Current transformer, switch cabinet, and manufacturing method of current transformer

Abstract

The embodiments of the present disclosure relate to a current transformer, a switch cabinet, and a method for manufacturing a current transformer. The current transformer includes: an insulating shell, a hole penetrating the insulating shell is provided in the insulating shell, and the hole is suitable for the primary conductor of the primary winding to pass through; and a secondary winding located in the insulating shell and arranged around the hole, and the terminal of the secondary conductor of the secondary winding is arranged on the outside of the insulating shell; and an insulating protrusion at least partially surrounding the opening of the hole and extending outward from the end face of the insulating shell so that the creepage distance between the primary conductor and the terminal is greater than the insulation distance threshold between the primary conductor and the terminal. Through the technical solution of the embodiments of the present disclosure, the number of components can be reduced, thereby reducing material and labor costs, and the insulation performance can be improved, effectively preventing breakdown and leakage.

Description

Technical Field

[0001] The present disclosure relates to the field of electronic equipment, and more specifically, to a current transformer, a switch cabinet, and a manufacturing method of the current transformer. Background Art

[0002] In power applications, the currents flowing through various circuits vary widely, sometimes dramatically. For ease of measurement and control, as well as for safety reasons, large currents need to be converted to smaller ones. Current transformers are often used to perform this current conversion.

[0003] A known current transformer requires additional insulating components to achieve electrical insulation between the terminals of the primary and secondary conductors, which must be bonded to the current transformer housing. This solution has drawbacks such as high labor costs and inability to guarantee insulation performance. Therefore, an improved solution is urgently needed that can reduce the material and labor costs of current transformer manufacturing while improving insulation performance. Summary of the Invention

[0004] The embodiments of the present disclosure provide a current transformer, a switch cabinet, and a method for manufacturing the current transformer to at least solve one of the above-mentioned and other potential problems of the prior art.

[0005] According to one aspect of the present disclosure, a current transformer is provided. The current transformer includes: an insulating housing having a hole extending through the insulating housing, the hole being adapted for passing a primary conductor of a primary winding through the hole; a secondary winding located within the insulating housing and disposed around the hole, with a terminal of the secondary conductor of the secondary winding disposed outside the insulating housing; and an insulating protrusion at least partially surrounding an opening of the hole and extending outward from an end surface of the insulating housing to ensure that a creepage distance between the primary conductor and the terminal is greater than a threshold insulation distance between the primary conductor and the terminal.

[0006] In the above embodiment, by providing the insulating protrusion at the end surface of the insulating shell, the additional insulating plate and the process of bonding the insulating plate are omitted, and the insulation performance is improved, which can effectively prevent high voltage breakdown or leakage.

[0007] In some embodiments, the secondary winding includes: an iron core having an annular structure and disposed concentrically with the axis of the hole; and a secondary conductor wound around the iron core. In these embodiments, by disposing the annular iron core concentrically with the hole, energy can be efficiently transferred via electromagnetic induction between the primary conductor and the secondary conductor when the primary conductor passes through the hole.

[0008] In some embodiments, the core has a square cross-section along an axis extending through the aperture.

[0009] In the above embodiment, by setting the cross section of the iron core to be square, the length of the required secondary conductor can be reduced while maintaining the same transformer capacity, thereby saving the consumption of wires (such as enameled wires).

[0010] In some embodiments, the insulating protrusion includes a plurality of concentrically arranged insulating ribs. In the above embodiment, by including a plurality of concentrically arranged insulating ribs in the insulating protrusion, sufficient creepage distance can be achieved through the plurality of insulating ribs without increasing the length of the housing in the axial direction, thereby preventing high voltage breakdown or leakage.

[0011] In some embodiments, each insulating rib extends along the axis of the hole, and each insulating rib has a sawtooth-shaped cross-section along the axis. In the above embodiment, by making each insulating rib have a sawtooth-shaped cross-section along the axis, the creepage distance between the terminals of the primary conductor and the secondary conductor can be effectively increased.

