Current transformer with plastic package type shell

Abstract

The invention discloses a current transformer with a plastic package type shell, and relates to the technical field of current transformers, the current transformer comprises a protective shell, the inner side of the protective shell is fixedly connected with four coil shells, the inner sides of the four coil shells are fixedly connected with iron cores, and the outer wall of each iron core is wound with a coil; the current switching mechanism is arranged on the inner side of the protective shell and is used for switching the flow direction of current; by arranging the current switching mechanism and switching the number of the coils participating in work, four-gear accurate current reduction of 1 / 5, 1 / 10, 1 / 15 and 1 / 20 is achieved, the current conversion requirements of different scenes can be flexibly met, multiple mutual inductors with different current conversion ratios do not need to be additionally purchased, one set of equipment can cover the multi-gear requirement, and the cost is reduced. The operation efficiency and the current reduction precision are improved through automatic control, the equipment purchase and maintenance cost is remarkably reduced, and the overall practicability of the device is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of current transformer technology, and more particularly to a current transformer with a plastic-encapsulated housing. Background Technology

[0002] Plastic-encapsulated current transformers are current measuring devices that encapsulate core components such as iron cores and windings in a fully sealed manner using flame-retardant alloys. They typically use toroidal iron cores to reduce magnetic leakage. The iron core material is selected based on accuracy requirements, such as silicon steel sheets and permalloy. They combine the advantages of light size, low cost, and maintenance-free operation, and are mainly used in low-voltage power distribution, new energy, and industrial automation scenarios.

[0003] The existing encapsulated current transformer operates as follows: the primary winding is connected in series with the circuit under test, and after current flows through it, it generates an alternating magnetic field. This magnetic field is concentrated into a magnetic flux through a high-permeability toroidal iron core, which in turn induces a secondary current in the secondary winding on the iron core that is proportional to the primary current, thus powering subsequent measurement or protection equipment. However, this method has obvious limitations: when the measured current is too large, the induced current on the secondary side will also exceed the limit. At this time, it is necessary to replace it with a special device equipped with more winding coils to reduce the current, which greatly increases the complexity of operation. To address this issue, we designed a current transformer with an encapsulated housing to solve the above problems. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the current transformer with a plastic-encapsulated housing, the present invention is proposed.

[0006] Therefore, the purpose of this invention is to provide a current transformer with a plastic-encapsulated housing, which solves the problem that when the measured current is too large, the induced current on the secondary side will also exceed the limit. In this case, it is necessary to replace it with a special device equipped with more winding coils to reduce the current, which greatly increases the complexity of operation.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a current transformer with a plastic-encapsulated shell, the device comprising: a protective shell, wherein four coil shells are fixedly connected to the inner side of the protective shell, and an iron core is fixedly connected to the inner side of each of the four coil shells, and a coil is wound around the outer wall of each iron core; a current switching mechanism, wherein the current switching mechanism is disposed inside the protective shell and is used to switch the direction of current flow, the current switching mechanism comprising four third terminals and four second terminals fixedly connected to the inner side of the protective shell, each second terminal having a second metal post at its top, and each end of each coil being fixedly connected to one of the third terminals and one of the second metal posts respectively; a current disconnector, wherein the current disconnector is disposed on one side of the coil shell and is used to disconnect the coil from the external current; and an air blowing unit, wherein the air blowing unit is disposed on one side of the second terminals and is used to clean the dust between the second terminals and the second metal posts.

[0008] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the current switching mechanism further includes four sets of terminals fixedly connected to the inner side of the protective housing. Each set of terminals is correspondingly arranged on one side of a coil housing. Each set of terminals has two terminals. A second connecting wire is installed between one terminal and the second terminal, and a third connecting wire is installed between the other terminal and the third terminal. A connecting groove is opened on the outer wall of each of the two terminals, and a current switch is provided on one side of each terminal.

