High-accuracy outdoor flexible current transformer capable of outputting 5A

Abstract

The invention discloses a high-accuracy outdoor flexible current transformer capable of outputting 5A. The transformer adopts an open type flexible iron core design, and an iron core is formed by winding a high-permeability silicon steel strip and has bendability. The open section is subjected to paint dipping reinforcement and high-precision cutting, so that the iron core can be seamlessly jointed again after being disconnected, a magnetic circuit is continuous after being closed, and the measurement accuracy of the open type mutual inductor is remarkably improved. The shell is composed of two halves and is provided with a dual fixing structure of buckling and rotary locking, and firm sealing in an outdoor vibration environment is ensured while quick disassembly and assembly are achieved. The peripheries of the iron core and the winding are covered with the flexible protection sheath, the sheath can adopt a high-flexibility corrugated pipe or a hinge type folding structure, and the weather resistance and the mechanical protection performance of the device are improved. The device has the advantages of being convenient to install, high in precision and high in protection level, and is particularly suitable for outdoor electric power system transformation and current measurement in metering occasions.

Description

Technical Field

[0001] This invention relates to the field of power measurement equipment, and specifically to a high-accuracy outdoor flexible current transformer with an output of 5A. Background Technology

[0002] Current transformers are crucial devices in power systems for measuring and monitoring current. Traditional current transformers typically employ a closed-core structure, forming a rigid ring. During installation, the primary conductor must pass through the center of the core. This type of solid-core transformer often requires disconnecting the primary circuit or dismantling the busbar, complicating on-site construction. To address this installation inconvenience, open-type (split-type) current transformers have emerged, where the core can be opened and clipped onto the conductor from the side. These transformers typically use hinges or clips to divide the core in two, allowing installation without dismantling the main circuit. However, traditional open-type current transformers suffer from a decrease in measurement accuracy due to the air gap in the core and discontinuous magnetic circuit. The accuracy is generally low (e.g., only reaching class 1.0 or 3.0), making it difficult to meet high-precision metering requirements. Especially in outdoor environments, the opening requires excellent sealing and mechanical strength to prevent water and dust damage and withstand temperature changes. Improper sealing allows moisture and dust to enter the air gap, further deteriorating measurement accuracy.

[0003] Currently, there are some flexible current sensor products on the market, such as those based on Rogowski coils. These consist of flexible windings that can be easily wound onto large-size busbars. However, the output voltage signal of a Rogowski coil requires a matching integrating circuit, and its accuracy and anti-interference capabilities are limited, making it impossible to directly provide a standard 5A secondary current output. On the other hand, some foreign companies (such as Flex-Core in the United States) offer split-type current transformers that can provide 5A or 1A secondary current output, claiming metrological-grade accuracy. However, most of these existing products have rigid structures and lack flexibility, making installation difficult in confined spaces or with irregular busbar shapes. Their measurement accuracy changes significantly under vibration or impact conditions, resulting in poor reliability. Furthermore, their waterproof and weather-resistant performance is limited, leading to insufficient reliability for long-term outdoor use. Moreover, achieving high accuracy still relies on precision machining and assembly, resulting in high costs. Therefore, there is an urgent need for an improved outdoor flexible current transformer that improves accuracy and reliability while ensuring ease of installation.

[0004] For the reasons mentioned above, it is necessary to propose a high-accuracy outdoor flexible current transformer with an output of 5A to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide a high-accuracy outdoor flexible current transformer with an output of 5A.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A high-accuracy outdoor flexible current transformer with an output of 5A includes a toroidal core, a waterproof connector, and a flexible sheath. The toroidal core is equipped with a secondary winding and an output cable is led out from a waterproof connector. The toroidal core includes a bent deformation section and a straight opening section. The shape of the bent deformation section can be bent and changed, while the straight opening section is inflexible and arranged in a straight line. The middle of the straight opening section is broken to form a splicing joint end. The two ends of the bent deformation section are respectively connected to the joint end. When the two joint ends are spliced ​​together, they form a complete straight opening section and make the toroidal core closed in a ring. When the two joint ends are separated, the toroidal core forms a C shape, forming an opening for the primary circuit to pass through the toroidal core. The waterproof connector includes a waterproof male connector and a waterproof female connector that fit together, with two disconnected ends respectively located inside the waterproof male connector and the waterproof female connector; The flexible sheath includes an iron core sheath and a joint sheath. The iron core sheath is wrapped around the annular iron core, and the joint sheath is fitted over the waterproof joint. The two ends of the joint sheath are respectively connected to the two ends of the iron core sheath to form an annular seal.

