Shielded coil assembly and method for dry-type transformer
By forming a conductive shielding layer on the coil surface of the dry transformer and embedding insulating material, the corrosion and static problems of dry transformer in harsh environments are solved, and safety and stability are improved.
Patent Information
- Application Number
- CN201880094380.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2018-06-07
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2038-06-07
AI Technical Summary
Dry transformers are susceptible to corrosion in harsh environments and may generate static charges and dangerous voltages, affecting safety.
Using shielded coil assembly, a conductive shield is formed by applying conductive coating or conductive grid through the surface of the coil and adding semiconductor coating, and embedded in the insulating material to provide a grounding path and prevent loop current.
It effectively prevents the accumulation of static charge and the generation of dangerous voltages, ensures the stability and safety of the transformer in a humid or corrosive environment, and avoids the formation of loop current.
Smart Images
Figure CN113056800B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to transformers for power distribution, and more particularly to shielding of coils for use in dry-type transformers. Background Art
[0002] Transformers are used to increase or decrease voltage levels during power distribution. To transmit power over long distances, transformers can be used to increase the voltage and reduce the current of the transmitted power. The reduced current level reduces the resistive losses of the cables used to transmit this portion of the power. When the power is to be consumed, a transformer can be used to reduce the voltage level and increase the current of the power to the level specified by the end user.
[0003] One type of transformer that may be employed is a dry submersible transformer such as described in U.S. Pat. No. 8,614,614. Such a transformer may be employed underground in cities and the like, and may be designed to withstand harsh environments that may expose the transformer to moisture, water, contaminants, etc. Improved apparatus, assemblies, and methods for submersible and other dry transformers are desired. Summary of the invention
[0004] In some embodiments, a shielded coil assembly is provided, the shielded coil assembly 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, the inner surface, the upper end surface, and the lower end surface of the coil; and (2) a conductive shielding layer, the conductive shielding layer comprising a conductive coating, the conductive coating being applied along the first insulating material so that the conductive coating extends over at least a portion of each of the outer surface, the inner surface, the upper end surface, and the lower end surface of the coil. In one or more embodiments, the shielded coil assembly can be used to form a dry transformer.
[0005] In some embodiments, a shielded coil assembly is provided, the shielded coil assembly 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, the inner surface, the upper end surface, and the lower end surface of the coil; and (2) a conductive shielding layer having (a) a conductive mesh, the conductive mesh being laid along the first insulating material so that the conductive mesh extends on at least a portion of the outer surface, the inner surface, the upper end surface, and the lower end surface of the coil; and a semi-conductive coating, the semi-conductive coating being 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, the inner surface, the upper end surface, and the lower end surface of the coil. In one or more embodiments, the shielded coil assembly can be used to form a dry transformer.
[0006] In some embodiments, a method for 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 so that the conductive coating extends over at least a portion of each of the outer surface, the inner surface, the upper end surface, and the lower end surface of the coil.
[0007] In some embodiments, a method for 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 the following operations: (a) laying a conductive mesh along the first insulating material so that the conductive mesh extends on at least a portion of the outer surface, inner surface, upper end surface, and lower end surface of the coil; and (b) applying a semi-conductive coating on the conductive mesh so 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.
[0008] Other aspects, features and advantages of the present disclosure may be apparent from the following detailed description illustrated by many example embodiments and implementations. The present disclosure may also be capable of other different embodiments, and several details of the present disclosure may be modified in various aspects. Therefore, the drawings and description are to be considered illustrative in nature, rather than restrictive. The drawings are not necessarily drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1A A front plan view of a submersible dry transformer according to embodiments provided herein is shown.
[0010] Figure 1B A perspective view of a coil assembly according to embodiments provided herein is shown.
[0011] Figure 2A Shown is a perspective view of a high voltage external coil according to embodiments provided herein.
[0012] Figure 2B Shown is a perspective view of a winding that may form part of a high voltage external coil according to embodiments provided herein.
[0013] Figure 2C According to the embodiments provided herein, Figure 2B A perspective view of a winding having a first insulating material formed on the winding.
[0014] Figure 2D and Figure 2EThe embodiments provided herein are respectively shown. Figure 2C A top perspective view and a bottom perspective view 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 a conductive shield layer provided herein is shown.
[0016] Figure 3B A partial cross-sectional side view of a coil having an alternative example embodiment of a conductive shield layer provided herein is shown.
[0017] Figure 3C A partial cross-sectional side view of a coil having another alternative example embodiment of a conductive shield layer provided herein is shown.
[0018] Figure 4 A flow chart of a method of manufacturing a high voltage external coil according to embodiments provided herein is shown.
[0019] Figure 5A According to the embodiments provided herein, Figure 3A A partial cross-sectional side view of a portion of a conductive shield layer wherein the conductive shield layer overlaps itself.
[0020] Figure 5B According to the embodiments provided herein, Figure 3B A partial cross-sectional side view of a portion of a conductive shield layer wherein the conductive shield layer overlaps itself.
