A low-voltage current transformer

Abstract

The present invention discloses a low-voltage current transformer, which relates to the technical field of current transformers and aims to solve the technical problems of complicated processes, low efficiency, and waste of a large amount of man-hours. It includes an upper transformer housing with a hollow center and a lower transformer housing. There are two energized terminals provided between one side of the upper transformer housing and the lower transformer housing. A iron core is arranged inside the upper transformer housing and the lower transformer housing. A winding is wound around the outer periphery of the iron core. The upper transformer housing and the lower transformer housing are respectively connected with a positioning rod and a positioning sleeve that are mutually adapted. Multiple ultrasonic melting heads are connected to the side of the upper transformer housing. An insulating cover is provided at the inner end of the energized terminal. An integral joint structure is arranged inside the insulating cover. A plurality of integral pressing structures are arranged on the outer periphery of the restraint ring. Protective wire structures are arranged on the outer peripheries of both ends of the iron core. The protective wire structure includes multiple groups of wire pressing structures, and a top pressing piece is also arranged on the protective wire structure. The present invention has the advantages of reducing production processes, improving production efficiency, and protecting the winding and the iron core.

Description

Technical Field

[0001] The present invention relates to the technical field of current transformers, and more specifically, to a low-voltage current transformer. Background Art

[0002] In the field of power metering and protection, low-voltage current transformers have become key devices in low-voltage distribution systems due to their characteristics of enclosed structure and convenient maintenance. The maintenance of low-voltage current transformers does not require the removal of the outer shell, and only the energized part needs to be maintained. Currently, the manufacturing of low-voltage current transformers generally adopts a multi-process step-by-step assembly mode: first, multi-layer insulation treatment is carried out on the iron core winding, and then the two ends of the winding and the energized end are connected by a welding process. This welding method not only requires precise control of the welding temperature and duration to avoid damage to the insulation layer, but also has quality hazards such as false soldering and insecure solder joints. After the winding assembly is completed, the iron core needs to be adhesively fixed to one side of the outer shell. During the adhesion process, the curing time of the glue is long, and problems such as position deviation and insufficient adhesion strength are likely to occur. Especially, finally, the plastic outer shell is fastened by bolts. The cumbersome bolt installation process not only consumes a large amount of man-hours, but also may cause the outer shell to deform due to uneven stress, affecting the overall sealing performance and insulation performance. In view of this, we propose a low-voltage current transformer. Summary of the Invention

[0003] The purpose of the present invention is to provide a low-voltage current transformer to solve the technical problems of complicated processes, low efficiency, and waste of a large amount of man-hours.

[0004] To solve the above technical problems, the present invention provides the following technical solution: A low-voltage current transformer includes an upper transformer outer shell and a lower transformer outer shell with a hollow center. Between one side of the upper transformer outer shell and the lower transformer outer shell, there are two energized ends. Inside the upper transformer outer shell and the lower transformer outer shell, there is an integrally formed restraint ring. Inside the restraint ring, there is an iron core. The outer periphery of the iron core is wrapped with an insulating layer. The outer periphery of the iron core is wound with a winding. The upper transformer outer shell and the lower transformer outer shell are respectively connected with a positioning rod and a positioning sleeve that are mutually adapted. The side of the upper transformer outer shell is connected with a plurality of ultrasonic melting heads. The upper transformer outer shell and the lower transformer outer shell are pressed together through an ultrasonic head. An energizing plate is installed at the inner end of the energized end. A live part shield is installed on one side of the energizing plate. Inside the live part shield, there is an integral joint structure. A plurality of integral pressing and fixing structures are arranged on the outer periphery of the restraint ring. On both ends of the outer periphery of the iron core, there are wire protection structures. The wire protection structures include multiple groups of wire pressing structures. The multiple groups of wire pressing structures are annularly arrayed with the winding end as the center and surround and closely adhere. A top joint piece is also provided on the wire protection structure.

[0005] Preferably, the energized end includes a plug socket, with convex cards integrally formed on both sides of the plug socket. The plug socket is inserted and fixed to the side walls of the upper housing and the lower housing of the current transformer, and an external connection bolt is threadedly connected to the plug socket.