[0007] Furthermore, the toroidal core is formed by winding high-permeability silicon steel strip into a ring shape, with multiple turns of the silicon steel strip forming a flexible bending deformation section. The joint ends are planar cuts, ensuring a tight fit between the two joint ends, guaranteeing magnetic circuit continuity and reducing magnetic resistance. During manufacturing, the open straight section of the core is first impregnated with paint for reinforcement, and then cut into joints using a high-precision cutting process. The cut joints fit tightly with minimal air gaps, ensuring almost no magnetic flux leakage after the core is closed, meeting the technical requirements of high-accuracy current transformers.

[0008] Furthermore, the joint end has an axial degree of freedom for axial extension and retraction relative to the waterproof male and female connectors.

[0009] Furthermore, the side of the butt joint end is provided with a side groove. The waterproof male connector has a cylindrical structure with an axial cavity for the butt joint end to pass through, and a concave groove is formed at one end of the waterproof male connector. The waterproof udder includes an outer sleeve and an inner sleeve. The outer sleeve is coaxially sleeved on the outside of the inner sleeve. The inner sleeve extends through both ends of the outer sleeve and has an axial cavity for the butt joint ends to pass through. One end of the inner sleeve protrudes and has a locking tongue that is inserted into a slot. The bottom surface of the slot has a sealing groove surrounding the butt joint ends, and a sealing ring is provided in the sealing groove. The end of the locking tongue is inserted into the sealing groove and abuts against the sealing ring. The waterproof male connector and inner sleeve are provided with a locking block structure that matches the side groove. The locking block structure is inserted into the side groove to limit the axial degree of freedom of the joint end.

[0010] Furthermore, the locking block structure includes two interlocking semi-circular locking flap structures, and an elastic element disposed on one side of the locking flap structure and in contact with the side groove. The locking flap structure has a central groove on its planar side, and side slots on both sides of the central groove. The locking flap structure is inserted into the interior of the waterproof male head and inner sleeve from the side, so that the central groove is engaged with the side groove from the side. After the two semi-circular locking flap structures are inserted relative to each other, they are spliced ​​together to form a circular locking block structure. The elastic element is configured to ensure that when the two broken ends are joined, the two broken ends always have a tendency to move towards each other, so that the two broken ends maintain good jointing when moving within a certain axial degree of freedom.

[0011] Furthermore, one end of the waterproof male head is provided with an external thread, and the outer sleeve is provided with an internal thread that is screwed into the external thread. As the outer sleeve is screwed in, its inner shoulder is squeezed and clamped.

[0012] Furthermore, the iron core sheath is a flexible threaded tube sheath, and the two ends of the flexible threaded tube sheath are fixed to the waterproof joint by adhesive or clips. The flexible threaded tube sheath is made of PVC or rubber material.

[0013] Furthermore, the iron core sheath is a hinged foldable sheath, which includes several rigid sleeves connected end to end to form a ring, with adjacent rigid sleeves hinged together.

[0014] Furthermore, an annular meshing tooth structure is machined on the plane of the fracture joint end. The annular meshing tooth structure includes several concentric arcs or rings of protruding parts, and the annular meshing tooth structures on the two fracture joint ends mesh with each other when they are joined.

[0015] A method for processing a toroidal iron core, comprising the aforementioned toroidal iron core, includes the following steps: S1: Core winding, using silicon steel sheets or nanocrystalline alloy strips as raw materials, the thin strips are wound in multiple layers to form the cross-sectional dimensions required for the ring core, thus forming a closed core. S2: Curing and shaping. A certain length is selected on the closed iron core as the part for machining the straight opening. The curvature of this part is straightened and assisted in fixing. Then, this part is impregnated with paint and cured to make the iron core layers at this end bonded and fixed to increase rigidity. The rest of the iron core is not cured. S3: Cut the opening. Use a precision wire cutting machine to cut the closed iron core along the predetermined cutting line on the straight opening and form two butt joint ends. S4: Grinding and smoothing: The flat surfaces cut out at the joint ends of the two fractures are precisely ground and smoothed to make the cuts straight and smooth, and the joint ends fit tightly together.

[0016] The advantages and beneficial effects of this invention are as follows: 1. Easy Installation: Utilizing a flexible open core and split housing design, the current transformer can be directly installed onto any cable or busbar without removing the primary busbar. The snap-fit ​​and twist-lock mechanism of the housing allows for quick installation and removal, enabling a single person to complete the installation, significantly improving on-site construction efficiency. It is especially suitable for retrofitting existing equipment or installation needs in confined spaces.

[0017] 2. High Measurement Accuracy: By impregnating and curing the open section of the core with varnish and performing high-precision cutting, the core fracture is closed with almost no air gap, ensuring a complete magnetic circuit and reducing measurement errors. High-performance silicon steel strip material and optimized winding design ensure the transformer maintains high accuracy over a wide current range, meeting metrological requirements (e.g., 0.2S class). Therefore, even as an open-type structure, this invention achieves measurement accuracy comparable to traditional closed-type transformers, overcoming the poor accuracy of conventional open-type transformers.