[0012] In some embodiments, multiple independent secondary windings are arranged side by side in the insulating housing. In the above embodiments, by arranging multiple independent secondary windings side by side in the insulating housing, multiple independent functions can be realized, such as current measurement, billing, overcurrent protection, etc., to meet different needs.

[0013] In some embodiments, the current transformer further includes a shield configured to be at the same potential as the primary conductor, the shield being made of a metal material and comprising a cylindrical portion disposed between the aperture and the secondary winding; and a bent portion extending from an edge of the cylindrical portion's opening to surround at least a portion of the secondary winding. In the above embodiment, by disposing the shield within the housing at the same potential as the primary conductor, the cylindrical portion can prevent air gap breakdown between the primary conductor and the housing due to a high voltage difference, while the bent portion can prevent air gap breakdown between the housing and adjacent high-voltage components.

[0014] In some embodiments, the shielding member is formed of a metal plate or a metal mesh. In the above embodiments, by forming the shielding member from a metal plate or a metal mesh, the electric field between the primary conductor and the secondary winding can be effectively shielded to prevent air gap breakdown.

[0015] In some embodiments, the current transformer further comprises a support rib disposed on an inner wall of the hole, wherein a support member is disposed within the support rib, and the support member is coupled to the cylindrical portion to support the shielding member. In the above embodiment, the support rib supports the shielding member during the casting process, maintaining it in a predetermined position and achieving smooth casting and molding.

[0016] In some embodiments, the support member includes: a support end portion having a threaded hole therein, the threaded hole being adapted to cooperate with a fastener to secure the primary conductor to the support rib, wherein the fastener is adapted to be disposed at an end surface of the insulating housing to clamp the side wall of the primary conductor; and a support rod extending from the support end portion along the axis of the hole to couple with the cylindrical portion, wherein the fastener is adapted to be disposed at the end surface of the insulating housing to clamp the side wall of the primary conductor. In the above embodiment, the threaded hole is provided in the support member to cooperate with the fastener to secure the primary conductor to the support rib, thereby enabling the housing structure to be utilized to secure the primary conductor, thereby avoiding the need for an additional, complex structure to secure the primary conductor.

[0017] In some embodiments, the shielding member is electrically connected to the primary conductor via the support member and the fastener. In the above embodiments, the shielding member is electrically connected to the primary conductor via the support member and the fastener, thereby achieving equal potential between the primary conductor and the shielding member, thereby preventing air gap breakdown.

[0018] In some embodiments, the current transformer further includes a secondary terminal portion disposed in the middle of a side surface of the insulating housing, into which a terminal of the secondary conductor extends. In the above embodiment, disposing the secondary terminal portion in the middle of a side surface of the insulating housing increases the distance between the terminal of the secondary conductor and the primary conductor, thereby increasing creepage distance and preventing high-voltage breakdown or leakage.

[0019] According to another aspect of the embodiments of the present disclosure, a switch cabinet including the above-mentioned current transformer is provided.

[0020] According to a third aspect of an embodiment of the present disclosure, a method for manufacturing the aforementioned current transformer is provided. The method comprises: winding a secondary conductor around an iron core to form a secondary winding; placing the secondary winding and a shielding member in a mold, while maintaining the relative positions of the secondary winding and the shielding member; pouring resin into the mold; and heating the resin to cure it. The mold is configured to form an insulating protrusion on an end surface of the insulating housing of the current transformer.

[0021] In the above embodiment, the manufacturing process of the current transformer can be simplified and the insulation performance can be improved.

[0022] It will be understood from the following description that the technical solution of the embodiment of the present disclosure can reduce the number of components, thereby reducing material and labor costs, and can improve insulation performance and effectively prevent breakdown and leakage.