[0006] Preferably, the integral joint structure includes an elastic rubber edge adhered to the lower half of the inner wall of the insulating cover. On one side of the elastic rubber edge, there is a fusion metal, which is a low-melting-point metal material that can be melted under ultrasonic pressure. On one side of the fusion metal, there is a sealing plate, and the end of the winding passes through the sealing plate and is located at the center of the fusion metal.

[0007] Preferably, the integral pressing and fixing structure includes an extension column. On both sides of the extension column, there are a pressing sleeve and a locking card connected to the upper housing and the lower housing of the current transformer respectively. The end of the extension column is connected with a ring cone convex head, which is composed of multiple solid ring bodies with increasing diameters. The locking card is in a U-shaped structure and passes through the ring cone convex head to contact the pressing sleeve.

[0008] Preferably, the wire protection structure includes a fixing seat. One side of the fixing seat is fixed to the inner wall of the lower housing of the current transformer. On one side of the fixing seat, there is a sliding sleeve, which is limited and slidable with respect to the fixing seat. The outer periphery of the sliding sleeve is connected with a pressing and moving column. On one side of the pressing and moving column, there is a slope pressing block fixed to the upper housing of the current transformer. The slope pressing block is in a slope conical shape, and a wire protection sleeve is arranged on the inner periphery of the sliding sleeve.

[0009] Preferably, the wire protection sleeve includes an elastic arc clamping sleeve, which is made of an elastic metal material in a horn shape. The outer edge of the horn shape of the elastic arc clamping sleeve extends to the inner wall of the sliding sleeve. On one side of the arc of the horn shape of the elastic arc clamping sleeve, there is a pressing cone seat fixed to the insulating cover.

[0010] Preferably, a rubber layer outer layer is bonded to the outer arc side of the elastic arc clamping sleeve. The bottom end of the inner arc side of the elastic arc clamping sleeve is connected with a fixing rod fixed to the side wall of the insulating cover. An inclined pressing rod is connected between the extended part of the horn shape of the elastic arc clamping sleeve and the inner arc side of the horn.

[0011] Preferably, the wire pressing structure includes a plurality of inner hollow grooves opened on the elastic arc clamping sleeve. A shaft rod is rotatably connected inside the inner hollow grooves, and a wire pressing head is fixed to the outer periphery of the shaft rod.

[0012] Preferably, the wire pressing head is composed of a flexible outer sleeve and a wire clamping groove. The wire clamping groove is opened on the outer peripheral side wall of the flexible outer sleeve. The flexible outer sleeve has a structure with the thickness gradually increasing from the side to the center. The thickness of the side of the flexible outer sleeve is the same as the width of the inner hollow groove. The contour of the flexible outer sleeve is a spiral structure with the diameter gradually increasing, and the flexible outer sleeve is made of a flexible material.

[0013] Preferably, the top - fitting piece is connected to the elastic arc clamping sleeve. The top - fitting piece is of an arc - shaped structure and made of an elastic material. One side of the top - fitting piece is a curved arc surface, and the top surface of the curved arc surface is the top - fitting end point.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. By adopting ultrasonic pressing in cooperation with the positioning rod and positioning sleeve for positioning and combining with the design of the ultrasonic melting head, the present invention integrates multiple processes such as fixing the upper and lower shells of the mutual inductor, connecting the winding end and the energizing plate, and fixing the iron core into one step, replacing traditional cumbersome steps such as welding, bonding, and bolt fastening. It significantly shortens the production cycle, reduces man - hour consumption, and remarkably improves production efficiency, solving the problems of complex processes, low efficiency, and waste of a large amount of man - hours.

[0016] 2. The present invention also makes the thermoplastic materials fuse through ultrasonic pressing to form a seamless connection, enhancing the integrity and firmness of the shell; the integrated joint structure utilizes the fusion of low - melting - point metals to ensure the stable connection between the winding and the energizing plate, avoiding virtual soldering and offset soldering; the integrated pressing and fixing structure cooperates with the ring - cone convex head and the locking card to make the iron core fixation more stable, preventing loosening and falling off, further solving the problems of complex processes, low efficiency, and waste of a large amount of man - hours.

