A large-size current transformer for inflatable cabinet

Abstract

The present invention relates to the technical field of mutual inductors, and specifically to a large-size current mutual inductor for an inflatable cabinet. The present invention comprises a shell, in which a voltage-equalizing ring, a primary winding, a secondary winding, an epoxy resin mixture and a winding fixing part are arranged, the primary winding is a first copper rod, the secondary winding ring is arranged outside the primary winding, the primary winding and the secondary winding are concentric, the two ends of the primary winding extend to the outside of the axial plane on the left and right sides of the secondary winding, the axial direction of the primary winding and the secondary winding is horizontal, a voltage-equalizing ring is fixed at each end of the primary winding, the voltage-equalizing ring is concentric with the primary winding, the winding fixing part is arranged below the secondary winding and connected to the shell, and the epoxy resin mixture fills the internal gap of the shell. The present invention greatly improves the partial discharge qualified rate of the mutual inductor through improvements in various aspects.

Description

Technical Field

[0001] The invention relates to the technical field of mutual inductors, and in particular to a large-size current mutual inductor for a gas-filled cabinet. Background Art

[0002] In the production of traditional pillar-type current transformers for inflatable cabinets, in order to ensure the sealing of the sealing groove surface, the transformer needs to be rotated 90 degrees during casting. Due to the particularity of casting, it is difficult to ensure uniform casting of both ends of the primary winding and the secondary winding during design. In addition, the position of the internal coil in the transformer will change during the production process, resulting in uneven casting layers in the inner holes of the primary and secondary windings, affecting the field strength and reducing the partial discharge level of the product. Due to the particularity of the primary lap row of the pillar-type transformer for traditional inflatable cabinets, when producing parameters of 1200-2500A specifications, the transformer adopts a primary copper strip design. However, since the copper strip is a rectangular structure with edges and corners, the electric field distribution is uneven, and there is a very high field strength inside the coil at the 1200-2500A specification, which makes the partial discharge pass rate of large-size products low.

[0003] Conventional current transformers use shielding nets to improve the partial discharge of products. However, most shielding nets are rectangular structures, which can only even out the field strength of the primary winding and a part of the secondary winding, and have little effect on improving the partial discharge of products. Therefore, the qualified rate of partial discharge of pillar-type current transformers used in conventional inflatable cabinets that meet the national standard can only reach about 75%. At the same time, conventional transformers use copper bars to overlap with the primary busbar in the cabinet, and the field strength of the components in the cabinet will also affect the transformer. Even if the transformer with qualified partial discharge is installed in the cabinet, the overall partial discharge of the cabinet will be too large due to the overlap problem.

[0004] Due to the above problems, customers will put forward higher requirements for partial discharge of transformers. The qualified rate of traditional partial discharge of transformers that can meet customer requirements can only reach about 50%.

[0005] How to effectively solve the above problems and produce a current transformer that meets the requirements is particularly important. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a large-size current transformer for an inflatable cabinet with a high partial discharge qualification rate and uniform field strength inside the coil.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a large-scale current transformer for an inflatable cabinet, including a shell, in which a voltage-equalizing ring, a primary winding, a secondary winding, an epoxy resin mixture and a winding fixing part are arranged, the primary winding is a first copper rod, the secondary winding ring is arranged on the periphery of the primary winding, the primary winding and the secondary winding are concentric, the two ends of the primary winding extend to the outside of the axial planes on the left and right sides of the secondary winding, the axial directions of the primary winding and the secondary winding are horizontal, a voltage-equalizing ring is fixed at each axial end of the primary winding, the voltage-equalizing ring is concentric with the primary winding, the winding fixing part is arranged below the secondary winding and connected to the shell, and the epoxy resin mixture fills the internal gap of the shell.

[0008] Furthermore, the winding fixing member includes a fixing plate, a supporting member and an insert. The fixing plate is an arc-shaped fixing plate supported under the secondary winding. One end of the supporting member is connected to the arc-shaped fixing plate and the other end is connected to the insert. The insert is fixed to the bottom of the shell.