[0009] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the current switch includes four second connecting rods disposed inside the protective housing, four drive motors are installed on one side of the protective housing, the output ends of the four drive motors are all fixedly connected to a connecting rod through the inner side of the protective housing, and the second connecting rods are fixedly connected to the outer wall of the connecting rods. A first metal post is fixedly connected to the top of the connecting rods, and a fourth connecting wire is installed between three of the second connecting rods and adjacent second connecting posts. A connecting assembly is provided on one side of the second connecting rods.

[0010] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the connection assembly includes a first terminal rod fixedly connected to the inner side of the protective housing, and a first connecting wire is installed on the outer wall of the first terminal rod and the outer wall of one of the second terminal rods.

[0011] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the current disconnector includes an insulating limiting rod fixedly connected to the top of the second terminal, and the second metal post is slidably connected to the outer wall of the insulating limiting rod, and a compression spring is installed between the second metal post and the insulating limiting rod.

[0012] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the current disconnector further includes a connecting strip disposed on the top of the second metal column, two connecting seats are fixedly connected to the bottom of the connecting strip, a rotating wheel is rotatably connected to the inner side of each of the two connecting seats, and a power component is disposed on one side of the connecting seat.

[0013] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the power assembly includes an insulating disk fixedly connected to the top of the connecting rod, a small cylinder fixedly connected to the top of the insulating disk, a connecting frame sleeved on the outer wall of the small cylinder, and the connecting frame fixedly connected to the connecting strip.

[0014] As a preferred embodiment of the current transformer with a plastic-encapsulated housing described in this invention, the outer wall of the second metal column is provided with an arc-shaped inclined surface.

[0015] As a preferred embodiment of the current transformer with a plastic-encapsulated shell according to the present invention, the air blowing unit includes four fixed plates fixedly connected to the inner side of the protective shell, and a fixed cylinder is fixedly connected to the top of each fixed plate. A vent plate is fixedly connected to the inner side of the fixed cylinder, and a plurality of vent grooves are opened on the inner side of the vent plate.

[0016] As a preferred embodiment of the current transformer with a plastic-encapsulated housing according to the present invention, the air blowing unit further includes a piston rod slidably connected to the inside of the fixed cylinder, and the other side of the piston rod extends through to the other end of the fixed plate and is fixedly connected to the connecting strip.

[0017] The beneficial effects of this invention are:

[0018] 1. By setting a current switching mechanism to switch the number of coils involved in the operation, four levels of precise current reduction (1 / 5, 1 / 10, 1 / 15, and 1 / 20) are achieved. This can flexibly adapt to the current conversion needs of different scenarios. There is no need to purchase multiple current transformers with different current ratios. One set of equipment can cover multiple levels of needs. It not only improves the operating efficiency and current reduction accuracy through automated control, but also significantly reduces the equipment purchase and maintenance costs. It is especially suitable for industrial scenarios with high requirements for current conversion flexibility, effectively improving the overall practicality of the device.

[0019] 2. By setting up a current switch, the faulty coil can be skipped and automatically connected to the backup coil. The path switching can be completed without manual intervention, which fundamentally avoids the problem of the entire operation of traditional current transformers caused by the failure of a single coil. By constructing redundant backup logic between coils, the device can not only ensure the continuity of the current conversion process and ensure the stable operation of downstream measurement and protection equipment, but also simplify the operation and maintenance process, greatly improve the fault resistance and operational reliability under complex industrial conditions, and further enhance the practical value of the equipment.

[0020] 3. By setting up a current disconnector, the second terminal and the second metal post are completely disconnected. This ensures that during the transition phase when the old connection is disconnected and the new connection is not yet fully established, the rigid synchronous action of the mechanical structure avoids the risk of both circuits conducting simultaneously. It completely eliminates the risk of short circuits and current shunting interference during the switching moment, strictly ensuring the uniqueness of the current path. At the same time, this design allows the disconnected coil to achieve complete electrical isolation from both ends of the main line. This not only completely eliminates the safety hazards and electromagnetic interference that may be caused by the idle coil, but also provides effective protection for the coil itself, further improving the stability and reliability of the entire system.