[0018] 3. Excellent Outdoor Performance: This invention structurally enhances waterproof, dustproof, and weather-resistant capabilities. Multi-layer silicone-sealed waterproof joints effectively prevent rainwater from seeping into the cable, and the outer shell material resists UV aging. The overall design ensures long-term reliable operation in outdoor environments. The sheath provides dual protection for the core and windings, preventing moisture and contaminants from penetrating the magnetic core windings while also preventing mechanical damage. Even in environments with high humidity, high salt spray, or drastic temperature changes, this transformer can operate stably with long maintenance intervals.

[0019] 4. Flexible and Reliable Structure: The flexible iron core, combined with hinged or threaded tubing sheaths, allows the transformer to adapt to conductors of different diameters and shapes. The tested conductor does not need to be a regular cylinder for a tight fit. The double-locking design of the casing ensures mechanical robustness and safety during use, preventing loosening of the opening and closing parts due to vibration and impact. Furthermore, the modular design of all components facilitates production and assembly, reducing manufacturing costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the annular iron core in this invention; Figure 2 This is one of the structural schematic diagrams of a high-accuracy outdoor flexible current transformer with an output of 5A in this invention; Figure 3 This is the second schematic diagram of a high-accuracy outdoor flexible current transformer with an output of 5A in this invention; Figure 4 This is a schematic diagram of the rigid protective sleeve in this invention; Figure 5 This is one of the exploded perspective views of the waterproof connector in this invention; Figure 6 This is the second exploded perspective view of the waterproof connector in this invention; Figure 7 This is a schematic diagram of the splicing of the annular meshing tooth structure in this invention; In the diagram: 1. Annular iron core; 2. Waterproof connector; 3. Flexible sheath; 4. Bending deformation section; 5. Straight opening section; 6. Joint end; 7. Waterproof male connector; 8. Waterproof female connector; 9. Iron core sheath; 10. Connector sheath; 11. Side groove; 12. Slot section; 13. Outer sleeve; 14. Inner sleeve; 15. Locking tongue section; 16. Sealing groove; 17. Sealing ring; 18. Clamping flap structure; 19. Central groove; 20. Side slot; 21. Shoulder; 22. Flexible threaded tube sheath; 23. Rigid sleeve; 24. Annular meshing tooth structure; 25. Output cable; 26. Guide side rib; 27. Bevel; 28. Elastic element. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0022] A high-accuracy outdoor flexible current transformer with an output of 5A. Figure 1-7 As shown, it includes a ring-shaped iron core 1, a waterproof connector 2, and a flexible sheath 3; The annular core 1 is provided with a secondary winding and an output cable 25 is led out from the waterproof connector 2. The annular core 1 includes a bending deformation part 4 and a straight opening part 5. In this embodiment, the total length of the straight opening part 5 is about 70mm. The shape of the bending deformation part 4 can be bent and changed. The straight opening part 5 is inflexible and arranged in a straight line. The middle part of the straight opening part 5 is broken to form a joint end 6 that is spliced ​​together. The two ends of the bending deformation part 4 are respectively connected to the joint end 6. When the two joint ends 6 are spliced ​​together, they form a complete straight opening part 5 and make the annular core 1 closed in an annular shape. When the two joint ends 6 are separated, the annular core 1 forms a C shape, forming an opening for the primary circuit to pass through the annular core 1. In this embodiment, the toroidal core 1 is made of high-permeability silicon steel strip or nanocrystalline alloy wound into a ring shape, and is treated with a special process to make it flexible, bendable, and openable. The toroidal core has a straight opening 5 in the middle, through which the core can be disassembled and assembled. In this embodiment, a toroidal core 1 with a diameter of 175mm is used as an example. During processing, silicon steel core 27085 or a similar grade is used. The height of the toroidal core 1 is 12mm, and its thickness is 5mm.

[0023] The processing method of the annular iron core 1 includes the following steps: S1: Core winding, using silicon steel sheets or nanocrystalline alloy material strips as raw materials, the thin strips are wound in multiple layers to form the cross-sectional dimensions required for the annular core 1, thus forming a closed core. S2: Curing and shaping. Select a certain length on the closed iron core as the part for machining the straight opening 5. Straighten the curvature of this part and fix it with assistance. Then, perform paint impregnation and curing treatment on this part to bond and fix the iron core layers at this end to increase rigidity. The rest of the iron core is not cured. S3: Cutting the opening: Using a precision wire cutting machine, the closed iron core is cut along a predetermined cutting line on the straight opening 5, forming two butt joint ends 6. The remaining annular portion of the iron core, except for the butt joint ends 6, is not hardened (not impregnated with paint for curing, i.e., the bending deformation portion 4), thus maintaining a certain degree of flexibility for easy installation around a large busbar. If necessary, several small slots or gaps are made at appropriate locations in the iron core to increase its flexibility, but the location and size are strictly controlled to avoid affecting the magnetic circuit performance. Through the above design, the entire iron core possesses both flexibility and ensures the overall permeability after closure; the iron core does not saturate under high current, resulting in high measurement accuracy.

