CN217035377U

CN217035377U - Insulating high-temperature-resistant ground screen for transformer

Info

Publication number: CN217035377U
Application number: CN202220374512.4U
Authority: CN
Inventors: 刘乾; 蒋志锋; 陈志平; 李洪
Original assignee: Changzhou Yingzhong Electrical Co ltd
Current assignee: Changzhou Yingzhong Electrical Co ltd
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2022-07-22
Anticipated expiration: 2032-02-23

Abstract

The utility model discloses an insulating high-temperature-resistant ground screen for a transformer, which comprises a conductive net, an insulating wrapping edge and a lug plate, wherein the lug plate comprises a metal sheet and an insulating paper layer wrapping the lug plate, one end of the metal sheet is welded with the conductive net, the other end of the metal sheet extends to the outer side of the conductive net, the surface of the end part of one side of the metal sheet, which is far away from the conductive net, is not wrapped with insulating paper, and the insulating wrapping edge is wrapped on the periphery of the conductive net. The bottom plate and the conductive shielding plate of the traditional insulating ground screen are replaced by the conductive net, and the conductive net with the hollow structure has the advantages of good mechanical strength, light weight, easiness in transportation and installation, difficulty in damage, good heat dissipation performance, contribution to controlling temperature rise in the operation process of the power transformer and better high-temperature resistance; the structural stability and the shape and size precision of the ground screen can be guaranteed; and can avoid generating the air cavity and causing and discharging when glue is bonded, can also improve the electric conductivity between lug and conductive mesh.

Description

Insulating high-temperature-resistant ground screen for transformer

Technical Field

The utility model relates to the field of power transformation equipment, in particular to an insulating high-temperature-resistant ground screen for a transformer.

Background

The ground shield is also called as an electrostatic shield and is used between an outer winding and a return yoke in the transformer and between the outer winding and an iron core, so that a distortion electric field generated by the sharp corner of the iron core cannot penetrate to the outside to influence the winding. Because the iron core of the power transformer is of a stepped circular structure, the field intensity of the sharp corner at the end part of the step is increased after the transformer is excited, when the field intensity of partial discharge is increased, the partial discharge phenomenon begins to appear, and the ground screen can effectively solve the partial discharge phenomenon.

As shown in fig. 4-5, the conventional ground shield structure is composed of a bottom plate, a terminal plate, a conductive shielding plate, and an insulating layer. The bottom plate is generally made of 1mm insulating paper boards, the wiring lugs are made of copper sheets and aluminum sheets, the conductive shielding plates are made of copper foils and aluminum foils, and the insulating layers are made of cable paper. There are two shortcomings to traditional structure ground screen: firstly, the welding between the lug and the conductive shielding plate is unreliable, the thickness of the copper and aluminum sheets is generally 0.15mm to 0.5mm, the lug and the conductive shielding plate are bonded with an insulating paperboard before welding, the paperboard is easily carbonized and embrittled due to overhigh welding temperature or overlong welding time, only a tin soldering mode can be adopted, and the welding time is strictly controlled, so that the welding strength is difficult to ensure, and welding points are easy to fall off in the subsequent transformer assembling and drying processes to influence the conductivity; secondly, electrically conductive shielding plate skin need use cable paper to bond, wrap up, later bond on insulating board surface, and the casein glue that bonds and use is the water-based binder, in order to guarantee that the bonding is abundant, does not have the bubble, needs use casein glue in a large number, can lead to the product whole deformation to appear when dry, causes the welding point accident to drop, also can lead to copper sheet surface oxidation simultaneously, influences electric conductive property.

Disclosure of Invention

The utility model aims to solve the problems that the connection strength of a lug plate and a conductive shielding plate of the conventional ground screen in the background art is poor, a welding point is easy to fall off, the conductivity is influenced, and when casein glue is used for bonding cable paper on the conductive shielding plate, the consumption of the casein glue is large, a product is easy to deform in the drying process of the casein glue, and the like.