[0021] Figure 5C According to the embodiments provided herein, Figure 3C A partial cross-sectional side view of a portion of a conductive shield layer wherein the conductive shield layer overlaps itself. DETAILED DESCRIPTION
[0022] As described above, submersible dry-type transformers may be employed underground and / or in other harsh environments that may expose the transformer to water, moisture, contaminants, etc. When a transformer is exposed to moisture, humidity, or other adverse environments, the transformer may be susceptible to corrosion. For proper operation and for safety reasons, such a transformer 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, and a method for forming such a shielded coil assembly are provided. The shielded coil assembly has a shield that can be grounded, so that a transformer using the shielded coil assembly does not generate static charges and / or there are no dangerous voltage levels on the outer surface of the transformer. The shield can be embedded in a protective layer such as an epoxy resin so that the shield will not corrode if the transformer using 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 member provided for at least the outer coil of the shielded coil assembly. For example, the outer coil may have an outer surface, an inner surface, an upper end surface, and a lower end surface, on which an insulating material, such as epoxy resin, is formed (e.g., on all surfaces). The conductive shielding layer includes a conductive paint, which can be applied to the insulated outer coil and extends on at least a portion of each of the outer surface, the inner surface, the upper end surface, and the lower end surface of the outer coil. In some embodiments, in order to prevent the formation of loop current, a gap can be set in the conductive paint. A ground lead or cable can be coupled to the conductive shielding layer, and the conductive shielding layer can be embedded in another insulating material (e.g., epoxy resin). In one or more embodiments, a semi-conductive paint can be provided under the conductive paint. For example, in some embodiments, the entire insulated outer coil can be coated with a semi-conductive paint before the conductive paint layer is formed. In such an embodiment, the conductive paint can be formed as a continuous layer (e.g., except for the gap area for reducing / preventing loop current), or the conductive paint is provided only in certain areas (e.g., by painting stripes or grid patterns with conductive paint). Many other embodiments are provided.In some embodiments, a dry transformer can be formed using a shielded coil assembly.
[0025] According to other embodiments, a conductive shielding layer can be formed by wrapping an insulated external coil with a conductive mesh and applying a semi-conductive coating on the conductive mesh (and / or between the conductive meshes). For example, a conductive mesh can be laid along the insulated external coil so that the conductive mesh extends on at least a portion of the outer surface, inner surface, upper end surface, and lower end surface of the external coil. A gap region can be formed in the conductive mesh to reduce / prevent loop current. The semi-conductive coating can help keep the conductive mesh in place during subsequent processing (e.g., during encapsulation of the external coil in a second insulating material (e.g., epoxy resin)). Since the semi-conductive coating can be applied to the conductive mesh and in any opening in the conductive mesh, the conductive mesh and the semi-conductive coating can 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 external coil. A ground lead or cable can be coupled to the conductive shielding layer. In one or more embodiments, a shielded coil assembly can be used to form a dry transformer.
[0026] Figure 1A is a front plan view of a dry-type transformer 100 according to an embodiment 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 employed. As used herein, "dry-type transformer" means a transformer that includes high-voltage and low-voltage coils that are not immersed in an oil bath or other similar fluid contained within an enclosure. Such dry-type transformers 100 have significant advantages: they do not use oil and can run cooler via cooling of air or water (when immersed).
[0027] As an example, the dry-type transformer 100 may include a core assembly 102 (shown in dotted 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 corresponding 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 by multiple stacks of magnetic materials. Example magnetic materials include iron, steel, amorphous steel or other amorphous magnetically permeable metals, silicon steel alloys, carbonyl iron, ferrite ceramics, and / or combinations of the above materials, etc. 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, the core assembly 102 may include a plurality of interconnects and may include vertical core columns or regions 102L, 102C, and 102R (each shown in dashed lines). The vertical core columns 102L, 102C, and 102R may be assembled with the top core member 102T and the bottom core member 102B (shown in dashed lines). The construction may include step-laps between the various components of the core assembly 102. For example, the construction of the core assembly 102 may be as shown in U.S. Patent No. 8,212,645. Other constructions of the core assembly 102 may be used. In some embodiments, in the transformer 100, each core column 102L, 102C, and 102R may be surrounded by a coil assembly (i.e., coil assembly 106, coil assembly 108, coil assembly 110).
[0029] Figure 1B A stereogram of the coil assembly 106 is shown. The coil assembly 106 is shown and described herein by way of example, and the coil assembly 108, the coil assembly 110 may be the same or substantially the same as the coil assembly 106. The coil assembly 106 includes a low voltage internal coil 112 and a high voltage external coil 114 that may be concentric with the low voltage internal coil 112. The low voltage internal coil 112 may be electrically insulated from the core assembly 102 and may also be electrically insulated from the high voltage external coil 114. For example, the low voltage internal coil 112 may be surrounded by an insulating material such as a molded resin. Similarly, as will be fully described herein, the high voltage external coil 114 may include a multi-stage insulating material (e.g., resin) provided in a plurality of sequential molding processes. Example insulating materials may include any suitable solid insulation, for example, epoxy resin, polyurethane, polyester, silicone resin, etc.
