive coating 317 can be formed on the semiconductive coating 316 formed on the first insulating material 216, wherein the conductive coating 317 covers at least a portion of each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 that has been covered with the semiconductive coating 316. Therefore, a conductive shielding layer 210 comprising the conductive coating 317 and the underlying semiconductive coating 316 is formed on at least a portion of each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage external coil 114. Figures 2C to 2E (As shown).

[0052] The conductive coating 317 may include a conductive metal, including one or more of copper, nickel, silver-plated copper, nickel-silver, and silver. Other suitable conductive coatings may be used. In some embodiments, the applied conductive coating 317 has a resistance between about 0.01 ohms / square inch / mil and 10 kiloohms / square inch / mil and / or a thickness between about 30 micrometers and 500 micrometers, and in some embodiments, a thickness between about 30 micrometers and 150 micrometers, but other suitable resistance and / or thickness ranges may also be used. The semiconductive coating 316 and / or conductive coating 317 may be applied by any suitable process such as brushing, rolling, spraying, and dip coating. In some embodiments, a pattern of conductive coating may be formed on the semiconductive coating 316 layer formed on the first insulating material 216 using a stencil or mask, the pattern including a grid pattern, a strip pattern, or any other suitable pattern. In some implementations, the application of the conductive shielding layer 210 can be carried out in a manner that ensures electrical continuity across each surface of the high-voltage outer coil 114 (e.g., each of the outer surface 220a, inner surface 220b, upper surface 220c, and lower surface 220d of the first insulating material 216 of the high-voltage outer coil 114).

[0053] In some embodiments, the conductive shielding layer 210 may include a loop separation region 212. The loop separation region 212 is interrupted by portions of the conductive coating 317 of the conductive shielding layer 210 on each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114. Figures 2C to 2EThe width of the interruption in the conductive coating 317 layer can be between 4 mm and 6 mm, but other suitable width ranges can also be used. The loop separation region 212 forms a continuous loop without any conductive coating 317 across all surfaces including the high-voltage outer coil 114 (extending across each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114). Figures 2C to 2E (And exposes the semi-conductive coating 316 of the undercoat in the gap region). Whether the conductive coating 317 is applied as a continuous layer or a pattern, the loop separation region 212 can exist in one form or another. In one or more embodiments, without the loop separation region 212, the resistance of the conductive coating 317 may be low enough to form a (measurable) current loop on the surface of the high-voltage outer coil 114. Such a current loop could cause heating and damage to the coil assembly.

[0054] The exposed semiconductive coating 316 in the loop separation region 212 of the conductive coating 317 helps prevent electric field leakage through the loop separation region 212 during operation of the high-voltage external coil 114. Furthermore, the higher resistance range of the semiconductive coating 316 layer helps prevent the formation of a ground loop within the semiconductive coating 316 layer (even though the semiconductive coating 316 may be present in the loop separation region 212). In one or more embodiments, the semiconductive coating 316 may have sufficiently high resistance to prevent the formation of a (measurable) current loop on the surface of the high-voltage external coil 114.

[0055] In some embodiments, the grounding connector 310 may be coupled to the conductive shielding layer 210. For example, in some embodiments, the grounding connector 310 may be a metal plate in direct contact with the conductive shielding layer 210 or a conductive strip formed on or under the conductive shielding layer 210. For example, in cases where the conductive shielding layer 210 includes a conductive coating, at least a portion of the grounding connector 310 may be disposed on top of or below the conductive coating (e.g., on top of a semi-conductive coating 316). Other grounding connectors may be used. A grounding terminal 312 may be attached to the grounding connector 310, and an external grounding lead or cable may be attached to the grounding terminal 312. In some embodiments, one or more of the high-voltage terminal 118, upper terminal 122, lower terminal 124, grounding terminal 128, and / or tap changer assembly 132 may be shielded during the application of the conductive shielding layer 210.

[0056] A second insulating material 314 can be applied to the conductive shielding layer 210 and the grounding connector 310. Similar to the first insulating material 216, the insulating material can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can also be used. Regardless of the insulating material used, the second insulating material 314 can protect the conductive shielding layer 210 from moisture, water, contamination, etc.

[0057] As described above, the combination of conductive shielding layer 210 and grounding connector 310 provides a low-resistance path to ground for static charge and / or high voltage across the outer surface of the high-voltage outer coil 114.