In order to realize the purpose, the utility model is realized by the following technical scheme: the utility model provides an insulating high temperature resistant ground screen for transformer, its includes electrically conductive net, insulating bordure and the lug, and the lug includes the insulating paper layer of sheetmetal and parcel lug, the one end and the electrically conductive net welded connection of sheetmetal, the other end of sheetmetal extends to the outside of electrically conductive net, keeps away from the surface of electrically conductive one side tip of net at the sheetmetal and does not wrap up insulating paper, insulating bordure the parcel in the periphery of electrically conductive net.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the insulating wrapping edge comprises a semi-conducting layer and an insulating layer, the semi-conducting layer is in contact with the edge of the conductive net and wraps the edge of the conductive net, the insulating layer wraps the outer part of the semi-conducting layer, the semi-conducting layer is bonded with the conductive net through glue, and the insulating layer is bonded with the semi-conducting layer through glue. Through the arrangement of the semi-conducting layer, sharp corners at the fracture of the conductive net can be shielded by utilizing the semi-conducting property of the semi-conducting layer, and partial discharge at the edge of the conductive net is avoided.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the conductive net is an aluminum wire net. The aluminum mesh is used as the conductive mesh, and compared with a copper mesh, the aluminum mesh is not easy to oxidize and has lower cost.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the metal sheet is a copper sheet or an aluminum sheet. The copper sheet or the aluminum sheet is selected as the conductive element of the wiring piece, so that the conductivity can be improved.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the semi-conducting layer is made of carbon black crepe paper, and the insulating layer is made of crepe paper.

As a further improvement of the above insulating high temperature resistant ground screen for transformer, the welding part of the metal sheet and the conductive mesh comprises two paths, one of the two paths is close to the inner end of the metal sheet, and the other path is close to one side edge of the conductive mesh. Through setting up twice weld part, it is more firm to enable the connection of sheetmetal and electrically conductive net, and electric conductivity is better.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the distance between the inner side end of the metal sheet and the edge of the conductive net is 5-8 cm. Through the arrangement, the connection between the metal sheet and the conductive net can be firmer.

As a further improvement of the insulating high-temperature-resistant ground screen for the transformer, the conductive net is a 12-16-mesh conductive net. Through the arrangement, the conductive performance of the conductive net is better, and the overall performance of the ground screen is improved.

The utility model has the positive effects that: 1) according to the insulating high-temperature-resistant ground screen for the transformer, the conductive net is adopted to replace a bottom plate and a conductive shielding plate of the traditional insulating ground screen, and meanwhile, the problems that the ground screen is deformed and the like in the drying process of casein glue caused by a large amount of casein glue used when cable paper is bonded on the conductive shielding plate are avoided; the structural stability and the shape and size precision of the ground screen can be guaranteed; meanwhile, the aluminum mesh is used as the bottom plate, so that the heat dissipation performance is better than that of an insulating paperboard used for a ground screen with a traditional structure, the temperature rise control in the operation process of the power transformer is facilitated, and the high-temperature resistance performance of the power transformer is better; 2) according to the insulating high-temperature-resistant ground screen for the transformer, the periphery of the conductive net is shielded and wrapped by the carbon black crepe paper and the crepe paper, the used glue is little, and because the carbon black crepe paper and the crepe paper are wrapped on the upper side surface and the lower side surface of the edge of the conductive net, a closed air cavity is not formed, partial discharge cannot occur after the transformer is subjected to vacuum oil immersion, the ground screen with the traditional structure needs to bond cable paper in a large area, the closed air cavity is easy to generate during bonding, and if air in the air cavity is not thoroughly removed during the vacuum oil immersion of the transformer, partial discharge can be generated during testing, so that the failure of the transformer test can be caused, and the risk can be avoided; 3) analyzed from the aspect of a welding method, the welding process of the ground screen with the traditional structure is that after a transverse conductive shielding plate is bonded with an insulating paperboard, the insulating paperboard can not be welded in a brazing mode due to the fact that the bearing temperature of the insulating paperboard is below 140 ℃, the insulating paperboard can only be welded in a soldering mode for a short time, if the welding time is too long, the insulating paperboard is easy to carbonize or become brittle, the aluminum mesh and the wiring sheet adopted by the utility model are both made of metal materials, the welding process can be carried out by adopting conventional methods such as argon arc welding and the like before wrapping insulation, the welding strength is superior to soldering, the ground screen is not easy to break, and the conductivity of the ground screen can be improved; 4) the method is characterized in that a large number of soldering welding points exist among conductive shielding plates, between the conductive shielding plates and lugs of the conventional ground screen from the aspect of stability of a welding area, and the soldering welding points are greatly risky to fall off in the use process due to the fact that the ground screen is required to be rolled to be round, so that poor conduction of the lugs among the conductive shielding plates is caused, the ground screen is only welded and connected at the connecting part of an aluminum net and the lugs, and the connecting part is not in the rolled area and is free of risk of falling of the welding points, so that the whole conduction performance of the ground screen can be guaranteed; 5) the insulating high-temperature-resistant ground screen for the transformer uses the conductive net with the hollow structure, has good mechanical strength and lighter weight, is easy to transport and install and is not easy to damage.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a schematic view of a structure of a lug plate with an insulating paper covering the surface

Fig. 3 is a sectional view taken along line a-a in fig. 1.