[0017] 3. The present invention also has a wire - protecting structure that, through the synergistic action of components such as the sliding sleeve, slope - surface pressing block, and elastic arc clamping sleeve, restricts the winding end during the ultrasonic pressing process to prevent connection detachment caused by shaking; the elastic arc clamping sleeve can straighten the winding line, tighten the excess winding, and avoid friction damage to the insulating layer with the iron core; the wire - pressing structure can automatically adjust the clamping force according to needs to ensure the stability of the winding line.

[0018] 4. The present invention also enables the top - fitting piece to move synchronously with the sliding sleeve, so that it can press the sealing plate, ensuring no gap between the fused metal and the winding end, guaranteeing the quality of the energizing connection, ensuring the tight fit at the connection between the winding end and the energizing end, and improving the connection integrity.

[0019] 5. The present invention also has an elastic design of the elastic arc clamping sleeve, which can not only fix the line during vibration but also adaptively adjust during the thermal expansion and contraction of the winding, avoiding damage to the insulating layer due to excessive stress and ensuring the stable operation of the mutual inductor in different weather environments.

[0020] The present invention reduces the use of materials such as welding, glue, and bolts, as well as the labor and equipment investment required for multiple processes, effectively reducing production costs; at the same time, the stable connection and line protection reduce the maintenance and replacement costs caused by product quality problems. Brief Description of the Drawings

[0021] Figure 1 is the structural schematic diagram of the present invention;

[0022] Figure 2 Schematic diagram of the structure of the lower housing of the mutual inductor of the present invention;

[0023] Figure 3 Schematic diagram of the structure of the upper housing of the mutual inductor in the present invention;

[0024] Figure 4 Schematic diagram of the structure of the integral pressing and fixing structure in the present invention;

[0025] Figure 5 Schematic diagram of the connection structure of the energized end part in the present invention;

[0026] Figure 6 Schematic diagram of the half-sectional structure of the integral joint structure part in the present invention;

[0027] Figure 7 Schematic diagram of the overall structure of the wire protection structure in the present invention;

[0028] Figure 8 Schematic diagram of the structure of the sliding sleeve in the present invention;

[0029] Figure 9 Schematic diagram of the half-sectional structure of the internal structure of the sliding sleeve in the present invention;

[0030] Figure 10 Schematic diagram of the structure of the elastic arc clamping sleeve in the present invention;

[0031] Figure 11 Schematic diagram of the structure of the wire pressing head in the present invention;

[0032] Figure 12 Schematic diagram of the structure of the lower housing part of the mutual inductor in the fixed state in the present invention.

[0033] Explanation of the reference numerals in the figure:

[0034] 1. Upper housing of the mutual inductor; 2. Lower housing of the mutual inductor; 3. Energized end; 4. Constraint ring; 5. Iron core; 6. Winding; 7. Energized plate; 8. Electric insulation cover; 9. Integral joint structure; 10. Integral pressing and fixing structure; 11. Wire protection structure; 12. Wire pressing structure; 13. Top closing piece; 14. Pressure cone seat;

[0035] 181. Positioning rod; 182. Positioning sleeve; 183. Ultrasonic melting head;

[0036] 301. Socket; 302. External connection bolt;

[0037] 901. Elastic rubber edge; 902. Fused metal; 903. Sealing plate;

[0038] 101. Extension column; 102. Pressing sleeve; 103. Locking card; 104. Ring cone convex head;

[0039] 111. Fixed seat; 112. Sliding sleeve; 113. Pressing and moving column; 114. Slope pressing block; 115. Wire protection sleeve; 1151. Elastic arc clamping sleeve; 1152. Outer rubber layer; 1153. Fixed rod; 1154. Pressing rod;

[0040] 121. Inner hollow groove; 122. Shaft rod; 123. Wire pressing head; 1231. Flexible outer sleeve; 1232. Wire clamping groove;