[0021] 4. By setting up an air blowing unit, a directional airflow is formed, which is precisely applied to the disconnection point between the second terminal and the second metal post. The airflow can simultaneously blow away residual metal debris, dust and oxide layer at this point, effectively preventing impurities from adhering to the surface of the terminal and the metal post. This cleaning effect can ensure that the contact surface always maintains a good conductivity when reconnecting in the future, greatly reducing the risk of local heating or poor contact caused by excessive contact resistance, and providing a guarantee for the stability of current transmission. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a cross-sectional view of the present invention.

[0025] Figure 3 This is a partial structural diagram of the current switching mechanism of the present invention.

[0026] Figure 4 This is a schematic diagram of the first metal pillar structure of the present invention.

[0027] Figure 5 This is a schematic diagram of the current switch structure of the present invention.

[0028] Figure 6 This is a schematic diagram of the current disconnector structure of the present invention.

[0029] Figure 7 For the present invention Figure 6 Enlarged view of point A in the middle.

[0030] Figure 8 This is an exploded view of the second terminal, the second metal post, and the insulating limit rod components of the present invention.

[0031] Figure 9 This is a schematic diagram of the fourth connecting line structure of the present invention.

[0032] Figure 10 This is a schematic diagram of the second connecting line structure of the present invention.

[0033] In the diagram: 1. Protective shell; 2. Coil outer shell; 3. Iron core; 4. Coil; 5. First connecting rod; 6. First connecting wire; 7. Second connecting rod; 8. Connecting rod; 9. Drive motor; 10. First metal post; 11. Terminal post; 12. Connecting groove; 13. Second connecting wire; 14. Third connecting wire; 15. Fixing plate; 16. Fixing cylinder; 17. Piston rod; 18. Connecting strip; 19. Connecting frame; 20. Insulating disc; 21. Small cylinder; 22. Connecting seat; 23. Rotating wheel; 24. Arc-shaped inclined surface; 25. Second terminal post; 26. Fourth connecting wire; 27. Second metal post; 28. Insulating limit rod; 29. ​​Compression spring; 30. Third terminal post; 31. Ventilation plate. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0038] Reference Figures 1-10 A current transformer with a plastic-encapsulated housing is provided, comprising: a protective housing 1, four coil housings 2 fixedly connected to the inner side of the protective housing 1, an iron core 3 fixedly connected to the inner side of each of the four coil housings 2, and a coil 4 wound around the outer wall of each iron core 3; a current switching mechanism, disposed inside the protective housing 1, for switching the direction of current flow, the current switching mechanism including four third terminals 30 and four second terminals 25 fixedly connected to the inner side of the protective housing 1, each second terminal 25 having a second metal post 27 at its top, and each coil 4 having its two ends fixedly connected to one third terminal 30 and one second metal post 27 respectively; the current switching mechanism further includes four sets of terminals 11 fixedly connected to the inner side of the protective housing 1, each set of terminals 11 corresponding to one side of a coil housing 2, each set of terminals 11 having two terminals, one of which is installed between a terminal 11 and a second terminal 25. There is a second connecting line 13, and a third connecting line 14 is installed between another terminal 11 and the third terminal 30. A connecting groove 12 is opened on the outer wall of each of the two terminals 11. A current switch is provided on one side of the terminal 11. The current switch includes four second connecting rods 7 set inside the protective shell 1. Four drive motors 9 are installed on one side of the protective shell 1. The output end of each of the four drive motors 9 passes through the inner side of the protective shell 1 and is fixedly connected to a connecting rod 8. The second connecting rods 7 are fixedly connected to the outer wall of the connecting rod 8. A first metal post 10 is fixedly connected to the top of the connecting rod 8. A fourth connecting line 26 is installed between three of the second connecting rods 7 and the adjacent second terminal 25. A connecting assembly is provided on one side of the second connecting rod 7. The connecting assembly includes a first connecting rod 5 fixedly connected inside the protective shell 1. A first connecting line 6 is installed on the outer wall of the first connecting rod 5 and the outer wall of one of the second connecting rods 7.