[0030] Refer again Figure 1A , as described in U.S. Pat. No. 8,614,614 entitled "Submersible Dry Transformer", coil assembly 106, coil assembly 108, coil assembly 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 operate together to seal the plane of the core opening or "window" between the core column 102L, the core column 102C and the core column 102R of the core assembly 102. As described in US8,614,614, if the core assembly 102 is immersed in liquid, the sealed core window will prevent the liquid from passing through and prevent the formation of a conductive spiral around the core column 102L, the core column 102C and the core column 120R. Insulating sheets 116A to 116F can be any suitable insulating material, for example, a resin with glass fiber.
[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 corresponding coil assembly 106, 108, and 110. The low voltage terminal 119 ( Figure 1B ) is disposed on the back side of coil assembly 106, coil assembly 108, coil assembly 110 or some other suitable location. Figure 1B As shown, the high voltage terminal 118 can be located in front of the top of the columnar front extension 126E of the high voltage external coil 114, and the low voltage terminal 119 can be located at the rear of the low voltage internal coil 112. However, the high voltage terminal 118 and the low voltage terminal 119 can be located elsewhere. The high voltage terminal 118 provides a power connection to the high voltage external coil 114 of the corresponding coil assembly 106, 108, 110. A connector (not shown) (e.g., a sealed plug-in connector) can be provided to facilitate the sealed connection of the high voltage terminal 118 to the cable (not shown). A triangle or Y-shaped connection (not shown) can be achieved with the low voltage terminal 119, etc. Other suitable sealed connections are also possible.
[0032] The transformer 100 may also include a delta connection 120A, a delta connection 120B, and a delta connection 120C ( Figure 1A ). For example, the triangle connection 120A, the triangle connection 120B, and the triangle connection 120C may include a shielded cable. As shown, the upper terminal 122 and the lower terminal 124 of the high-voltage external coil 114 of each of the coil assemblies 106, 108, and 110 may be connected to achieve each of the triangle connection 120A, the triangle connection 120B, and the triangle connection 120C. In some embodiments, the electrical connection may be a sealed connection. The upper terminal 122 and the lower terminal 124 may extend horizontally from the columnar front extension 126E of the high-voltage external coil 114 (such as Figure 1B For example, in some embodiments, the upper terminal 122 and the lower terminal 124 can extend outward from the front face 126F of the columnar front extension 126E.
[0033] A tap changer assembly 132 may be included on each of the high voltage external coils 114. For example, the tap changer assembly 132 may be provided as an extension from the front of the high voltage external coil 114. More specifically, in some embodiments, the tap changer assembly 132 may be as shown in FIG. Figure 1B It is shown extending from the cylindrical front extension 126E and may be tapered in shape.
[0034] The high voltage external coil 114 of each of the coil assemblies 106, 108, 110 may include a ground terminal 128. For example, a ground conductor 129 ( Figure 1A ) can be connected between the corresponding ground terminal 128 of the high voltage external coil 114 and the lower frame 104L. The common ground strap 130 can be attached to the lower frame 104L and can provide grounding. The high voltage external coil 114 of each of the 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] The conductive shielding layer 210 (shown in phantom) 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. The grounding terminal 128 is connected to the conductive shielding layer 210, thereby providing a means for electrically grounding the outer surface of the high-voltage external coil 114.
[0037] A loop separation region 212 may be included in the conductive shielding layer 210 on each surface of the high voltage external coil 114 on which the conductive shielding layer 210 is formed. As shown, the loop separation region 212 is formed as an interruption of the conductive shielding layer 210 (under each of the outer surface 202, the inner surface 204, the upper end surface 206, and the lower end surface 208 of the high voltage external coil 114). The loop separation region 212 forms a continuous loop (e.g., an open loop) that 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 external coil 114.
[0038] In terms of wide applicability to transformers, an improved conductive shielding layer 210 applied to each surface of the high voltage external coil 114 is provided.
[0039] FIG. 2B to FIG. 2E The formation of the conductive shield layer 210 of the high voltage external coil 114 is shown. Figure 2B A perspective view of a winding 214 that may form part of the high voltage external coil 114 is shown. Figure 2CA perspective view of the winding 214 is shown with a first insulating material 216 formed on the winding 214 . Figure 2D and Figure 2E A top side perspective view and a bottom side perspective view of a winding 214 having a conductive shield layer 210 formed on a first insulating material 216 are shown, respectively.
[0040] Reference Figure 2B to Figure 2C In some embodiments, to form the high voltage external coil 114 ( Figure 2A ), the first insulating material 216 (in Figure 2C ) covers the winding 214 (in Figure 2B The conductive shielding layer 210 (shown in FIG. 1 ) may be provided with an outer surface 218a, an inner surface 218b, an upper end surface 218c, and a lower end surface 218d. Figure 2D and 2E ) covers the first insulating material 216 (in Figure 2C The conductive shielding layer 210 includes an outer surface 220a, an inner surface 220b, an upper end surface 220c, and a lower end surface 220d. A loop separation region 212 may be included in the conductive shielding layer 210 across each surface including the high voltage external coil 114. 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, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 of the winding 214 of the high voltage external coil 114. The loop separation region 212 forms a continuous loop along each surface of the first insulating material 216 including the high voltage external 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 external coil 114.