[0023] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram showing a switch cabinet equipped with a current transformer according to an embodiment of the present disclosure

[0025] Figure 2 shows a perspective schematic diagram of a current transformer according to some exemplary embodiments of the present disclosure;

[0026] Figure 3 Shown as Figure 2 Another three-dimensional schematic diagram of the current transformer shown;

[0027] Figure 4 shows a perspective cross-sectional view of a current transformer according to some exemplary embodiments of the present disclosure;

[0028] Figure 5 Shown as Figure 4 A main cross-sectional view of the current transformer shown;

[0029] Figure 6 shows a perspective schematic diagram of a shield according to some exemplary embodiments of the present disclosure;

[0030] Figure 7 shows a perspective schematic diagram of a secondary winding according to some exemplary embodiments of the present disclosure;

[0031] Figure 8 Shown according to Figure 7 a perspective cutaway view of the secondary winding shown; and

[0032] Figure 9 A flow chart of a method for manufacturing a current transformer according to some exemplary embodiments of the present disclosure is shown.

[0033] In the various drawings, the same or corresponding reference numerals denote the same or corresponding parts. DETAILED DESCRIPTION

[0034] The principles of the present disclosure will be described below with reference to the various exemplary embodiments shown in the accompanying drawings. It should be understood that the description of these embodiments is only to enable those skilled in the art to better understand and further implement the present disclosure, and is not intended to limit the scope of the present disclosure in any way. It should be noted that similar or identical reference numerals can be used in the figures where possible, and similar or identical reference numerals can represent similar or identical functions. Those skilled in the art will readily recognize, from the description below, that alternative embodiments of the structures and methods described herein can be adopted without departing from the principles of the present invention described herein.

[0035] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "one example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or identical objects.

[0036] As mentioned earlier, some current transformers require additional insulation to achieve electrical insulation between the terminals of the primary and secondary conductors. In this solution, a groove is created on the end face of the transformer housing, into which an insulating plate is inserted and manually secured with glue. The glue must completely fill the groove, leaving no gaps, otherwise current will flow through the gaps, as the primary conductor inside the housing carries high voltage. This solution requires minimal partial discharge (PD), for example, less than 20 pc. The insulating plate (typically an epoxy resin plate) itself cannot be tested for withstand voltage or partial discharge. Therefore, if the insulating plate itself has partial discharge defects, the entire current transformer is at risk of breakdown. Overall, this solution has the following drawbacks: First, the large number of components requires labor-intensive management and on-site installation, resulting in high costs. Second, bonding cannot guarantee uniformity across the bonded surface, which can lead to insulation defects in certain areas, potentially causing high-voltage breakdown. Third, quality defects in the insulating plate itself, such as bubbles or other defects, can cause partial discharge problems.

[0037] Therefore, an improved solution is urgently needed to reduce costs, improve insulation performance, and prevent high-voltage breakdown or leakage.

[0038] An embodiment of the present disclosure provides an improved current transformer. The current transformer includes: an insulating shell, a secondary winding, and an insulating protrusion. A hole is provided in the insulating shell, which passes through the insulating shell. The primary conductor can pass through the hole. The secondary winding is located in the insulating shell and is arranged around the hole. The terminal of the secondary conductor of the secondary winding is arranged on the outside of the insulating shell. The insulating protrusion at least partially surrounds the opening of the hole and extends outward from the end face of the insulating shell. In other words, at least a portion of the insulating protrusion is arranged between the primary conductor and the secondary terminal portion to insulate the two. The insulating protrusion is arranged so that the creepage distance between the primary conductor and the terminal is greater than the insulation distance threshold between the primary conductor and the terminal. In this way, the current transformer of the embodiment of the present disclosure can improve the insulation performance and effectively prevent high-voltage breakdown or leakage.

[0039] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Figure 1 FIG1 shows a schematic diagram of a switch cabinet equipped with a current transformer according to an embodiment of the present disclosure. Figure 1The switchgear shown can be used in, for example, a 10-35 kV medium voltage power system. Those skilled in the art will appreciate that the embodiments of the present disclosure are not limited thereto, but can be applied to other low voltage, medium voltage, and high voltage power systems as needed.