[0039] Each coil has 25 turns, and the outer primary coil has 5 turns, corresponding to a turns ratio of 1:5;

[0040] The drive motor 9 is controlled by a PLC controller, which can control the intermittent start of the drive motor 9. When the operator needs to reduce the current, simply connect the external power cord to one end of the first terminal 5 and connect the detection power cord to the bottom of the fourth second terminal 25. In the initial state of the device, all four first metal terminals 10 are connected to the first terminal 11. If it is necessary to reduce the current to 1 / 5, the PLC controller starts the second, third, and fourth drive motors 9, driving the second terminal 7 at their top to rotate, causing the corresponding three first metal terminals 10 to switch to connection with the second terminal 11, so that the current only flows through the first coil 4, avoiding excessive current reduction. If it is necessary to reduce the current to 1 / 10, the PLC starts the third and fourth drive motors 9, causing the corresponding two first metal terminals 10 to switch to connection with the second terminal 11, so that the current only flows through the first coil 4, avoiding excessive current reduction. When the connection of column 10 is switched, the current flows through the first and second coils 4; and so on. When the current drops to 1 / 15, only the fourth drive motor 9 is activated, and the current flows through the first three coils 4; when the current drops to 1 / 20, the current flows directly through all four coils 4. This design achieves precise current reduction at four levels: 1 / 5, 1 / 10, 1 / 15, and 1 / 20 by switching the number of coils involved in the operation. It can flexibly adapt to the current conversion needs of different scenarios. There is no need to purchase multiple current transformers with different current ratios. One set of equipment can cover multiple levels of needs. It improves the operating efficiency and current reduction accuracy through automated control, and significantly reduces the equipment purchase and maintenance costs. It is especially suitable for industrial scenarios with high requirements for current conversion flexibility, and effectively improves the overall practicality of the device.

[0041] When current flows through the first coil 4, if an open circuit fault occurs, the PLC controller will immediately start the first and second drive motors 9, driving the corresponding first metal post 10 to rotate, causing the first metal post 10 to switch to the first group of second terminals 11, and the second first metal post 10 to switch to the second group of first terminals 11. The current will then automatically skip the faulty coil and flow through the second coil 4. Similarly, if the second coil 4 fails, the second and third drive motors 9 will start, connecting the second first metal post 10 to the second group of second terminals 11 and the third first metal post 10 to the third group of first terminals 11. 1. The current is redirected to flow through the third coil, ensuring that the faulty coil is accurately isolated. This closed-loop mechanism of "real-time fault detection - drive motor linkage switching - automatic access of backup coil" can complete millisecond-level path switching without manual intervention. It fundamentally avoids the problem of overall shutdown caused by a single coil failure in traditional current transformers. By constructing redundant backup logic between coils, the device can not only ensure the continuity of the current conversion process and ensure the stable operation of downstream measurement and protection equipment, but also simplify the operation and maintenance process, greatly improve the fault resistance and operational reliability under complex industrial conditions, and further enhance the practical value of the equipment.