[0041] Refer to the following FIG. 3A to FIG. 3C An example conductive shield for the high voltage external coil 114 is described. For convenience, FIG. 3A to FIG. 3C Only a portion of the winding 214 is shown. It should be appreciated that in some embodiments, the conductive shielding layer may provide shielding for most, if not all, of the surface of the high voltage external coil 114.
[0042] Figure 3A A partial cross-sectional side view of a portion of a high voltage external coil 114 having a conductive shield layer according to embodiments provided herein is shown. Figure 3A , the winding 214 of the high voltage external coil 114 is covered by the first insulating material 216. For example, the winding 214 can be wound into a cylindrical shape to form 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. 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. in Sao 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, although other suitable thickness ranges may be used.
[0043] The conductive shielding layer 210 is formed on the first insulating material 216. Specifically, the conductive shielding layer 210 is formed on the insulating material 216 on at least a portion of each surface of the high voltage external coil 114. For example, FIG. 2C to FIG. 2E As shown, the conductive shielding layer 210 can be formed on the first insulating material 216 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.
[0044] In some embodiments, the conductive shielding layer 210 can be a conductive paint applied to the first insulating material 216. The conductive paint can include a conductive metal, including one or more of copper, nickel, silver-plated copper, nickel-silver, and silver. Other suitable conductive paints can be used. In some embodiments, the resistance of the applied conductive paint can be between about 0.01 ohm / sq in / mil and 1 ohm / sq in / mil, and / or the thickness is between about 30 microns and 500 microns, and in some embodiments, the thickness is between about 30 microns and 150 microns, but other suitable resistance and / or thickness ranges can also be used (wherein "sq in" is an abbreviation for "square inch" and "mil" is 0.001 inch). The conductive paint can be applied by any suitable process such as brushing, rolling, spraying, and dipping. In addition, a stencil or mask may be used to form a pattern on the first insulating material 216, the pattern including a grid pattern, a stripe pattern, or any other suitable pattern. In some embodiments, the application of the conductive shielding layer 210 may be performed in a manner that ensures electrical continuity across each surface of the high-voltage external coil 114 (e.g., each of the outer surface 220a, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 of the high-voltage external 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, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 of the high voltage external coil 114 ( FIG. 2C to FIG. 2E ). In some embodiments, the width of the interruption 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 (e.g., an open loop) without any conductive coating across all surfaces including the high-voltage external 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 external coil 114 ( FIG. 2C to FIG. 2E )). Whether the conductive paint is applied as a continuous sheet or a pattern, the loop separation area 212 can be provided in one form or another.
[0046] In some embodiments, the ground connector 310 can be coupled to the conductive shielding layer 210. For example, in some embodiments, the ground connector 310 can be a metal plate in direct contact with the conductive shielding layer 210 or a conductive tape formed on the conductive shielding layer 210 or under the conductive shielding layer 210. For example, in the case where the conductive shielding layer 210 includes a conductive paint, at least a portion of the ground connector 310 can be arranged on top of the conductive paint or under the conductive paint. Other ground connectors can be used. A ground terminal 312 can be attached to the ground connector 310, and an external grounding lead or cable can be attached to the ground terminal 312. The ground connector 310 and / or the ground terminal 312 can 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 ground terminal 128 and / or the tap changer assembly 132 can be shielded during the application of the conductive shielding layer 210.
[0047] A second insulating material 314 may be applied to the conductive shielding layer 210 and the grounding connector 310. Like the first insulating material 216, the insulating material may be epoxy, polyurethane, polyester, silicone, etc. Other suitable insulating materials may be used. Regardless of the insulating material used, the second insulating material 314 may 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 a conductive shielding layer provided herein is shown. Figure 3B, the winding 214 of the high voltage external coil 114 is covered by the first insulating material 216. For example, a continuous layer of the first insulating material 216 may completely cover the winding 214. The first insulating material 216 may cover the outer surface 218a, the inner surface 218b, the upper end surface 218c and the lower end surface 218d of the winding 214 of the high voltage external coil 114 ( Figure 2B to Figure 2C ). The first insulating material 216 may be epoxy, polyurethane, polyester, silicone, etc. Other suitable insulating materials may be used. Example resins include those available from Huntsman Quimica Ltda. of Sao 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, although other suitable thickness ranges may also be used.