[0009] Furthermore, the voltage-equalizing ring is fixed to the primary winding by welding a copper tape on the voltage-equalizing ring, the copper tape is tightly attached to the surface of the primary winding, and the copper tape and the primary winding are wrapped with a self-adhesive semi-conductive tape to fix the voltage-equalizing ring to the primary winding.

[0010] Furthermore, the left and right side surfaces of the shell are overlapping surfaces, the left side surface of the shell is overlapped with a second copper rod, one end of the second copper rod extends into the shell to completely wrap one end of the first copper rod, and the right side surface of the shell is overlapped with a copper busbar, one end of the copper busbar extends into the shell and overlaps with the other end of the first copper rod.

[0011] Furthermore, a pouring port is arranged on the upper side of the shell, and the pouring port is used for pouring the epoxy resin mixture.

[0012] Furthermore, the pressure equalizing ring is wound by a spring.

[0013] Furthermore, the first copper rod is a hollow copper rod, and the second copper rod is a solid copper rod.

[0014] Furthermore, the specific structure of the voltage-equalizing ring wound by a spring includes an annular copper wire mesh, a copper wire skeleton arranged around the annular edge of the annular copper wire mesh, and a bare copper wire wound around the copper wire skeleton with the copper wire skeleton as the axis.

[0015] Furthermore, the cross-sectional diameter of the coil formed by winding the bare copper wire on the copper wire skeleton is not less than 16 mm.

[0016] Furthermore, the support member, the fixing plate and the insert are welded into one body, and the insert is an embedded nut.

[0017] The technical solution of the present invention has the following advantages:

[0018] 1. The primary winding of the present invention is a round copper rod, which replaces the copper strip of the primary winding in the traditional current transformer. The copper strip is a square structure with edges and corners, which leads to uneven field strength around the primary winding. The primary winding of the present invention is a round copper rod. The copper rod with a round structure is smooth all around, and the electric field is evenly distributed, which improves the product partial discharge qualification rate.

[0019] 2. The primary winding of the present invention is further designed as a hollow copper rod to disperse the current, reduce the resistance and loss of the conductor, facilitate heat dissipation during the operation of the transformer, and make the transformer work more stably and reliably.

[0020] 3. After the primary winding of the present invention is changed into a round copper rod, a voltage grading ring can be installed on the space structure inside the shell. The voltage grading ring is installed on both ends of the primary winding to even out the electric field and improve the partial discharge pass rate.

[0021] 4. The voltage-grading ring of the present invention is also designed as a circular ring structure, replacing the square voltage-grading ring in the traditional current transformer. The circular voltage-grading ring has a better uniform electric field effect than the square voltage-grading ring, and improves the partial discharge pass rate.

[0022] 5. The voltage-equalizing ring of the present invention comprises an annular copper wire mesh, a copper wire skeleton arranged on the annular edge of the annular copper wire mesh, and a bare copper wire wound on the copper wire skeleton with the copper wire skeleton as the axis. The annular copper wire mesh and the copper wire are used as the annular edge skeleton of the annular copper wire mesh. The structure is firm and not easy to deform, which ensures that the circle formed by the bare copper wire is more stable and improves the reliability of the uniform electric field of the voltage-equalizing ring during the operation of the transformer.

[0023] 6. The overlapping surface of the current transformer of the present invention can be changed from the traditional upper side overlapping to the left and right sides of the shell as overlapping surfaces, so that a pouring port can be opened on the upper side of the shell, and the epoxy resin mixture can be poured into the shell from the upper side of the shell. The entire process from the beginning of pouring to the completion of pouring does not require the transformer to rotate. During the process from molding to curing, the secondary winding inside the transformer is stabilized by the support, and the relative positions of the primary winding and the secondary winding will not change, thereby ensuring that the field strength inside the secondary winding is uniform, thereby improving the partial discharge pass rate.

[0024] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0025] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a schematic structural diagram of a large-size current transformer for an inflatable cabinet of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of a traditional current transformer.

[0029] Figure 3 for Figure 2 Schematic diagram of the structure of the square pressure equalizing ring.

[0030] Figure 4 It is a front view of the grading ring in the large-size current transformer for the inflatable cabinet of the present invention.