[0042] Reference Figures 2-7A current transformer with a plastic-encapsulated housing and a current disconnector are provided. The current disconnector is disposed on one side of the coil housing 2 and is used to disconnect the coil 4 from the external current. The current disconnector includes an insulating limiting rod 28 fixedly connected to the top of the second terminal 25, and a second metal post 27 slidably connected to the outer wall of the insulating limiting rod 28. A compression spring 29 is installed between the second metal post 27 and the insulating limiting rod 28. The current disconnector also includes a connecting strip 18 disposed on the top of the second metal post 27. Two connecting seats 22 are fixedly connected to the bottom of the connecting strip 18. Rotating wheels 23 are rotatably connected to the inner side of each of the two connecting seats 22. A power assembly is disposed on one side of the connecting seat 22. The power assembly includes an insulating disk 20 fixedly connected to the top of the connecting rod 8. A small cylinder 21 is fixedly connected to the top of the insulating disk 20. A connecting frame 19 is sleeved on the outer wall of the small cylinder 21, and the connecting frame 19 is fixedly connected to the connecting strip 18. An arc-shaped inclined surface 24 is provided on the outer wall of the second metal post 27.

[0043] When the first metal post 10 disengages from the first terminal post 11 and rotates to switch to the second terminal post 11, it will synchronously drive the insulating disk 20 to rotate, thereby driving the small cylinder 21 to rotate, pushing the connecting frame 19 to move towards the insulating limit rod 28, causing the connecting strip 18 to move in the same direction, and finally driving the rotating wheel 23 to move. When the bottom of the rotating wheel 23 contacts the curved inclined surface 24, the second metal post 27 is pulled upward under the combined mechanical action and the elastic force of the compression spring 29, so that the second terminal 25 and the second metal post 27 are completely disconnected. The core value of this precise linkage process is that, in the transition stage where "the old connection is disconnected and the new connection has not yet been fully established", the rigid synchronous action of the mechanical structure avoids the risk of two circuits being turned on at the same time from the root, completely eliminates the short circuit hazard and current shunting interference at the moment of switching, and strictly ensures the uniqueness of the current path. At the same time, this design can achieve complete electrical isolation between the disconnected coil 4 and the two ends of the main line, which not only completely eliminates the safety hazards and electromagnetic interference that may be caused by the idle coil, but also effectively protects the coil itself, further improving the stability and reliability of the entire system operation.

[0044] Reference Figures 4-10 A current transformer with a plastic-encapsulated housing is provided, and an air blowing unit is provided. The air blowing unit is disposed on one side of the second terminal 25 and is used to clean the dust between the second terminal 25 and the second metal post 27. The air blowing unit includes four fixed plates 15 fixedly connected to the inside of the protective housing 1. Each fixed plate 15 has a fixed cylinder 16 fixedly connected to its top. A vent plate 31 is fixedly connected to the inside of the fixed cylinder 16. The vent plate 31 has multiple vent grooves on its inside side. The air blowing unit also includes a piston rod 17 slidably connected to the inside of the fixed cylinder 16. The other side of the piston rod 17 extends through to the other end of the fixed plate 15 and is fixedly connected to a connecting strip 18.

[0045] When the connecting bar 18 moves toward the insulating limit rod 28, it will drive the piston rod 17 to move synchronously in that direction. During the displacement, the piston rod will squeeze the internal space of the fixed cylinder 16, expelling the air inside the cylinder and forming a directional airflow. This airflow will precisely act on the disconnection point between the second terminal 25 and the second metal post 27. The ejected airflow can simultaneously blow away residual metal debris, dust, and oxide layer at this point, effectively preventing impurities from adhering to the surface of the terminal and the metal post. This cleaning action can ensure that the contact surface always maintains a good conductive state when reconnecting later, greatly reducing the risk of local heating or poor contact caused by excessive contact resistance, and providing a guarantee for the stability of current transmission.

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A current transformer with a plastic-encapsulated housing, characterized in that, include: A protective shell (1) has four coil shells (2) fixedly connected to its inner side. Each of the four coil shells (2) has an iron core (3) fixedly connected to its inner side. Each iron core (3) has a coil (4) wound around its outer wall. A current switching mechanism is provided inside the protective shell (1) for switching the direction of current flow. The current switching mechanism includes four third terminals (30) and four second terminals (25) fixedly connected inside the protective shell (1). Each second terminal (25) is provided with a second metal post (27) at its top, and both ends of each coil (4) are fixedly connected to one third terminal (30) and one second metal post (27), respectively. A current disconnector is disposed on one side of the coil housing (2) and is used to disconnect the coil (4) from the external current. An air blowing unit is provided on one side of the second terminal (25) for cleaning dust between the second terminal (25) and the second metal post (27).