[0058] Figure 3C A partial cross-sectional side view of a coil having another alternative example embodiment of the conductive shielding layer provided herein is shown. (Refer to...) Figure 3C The winding 214 of the high-voltage external coil 114 is covered by a first insulating material 216. For example, a continuous layer of the first insulating material 216 can completely cover the winding 214. The first insulating material 216 can cover the outer surface 218a, inner surface 218b, upper end surface 218c, and lower end surface 218d of the winding 214 of the high-voltage external coil 114. Figures 2B to 2C The first insulating material 216 can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can be used. Example resins include those available from Huntsman Quimica Ltda., São Paulo, Brazil. HY 926CH and / or CY 5948. In some embodiments, the resin may be glass fiber reinforced. The thickness of the first insulating material 216 may be between 6 mm and 7 mm, but other suitable thickness ranges may also be used.

[0059] exist Figure 3C In one embodiment, the conductive shielding layer 210 is formed of a conductive mesh laid along the first insulating material 216 and a semi-conductive coating formed on the conductive mesh. (Refer to...) Figure 3C The conductive mesh 318 is arranged on the first insulating material 216. For example, the conductive mesh 318 can be laid on the high-voltage external coil 114. Figure 2C The first insulating material 216 is applied to each of the outer surface 220a, inner surface 220b, upper surface 220c, and lower surface 220d of the first insulating material 216. As described above, the first insulating material 216 can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other insulating materials can be used. In some embodiments, the resin can be glass fiber reinforced. The thickness of the first insulating material 216 layer can be between 6 mm and 7 mm, but other suitable thickness ranges can also be used.

[0060] The conductive mesh 318 may include a conductive material formed in a pattern (e.g., a grid or silkscreen). Example conductive materials for the conductive mesh 318 include one or more conductive metals, such as copper, nickel, silver-plated copper, nickel-silver, silver, etc., but other types of conductive meshes may also be used. In some embodiments, the resistance of the conductive mesh 318 may be between about 0.01 ohms / sq cm and 1 ohm / sq cm, but other suitable resistance ranges may also be used.

[0061] In some embodiments, a semiconductive coating (not shown separately) may be used to hold the conductive mesh 318 in place and / or fill the gaps in the conductive mesh 318. The semiconductive coating applied to the conductive mesh 318 may include a conductive metal, including one or more of pulverized coal, copper, nickel, silver-plated copper, nickel-silver, and silver, but other suitable types of semiconductive coatings may also be used. In some embodiments, the resistance of the semiconductive coating may be between about 1 kilo-ohm / sq in / mil and 10 kilo-ohm / sq in / mil, but other suitable resistance ranges may be used.

[0062] Once the conductive mesh 318 has been arranged on the first insulating material 216, the semi-conductive coating can be applied to the conductive mesh 318 using any suitable process (e.g., brushing, rolling, spraying, and dipping). The composite structure of the conductive mesh material and the semi-conductive coating serves as the conductive shielding layer 210. In some embodiments, the thickness of the composite structure can be between about 100 micrometers and 500 micrometers, but other suitable thickness ranges can also be used.

[0063] In some embodiments, the conductive shielding layer 210 may include a loop separation region 212. The loop separation region 212 may be formed as an interruption of the conductive shielding layer 210 on each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114. Figures 2C to 2E In some embodiments, the width of the interruption can be between 4 mm and 6 mm, but other suitable width ranges may also be used. The loop separation region 212 forms a continuous loop without any conductive mesh across all surfaces including the high-voltage outer coil 114 (extending across each of the outer surface 220a, inner surface 220b, upper end surface 220c, and lower end surface 220d of the first insulating material 216 of the high-voltage outer coil 114). Figures 2C to 2EWhether the conductive mesh is laid as a continuous sheet or a series of sheets, the loop separation region 212 can be provided in one form or another. In one or more embodiments, the loop separation region 212 may include a semi-conductive coating.

[0064] In some embodiments, the grounding connector 310 may be coupled to the conductive shielding layer 210. For example, in some embodiments, the grounding connector 310 may be a metal plate in direct contact with the conductive shielding layer 210 or a conductive strip formed on or under the conductive shielding layer 210. For example, in the case where the conductive shielding layer 210 comprises a conductive mesh with a semi-conductive coating, at least a portion of the grounding connector 310 may be arranged on top of or below the conductive mesh. Other grounding connectors may be used. The grounding terminal 312 may be attached to the grounding connector 310, and an external grounding lead or cable may be attached to the grounding terminal 312. In some embodiments, one or more of the high-voltage terminal 118, the upper terminal 122, the lower terminal 124, the grounding terminal 128, and / or the tap changer assembly 132 may be shielded during the application of the conductive shielding layer 210.