[0041] 131. Bent arc surface; 132. Top mating end point. Specific implementation manner

[0042] As Figures 1 to 12 shown, a low-voltage current transformer related to the present invention includes a transformer upper housing 1 with a hollow center and a transformer lower housing 2. There are two energized end heads 3 provided between one side of the transformer upper housing 1 and the transformer lower housing 2. The energized end head 3 includes an insertion card seat 301. Convex cards are integrally formed on both sides of the insertion card seat 301. The insertion card seat 301 is inserted and fixed to the side walls of the transformer upper housing 1 and the transformer lower housing 2. An external connection bolt 302 is threadedly connected to the insertion card seat 301. An energized plate 7 is installed on the inner side surface of the insertion card seat 301. An insulating cover 8 is installed on one side of the energized plate 7. A restraint ring 4 is integrally formed inside the transformer upper housing 1 and the transformer lower housing 2. An iron core 5 is arranged inside the restraint ring 4. The outer periphery of the iron core 5 is wrapped with an insulating layer, which is generally inexpensive crumpled paper. A winding 6 is wound around the outer periphery of the iron core 5. The winding 6 passes through the insulating cover 8 and is connected to the energized plate 7.

[0043] The transformer upper housing 1 and the transformer lower housing 2 are respectively connected with a positioning rod 181 and a positioning sleeve 182 that are mutually adapted. A plurality of ultrasonic melting heads 183 are connected to the side of the transformer upper housing 1. The transformer upper housing 1 and the transformer lower housing 2 are pressed and combined through an ultrasonic machine head.

[0044] The transformer upper housing 1 and the transformer lower housing 2 are made of thermoplastic materials, such as common polypropylene, polycarbonate, acrylonitrile-butadiene-styrene copolymer, etc. These thermoplastic materials have certain strength and shape stability at normal temperature, and can ensure the structural integrity of the transformer housing during normal use.

[0045] Working principle: Place the upper shell 1 and the lower shell 2 of the transformer under the ultrasonic pressure head, insert the card holder 301 into the lower shell 2 of the transformer, and when fixing, insert the positioning rod 181 on the upper shell 1 of the transformer into the positioning sleeve 182 of the lower shell 2 of the transformer, and press down the ultrasonic pressure head. When the ultrasonic wave acts on the ultrasonic melting head 183, the material in this area quickly absorbs the energy generated by the ultrasonic vibration, the intermolecular friction intensifies, and the temperature rises sharply, causing the thermoplastic material to change from a solid state to a viscous flow state. The material in the viscous flow state has good fluidity, compensating for the gap between the upper shell 1 and the lower shell 2 of the transformer. As the ultrasonic wave stops acting, the temperature gradually decreases, and the viscous flow materials filled in the gap re-solidify and form a whole with the surrounding materials, thereby effectively filling the gap, which not only enhances the sealing of the connection part, but also greatly improves the integrity and firmness of the shell. At the same time, it replaces the fixation of multiple bolts, and its processing convenience and efficiency are improved.

[0046] In order to improve processing efficiency and reduce the number of steps, an integrated joint structure 9 is provided inside the insulating cover 8. The integrated joint structure 9 includes an elastic rubber edge 901 adhered to the lower half of the inner wall of the insulating cover 8. A fusion metal 902 is provided on one side of the elastic rubber edge 901. The fusion metal 902 is a low-melting-point metal material that can be melted by ultrasonic pressing, such as Wood's alloy. A sealing plate 903 is provided on one side of the fusion metal 902. The end of the winding 6 passes through the sealing plate 903 and is located in the center of the fusion metal 902.