[0040] like Figure 1 As shown, the switch cabinet 200 mainly includes a current transformer 100, a primary conductor 215, a grounding busbar 204, a fixing member 208, a grounding knife 210, a grounding knife holder 211, a fastener 202, a contact box 212, etc. The current transformer 100 can be fixedly mounted on a side panel of the switch cabinet 200.

[0041] The current transformer 100 primarily performs electromagnetic conversion and insulation isolation. For example, in some embodiments, a primary winding voltage of 10 kV and a current of 600 A can be converted to 1 A or 5 A using the current transformer 100. Furthermore, the voltage can be converted accordingly using a voltage transformer. The pre-conversion voltage / current values can be determined based on the post-conversion voltage / current values.

[0042] like Figure 1 As shown, the current transformer 100 is generally cylindrical and is installed vertically in the switch cabinet. The shape and installation method of the current transformer 100 disclosed in the present invention are not limited to this, but can be varied. For example, the shape can be a square like a tofu block, and the installation method can be horizontal, etc.

[0043] The primary conductor 215 can be arranged to pass through the hole 112 in the current transformer 100 and be fixed to the two end surfaces of the current transformer 100 by fasteners 202. In some embodiments, the fasteners 202 can be flanges, but the embodiments of the present disclosure are not limited thereto and can be any component suitable for fixing the primary conductor 215. In known solutions, complex structures are required to fix the primary conductor 215. In the embodiments of the present disclosure, the primary conductor 215 can be fixed by fasteners 202 with simple structures that utilize the structure within the housing, thereby simplifying the structure within the switch cabinet 200.

[0044] In some embodiments, primary conductor 215 may be a copper rod. In other embodiments, primary conductor 215 may be a copper tube. Copper tubes have the advantage of avoiding the skin effect. The skin effect refers to the uneven current distribution within a conductor when alternating current or an alternating electromagnetic field is present. The current is concentrated in the conductor's "skin," a thin layer on the conductor's surface. The closer to the conductor's surface, the greater the current density, while the actual current inside the conductor is less. This results in an increased resistance of the conductor, which in turn increases its power loss and, in turn, increases heat generation.

[0045] The lower end of primary conductor 215 is connected to grounding busbar 204, which in turn is electrically connected to L-shaped copper busbar 206, fixing member 208, grounding knife holder 211, and grounding knife 210. The function of grounding knife 210 is to close grounding knife 210 after the switch is disconnected and a power test confirms that there is no power when equipment requires power outage maintenance. This facilitates safe maintenance. In other words, grounding knife 210 facilitates discharging of the circuit and prevents accidental power supply to the maintenance line.

[0046] The contact box 212 may be provided with a static contact for connecting to the moving contact of the circuit breaker. Figure 1 The reinforcing ribs 214 are used to reinforce the contact box 212 to ensure that it is firmly fixed to the inner wall of the switch cabinet 200 .

[0047] The following will be combined Figures 2 to 8 The structure of the current transformer 100 according to the exemplary embodiment of the present disclosure will be described in detail. Figure 2 and Figure 3 ,in Figure 2 shows a perspective schematic diagram of a current transformer 100 according to some exemplary embodiments of the present disclosure; Figure 3 Shown as Figure 2 Another perspective schematic diagram of the current transformer 100 is shown.

[0048] like Figure 2 and Figure 3 As shown, the current transformer 100 as a whole includes an insulating housing 110 , a secondary terminal portion 130 , an insulating protrusion 120 , and a shielding envelope 134 .

[0049] like Figure 2 and Figure 3 As shown, the insulating housing 110 is provided with a hole 112, which extends through the insulating housing 110. The primary conductor 215 can pass through the hole 112. A support rib 140 can be provided on the inner wall of the hole 112. The support rib 140 is provided with a support member 142, which can support the shielding member 150 in the housing, which will be further described below.