Fig. 4 is a schematic structural diagram of a conventional ground screen.

Fig. 5 is a sectional view taken along line B-B in fig. 4.

The reference numerals in fig. 1-3 are as follows: the insulation binding comprises a conductive net 1, an insulation binding edge 2, a semi-conductive layer 21, an insulation layer 22, a wiring piece 3, a metal sheet 31, an insulation paper layer 32 and a welding part 33.

The reference numerals in fig. 4-5 are as follows: the cable comprises a base plate 01, a lug plate 02, a transverse conductive shielding plate 03, a longitudinal conductive shielding plate 04, cable paper 05, an insulating paper board 06 and a welding area 07.

Detailed Description

The technical solutions of the present invention are described below clearly and completely by way of examples, and it is obvious that the described examples are only some examples of the present invention, and not all examples. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 to 3 show an insulating high temperature resistant ground screen for a transformer according to the present invention, which comprises a conductive mesh 1, an insulating cover 2 and a lug 3.

The conductive net 1 can be 12-16 mesh aluminum wire net with diameter of 0.9-1.0 mm. And an aluminum wire mesh is used as a conductive mesh, so that compared with a copper mesh, the aluminum wire mesh is not easy to oxidize and has lower cost.

The lug 3 comprises a metal sheet 31 and an insulating paper layer 32 wrapping the lug, the metal sheet 31 is a copper sheet or an aluminum sheet, one end of the metal sheet 31 is connected with the conductive net 1 in a welding mode, argon arc welding can be adopted as the welding mode, and compared with the existing connection mode of soldering of the lug and the conductive shielding plate, the connection strength is stronger, disconnection is not easy, and the conductivity of the metal sheet 31 and the conductive net 1 is better. The welding 33 of the metal sheet 31 and the conductive mesh 1 may be one or more, and in the embodiment shown in the drawings, the welding 33 includes two passes, one of which is close to the inner end of the metal sheet, and the other is close to one side edge of the conductive mesh. The distance between the inner end of the metal sheet 31 and the edge of the conductive mesh 1 may be 5-8 cm. The other end of the metal sheet 31 extends to the outer side of the conductive net 1, the surface of the end part of one side of the metal sheet 31 far away from the conductive net 1 is not wrapped by insulating paper, and the metal sheet 31 is exposed outside so as to be convenient for connection with other conductive elements. The wrapping manner of the insulating paper layer 32 and the metal sheet 31 may be: two pieces of insulating paper are folded, then the two pieces of folding paper are wrapped on the metal sheet 31 from the left side and the right side of the metal sheet 31 respectively, during wrapping, two side edges of the metal sheet 31 are located at the bottom of a groove formed by folding the insulating paper, and after wrapping, the insulating paper is bonded with the metal sheet through glue. For the convenience of welding, the vicinity of the inner end of the insulating paper near the metal sheet 31 is divided into two front and rear pieces along the groove bottom, and after the metal sheet 31 is welded to the conductive mesh 1, the insulating paper is bonded to the metal sheet 31.

The insulating binding 2 comprises a semi-conducting layer 21 and an insulating layer 22, wherein the semi-conducting layer 21 can be made of carbon black crepe paper, the insulating layer 22 can be made of crepe paper, the semi-conducting layer 21 is in contact with the edge of the conductive net 22 and is wrapped on the edge of the conductive net 1, the semi-conducting layer 21 wraps the edge of the conductive net 1 in a mode that the semi-conducting layer 21 is folded out of a groove, the edge of the conductive net 1 is inserted into the bottom of the groove, then the semi-conducting layer 21 is bonded with the conductive net 1 through glue, the insulating layer 22 wraps the outside of the semi-conducting layer 21, the insulating layer 22 wraps the semi-conducting layer 21 in a mode that the insulating layer 22 is folded out of a groove, the edge of the conductive net bonded with the semi-conducting layer 21 is inserted into the bottom of the groove, then the insulating layer 22 is bonded with the semi-conducting layer 21 through glue, and when bonding, the insulating layer 22 completely wraps the semi-conducting layer 21. In the bonding process, casein glue can be used for bonding.