[0031] Figure 5 It is a schematic diagram of the structure of fixing the grading ring and the primary winding in the large-size current transformer for the inflatable cabinet of the present invention.

[0032] Figure 6 This is a schematic diagram of the external connection of a large-size current transformer for an inflatable cabinet of the present invention.

[0033] Description of Figure Numbers:

[0034] 1-voltage-equalizing ring; 2-secondary winding; 3-epoxy resin mixture; 4-primary winding; 5-support; 6-insert; 8-fixed plate; 9-pouring port; 10-copper strip; 11-second copper rod; 12-copper busbar; 101-square voltage-equalizing ring; 102-lap joint; 103-primary winding in traditional mutual inductor; 104-secondary winding in traditional mutual inductor; 100-bare copper wire; 200-purple copper wire skeleton; 300-annular copper wire mesh. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0036] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] Conventional current transformers use shielding nets to improve the partial discharge of products. However, most shielding nets are rectangular structures, which can only even out the field strength of the primary winding and a part of the secondary winding, and have little effect on improving the partial discharge of products. At the same time, conventional transformers use copper bars to overlap with the primary busbar in the cabinet. The field strength of the components in the cabinet will also affect the transformer. Even if the transformer with qualified partial discharge is installed in the cabinet, the overall partial discharge of the cabinet will be too large due to the overlap problem.

[0038] Based on the above problems, the present invention provides a large-size current transformer for an inflatable cabinet, which greatly improves the partial discharge qualification rate through coordinated improvements in various aspects.

[0039] See also Figure 1As shown, an embodiment of the present invention provides a large-scale current transformer for an inflatable cabinet, including a shell, wherein a voltage-equalizing ring 1, a primary winding 4, a secondary winding 2, an epoxy resin mixture 3 and a winding fixing part are arranged in the shell, the primary winding 4 is a first copper rod, the secondary winding 2 is arranged around the periphery of the primary winding 4, the primary winding 4 and the secondary winding 2 are concentric, the two ends of the primary winding 4 extend to the outside of the axial planes on the left and right sides of the secondary winding 2, the axial directions of the primary winding 4 and the secondary winding 2 are horizontal, a voltage-equalizing ring 1 is fixed to each of the two axial ends of the primary winding 4, the voltage-equalizing ring 1 is concentric with the primary winding 4, the winding fixing part is arranged below the secondary winding 2 and connected to the shell, and the epoxy resin mixture 3 fills the internal gap of the shell.

[0040] The primary winding 4 of the present invention is designed as a copper rod, replacing the traditional copper strip structure, see Figure 2 As shown, the primary winding 103 in the traditional transformer adopts a copper strip structure. Since the copper strip structure is a rectangular structure with edges and corners, it will cause uneven electric field strength around the primary. The primary winding in the current transformer of the present invention replaces the copper strip with a copper rod. The copper rod is a circular structure with smooth sides, so that the surrounding electric field is evenly distributed, which improves the partial discharge qualification rate of the product. Figure 2 and Figure 3 As shown, due to the characteristics of the copper strip structure of the primary winding 103 in the traditional transformer, the uniform ring in the traditional transformer can only be designed as a square voltage-grading ring 101, and the partial discharge pass rate is low.

[0041] The present invention fills the gap inside the shell by pouring epoxy resin mixture, thereby ensuring the insulation level.

[0042] In some embodiments of the present invention, the winding fixing member includes a fixing plate 8, a support member 5 and an insert 6. The fixing plate 8 is an arc-shaped fixing plate supported under the secondary winding 2. One end of the support member 5 is connected to the arc-shaped fixing plate and the other end is connected to the insert 6. The insert 6 is fixed to the bottom of the shell.

[0043] See also Figure 5 As shown, in some embodiments of the present invention, the voltage-equalizing ring 1 is fixed to the primary winding 4 by welding a copper tape 10 on the voltage-equalizing ring 1, the copper tape 10 is closely attached to the surface of the primary winding 4, and a self-adhesive semi-conductive tape is used to wrap the copper tape and the primary winding 4 so as to fix the voltage-equalizing ring to the primary winding 4.