[0024] S4: Grinding and smoothing: Precision grinding and smoothing are performed on the flat surfaces cut out at the two joint ends 6 to make the cuts straight and smooth, and the joint ends 6 fit tightly together.

[0025] The toroidal core of the current transformer of this invention has an open toroidal structure and is made of multiple layers of silicon steel strip. The toroidal core has a straight, flat opening 5 (formed after butt joint assembly) in the middle of the ring, with a length of approximately 70mm, occupying a certain arc of the core circumference. This straight opening 5 is the detachable interface of the core, through which the core is divided into a bent deformation section 4 and a straight opening 5.

[0026] To ensure magnetic circuit continuity and reduce magnetic resistance, the straight opening 5 is first reinforced by impregnation with paint during manufacturing, and then cut into a break using a high-precision cutting process. The cut interface fits tightly with minimal air gap, ensuring almost no magnetic flux leakage after the core is closed, thus meeting the technical requirements of high-accuracy current transformers.

[0027] In the specific manufacturing process, silicon steel strips are first layered and wound to form a complete closed ring. Then, a straight section of about 70mm in length is selected as the three-dimensional position of the straight opening 5. This section of the core is subjected to insulation impregnation treatment (curing and shaping), such as impregnation with epoxy resin or insulating varnish and curing, so that the interlayers of this section of the core are bonded and fixed, increasing rigidity. Subsequently, a precision wire cutting machine is used to cut this section of the core along the predetermined cutting line. Because the silicon steel strips of the core are firmly bonded after impregnation and curing, the interlayers of the cut surface will not be loose, and the cut is straight and smooth. The two cross-sections formed after the opening section is cut are precision ground and trimmed to ensure a tight fit when assembled. During installation and use, the cores at the butt joint ends 6 are aligned and closed, and the locking mechanism of the waterproof connector 2 is used to press and fix them. At this time, the two cross-sections are in close contact, forming a magnetic circuit connection with almost no air gap, thereby ensuring the high measurement accuracy of the transformer. The remaining annular portion of the core, since it is not impregnated with enamel for fixation, retains a certain degree of flexibility. It can be slightly opened during installation to increase its diameter, facilitating passage over the conductor being tested; it can then be closed again after assembly. It should be noted that, to further increase the core's flexibility, several small holes or gaps can be created on the core.

[0028] The secondary winding (not shown in the figure) is wound on the iron core and is used to sense and output a standard 5A current. The winding can be made of multiple strands of fine wire evenly distributed on the toroidal iron core, or concentrated on one side of the iron core as needed. To accommodate the open structure of the iron core, the secondary winding is disconnected at the open section, with a lead wire crossing the opening for connection, ensuring that the iron core is detachable while the winding forms a complete circuit. The secondary winding and its leads are covered with weather-resistant insulating material, capable of withstanding long-term temperature and humidity changes in outdoor environments. The parameters of the secondary winding are designed to meet the required current ratio and accuracy, providing a rated output of 5A while possessing sufficient capacity (e.g., 5VA or higher) to drive meters or protective relays.

[0029] In this embodiment, the secondary winding uses multiple strands of fine copper wire wound in parallel, with several turns evenly wound around the toroidal iron core to improve the uniformity of magnetic flux coupling and measurement accuracy. The number of turns in the winding is selected according to the transformer ratio and rated input current to induce a 5A secondary current under the rated primary current. For example, for a current ratio of 1000 / 5, the winding needs to be wound with 200 turns (ignoring the excitation current approximation). After the winding is completed, it undergoes vacuum impregnation to enhance the insulation strength and mechanical retention capability of the winding, and is then dried and cured to form an insulation layer. After complete assembly, the winding forms a closed loop, which can induce a secondary current output proportional to the primary current in accordance with the transformer ratio. One end of the secondary output cable 25 is connected to the winding lead wire, and the other end is led out of the transformer housing through the waterproof connector 2 and connected to an external measuring instrument. The output cable 25 is a weather-resistant rubber-sheathed cable (such as a secondary-specific cable with a rated voltage of 0.6 / 1kV), typically 2-core (S1 and S2 ends), with a cross-sectional area selected appropriately according to the 5A current (e.g., 2.5mm²).2 Copper wire is used to reduce voltage drop in the circuit. The cable length can be determined according to the application, and the factory-supplied length can also be spliced ​​in the field. The connection between the cable and the windings and leads is made with wire caps or brazed joints and strictly insulated to prevent moisture and oxidation.