[0065] A second insulating material 314 can be applied to the conductive shielding layer 210 and the grounding connector 310. Similar to the first insulating material 216, the insulating material can be epoxy resin, polyurethane, polyester, silicone resin, etc. Other suitable insulating materials can also be used. Regardless of the insulating material used, the second insulating material 314 can protect the conductive shielding layer 210 from moisture, water, contamination, etc.

[0066] Now refer to Figure 4 In some embodiments, a method 400 is provided for forming a high-voltage external coil (e.g., high-voltage external coil 114) of a dry-type transformer (e.g., transformer 100). Method 400 includes providing a high-voltage external coil (e.g., high-voltage external coil 114) having an external surface in 402. Figure 2B The winding 214). The outer surface includes an outer surface, an inner surface, an upper end surface, and a lower end surface (e.g., outer surface 218a, inner surface 218b, upper end surface 218c, and lower end surface 218d).

[0067] Method 400 further includes providing a first insulating material layer (e.g., ...) on the outer surface of the coil (e.g., winding 214) in 404. Figure 2C The first insulating material layer (216) can completely encapsulate or cover the outer surface, inner surface, upper surface, and lower surface of the coil. The insulating material can be, for example, epoxy resin, polyurethane, polyester, silicone resin, etc.

[0068] Furthermore, method 400 includes, in 406, providing a conductive shielding layer (e.g., conductive shielding layer 210) on at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil. The conductive shielding layer may be a conductive coating (e.g., Figure 3A ), and a combination of conductive coatings covering a semiconductive coating (e.g., Figure 3B Or a composite structure formed by a conductive mesh and a semi-conductive coating (e.g., Figure 3C The conductive shielding layer may include breaks (e.g., loop separation region 212) that are continuous annular separations in the conductive shielding layer across each surface of the coil. Such separations prevent the formation of loop currents within the conductive shielding layer.

[0069] Furthermore, method 400 includes providing a grounding connection (e.g., grounding connection 310) coupled to the conductive shielding layer in 408. In some embodiments, the grounding connection may be a metal plate in direct contact with the conductive shielding layer, a conductive strip formed on or under the conductive shielding layer, etc. A grounding terminal may be attached to the grounding connection, and an external grounding lead or cable may be attached to the grounding terminal.

[0070] Additionally, method 400 further includes providing a second insulating material layer (e.g., second insulating material 314) on the outer surface of the coil in step 410. The second insulating material layer may completely encapsulate or cover the conductive shielding layer on the surface of the coil. Like the first insulating material, the second insulating material may be epoxy resin, polyurethane, polyester, silicone resin, etc.

[0071] Reference Figures 1A to 4 The described embodiments illustrate the use of conductive shielding 210 and / or loop separation region 212 with high-voltage outer coil 114. In some embodiments, conductive shielding 210 (with or without loop separation region 212) may be similarly provided for low-voltage inner coil 112. Additionally, in some embodiments, outer coil 114 may be a low-voltage coil and inner coil 112 may be a high-voltage coil. More generally, the coil assembly may include a first inner coil and a second outer coil (e.g., concentrically arranged) or a single coil. In some embodiments, the first inner coil may be a low-voltage coil and the second outer coil may be a high-voltage coil, while in other embodiments, the first inner coil may be a high-voltage coil and the second outer coil may be a low-voltage coil. Either or both of the inner and outer coils may have conductive shielding and / or loop separation regions as described herein.