[0049] exist Figure 3B In the embodiment of the present invention, the conductive shielding layer 210 is formed by a layer of a semi-conductive coating 316 and a layer of a conductive coating 317. For example, the layer of the semi-conductive coating 316 can be formed on the first insulating material 216. The semi-conductive coating 316 can be applied to the first insulating material 216 on all surfaces including the high-voltage external coil 114. For example, the semi-conductive coating 316 can be applied to the first insulating material 216 ( Figure 2C ) on the insulating material 216 on each of the outer surface 220a, the inner surface 220b, the upper end surface 220c and the lower end surface 220d. The semi-conductive coating 316 layer may be across the high voltage external coil 114 ( Figure 2A )'s outer surface 202, inner surface 204, upper end surface 206 and lower end surface 208 provide a uniform electric field and / or voltage potential.
[0050] Semiconductive coating 316 can be similar in composition to conductive coating 317, and can include a conductive metal including one or more of copper, nickel, silver-plated copper, nickel-silver, and silver. Other suitable types of semiconductive coatings can be used. Semiconductive coating 316 differs from conductive coating 317 in that semiconductive coating 316 generally covers a higher resistance range. In some embodiments, the applied semiconductive coating 316 can have a resistance between about 1 kilo-ohm / sq in / mil and 10 kilo-ohm / sq in / mil, and / or a thickness between about 10 microns and 500 microns, and in some embodiments, a thickness between about 10 microns and 50 microns, but other suitable resistance and / or thickness ranges can 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 may 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, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 covered with the semiconductive coating 316. Thus, the conductive shielding layer 210 (e.g., the conductive coating 317 and the underlying semiconductive coating 316) including the conductive coating 317 is formed on at least a portion of each of the outer surface 220a, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 of the high voltage external coil 114. FIG. 2C to FIG. 2E shown).
[0052] 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 microns and 500 microns, and in some embodiments, a thickness between about 30 microns and 150 microns, but other suitable resistance and / or thickness ranges may also be used. Semiconductive coating 316 and / or conductive coating 317 may be applied by any suitable process such as brushing, rolling, spraying, and dipping. In some embodiments, a pattern of conductive coating may be formed on a layer of semiconductive coating 316 formed on first insulating material 216 using a stencil or mask, the pattern including a grid pattern, a stripe pattern, or any other suitable pattern. In some embodiments, the application of the conductive shielding layer 210 can be performed in a manner to ensure electrical continuity across each surface of the high voltage external coil 114 (e.g., 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 external coil 114).
[0053] In some embodiments, the conductive shielding layer 210 may include a loop separation region 212. The loop separation region 212 is formed as an interruption of the conductive coating 317 portion of the conductive shielding layer 210 on each of the outer surface 220a, the inner surface 220b, the upper end surface 220c, and the lower end surface 220d of the first insulating material 216 of the high voltage external coil 114 ( FIG. 2C to FIG. 2EThe width of the interruption of the conductive paint 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 paint 317 across all surfaces including the high voltage external 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 external coil 114 ( FIG. 2C to FIG. 2E ) and expose the underlying semi-conductive coating 316 in the gap area). Whether the conductive coating 317 is applied as a continuous layer or a pattern, the loop separation area 212 can exist in one form or another. In one or more embodiments, if the loop separation area 212 is not used, the resistance of the conductive coating 317 may be low enough to form a (measurable) current loop on the surface of the high voltage external coil 114. Such a current loop may cause heating and damage to the coil assembly.
[0054] The semiconductive coating 316 exposed in the loop separation area 212 in the conductive coating 317 helps prevent electric field leakage through the loop separation area 212 during operation of the high voltage external coil 114. In addition, the higher resistance range of the semiconductive coating 316 layer helps prevent the formation of ground loops within the semiconductive coating 316 layer (even though the semiconductive coating 316 may be present in the loop separation area 212). In one or more embodiments, the semiconductive coating 316 may have a 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 ground connector 310 can be coupled to the conductive shield layer 210. For example, in some embodiments, the ground connector 310 can be a metal plate in direct contact with the conductive shield layer 210 or a conductive tape formed on the conductive shield layer 210 or under the conductive shield layer 210. For example, in the case where the conductive shield layer 210 includes a conductive paint, at least a portion of the ground connector 310 can be arranged on top of the conductive paint or under the conductive paint (e.g., on top of the semi-conductive paint 316). Other ground connectors can be used. A ground terminal 312 can be attached to the ground connector 310, and an external ground lead or cable can be attached to the ground terminal 312. In some embodiments, one or more of the high voltage terminal 118, the upper terminal 122, the lower terminal 124, the ground terminal 128 and / or the tap changer assembly 132 can be shielded during the application of the conductive shield layer 210.
[0056] A second insulating material 314 may be applied to the conductive shielding layer 210 and the grounding connector 310. Like the first insulating material 216, the insulating material may be epoxy, polyurethane, polyester, silicone, etc. Other suitable insulating materials may be used. Regardless of the insulating material used, the second insulating material 314 may protect the conductive shielding layer 210 from moisture, water, contamination, etc.
[0057] As described above, the combination of the conductive shield layer 210 and the ground connection 310 provides a low resistance path to ground for static charges and / or high voltages across the exterior surface of the high voltage external coil 114 .