[0047] Working principle: When the ends of the winding 6 are connected, the ends are passed through the sealing plate 903 and placed in the center of the fused metal 902, and the above-mentioned ultrasonic pressing is performed. During the pressing process, since the fused metal 902 is located at the position of the upper shell 1 and the lower shell 2 of the transformer, the fused metal 902 absorbs the energy generated by the ultrasonic vibration, the intermolecular friction is intensified, and the temperature rises sharply, causing it to melt into a viscous liquid similar to molten iron. The sealing plate 903 then seals the viscous liquid fused metal 902. After the ultrasound stops, the fused metal 902 returns to a solid state, so that it is fused into a whole with the power-carrying plate 7 and the end of the winding 6, which ensures the stability of the connection and does not cause the end of the winding 6 to fall off due to cold welding or biased welding. The overall operation is simple, and it is formed in one step with the above-mentioned pressed shell, which reduces the processing steps and improves production efficiency.

[0048] In order to further improve the processing efficiency and reduce the number of processes, a plurality of integral pressing structures 10 are arranged on the outer periphery of the restraint ring 4. The integral pressing structure 10 includes an extension column 101. On both sides of the extension column 101, a pressing sleeve 102 and a locking card 103 connected to the upper outer shell 1 and the lower outer shell 2 of the transformer are respectively arranged. The end of the extension column 101 is connected with a ring cone convex head 104. The ring cone convex head 104 is composed of multiple solid rings with increasing diameters. The locking card 103 is a U-shaped structure and passes through the ring cone convex head 104 to contact the pressing sleeve 102.

[0049] Working principle: When the iron core 5 is fixed, the iron core 5 wound with coils is placed on the inner periphery of the restraint ring 4, and the ring cone convex head 104 is placed in the corresponding pressing sleeve 102. During the ultrasonic pressing process, the locking card 103 contacts the bottom wall of the pressing sleeve 102, so that the locking card 103 is fused. With the design of the conical concave-convex head of the ring cone convex head 104 composed of multiple solid rings with increasing diameters, the connection is more stable. Compared with the existing methods of fixing the iron core 5 such as using glue, it ensures the stability of the connection, and will not occur situations such as falling off, unstable fixing and shaking. Moreover, the overall operation is simple, and it is formed in one step with the above-mentioned pressing shell, reducing the processing process and improving the production efficiency.

[0050] In order to stabilize the circuit, wire protection structures 11 are arranged on the outer peripheries of both ends of the iron core 5. The wire protection structure 11 includes a fixing seat 111. One side of the fixing seat 111 is fixed to the inner wall of the lower outer shell 2 of the transformer. A sliding sleeve 112 is arranged on one side of the fixing seat 111. The sliding sleeve 112 is limited to slide with the fixing seat 111, and the limited sliding is realized through a slider and a chute. A pressing displacement column 113 is connected to the outer periphery of the sliding sleeve 112. A slope pressing block 114 fixed to the upper outer shell 1 of the transformer is arranged on one side of the pressing displacement column 113. The slope pressing block 114 is a slope cone. A wire protection sleeve 115 is arranged on the inner periphery of the sliding sleeve 112.

[0051] The wire protection sleeve 115 plays a role in restraining the outer periphery of the end of the winding 6, avoiding large shaking during ultrasonic pressing, resulting in the end falling off from the fusion metal 902, and ensuring the stability of the electrical connection.

[0052] Working principle: During the ultrasonic pressing process, the upper outer shell 1 of the transformer gradually approaches the lower outer shell 2 of the transformer. At the same time, the slope pressing block 114 squeezes the pressing displacement column 113, causing the sliding sleeve 112 to move. During the moving process, the wire protection sleeve 115 will move towards the energized end direction at the end of the winding 6, realizing the function of restraining the end wire, ensuring that the end does not fall off from the fusion metal 902, and ensuring the stability of the connection.

[0053] To protect the insulation between the iron core 5 and the winding 6, the wire guard sleeve 115 includes an elastic arc sleeve 1151. The elastic arc sleeve 1151 is made of elastic metal material in a horn shape. The outer edge of the horn shape of the elastic arc sleeve 1151 extends to the inner wall of the sliding sleeve 112. On one side of the arc of the horn shape of the elastic arc sleeve 1151, there is a pressure cone seat 14 fixed to the insulating cover 8. A rubber layer outer layer 1152 is bonded to the outer arc side of the elastic arc sleeve 1151. The bottom end of the inner arc side of the elastic arc sleeve 1151 is connected to a fixing rod 1153 fixed to the side wall of the insulating cover 8. An inclined pressing rod 1154 is connected between the extended part of the horn of the elastic arc sleeve 1151 and the inner arc side of the horn.