[0044] Depend on Figure 2It can be seen that the original equalizing ring of the traditional transformer is a square equalizing ring, which is directly fixed on the primary winding in the traditional transformer by being tied to the primary winding through an extended copper tape. After the equalizing ring in the current transformer of the present invention is changed to a circular shape, the equalizing ring 1 is located at the axial ends of the primary winding 4, with a sufficient casting layer away from the primary winding. At the same time, there is also a sufficient casting layer between the equalizing ring 1 and the inner wall of the shell. The equalizing ring 1 is in a suspended position. In order to stabilize the position of the equalizing ring, two copper tapes 10 are welded on the inner ring of the equalizing ring 1, and the copper tape 10 is pressed against the surface of the primary winding 4. The copper tape and the primary winding 4 are wrapped with a self-adhesive semi-conductive tape to fix the equalizing ring to the primary winding 4. In this way, the position of the equalizing ring 1 is fixed, and the contact surface between the copper tape 10 and the primary winding 4 is closer than the contact surface between the square equalizing ring and the primary winding in the traditional transformer, and the connection is more reliable, thereby improving the effect of uniform electric field action between the primary winding 4 and the secondary winding 2.

[0045] See also Figure 6 As shown, in some embodiments of the present invention, the left and right side surfaces of the shell are overlapping surfaces, the left side surface of the shell is overlapped with the second copper rod 11, one end of the second copper rod 11 extends into the shell to completely wrap one end of the first copper rod, and the right side surface of the shell is overlapped with a copper bus 12, one end of the copper bus 12 extends into the shell and overlaps with the other end of the first copper rod.

[0046] See also Figure 2 As shown, the primary winding 103 in the traditional current transformer is a square structure. When overlapping with the outside, the two ends of the primary winding can only be overlapped with copper bars. However, the current transformer of the present invention has the primary winding designed as a copper rod with a circular structure. One section can be overlapped with an external solid copper rod and one end can be overlapped with a copper bar. The first copper rod is completely wrapped at the overlap between the solid copper rod and the first copper rod, which reduces the influence of the external field strength on the current transformer, ensures the local discharge level, and improves the overall local discharge pass rate of the inflatable cabinet.

[0047] There is a lap joint 102 at the lap joint of the primary winding 103 in the traditional transformer. The diameter of the circular hole is small and can only pass through a primary copper busbar. If the diameter of the circular hole is increased to allow the terminal block or copper busbar to pass through, part of the field strength between the primary winding and the secondary winding in the traditional transformer will not be evenly distributed due to the voltage equalizing ring, which will not be effective in improving the partial discharge pass rate of the product.

[0048] In some embodiments of the present invention, a pouring port is disposed on the upper side of the shell, and the pouring port is used for pouring the epoxy resin mixture.

[0049] Since the primary winding inside the shell of the current transformer of the present invention is changed from a square structure to a circular structure, the primary winding 4 and the secondary winding 2 can be concentrically arranged horizontally in the shell, so the overlapping surface of the transformer can be changed from the traditional upper side overlapping to the left and right sides of the shell as overlapping surfaces, so that a pouring port can be opened on the upper side of the shell, and the epoxy resin mixture 3 can be poured into the shell from the upper side of the shell. The transformer does not need to be rotated during the entire process from the beginning of pouring to the completion of pouring. The secondary winding 2 inside the transformer is firmly fixed by the support 5 during the process from molding to curing, and the relative positions of the primary winding 4 and the secondary winding 2 will not change, thereby ensuring that the field strength inside the secondary winding 2 is uniform, thereby improving the partial discharge pass rate.

[0050] See also Figure 2 As shown, the upper side surface of the traditional current transformer housing is a lap surface, and the pouring port 9 can only be designed on the left or right side of the housing. During the pouring process, the transformer needs to be rotated 90°. It is impossible to guarantee what kind of displacement change will occur in the relative position between the primary winding 103 in the traditional transformer and the secondary winding 104 in the traditional transformer during the rotation process, and the partial discharge level of each transformer will be reduced to varying degrees.