[0058] Figure 3C A partial cross-sectional side view of a coil having another alternative example embodiment of a conductive shielding layer provided herein is shown. Figure 3C , the winding 214 of the high voltage external coil 114 is covered by the first insulating material 216. For example, a continuous layer of the first insulating material 216 may completely cover the winding 214. The first insulating material 216 may cover the outer surface 218a, the inner surface 218b, the upper end surface 218c and the lower end surface 218d of the winding 214 of the high voltage external coil 114 ( Figure 2B to Figure 2C ). The first insulating material 216 may be epoxy, polyurethane, polyester, silicone, etc. Other suitable insulating materials may be used. Example resins include those available from Huntsman Quimica Ltda. of Sao 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, although other suitable thickness ranges may also be used.
[0059] exist Figure 3C In the embodiment of the present invention, the conductive shielding layer 210 is formed by a conductive mesh laid along the first insulating material 216 and a semi-conductive coating formed on the conductive mesh. 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 ) on each of the outer surface 220a, the inner surface 220b, the upper end surface 220c and the lower end 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 6mm and 7mm, but other suitable thickness ranges can also be used.
[0060] The conductive mesh 318 may include a conductive material formed into a pattern (e.g., a grid or a wire mesh). Example conductive materials for the conductive mesh 318 include conductive metals, such as one or more of copper, nickel, silver-plated copper, nickel-silver, silver, etc., although other types of conductive meshes may also be used. In some embodiments, the conductive mesh 318 may have a resistance between about 0.01 Ohm / sq cm and 1 Ohm / sq cm, although other suitable resistance ranges may also be used.
[0061] In some embodiments, a semiconductive coating (not separately shown) may be used to hold the conductive mesh 318 in place and / or fill gap areas of the conductive mesh 318. The semiconductive coating applied to the conductive mesh 318 may include a conductive metal including one or more of coal powder, copper, nickel, silver-plated copper, nickel-silver, and silver, although 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, although other suitable resistance ranges may be used.
[0062] Once the conductive mesh 318 has been disposed on the first insulating material 216, a semiconductive coating may be applied to the conductive mesh 318 by any suitable process (e.g., brushing, rolling, spraying, and dipping). The composite structure of the conductive mesh material and the semiconductive coating serves as the conductive shielding layer 210. In some embodiments, the thickness of the composite structure may be between about 100 microns and 500 microns, although other suitable thickness ranges may 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 ( FIG. 2C to FIG. 2E ). In some embodiments, the width of the interruption 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 mesh across all surfaces including the high-voltage external 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 external coil 114 ( FIG. 2C to FIG. 2E)). Whether the conductive mesh is applied as a continuous sheet or a series of mesh sheets, the loop separation area 212 can be provided in one form or another. In one or more embodiments, the loop separation area 212 can include a semi-conductive paint.
[0064] In some embodiments, the ground connector 310 can be coupled to the conductive shielding layer 210. For example, in some embodiments, the ground connector 310 can be a metal plate in direct contact with the conductive shielding layer 210 or a conductive tape formed on or under the conductive shielding layer 210. For example, in the case where the conductive shielding layer 210 includes a conductive mesh with a semi-conductive coating, at least a portion of the ground connector 310 can be arranged on top of or under the conductive mesh. Other ground connectors can be used. A ground terminal 312 can be attached to the ground connector 310, and an external ground lead or cable can be attached to the ground terminal 312. In some embodiments, one or more of the high voltage terminal 118, the upper terminal 122, the lower terminal 124, the ground terminal 128, and / or the tap changer assembly 132 can be shielded during the application of the conductive shielding layer 210.
[0065] A second insulating material 314 may be applied to the conductive shielding layer 210 and the grounding connector 310. Like the first insulating material 216, the insulating material may be epoxy, polyurethane, polyester, silicone, etc. Other suitable insulating materials may be used. Regardless of the insulating material used, the second insulating material 314 may protect the conductive shielding layer 210 from moisture, water, contamination, etc.
[0066] Now refer to Figure 4 In some embodiments, a method 400 of forming a high voltage external coil (e.g., high voltage external coil 114) of a dry transformer (e.g., transformer 100) is provided. The method 400 includes providing a high voltage external coil (e.g., Figure 2B The outer surface includes an outer surface, an inner surface, an upper end surface, and a lower end surface (eg, an outer surface 218a, an inner surface 218b, an upper end surface 218c, and a lower end surface 218d).
[0067] The method 400 also includes providing a first insulating material layer (eg, Figure 2C The first insulating material layer may completely encapsulate or cover the outer surface, inner surface, upper surface and lower surface of the coil. The insulating material may be, for example, epoxy resin, polyurethane, polyester, silicone resin, etc.
[0068] In addition, method 400 includes providing a conductive shielding layer (e.g., conductive shielding layer 210) on at least a portion of each of the outer surface, the inner surface, the upper end surface, and the lower end surface of the coil at 406. The conductive shielding layer can be a conductive paint (e.g., Figure 3A ), a combination of a conductive coating overlying a semi-conductive coating (e.g., Figure 3B ) or a composite structure formed of a conductive mesh and a semi-conductive coating (e.g. Figure 3C ). The conductive shield layer may include a break (eg, loop separation region 212) that is a continuous annular separation in the conductive shield layer across each surface of the coil. Such separation may prevent loop currents from forming within the conductive shield layer.