[0072] In some implementations, the conductive shielding layers can be configured to overlap while maintaining loop separation regions. For example, such an arrangement can be used in applications with very high electric fields. Figure 5AThe embodiments provided herein are illustrated. Figure 3A A partial cross-sectional side view of a portion of the conductive shielding layer 210, wherein the conductive shielding layer 210 overlaps itself. (Refer to...) Figure 5A An insulating material 502, such as an insulating foil, can be disposed on a first portion 210a of the conductive shielding layer 210, such that a second portion 210b of the conductive shielding layer 210 overlaps with the first portion 210a. For example, in a conductive shielding layer 210 that is a conductive coating... Figure 3A In one embodiment, a first portion 210a of the conductive shielding layer 210 may be applied, and an insulating material 502 may be placed on the first portion 210a of the conductive shielding layer 210 before the second portion 210b of the conductive shielding layer 210 is applied. A gap (e.g., a loop separation region 212) may be maintained. In some embodiments, in addition to or in place of the insulating material 502, a separating material or mesh (not shown) may be used to allow subsequent insulating material (e.g., resin) applied to the conductive shielding layer 210 to enter between the first portion 210a and the second portion 210b of the conductive shielding layer 210 and to insulate between the first portion 210a and the second portion 210b. In one or more embodiments, the first portion 210a of the conductive shielding layer 210 may overlap the second portion 210b by about 8 mm to 12 mm, but other overlap amounts may also be used. Example insulating materials include polyurethane, polyester, silicone, etc.

[0073] When the conductive shielding layer 210 includes an underlying semi-conductive coating layer ( Figure 3B Or when the conductive shielding layer 210 includes a conductive mesh ( Figure 3C In this case, a similar overlap can be used in the conductive shielding layer 210. For example, Figure 5B The embodiments provided herein are illustrated. Figure 3B A partial cross-sectional side view of a portion of the conductive shielding layer 210, wherein the conductive shielding layers overlap themselves, and Figure 5C The embodiments provided herein are illustrated. Figure 3C A partial cross-sectional side view of a portion of the conductive shielding layer 210, wherein the conductive shielding layers overlap. Figure 5B In one embodiment, the first portion 317a of the conductive coating 317 covers the semiconductive coating 316 layer and lies beneath the insulating material 502 and the second portion 317b of the conductive coating 317, while maintaining a gap (e.g., a loop separation region 212). Similarly, in Figure 5C In one embodiment, the first portion 210a of the conductive shielding layer 210 is located below the insulating material 502 and the second portion 210b of the conductive shielding layer 210, while maintaining a gap (e.g., a loop separation region 212).

[0074] Although this disclosure is primarily described in relation to submersible dry-type transformers, it should be understood that the disclosed conductive shielding can also be used with other types of transformers or coil assemblies (e.g., inductors).

[0075] The foregoing description discloses only exemplary embodiments. Modifications to the disclosed components and methods falling within the scope of this disclosure will be apparent to those skilled in the art. For example, although the examples discussed above are illustrated with respect to dry-type transformers, other embodiments according to this disclosure can also be implemented for other devices. This disclosure is not intended to limit the invention to the specific components and / or methods disclosed, but rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the claims.

Claims

1. A shielded coil assembly, comprising: A coil having an outer surface, an inner surface, an upper end surface, and a lower end surface, and a first insulating material formed on the outer surface, inner surface, upper end surface, and lower end surface of the coil; as well as A conductive shielding layer comprising a conductive coating applied along the first insulating material such that the conductive coating extends over at least a portion of each of the outer surface, inner surface, upper surface, and lower surface of the coil.

2. The shielded coil assembly according to claim 1, wherein, The conductive coating comprises a conductive metal, which includes one or more of copper, nickel, silver-plated copper, nickel-silver, and silver.

3. The shielded coil assembly according to claim 1, wherein, The resistance of the conductive coating is less than 1 ohm / square inch / mil.

4. The shielded coil assembly according to claim 1, wherein, The thickness of the conductive coating is between 30 micrometers and 500 micrometers.

5. The shielded coil assembly according to claim 1, wherein, The conductive coating includes a loop separation region that is interrupted in the conductive coating along the outer surface, inner surface, upper end surface, and lower end surface of the coil.

6. The shielded coil assembly according to claim 5, wherein, The circuit separation region includes gaps in the conductive coating, which extend around the outer surface, inner surface, upper end surface, and lower end surface of the coil to form an open circuit in the conductive coating.

7. The shielded coil assembly of claim 1, comprising a semi-conductive coating applied to the first insulating material and beneath the conductive coating.

8. The shielded coil assembly according to claim 7, wherein, The resistance of the semiconductive coating is from 1 kΩ / cm to 10 kΩ / sq. inch / mil.

9. The shielded coil assembly of claim 1, comprising a second insulating material formed on the conductive shielding layer.

10. The shielded coil assembly according to claim 9, wherein, The first insulating material and the second insulating material include materials comprising epoxy resin.

11. The shielded coil assembly of claim 1, comprising a grounding cable connected to the conductive shielding layer.

12. The shielded coil assembly of claim 1, further comprising an additional coil concentrically positioned relative to the shielded coil.