[0050] like Figure 2 As shown, the secondary terminal portion 130 is disposed in the middle of the side surface of the insulating housing 110, and the secondary conductor 170 ( Figure 2 and 3 The terminal 172 (not shown in the figure, described in detail later) of the secondary conductor 170 extends into the secondary terminal portion 130. In this way, it is easy to connect the wires from the side. Figure 2 and Figure 3 Not shown, see Figure 7 ) is located in the wiring hole 132. Each secondary winding 180 ( Figures 1 to 3 Not shown, see Figure 4The terminals (described in detail later) can be upper and lower wiring holes 132. Of course, other terminal lead-out methods can also be provided as needed. The mounting insert 133 is used to fix the current transformer 100 to the side panel of the switch cabinet 200.

[0051] The secondary winding is located within the insulating housing 110 and is arranged around the hole 112. The terminal of the secondary conductor 170 of the secondary winding 180 is arranged on the outside of the insulating housing 110, that is, in the secondary terminal portion 130 mentioned above. The insulating protrusion 120 at least partially surrounds the opening of the hole 112 and extends outward from the end surface of the insulating housing 110. In other words, at least a portion of the insulating protrusion 120 is arranged between the primary conductor 215 and the secondary terminal portion 130 to insulate the two. The insulating protrusion 120 is arranged so that the creepage distance between the primary conductor 215 and the terminal is greater than the insulation distance threshold between the primary conductor 215 and the terminal. The term "creepage distance" used herein refers to the shortest path measured along the surface of an insulator between two conductive parts or between a conductive part and the protective interface of the equipment. That is, under different usage conditions, the distance at which the insulating material around the conductor becomes electrically polarized, causing the insulating material to become charged. Safety standards such as UL, CSA, and VDE emphasize creepage distance requirements to prevent sparks between components or between a component and ground, which could threaten personal safety. The insulation distance threshold is the safe distance between two conductors to prevent breakdown or leakage.

[0052] In some embodiments, because at least a portion of insulating protrusion 120 is disposed between primary conductor 215 and secondary terminal portion 130 , the surface shape of insulating protrusion 120 increases the shortest distance between the primary conductor 215 and terminal 172 on the insulating surface, i.e., the creepage distance. This is further described below.

[0053] like Figure 2 and Figure 3 As shown, the insulating protrusion 120 includes a plurality of insulating ribs 122. These insulating ribs 122 are concentrically arranged. In some embodiments, the insulating ribs 122 may have an shed or shed-like structure. Figure 2 and Figure 3In the embodiment described, the creepage distance is the shortest distance traveled by the surface of the primary conductor 215 at the end face of the insulating housing 110, passing through the surfaces of the insulating ribs 122 in the insulating raised portion 120, and reaching the terminal 172 of the secondary conductor 170. If each rib is compared to a mountain peak, the creepage distance is equivalent to climbing from the foot of the mountain along the shortest distance to the top, continuing along the shortest distance to reach the valley, then continuing forward to climb the next mountain peak, and so on, until the last mountain peak is reached, and then passing through the surface of the secondary terminal portion 130 to reach the terminal 172 in the wiring hole 132. It can be seen that in the embodiment of the present disclosure, by providing the insulating raised portion 120, the end face of the insulating housing 110, which would not have been provided with the insulating raised portion 120, is curved instead of flat, thereby increasing the distance between the insulating surfaces of the primary conductor 215 and the terminal 172, thereby increasing the creepage distance between the primary conductor 215 and the terminal 172.

[0054] As mentioned above, in the known solution, a groove is provided on the end face of the shell of the current transformer, an insulating plate is inserted into the groove, and fixed with glue. In the embodiment of the present disclosure, the insulating protrusion 120 is integrally formed with the insulating shell 110, for example, by casting in a mold. This reduces the number of parts and components and reduces the costs of management, processing, installation, etc. of the parts. More importantly, it can avoid the defects of the existing solution in that the insulation performance is reduced due to inconsistent bonding uniformity, poor firmness, etc. In this way, the reliability of the insulation is improved, and high-voltage breakdown or leakage can be effectively prevented.