[0054] Working principle: When the sliding sleeve 112 moves, the structure of the elastic arc sleeve 1151 enables the end of the elastic arc sleeve 1151 to restrain the end of the winding 6. During its movement, it can straighten the end line and push the line towards the energized end direction. During the pulling process, the excess lines of the winding 6 outside the iron core 5 are tightened, preventing the winding gaps of the winding 6 from vibrating and contacting the outside of the iron core 5 during vibration, which may cause abrasion and damage to the insulation layer.

[0055] When reaching the movement limit, the bent arc part of the elastic arc sleeve 1151 contacts the pressure cone seat 14, causing the extended part of the horn of the elastic arc sleeve 1151 to move towards the sliding sleeve 112. Further, the inclined pressing rod 1154 moves in the inclined direction, reducing the inclination angle of the pressing rod 1154. One end of it squeezes the position of the elastic arc sleeve 1151, realizing the extrusion at two points and fixing the end.

[0056] It is worth introducing that since the elastic arc sleeve 1151 is made of elastic material, when vibration occurs, the elastic tension of the elastic arc sleeve 1151 can play a role in fixing the wire position. At the same time, when thermal expansion and contraction occur, large stress is generated, which can further pull the elastic arc sleeve 1151 to contract, preventing the insulation layer from being squeezed too tightly during thermal expansion and causing damage to the insulation layer.

[0057] To ensure the clamping effect, the wire protection structure 11 includes multiple groups of wire pressing structures 12. The multiple groups of wire pressing structures 12 are annularly arrayed with the end of the winding 6 as the center and surround and closely adhere. The wire pressing structure 12 includes a plurality of inner hollow grooves 121 opened on the elastic arc sleeve 1151. A shaft rod 122 is rotatably connected inside the inner hollow groove 121. A wire pressing head 123 is fixed to the outer periphery of the shaft rod 122. The wire pressing head 123 is composed of a flexible outer sleeve 1231 and a wire clamping groove 1232. The wire clamping groove 1232 is opened on the outer peripheral side wall of the flexible outer sleeve 1231. The flexible outer sleeve 1231 has a structure with the thickness gradually increasing from the side to the center. The thickness of the side of the flexible outer sleeve 1231 is the same as the width of the inner hollow groove 121. The contour of the flexible outer sleeve 1231 is a spiral structure with the diameter gradually increasing. The flexible outer sleeve 1231 is made of flexible material, preferably high-friction materials such as latex and rubber.

[0058] Working principle: When the sliding sleeve 112 undergoes displacement, multiple flexible outer sleeves 1231 come into contact with the outer periphery of the end. During the process of their insertion, when the friction is small and insufficient to generate enough fixing force to tighten the winding 6 around the coil, the flexible outer sleeves 1231 rotate. Since the contour of the flexible outer sleeves 1231 has an increasing diameter, it can make the contact closer. Also, due to the width limitation of the inner hollow groove 121 and the increasing thickness of the flexible outer sleeves 1231, during the process of the flexible outer sleeves 1231 rotating out, with the thickness increasing and the inner hollow groove 121 remaining unchanged, a squeezing effect towards the center will gradually be generated. The centers of both sides of the wire clamping groove 1232 move, and the wire clamping groove 1232 can clamp the outer periphery of the wire. In combination with the self-clamping of the flexible outer sleeves 1231 themselves, a stable clamping state can be generated, so that when the sliding sleeve 112 slides, sufficient binding force can be ensured to tighten the wire of the winding 6 and avoid the occurrence of insufficient clamping force.