[0051] In some embodiments of the present invention, the pressure equalizing ring 1 is wound by a spring.

[0052] In some embodiments of the present invention, the first copper rod is a hollow copper rod, and the second copper rod 11 is a solid copper rod.

[0053] When the primary winding adopts a copper rod structure, a new problem will arise, which is the skin effect. The skin effect means that when there is alternating current or alternating electromagnetic field in the conductor, the current distribution inside the conductor is uneven, and the current is concentrated in the "skin" part of the conductor, that is, the current is concentrated in a thin layer on the surface of the conductor. The closer to the surface of the conductor, the greater the current density, resulting in a smaller current inside the conductor. Therefore, the embodiment of the present invention can further improve the copper rod and design the copper rod into a hollow copper rod to disperse the current, reduce the resistance and loss of the conductor, facilitate heat dissipation of the transformer during operation, and make the transformer more stable and reliable during operation.

[0054] See also Figure 4 As shown, in some embodiments of the present invention, the specific structure of the voltage equalizing ring 1 wound by a spring includes an annular copper wire mesh 300, a copper wire skeleton 200 arranged around the annular edge of the annular copper wire mesh 300, and a bare copper wire 100 wound around the copper wire skeleton 200 with the copper wire skeleton 200 as the axis. Figure 4 The bare copper wire 100 shown in the figure only shows a part, which shows that the bare copper wire 100 is wound on the copper wire skeleton 200.

[0055] Since the primary winding of the present invention is replaced by a copper rod structure instead of a copper strip structure in a traditional current transformer, a voltage-equalizing ring can be arranged at both ends of the primary winding, and the structure of the voltage-equalizing ring can also be changed from an original square ring to a circular uniform ring in the present invention, which is more conducive to a uniform electric field and improves the partial discharge pass rate.

[0056] The equalizing ring in the embodiment of the present invention is designed to include an annular copper wire mesh 300, with a copper wire skeleton 200 as the ring edge of the annular copper wire mesh 300, and then a bare copper wire 100 is wound on the copper wire skeleton 200. The circular structure is firm and not easy to deform, which further improves the use effect and service life of the equalizing ring and ensures the stability of the local discharge level of the transformer during operation.

[0057] In some embodiments of the present invention, the cross-sectional diameter of the coil formed by winding the bare copper wire 100 on the copper wire skeleton 200 is not less than 16 mm.

[0058] The current transformer of this embodiment is applied to 35kV. The insulation distance of the 35kV current transformer is generally not less than 16mm, so the cross-sectional diameter of the coil formed by winding the bare copper wire 100 on the copper wire skeleton 200 is not less than 16mm, which is beneficial to improving the partial discharge qualification rate of the transformer.

[0059] In some embodiments of the present invention, the support member 5, the fixing plate 8 and the insert 6 are welded together, and the insert 6 is an embedded nut, which is fixed to the bottom surface of the shell by the embedded nut to fix the support member 5 and the fixing plate 8 in the shell.

[0060] By welding a support member 5 of corresponding length on the fixed plate and welding an insert 6 at the bottom of the support member 5, it is only necessary to fix the insert 6 to the shell when fixing the coil of the secondary winding 2. When demolding, it is only necessary to remove the bolts in the insert 6. Because the insert 6 has no threads, no epoxy resin mixture 3 will enter, and there is no need to adjust the casting layer. The height of the support member 5 has been fixed during the design, and the secondary winding 2 can be directly installed to the corresponding position on the fixed plate 8.

[0061] Through the above improvements, the partial discharge qualified rate of the current transformer of the present invention is greatly improved compared with the partial discharge qualified rate of the traditional current transformer. For relevant data, see the following Table 1.

[0062] Table 1

[0063]

[0064] 1.2Um / √3, 1.2Um represents the measurement point of partial discharge, pC is the unit of discharge, L in LZZB represents current transformer, the first Z represents pillar type, the second Z represents cast insulation, B represents belt protection grade, 8 and 9 in LZZB8 and LZZB9 represent design numbers, CQ represents for inflatable cabinets, and 198 represents product width.