The insulating high-temperature-resistant ground screen for the transformer can be used for a wind power transformer, and when the insulating high-temperature-resistant ground screen is used, the conductive net needs to be bent into a cylindrical shape and is arranged on the outer side of the transformer in the same using mode as the traditional ground screen. The conductive net is adopted to replace the traditional bottom plate and the conductive shielding plate which replace the traditional insulating ground screen, and meanwhile, the problems that the ground screen is deformed and the like in the drying process of casein glue caused by a large amount of casein glue used when the cable paper is bonded on the conductive shielding plate are avoided; the structural stability and the shape and size precision of the ground screen can be guaranteed; meanwhile, the aluminum mesh is used as the bottom plate, the heat dissipation performance is better than that of an insulating paper board used by a ground screen with a traditional structure, the temperature rise control in the operation process of the power transformer is facilitated, and the high-temperature resistance performance of the power transformer is better. The ground screen with the traditional structure needs to bond cable paper in a large area, a closed air cavity is easily generated during bonding, if air in the air cavity is not completely removed in the vacuum oil immersion process of the transformer, partial discharge can be generated during testing, and the transformer test fails; analyzed from the aspect of a welding method, the welding process of the ground screen with the traditional structure is that after a transverse conductive shielding plate is bonded with an insulating paperboard, the insulating paperboard can not be welded in a brazing mode due to the fact that the bearing temperature of the insulating paperboard is below 140 ℃, the insulating paperboard can only be welded in a soldering mode for a short time, if the welding time is too long, the insulating paperboard is easy to carbonize or become brittle, the aluminum mesh and the wiring sheet adopted by the utility model are both made of metal materials, the welding process can be carried out by adopting conventional methods such as argon arc welding and the like before wrapping insulation, the welding strength is superior to soldering, the ground screen is not easy to break, and the conductivity of the ground screen can be improved; from the analysis in the aspect of welding regional stability, current ground screen exists a large amount of soldering solder joints between electrically conductive shield plate, electrically conductive shield plate and lug, in the use, because the circle of will rolling up, these soldering solder joints have very big risk to appear droing, lead to the lug to lead to the conducting badly between electrically conductive shield plate, and this patent only carries out welded connection at the junction of aluminium net and lug, this department is also not in the region of circle of rolling up, does not have the risk that the solder joint drops, therefore can guarantee the whole electric conductive property of ground screen.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides an insulating high temperature resistant ground screen for transformer which characterized in that: it includes electrically conductive net, insulating bordure and the lug, and the lug includes the sheetmetal and wraps up the insulating paper layer of lug, the one end and the electrically conductive net welded connection of sheetmetal, and the other end of sheetmetal extends to the outside of electrically conductive net, keeps away from the surface of electrically conductive one side tip of net at the sheetmetal and does not wrap up insulating paper, insulating bordure the parcel in the periphery of electrically conductive net.

2. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the insulating wrapping edge comprises a semi-conducting layer and an insulating layer, the semi-conducting layer is in contact with the edge of the conductive net and wraps the edge of the conductive net, the insulating layer wraps the outer portion of the semi-conducting layer, the semi-conducting layer is bonded with the conductive net through glue, and the insulating layer is bonded with the semi-conducting layer through glue.

3. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the conductive net is an aluminum wire net.

4. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the metal sheet is a copper sheet or an aluminum sheet.

5. The insulating high-temperature-resistant ground shield for the transformer according to claim 2, wherein: the semi-conductive layer is made of carbon black crepe paper, and the insulating layer is made of crepe paper.

6. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the welding part of the metal sheet and the conductive net comprises two paths, wherein one path is close to the end part of the inner side of the metal sheet, and the other path is close to the edge of one side of the conductive net.

7. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the distance between the end part of the inner side of the metal sheet and the edge of the conductive net is 5-8 cm.

8. The insulating high-temperature-resistant ground shield for the transformer according to claim 1, wherein: the conductive net is 12-16 meshes, and the diameter of the metal wire of the conductive net is 0.9-1.0 mm.