[0055] Shielding envelope 134 is a cast protrusion on the sidewall of insulating housing 110 that encloses shielding element 150. Shielding insert 135 is disposed within the shielding envelope. Because shielding element 150 is a thin metal mesh or sheet that is susceptible to deformation, shielding insert 135 is used to secure the relative position of shielding element 150. Excess cast material may leak out of shielding insert 135.

[0056] The following combination Figure 4 and Figure 5 The internal structure of the current transformer 100 according to the embodiment of the present disclosure is further described. Figure 4 shows a perspective cross-sectional view of a current transformer 100 according to some exemplary embodiments of the present disclosure; Figure 5 Shown as Figure 4 A main cross-sectional view of the current transformer 100 is shown.

[0057] like Figure 4As shown, the secondary winding 180 includes an iron core 160 and a secondary conductor 170. The iron core 160 has an annular structure and is arranged concentrically with the axis of the hole 112. The secondary conductor 170 is wound around the iron core 160. In addition, it should be noted that the iron core referred to herein is not limited to being made of iron, but can be a magnetic core. Figure 4 In the insulating housing 110 shown in the figure, four independent secondary windings 180 are arranged side by side. Each secondary winding 180 can have different functions. For example, the first secondary winding 180 can be used for billing in the electricity meter; the second secondary winding 180 can be used for current measurement and monitoring; the third secondary winding 180 can be used for overcurrent protection and is connected to the inside of the relay instead of the electricity meter; the fourth secondary winding 180 can be used to connect to the relay to achieve quick disconnection (short time, for example 0.05 seconds). Four secondary windings 180 are shown in the figure, but the embodiments of the present disclosure are not limited thereto. Instead, any number of windings can be set as needed to achieve the required functions.

[0058] In some embodiments, the current transformer 100 may further include a shield 150. The shield 150 is configured to be at the same potential as the primary conductor 215. The shield 150 is made of a metal material, for example, a metal plate or a metal mesh (referred to as a shielding mesh).

[0059] Figure 6 FIG. 1 shows a perspective view of a shielding member 150 according to some exemplary embodiments of the present disclosure. Figure 6 As shown, the shielding member 150 may include a cylindrical portion 152 and a bent portion 154. Return to Reference Figure 4 and Figure 5 The cylindrical portion 152 may be disposed between the hole 112 and the secondary winding 180 . The bent portion 154 extends from an edge of the opening of the cylindrical portion 152 to surround at least a portion of the secondary winding 180 .

[0060] The function of the shield 150 is to provide high-voltage shielding. Because there is an air gap between the primary conductor 215 (e.g., the copper tube) and the cast body (i.e., between the primary conductor 215 and the inner wall of the hole 112), the shield 150 is used for shielding. Without the shield 150, the electric field strength in the air gap would be very high, and the air gap between the copper tube and the resin would be broken down, leading to discharge. In existing solutions without the shield 150, the high-voltage copper tube and the low-voltage secondary winding 180 are separated by composite insulation (epoxy resin and air gap). Due to the high dielectric constant of epoxy resin and the low dielectric constant of air, the electric field strength in the air is even higher, leading to air discharge. According to the embodiments of the present disclosure, due to the provision of the shield 150, the shielding effect of the shield 150 makes the shield 150 and the high voltage (copper tube and fastener 202) equipotential, thereby reducing the air gap field strength to zero and ensuring a single insulation (epoxy resin) between the high voltage (shielding mesh) and the low voltage (secondary winding 180). In this way, a uniform field strength can be achieved. In addition, since the shielding member 150 can shield the electric field but not the magnetic field, it does not affect the electromagnetic conversion (current mutual inductance).