[0059] In order to improve the connection stability of the winding 6, a top contact piece 13 is further provided on the wire protection structure 11. The top contact piece 13 is connected to the elastic arc clamping sleeve 1151. The top contact piece 13 is of an arc-shaped structure and made of an elastic material. One side of the top contact piece 13 is a curved arc surface 131, and the top end surface of the curved arc surface 131 is the top contact end point 132.

[0060] Working principle: When the sliding sleeve 112 moves, the top contact piece 13 moves along. When it reaches the limit, the top contact piece 13 contacts and presses against the sealing plate 903, so as to avoid generating a gap at the connection between the end of the winding 6 and the energized end 3 and ensure the integrity of the fusion connection.

[0061] It should be noted that all the above operations are synchronously realized in one process of ultrasonic pressing of the outer shell, reducing the processes such as the end connection of the winding 6, bonding the iron core 5, and thread-fixing the outer shell. The connection quality is improved, the production process is reduced, the production efficiency is greatly improved, and the winding 6 and the iron core 5 are protected, adapting to different weather environments.

[0062] The embodiments disclosed in the present invention are the preferred embodiments, but are not limited thereto. Those of ordinary skill in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not depart from the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A low-voltage current transformer, characterized in that, It includes a center-hollow upper transformer housing and a lower transformer housing. There are two energized terminals provided between one side of the upper transformer housing and the lower transformer housing. An integral restraint ring is formed inside the upper transformer housing and the lower transformer housing. A iron core is arranged inside the restraint ring. An insulating layer is wrapped around the outer periphery of the iron core, and a winding is wound around the outer periphery of the iron core; The upper transformer housing and the lower transformer housing are respectively connected with a positioning rod and a positioning sleeve that are mutually adapted. A plurality of ultrasonic fusing heads are connected to the side of the upper transformer housing. The upper transformer housing and the lower transformer housing are pressed together by an ultrasonic machine head. An energizing plate is installed at the inner end of the energized terminal. An insulating cover is installed on one side of the energizing plate. An integral joint structure is arranged inside the insulating cover. The integral joint structure includes an elastic rubber edge pasted on the lower half of the inner wall of the insulating cover. A fusing metal is arranged on one side of the elastic rubber edge. The fusing metal is a low-melting-point metal material that can be melted by ultrasonic pressing. A sealing plate is arranged on one side of the fusing metal. The end of the winding passes through the sealing plate and is located at the center of the fusing metal. A plurality of integral pressing structures are arranged on the outer periphery of the restraint ring. The integral pressing structure includes an extension column. Pressing sleeves and locking cards connected to the upper transformer housing and the lower transformer housing are respectively arranged on both sides of the extension column. The end of the extension column is connected with a ring cone convex head. The ring cone convex head is composed of multiple solid ring bodies with increasing diameters. The locking card is a U-shaped structure and passes through the ring cone convex head to contact the pressing sleeve. Protective wire structures are arranged on the outer peripheries of both ends of the iron core. The protective wire structure includes multiple groups of wire pressing structures. The multiple groups of wire pressing structures are arranged in a circular array centered on the winding end and surround and tightly adhere. A top pressing piece is also arranged on the protective wire structure. The top pressing piece is an arc-shaped structure and is made of an elastic material. One side of the top pressing piece is a curved arc surface, and the top surface of the curved arc surface is the top pressing end point.

2. The low-voltage current transformer according to claim 1, characterized in that, The energized terminal includes a socket. Convex cards are integrally formed on both sides of the socket. The socket is inserted and fixed to the side walls of the upper transformer housing and the lower transformer housing. An external connection bolt is threadedly connected to the socket.

3. A low-voltage current transformer according to claim 1 or 2, characterized in that, The protective wire structure includes a fixed seat. One side of the fixed seat is fixed to the inner wall of the lower transformer housing. A sliding sleeve is arranged on one side of the fixed seat. The sliding sleeve is limited and slides with the fixed seat. A pressing displacement column is connected to the outer periphery of the sliding sleeve. A slope pressing block fixed to the upper transformer housing is arranged on one side of the pressing displacement column. The slope pressing block is slope-shaped and conical. A wire protection sleeve is arranged on the inner periphery of the sliding sleeve.

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