2. A current transformer with a plastic-encapsulated housing according to claim 1, characterized in that: The current switching mechanism also includes four sets of terminals (11) fixedly connected to the inner side of the protective shell (1). Each set of terminals (11) is correspondingly arranged on one side of a coil shell (2). Each set of terminals (11) has two terminals. One terminal (11) is connected to the second terminal (25) with a second connecting line (13), and the other terminal (11) is connected to the third terminal (30) with a third connecting line (14). A connecting groove (12) is opened on the outer wall of each of the two terminals (11). A current switcher is provided on one side of the terminal (11).

3. A current transformer with a plastic-encapsulated housing according to claim 2, characterized in that: The current switch includes four second terminal rods (7) disposed inside the protective shell (1). Four drive motors (9) are installed on one side of the protective shell (1). The output ends of the four drive motors (9) all pass through the inner side of the protective shell (1) and are fixedly connected to a connecting rod (8). The second terminal rods (7) are fixedly connected to the outer wall of the connecting rod (8). A first metal post (10) is fixedly connected to the top of the connecting rod (8). A fourth connecting line (26) is installed between three of the second terminal rods (7) and the adjacent second terminal post (25). A connecting component is provided on one side of the second terminal rod (7).

4. A current transformer with a plastic-encapsulated housing according to claim 3, characterized in that: The connection assembly includes a first terminal rod (5) fixedly connected to the inner side of the protective shell (1), and a first connecting line (6) is installed on the outer wall of the first terminal rod (5) and the outer wall of one of the second terminal rods (7).

5. A current transformer with a plastic-encapsulated housing according to claim 4, characterized in that: The current disconnector includes an insulating limit rod (28) fixedly connected to the top of the second terminal (25), and the second metal post (27) is slidably connected to the outer wall of the insulating limit rod (28). A compression spring (29) is installed between the second metal post (27) and the insulating limit rod (28).

6. A current transformer with a plastic-encapsulated housing according to claim 5, characterized in that: The current disconnector also includes a connecting strip (18) disposed on the top of the second metal column (27). Two connecting seats (22) are fixedly connected to the bottom of the connecting strip (18). Rotating wheels (23) are rotatably connected to the inner side of the two connecting seats (22). A power component is disposed on one side of the connecting seat (22).

7. A current transformer with a plastic-encapsulated housing according to claim 6, characterized in that: The power assembly includes an insulating disc (20) fixedly connected to the top of the connecting rod (8), a small cylinder (21) fixedly connected to the top of the insulating disc (20), a connecting frame (19) sleeved on the outer wall of the small cylinder (21), and the connecting frame (19) fixedly connected to the connecting strip (18).

8. A current transformer with a plastic-encapsulated housing according to claim 7, characterized in that: The outer wall of the second metal column (27) is provided with an arc-shaped inclined surface (24).

9. A current transformer with a plastic-encapsulated housing according to claim 8, characterized in that: The air blowing unit includes four fixed plates (15) fixedly connected to the inside of the protective shell (1). Each fixed plate (15) has a fixed cylinder (16) fixedly connected to its top. The inside of the fixed cylinder (16) is fixedly connected to a breathable plate (31), and the inside of the breathable plate (31) has multiple breathable grooves.

10. A current transformer with a plastic-encapsulated housing according to claim 9, characterized in that: The air blowing unit also includes a piston rod (17) slidably connected to the inside of the fixed cylinder (16), and the other side of the piston rod (17) extends through to the other end of the fixed plate (15) and is fixedly connected to the connecting strip (18).

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