[0069] Additionally, method 400 includes providing a ground connector (e.g., ground connector 310) coupled to the conductive shielding layer at 408. In some embodiments, the ground connector can be a metal plate in direct contact with the conductive shielding layer, a conductive tape formed on or under the conductive shielding layer, etc. A ground terminal can be attached to the ground connector, and an external ground lead or cable can be attached to the ground terminal.
[0070] In addition, method 400 also includes providing the coil with a second insulating material layer (e.g., second insulating material 314) on an outer surface of the coil at 410. The second insulating material layer can completely encapsulate or encapsulate the conductive shielding layer on the surface of the coil. Like the first insulating material, the second insulating material can be epoxy, polyurethane, polyester, silicone, etc.
[0071] Reference Figures 1A to 4 The described embodiments describe the use of a conductive shielding layer 210 and / or a loop separation region 212 with a high voltage external coil 114. In some embodiments, a conductive shielding layer 210 (with or without a loop separation region 212) may be similarly provided for a low voltage internal coil 112. In addition, in some embodiments, the external coil 114 may be a low voltage coil and the internal coil 112 may be a high voltage coil. More generally, the coil assembly may include a first internal coil and a second external coil (e.g., a concentric arrangement) or a single coil. In some embodiments, the first internal coil may be a low voltage coil and the second external coil may be a high voltage coil, while in other embodiments, the first internal coil may be a high voltage coil and the second external coil may be a low voltage coil. Either or both of the internal coil and the external coil may have a conductive shielding layer and / or a loop separation region as described herein.
[0072] In some embodiments, the conductive shield layer can be configured to overlap itself while maintaining loop separation regions. For example, such an arrangement can be used in very high electric field applications. Figure 5AAccording to the embodiments provided herein, 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. Figure 5A , an insulating material 502 such as an insulating foil may be disposed on the first portion 210a of the conductive shielding layer 210 such that the second portion 210b of the conductive shielding layer 210 overlaps the first portion 210a. For example, in the case where the conductive shielding layer 210 is a conductive paint Figure 3A In some embodiments, a first portion 210a of the conductive shield layer 210 may be applied, and an insulating material 502 may be placed on the first portion 210a of the conductive shield layer 210 before applying the second portion 210b of the conductive shield layer 210. 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 separator material or mesh (not shown) may be employed to allow a subsequent insulating material (e.g., a resin) applied to the conductive shield layer 210 to enter between and insulate the first portion 210a and the second portion 210b of the conductive shield layer 210. In one or more embodiments, the first portion 210a of the conductive shield layer 210 may overlap the second portion 210b by approximately 8 mm to 12 mm, although other overlap amounts may also be used. Example insulating materials include polyurethane, polyester, silicone, and the like.
[0073] When the conductive shielding layer 210 includes an underlying semi-conductive coating layer ( Figure 3B ) or when the conductive shielding layer 210 comprises a conductive mesh ( Figure 3C ), a similar overlap may be employed in the conductive shielding layer 210. For example, Figure 5B According to the embodiments provided herein, Figure 3B A partial cross-sectional side view of a portion of the conductive shield layer 210, wherein the conductive shield layer overlaps itself, and Figure 5C According to the embodiments provided herein, Figure 3C A partial cross-sectional side view of a portion of the conductive shield layer 210 of FIG. 2 , wherein the conductive shield layer overlaps itself. Figure 5B In the embodiment of , the first portion 317a of the conductive coating 317 covers the layer of semi-conductive coating 316 and is located below the insulating material 502 and the second portion 317b of the conductive coating 317 while maintaining a gap (e.g., the loop separation area 212). Figure 5C In an embodiment, the first portion 210a of the conductive shield layer 210 is located below the insulating material 502 and the second portion 210b of the conductive shield layer 210 while maintaining a gap (eg, the loop separation region 212).
[0074] Although the present disclosure is primarily described with respect to submersible dry transformers, it should be understood that the disclosed conductive shields may also be used with other types of transformers or coil assemblies (eg, inductors).
[0075] The foregoing description discloses only example embodiments. Modifications of the above disclosed components and methods that fall within the scope of the present disclosure will be apparent to those of ordinary skill in the art. For example, although the examples discussed above are shown for dry-type transformers, other embodiments according to the present disclosure may also be implemented for other devices. The present disclosure is not intended to limit the present invention to the specific components and / or methods disclosed, but on the contrary, the present invention is intended to cover all modifications, equivalents, and alternatives that fall 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, the inner surface, the upper end surface, and the lower end surface of the coil; a conductive shielding layer, the conductive shielding layer comprising a conductive paint, the conductive paint being applied along the first insulating material so that the conductive paint extends over at least a portion of each of an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil; as well as A semi-conductive coating is applied to the first insulating material below the conductive coating.