[0030] Furthermore, in a further improved embodiment of the break-end mating end 6, such as... Figure 7 As shown, an annular meshing tooth structure 24 is machined on the plane of the joint end 6. The annular meshing tooth structure 24 includes several concentric arcs or rings of protruding parts, and the annular meshing tooth structures 24 on the two joint ends 6 mesh with each other. In this embodiment, the cross-section of the protruding part can be triangular, so that when the two ends are inserted and meshed with each other, they are aligned with each other through the arc-shaped protruding part of the triangular cross-section, thereby ensuring the effective alignment of the two joint ends 6.

[0031] The waterproof connector 2 includes a waterproof male connector 7 and a waterproof female connector 8 that are plugged in and closed, with two disconnected ends 6 respectively located in the waterproof male connector 7 and the waterproof female connector 8. The waterproof connector 2 of the present invention is composed of two parts: the waterproof male connector 7 and the waterproof female connector 8. The material is an outdoor weather-resistant insulating material (such as flame-retardant ABS or polycarbonate PC), which can withstand long-term exposure to sunlight, rain and temperature changes without cracking or aging.

[0032] The waterproof male connector 7 has a cylindrical structure and an axial cavity through which the butt joint end 6 passes. The axial cavity is a cavity that accommodates the iron core and windings. Its shape matches the cross-sectional profile of the iron core. A concave groove 12 is formed at one end of the waterproof male connector 7. As one embodiment of the installation of the break-end joint 6, the waterproof nut 8 includes an outer sleeve 13 and an inner sleeve 14. The outer sleeve 13 is coaxially sleeved outside the inner sleeve 14. The inner sleeve 14 is provided through both ends of the outer sleeve 13. The inner sleeve 14 has an axial cavity for the break-end joint 6 to pass through. One end of the inner sleeve 14 has a protruding locking tongue 15, which is inserted into the slot 12. Specifically, since the cross-section of the iron core is rectangular, the slot 12 is designed as a virtual rectangular structure surrounded by multiple guide side ribs 26. That is, multiple guide side ribs 26 are provided axially around the iron core, and the guide side ribs 26 are provided with inclined surfaces 27, so that the slot 12 forms a guide groove with a large outer opening and a small inner opening. This makes it easier for the locking tongue 15 to be inserted into the slot 12 when initially inserted. As the inclined surface 27 guides, the inner opening gradually shrinks, thereby accurately guiding the locking tongue 15, so that the two break-end joints 6 can be accurately connected and avoid lateral displacement.

[0033] In this embodiment, there are two joint ends 6. One joint end 6 is fixedly disposed within the axial cavity of the waterproof male connector 7 to form the male end, and the other joint end 6 is fixed within the inner sleeve 14 of the waterproof female connector 8. It can be understood that both joint ends 6 are sealed and fixed, thus providing a good sealing and waterproof effect at the end of the iron core. The inner sleeve 14 of the waterproof female connector 8 passes axially through the outer sleeve 13, allowing the outer sleeve 13 to be retracted a certain distance during actual use, thereby causing the locking tongue 15 of the inner sleeve 14 to protrude. During insertion, the insertion of the locking tongue 15 can be directly observed with the naked eye. The inner sleeve 14 is pushed into the slot 12 to improve the docking accuracy. Then, the outer sleeve 13 is pushed to move towards the waterproof male connector 7 to connect with it. When the outer sleeve 13 is connected to the waterproof male connector 7, its wrapping structure can form a double-layer wrapping seal at the joint of the iron core to effectively prevent dust. In actual use, the outer sleeve 13 and the waterproof male connector 7 can be connected by threads. Specifically, one end of the waterproof male connector 7 has an external thread, and the outer sleeve 13 has an internal thread that is screwed to the external thread. When the outer sleeve 13 rotates, it can further push the inner sleeve 14 to move towards the slot 12 and form a locking fixation. Furthermore, the bottom surface of the slot 12 is provided with a sealing groove 16 around the broken docking end 6. The sealing groove 16 is provided with a sealing ring 17. The end of the locking tongue 15 is inserted into the sealing groove 16 and abuts against the sealing ring 17. When the outer sleeve 13 pushes the inner sleeve 14 to move axially, the end of the locking tongue 15 can further abut against and compress the sealing ring 17, thereby improving the sealing performance.

[0034] As another embodiment of the installation of the break-end joint 6, this embodiment is largely the same as the aforementioned embodiment, with the improvement being that the break-end joint 6 is configured with axial freedom of axial extension and retraction relative to the waterproof male head 7 and the waterproof female head 8. It is understood that in the aforementioned embodiment, the break-end joint 6 is relatively fixed. During docking, the relative position of the locking tongue 15 and the break-end joint 6 inside the locking tongue 15 needs to be designed with particular precision. Otherwise, it is easy to cause the gap between the two break-end joints 6 to be too large, thus affecting the magnetic flux. Specifically, if the locking tongue 15 protrudes too long, the outer sleeve 13 will push the locking tongue 15 to contact the sealing ring 17 first. With continuous twisting, the locking tongue 15 will be pressed into place. Because of its long protrusion, the break-end joint 6 fixed inside may still not be tightly fitted to the other end.