[0065] The data in Table 1 were obtained under this test environment. The partial discharge test was carried out in accordance with the requirements of 7.3.3.2 of GB / T20840.1-2010: The partial discharge test was carried out after the power frequency withstand voltage test. The applied voltage was increased to 80% of the rated power frequency withstand voltage, maintained for at least 60 seconds, and then continuously reduced to the specified partial discharge measurement voltage.

[0066] It can be seen from the data in Table 1 that the partial discharge qualification rate of the current transformer of the present invention that meets customer requirements can reach 98%, which is significantly improved compared with 50% of the traditional current transformer.

[0067] To summarize, after the primary winding is replaced from a square copper strip to a round copper rod in the present invention, the other corresponding adjustments include that the voltage equalizing ring can be designed to be round, the pouring port can be changed from the left and right sides of the shell to the upper side, and the external overlap can be changed from only overlapping copper bars to a section that can overlap solid copper rods. These improvements are all based on the improvement of replacing the primary winding from a square copper strip to a round copper rod. All of the above improvements are closely linked and cooperate with each other, rather than a simple superposition of local improvements, which greatly improves the partial discharge pass rate of the transformer.

[0068] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A large-size current transformer for an inflatable cabinet, comprising a housing, characterized in that: The shell is provided with a voltage-equalizing ring, a primary winding, a secondary winding, an epoxy resin mixture and a winding fixing part, the primary winding is a first copper rod, the secondary winding ring is arranged outside the primary winding, the primary winding and the secondary winding are concentric, the two ends of the primary winding extend to the outside of the axial planes on the left and right sides of the secondary winding, the axial directions of the primary winding and the secondary winding are horizontal, a voltage-equalizing ring is fixed at each axial end of the primary winding, the voltage-equalizing ring is concentric with the primary winding, the winding fixing part is arranged below the secondary winding and connected to the shell, and the epoxy resin mixture fills the internal gap of the shell; The left and right sides of the shell are overlapping surfaces, the left side of the shell is overlapped with a second copper rod, one end of the second copper rod extends into the shell to completely wrap one end of the first copper rod, and the right side of the shell is overlapped with a copper bar, one end of the copper bar extends into the shell and overlaps the other end of the first copper rod; A pouring port is arranged on the upper side of the shell, and the pouring port is used for pouring epoxy resin mixture.

2. The large-size current transformer for an inflatable cabinet according to claim 1 is characterized in that: The winding fixing member includes a fixing plate, a supporting member and an insert. The fixing plate is an arc-shaped fixing plate supported under the secondary winding. One end of the supporting member is connected to the arc-shaped fixing plate and the other end is connected to the insert. The insert is fixed to the bottom of the shell.

3. The large-size current transformer for an inflatable cabinet according to claim 2 is characterized in that: The support member, the fixing plate and the insert are welded into one body, and the insert is an embedded nut.

4. The large-size current transformer for an inflatable cabinet according to claim 1 is characterized in that: The voltage-equalizing ring is fixed to the primary winding by welding a copper tape on the voltage-equalizing ring, the copper tape is closely attached to the surface of the primary winding, and the copper tape and the primary winding are wrapped with a self-adhesive semi-conductive tape to fix the voltage-equalizing ring to the primary winding.

5. The large-size current transformer for an inflatable cabinet according to claim 1, characterized in that: The first copper rod is a hollow copper rod, and the second copper rod is a solid copper rod.

6. The large-size current transformer for an inflatable cabinet according to claim 1, characterized in that: The pressure equalizing ring is formed by winding a spring.

7. The large-size current transformer for an inflatable cabinet according to claim 6, characterized in that: The specific structure of the equalizing ring made of spring includes an annular copper wire mesh, a copper wire skeleton arranged around the annular edge of the annular copper wire mesh, and a bare copper wire wound on the copper wire skeleton with the copper wire skeleton as the axis.

8. The large-size current transformer for an inflatable cabinet according to claim 7, characterized in that: The cross-sectional diameter of the coil formed by the bare copper wire being wound around the copper wire skeleton is not less than 16 mm.

Images