2. The shielded coil assembly of claim 1, wherein: The conductive paint includes a conductive metal, and the conductive metal includes one or more of copper, nickel, silver-plated copper, nickel-silver, and silver.
3. The shielded coil assembly of claim 1, wherein: The conductive coating has a resistance of less than 1 ohm / square inch / mil.
4. The shielded coil assembly of claim 1, wherein: The thickness of the conductive coating is between 30 micrometers and 500 micrometers.
5. The shielded coil assembly of claim 1, wherein: The conductive paint includes a loop separation region having interruptions in the conductive paint along an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil.
6. The shielded coil assembly of claim 5, wherein: The loop separation region includes a gap in the conductive paint, the gap extending around an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil to form an open loop in the conductive paint.
7. The shielded coil assembly of claim 1, wherein: The semiconductive coating has a resistance of 1 kOhm / square inch / mil to 10 kOhm / square inch / mil.
8. The shielded coil assembly of claim 1, comprising a second insulating material formed on the conductive shield layer.
9. The shielded coil assembly of claim 8, wherein: The first insulating material and the second insulating material include a material including epoxy resin.
10. The shielded coil assembly of claim 1, comprising a ground cable connected to the conductive shield layer.
11. The shielded coil assembly of claim 1, comprising an additional coil positioned concentrically relative to the shielded coil.
12. A dry-type transformer, comprising: core area; as well as The shielded coil assembly of claim 1, formed around a portion of the core region.
13. 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, the inner surface, the upper end surface, and the lower end surface of the coil; as well as A conductive shielding layer, the conductive shielding layer comprising: a conductive mesh laid along the first insulating material so that the conductive mesh extends over at least a portion of an outer surface, an inner surface, an upper end surface, and a 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 semi-conductive coating form a composite structure on at least a portion of each of the outer surface, the inner surface, the upper end surface and the lower end surface of the coil.
14. The shielded coil assembly of claim 13, wherein: The conductive shielding layer includes a plurality of loops of the conductive mesh, each of the plurality of loops extending over a portion of an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil.
15. The shielded coil assembly of claim 14, wherein: The conductive shielding layer includes a loop separation region including gaps between the plurality of loops.
16. The shielded coil assembly of claim 13, comprising a second insulating material formed on the conductive shield layer.
17. The shielded coil assembly of claim 13, comprising a ground cable connected to the conductive shield layer.
18. The shielded coil assembly of claim 13, comprising an additional coil positioned concentrically relative to the shielded coil.
19. A dry-type transformer, comprising: core area; as well as The shielded coil assembly of claim 13, formed around a portion of the core region.
20. A method of forming a coil assembly, comprising: providing a coil having an outer surface, an inner surface, an upper end surface, and a lower end surface; Encapsulating the coil in a first insulating material; forming a conductive shielding layer on the coil by applying a conductive paint so that the conductive paint extends over at least a portion of each of an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil; as well as A semi-conductive coating is applied to the first insulating material, beneath the conductive coating.
21. The method according to claim 20, wherein: The conductive paint includes a conductive metal, and the conductive metal includes one or more of copper, nickel, silver-plated copper, nickel-silver, and silver.
22. The method according to claim 20, wherein: The conductive coating has a resistance of less than 1 ohm / square inch / mil.
23. The method according to claim 20, wherein: The thickness of the conductive coating is between 30 micrometers and 500 micrometers.
24. The method of claim 20, further comprising forming a loop separation region in the conductive paint by forming interruptions in the conductive paint along an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil.
25. The method according to claim 24, wherein: The loop separation region includes a gap in the conductive paint, the gap extending around an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil to form an open loop in the conductive paint.
26. The method of claim 20, wherein: The semiconductive coating has a resistance of 1 kOhm / square inch / mil to 10 kOhm / square inch / mil.
27. The method of claim 20, further comprising forming a second insulating material on the conductive shield layer.
28. The method according to claim 27, wherein: The first insulating material and the second insulating material include epoxy resin.
29. The method of claim 20, further comprising attaching a ground cable connected to the conductive shielding layer.
30. A method of forming a coil assembly, comprising: providing a coil having an outer surface, an inner surface, an upper end surface, and a lower end surface; Encapsulating the coil in a first insulating material; as well as A conductive shielding layer is formed on the coil by the following operations: Laying a conductive mesh along the first insulating material so that the conductive mesh extends over at least a portion of an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil; and A semiconductive paint is applied on the conductive mesh so that the conductive mesh and the semiconductive paint form a composite structure on at least a portion of each of the outer surface, the inner surface, the upper end surface, and the lower end surface of the coil.
31. The method according to claim 30, wherein: Laying the conductive mesh includes laying a plurality of loops of the conductive mesh, each of the plurality of loops extending over a portion of an outer surface, an inner surface, an upper end surface, and a lower end surface of the coil.
32. The method of claim 31, further comprising forming a loop separation region comprising gaps between the plurality of loops.
33. The method of claim 30, further comprising forming a second insulating material on the conductive shield layer.
34. The method of claim 30, further comprising attaching a ground cable connected to the conductive shielding layer.