[0035] Specifically, in this embodiment, the side of the butt joint end 6 is provided with a side groove 11. Specifically, side grooves 11 can be machined on both sides of the two butt joint ends 6, such as... Figure 1 , 7 As shown, a side groove 11 with a length and width of approximately 10mm × 1.5mm is machined by wire cutting at the core position near both sides of the opening end.

[0036] The waterproof male connector 7 and inner sleeve 14 are provided with a locking block structure that mates with the side groove 11. The locking block structure engages with the side groove 11, limiting the axial freedom of the butt joint end 6. Specifically, the locking block structure includes two interlocking semi-circular locking flap structures 18. Each locking flap structure 18 has a central groove 19 on its planar side. The opening width of the central groove 19 corresponds to the thickness of the iron core. When the locking flap structure 18 is inserted from the outside, it can be locked into the side groove 11 through the central groove 19 to form a cross-shaped interlocking. Therefore, the butt joint end 6 can be axially pulled and moved, and its movement stroke is the length of the side groove 11. Side slots 20 are also provided on both sides of the central groove 19. The side slots 20 are used to facilitate the operation of the waterproof male connector. 7 or inner sleeve 14 and form mutually interlocking clearance grooves. The snap-fit ​​structure 18 is inserted into the interior of the waterproof male head 7 and inner sleeve 14 from the side, so that the central groove 19 is snapped into the side groove 11 from the side. After the two semi-circular snap-fit ​​structures 18 are inserted relative to each other, they are spliced ​​to form a circular whole snap-fit ​​structure. It can be understood that after the two semi-circular snap-fit ​​structures 18 are formed into a circular whole, their shape is fixed and they will not be disassembled during normal use. A buckle can be set between the two snap-fit ​​structures 18 to make the two connections firm, or they can be glued to form a whole snap-fit ​​structure. Furthermore, this embodiment also provides an elastic element 28. In this embodiment, the elastic element 28 is taken as an elastic pad, such as Figure 5 , 6 As shown, the elastic element 28 is fitted onto the side of the latch structure 18 near the slot 12. Since the elastic element 28 is provided in this embodiment, the relative position of the end of the latch 15 and the internal break-end 6 does not need to be designed with particular precision. One advantage is that it is easier to process and manufacture. Another advantage is that in actual use, if the error in the relative position between the two is used for a long time, it can be compensated by the elastic element 28, so that the end face fit effect can still be maintained after long-term use, thereby ensuring the magnetic flux. Understandably, during actual docking, the locking tongue 15 is first inserted into the slot 12, and then the outer sleeve 13 is screwed in. As the outer sleeve 13 is screwed in, its inner shoulder 21 presses against the locking block structure. The outer sleeve 13 pushes the inner sleeve 14 to move through the locking flap structure 18. Understandably, one side of the locking flap structure 18 is in hard contact with the side of the inner sleeve 14, thereby directly transmitting the thrust of the outer sleeve 13. On the other hand, the contact part between the locking flap structure 18 and the side slot 11 is provided with an elastic element 28, so that the joint end 6 can maintain a small degree of axial displacement freedom within a certain range through the elastic element 28. Then, when the outer sleeve 13 is locked with the waterproof male head 7, the locking tongue 15 has already pressed against the sealing ring 17 to seal the sealing groove 16. At this time, the internal joint end 6 is pressed against the locking flap structure 18 through the elastic element 28, so that the two joint ends 6 can maintain elastic mutual compression and docking, thereby maintaining a good connection effect. Figure 4-6Both sides of the card-shaped structure 18 are provided with elastic elements 28, and the elastic elements 28 push their respective break-end docking ends 6 to move towards each other. At this time, the straight opening 5 formed and the waterproof structure are allowed to move relative to each other within a certain range. This structure is particularly suitable for situations where the current transformer is subjected to tension, vibration or collision after installation. Therefore, it can still maintain a good connection effect in the above-mentioned usage scenarios, thereby maintaining high-precision current measurement and output.

[0037] Furthermore, the flexible sheath 3 includes an iron core sheath 9 and a connector sheath 10. The iron core sheath 9 is wrapped around the annular iron core 1, and the connector sheath 10 is fitted over the waterproof connector 2. The two ends of the connector sheath 10 are respectively connected to the two ends of the iron core sheath 9 to form an annular seal.

[0038] The annular core is also covered with a flexible protective sleeve to improve the environmental adaptability and mechanical strength of the entire device. The sleeve material can be a UV-resistant soft flame-retardant rubber or engineering plastic. Preferably, the sleeve is in the form of a highly flexible threaded tube (corrugated tube) surrounding the core. The threaded tube has good flexibility, wear resistance, and waterproof performance, and can bend with the core while providing cushioning protection to the interior.