13. A dry-type transformer, comprising: Core region; as well as The shielded coil assembly of claim 1, wherein the shielded coil assembly is formed around a portion of the core region.

14. A shielded coil assembly, comprising: A coil having an outer surface, an inner surface, an upper end surface, and a lower end surface, and a first insulating material formed on the outer surface, inner surface, upper end surface, and lower end surface of the coil; as well as A conductive shielding layer, the conductive shielding layer comprising: A conductive mesh, the conductive mesh being laid along the first insulating material such that the conductive mesh extends over at least a portion of the outer surface, inner surface, upper end surface, and lower end surface of the coil; and A semi-conductive coating, wherein the semi-conductive coating is formed on the conductive mesh; The conductive mesh and the semiconductive coating form a composite structure on at least a portion of each of the outer surface, inner surface, upper surface and lower surface of the coil.

15. The shielded coil assembly of claim 14, wherein, The conductive shielding layer includes multiple conductive mesh loops, each of which extends on a portion of the outer surface, inner surface, upper surface, and lower surface of the coil.

16. The shielded coil assembly of claim 15, wherein, The conductive shielding layer includes a loop separation region, which includes gaps between the plurality of loops.

17. The shielded coil assembly of claim 14, comprising a second insulating material formed on the conductive shielding layer.

18. The shielded coil assembly of claim 14, comprising a grounding cable connected to the conductive shielding layer.

19. The shielded coil assembly of claim 14, comprising an additional coil concentrically positioned relative to the shielded coil.

20. A dry-type transformer, comprising: Core region; as well as The shielded coil assembly of claim 14, wherein the shielded coil assembly is formed around a portion of the core region.

21. A method of forming a coil assembly, comprising: A coil is provided, the coil having an outer surface, an inner surface, an upper end surface, and a lower end surface; The coil is encapsulated in a first insulating material; as well as A conductive shielding layer is formed on the coil by applying a conductive coating such that the conductive coating extends over at least a portion of each of the outer, inner, upper, and lower surfaces of the coil.

22. The method according to claim 21, wherein, The conductive coating comprises a conductive metal, which includes one or more of copper, nickel, silver-plated copper, nickel-silver, and silver.

23. The method according to claim 21, wherein, The resistance of the conductive coating is less than 1 ohm / square inch / mil.

24. The method according to claim 21, wherein, The thickness of the conductive coating is between 30 micrometers and 500 micrometers.

25. The method of claim 21, further comprising forming a loop separation region in the conductive coating by forming an interruption in the conductive coating along the outer surface, inner surface, upper end surface and lower end surface of the coil.

26. The method of claim 25, wherein, The circuit separation region includes gaps in the conductive coating, which extend around the outer surface, inner surface, upper end surface, and lower end surface of the coil to form an open circuit in the conductive coating.

27. The method of claim 21, further comprising applying a semiconductive coating to the first insulating material, beneath the conductive coating.

28. The method according to claim 27, wherein, The resistance of the semiconductive coating is from 1 kΩ / square inch / mil to 10 kΩ / square inch / mil.

29. The method of claim 21, further comprising forming a second insulating material on the conductive shielding layer.

30. The method according to claim 29, wherein, The first insulating material and the second insulating material both include epoxy resin.

31. The method of claim 21, further comprising attaching a grounding cable connected to the conductive shielding layer.

32. A method of forming a coil assembly, comprising: A coil is provided, the coil having an outer surface, an inner surface, an upper end surface, and a lower end surface; The coil is encapsulated in a first insulating material; as well as A conductive shielding layer is formed on the coil by the following operations: A conductive mesh is laid along the first insulating material such that the conductive mesh extends over at least a portion of the outer surface, inner surface, upper end surface, and lower end surface of the coil; and A semi-conductive coating is applied to the conductive mesh, such that the conductive mesh and the semi-conductive coating form a composite structure on at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil.

33. The method according to claim 32, wherein, Laying the conductive mesh includes laying multiple conductive mesh loops, each conductive mesh loop extending on a portion of the outer surface, inner surface, upper end surface, and lower end surface of the coil.

34. The method of claim 33, further comprising forming a loop separation region, the loop separation region including gaps between the plurality of loops.

35. The method of claim 32, further comprising forming a second insulating material on the conductive shielding layer.

36. The method of claim 32, further comprising attaching a grounding cable connected to the conductive shielding layer.

Images