[0039] The corrugated section consists of a flexible sheath with annular corrugations that wraps around the circumference of the core. The threaded tube is typically made of PVC or rubber, offering good bending performance, wear resistance, and water resistance. Its inner diameter is slightly larger than the outer diameter of the core plus the windings. During installation, the threaded tube passes through the entire length of the core from one end, covering most of its circumference, leaving only a gap near the opening for the outer casing to be installed and locked. The end of the threaded tube sheath is secured to the outer casing with adhesive or clips, preventing slippage. The thread shape not only gives the sheath flexibility but also increases the friction and rigidity of its outer surface. When the transformer bends, each corrugation can move slightly, allowing the sheath to be evenly stressed with the core without damage. Simultaneously, the corrugated tube encloses the core and coils, effectively preventing dust, moisture, and direct sunlight, extending the lifespan of internal components.

[0040] As an alternative, the sheath can also be composed of several hinged, foldable sections. This hinged sheath consists of multiple rigid sleeves 23 joined together, each section connected by hinges. Adjacent rigid sleeves 23 can be folded and moved, allowing the sheath to bend around the core like a chain. When the transformer needs to be unfolded or tightened, the sections of the hinged sheath rotate relative to each other, maintaining a certain level of rigid support while allowing for flexible bending. Regardless of the form of the sheath used, it serves to prevent the core and coils from being exposed, to protect against moisture and contamination, and to prevent damage during transportation and installation. Additionally, the sheath surface can be designed with slots or positioning structures for easy engagement and positioning with the outer casing.

[0041] The sheath consists of several rigid sleeves 23 connected end to end to form a ring, with each rigid sleeve 23 covering an arc segment of the outer circumference of the core. Adjacent rigid sleeves 23 are connected by hinges, which can be stainless steel pins or integrally formed thin-film hinges, allowing the rigid sleeves 23 to rotate relative to each other at a certain angle. When the transformer needs to be unfolded, each rigid sleeve 23 can be rotated sequentially to straighten the entire sheath, exposing the core for easy installation; after installation, the hinges are bent to close the rigid sleeves 23 into a ring, re-covering and protecting the core and windings. A specific locking structure can be designed at the end of the hinged sheath adjacent to the outer casing to fix the end of the rigid sleeve 23 to the outer casing to form a closed loop. The hinges are usually made of tough engineering plastics or lightweight metals, with rubber pads on the inside to fit the core surface and buffer stress. Compared to threaded tube sheaths, the rigid sleeves 23 provide protection while also providing some reinforcement, as they are composed of multiple rigid plates, which improves the overall deformation resistance of the transformer. Users can choose between threaded tube sleeves or hinged sleeves according to their actual application needs. Both can provide reliable environmental sealing and mechanical protection for the internal core and coil. In this embodiment, threaded tube sleeves are preferred because of their simple structure, low cost, and good continuous sealing performance.

[0042] Working Principle and Usage: When using this outdoor flexible current transformer, open its open section and fit it onto the primary conductor being measured (such as a cable or busbar) to the appropriate position. Then close the open section of the core and close the outer casing, securing it with the waterproof connector 2. At this point, the transformer core forms a closed magnetic circuit. The magnetic flux generated by the primary current is mainly closed within the high-permeability silicon steel core, crossing only at the open section through a tightly coupled interface with a very small air gap. Therefore, the transformer can accurately sense the primary current. The current in the primary conductor induces magnetic flux in the core, which couples to the secondary winding surrounding the core, generating a current on the secondary side that decays according to the turns ratio. Since this invention is designed for a standard 5A output, when the primary current is at its rated value, the current flowing out of the secondary winding is 5A, supplying external meters or protection devices. Throughout operation, the transformer casing and sheath isolate the internal core and coils from the outside environment, preventing environmental factors from interfering with the measurement. Meanwhile, the waterproof connector 2 ensures a reliable seal at the interface of the lead-out cable, preventing potential hazards such as reduced insulation of the secondary winding to ground or short circuits caused by rainwater intrusion. For applications with different primary current capacities, current transformers can be customized by changing the number of turns in the winding or the core material of different cross-sections, but their structural principles are similar. Because this invention employs a detachable structure, maintenance personnel can quickly remove the current transformer from the primary conductor by simply reversing the rotation of the locking ring to loosen the latch when replacing or inspecting the transformer, without needing to disconnect power or cut the wires. This greatly facilitates maintenance and improves safety.

[0043] It should be noted that while the specific embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, those skilled in the art can make various equivalent substitutions and modifications to the present invention, and these equivalent changes also fall within the protection scope of the present invention. The protection scope of the present invention is defined by the appended claims.

Claims

1. A high-accuracy outdoor flexible current transformer with an output of 5A, characterized in that, Includes toroidal core, waterproof joint, and flexible sheath; The toroidal core is equipped with a secondary winding and an output cable is led out from a waterproof connector. The toroidal core includes a bent deformation section and a straight opening section. The shape of the bent deformation section can be bent and changed, while the straight opening section is inflexible and arranged in a straight line. The middle of the straight opening section is broken to form a joint end that can be spliced ​​together. The two ends of the bent deformation section are respectively connected to the joint end. When the two joint ends are spliced ​​together, they form a complete straight opening section and make the toroidal core closed in a ring. When the two joint ends are separated, the toroidal core forms a C shape, forming an opening for the primary circuit to pass through the toroidal core. The waterproof connector includes a waterproof male connector and a waterproof female connector that fit together, with two disconnected ends respectively located inside the waterproof male connector and the waterproof female connector; The flexible sheath includes an iron core sheath and a joint sheath. The iron core sheath is wrapped around the annular iron core, and the joint sheath is fitted over the waterproof joint. The two ends of the joint sheath are respectively connected to the two ends of the iron core sheath to form an annular seal.

2. The high-accuracy outdoor flexible current transformer with an output of 5A according to claim 1, characterized in that, The annular iron core is formed by winding a high-permeability silicon steel strip into a ring. The silicon steel strip is wound in multiple turns to form a bending deformation section with bending flexibility. The joint end of the fracture is a planar cut to ensure that the two joint ends are tightly fitted together.

3. The high-accuracy outdoor flexible current transformer with an output of 5A according to claim 1, characterized in that, The waterproof male connector has a cylindrical structure with an axial cavity for the butt joint end to pass through, and a concave groove is formed at one end of the waterproof male connector. The waterproof sash head includes an outer sleeve and an inner sleeve. The outer sleeve is coaxially sleeved outside the inner sleeve. The inner sleeve is provided through both ends of the outer sleeve. The inner sleeve has an axial cavity for the butt joint end to pass through. One end of the inner sleeve protrudes and has a locking tongue. The locking tongue is inserted into the slot. The bottom surface of the slot has a sealing groove around the butt joint end. A sealing ring is provided in the sealing groove. The end of the locking tongue is inserted into the sealing groove and abuts against the sealing ring.

4. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 3, characterized in that, The joint end has axial freedom of movement relative to the waterproof male and female connectors; The side of the joint end is provided with a side groove, and the waterproof male and inner sleeve are provided with a locking block structure that cooperates with the side groove. The locking block structure is inserted into the side groove to limit the axial degree of freedom of the joint end.

5. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 4, characterized in that, The locking block structure includes two interlocking semi-circular locking flap structures and an elastic element disposed on one side of the locking flap structure and in contact with the side groove. The locking flap structure has a central groove on its planar side and side slots on both sides of the central groove. The locking flap structure is inserted into the interior of the waterproof male head and inner sleeve from the side, so that the central groove is engaged into the side groove from the side. The two semi-circular locking flap structures are inserted relative to each other and spliced ​​to form a circular locking block structure. The elastic element is configured to ensure that when the two broken ends are joined, the two broken ends always have a tendency to move towards each other, so that the two broken ends maintain good jointing when moving within a certain axial degree of freedom.

6. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 5, characterized in that, The waterproof male end has an external thread, and the outer sleeve has an internal thread that is screwed into the external thread. As the outer sleeve is screwed in, its inner shoulder is squeezed and clamped.

7. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 1, characterized in that, The core sheath is a flexible threaded tube sheath, and the two ends of the flexible threaded tube sheath are fixed to the waterproof joint by adhesive or clips. The flexible threaded tube sheath is made of PVC or rubber material.

8. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 1, characterized in that, The iron core sheath is a hinged foldable sheath, which includes several rigid sleeves connected end to end to form a ring, with adjacent rigid sleeves connected by hinges.

9. A high-accuracy outdoor flexible current transformer with an output of 5A according to claim 1, characterized in that, A ring-shaped meshing tooth structure is machined on the plane of the fracture end. The ring-shaped meshing tooth structure includes several concentric arcs or rings of protruding parts, and the ring-shaped meshing tooth structures on the two fracture ends mesh with each other when they are joined.

10. A method for processing a toroidal iron core, comprising the toroidal iron core as described in claim 1, characterized in that, Includes the following steps: S1: Core winding, using silicon steel sheets or nanocrystalline alloy strips as raw materials, the thin strips are wound in multiple layers to form the cross-sectional dimensions required for the ring core, thus forming a closed core. S2: Curing and shaping. A certain length is selected on the closed iron core as the part for machining the straight opening. The curvature of this part is straightened and assisted in fixing. Then, this part is impregnated with paint and cured to make the iron core layers at this end bonded and fixed to increase rigidity. The rest of the iron core is not cured. S3: Cut the opening. Use a precision wire cutting machine to cut the closed iron core along the predetermined cutting line on the straight opening and form two butt joint ends. S4: Grinding and smoothing: The flat surfaces cut out at the joint ends of the two fractures are precisely ground and smoothed to make the cuts straight and smooth, and the joint ends fit tightly together.

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