[0061] Since there is an air gap between the L-shaped copper busbar 206 and the grounding knife seat 211 and the casting body, and the L-shaped copper busbar 206 and the grounding knife seat 211 are electrically connected to the copper pipe and are at high voltage, they also need to be shielded. Figure 6 As shown, the bending portion 154 of the shielding member 150 may be provided to shield the L-shaped copper bus 206 and the grounding knife seat 211 .

[0062] exist Figure 3 In the illustrated embodiment, the current transformer 100 may further include a support rib 140 . The support rib 140 is disposed on the inner wall of the hole 112 . A support member 142 may be disposed in the support rib 140 . The support member 142 is coupled to the cylindrical portion 152 to support the shielding member 150 .

[0063] like Figure 5 As shown, each insulating rib 122 extends along the axis of the hole 112, and the cross section of each insulating rib 122 along the axis is sawtooth-shaped. In this way, the creepage distance between the terminals of the primary conductor 215 and the secondary conductor 170 can be effectively increased by the sawtooth-shaped back-and-forth profile.

[0064] Continue to refer Figure 6As shown, the support member 142 may include a support end portion 144 and a support rod 136. A threaded hole is provided in the support end portion 144 for cooperating with a fastener 202 to secure the primary conductor 215 to the support rib 140, wherein the fastener 202 is adapted to be disposed at an end surface of the insulating housing 110 to clamp the sidewall of the primary conductor 215. The support rod 136 extends from the support end portion 144 along the axis of the hole 112 to couple with the cylindrical portion 152. The shield 150 may be electrically connected to the primary conductor 215 via the support member 142 and the fastener 202.

[0065] Support member 142 supports shielding member 150 before casting and supports and secures fastener 202 after casting. Support member 142 is provided with a threaded hole for engaging fastener 202 to secure the copper tube. Support insert 156 supports shielding member 150 before casting and, in other words, secures shielding member 150 during mold assembly, thereby maintaining its relative position within the mold.

[0066] In some embodiments, during the casting process, the secondary winding 180 and the shielding component 150 in the housing can be cast and encapsulated with resin (or polyurethane or other materials), so that the secondary winding 180 and the shielding component 150 form an integrated structure after curing.

[0067] The following combination Figure 7 and Figure 8 The structure of the secondary winding 180 of the embodiment of the present disclosure is further described, wherein Figure 7 shows a perspective schematic diagram of a secondary winding according to some exemplary embodiments of the present disclosure; Figure 8 Shown according to Figure 7 A cross-sectional view of the secondary winding is shown.

[0068] like Figure 7 As shown, the secondary winding 180 includes an iron core 160 and a secondary conductor 170. The iron core 160 has a ring structure, and the secondary conductor 170 is wound around the iron core 160. Figure 8As shown, the cross-section of the core 160 extending through the axis of the hole 112 is square. For the same transformer capacity, the same number of coils requires the same core cross-sectional area. For the same cross-sectional area, the perimeter of a square is smaller than that of a rectangle, so the length of the secondary conductor of the required secondary winding is smaller. In this way, the length of the required secondary conductor 170 can be reduced while maintaining the same transformer capacity, thereby saving wire, such as enameled wire. In addition, for a circle and a square with the same cross-sectional area, the perimeter of a circle is smaller than that of a square, but due to the difficulty of manufacturing, cores with a circular cross-section are usually rarely suitable. In addition, when multiple secondary windings need to be used side by side, the circular cores cannot be arranged as closely as square cores without gaps, which will result in the overall size being larger than that of a square cross-section. In this regard, cores with a square cross-section are more advantageous.

[0069] Compared with existing solutions, the structure according to the embodiment of the present disclosure can achieve an increased creepage distance, thereby increasing insulation and reliability.

[0070] In the above embodiment, the structure of the current transformer 100 shown is merely illustrative, and the embodiments of the present disclosure are not limited thereto, but may be modified in various ways.

[0071] Temperature simulations of the disclosed embodiments show that compared to known solutions, the temperature can be reduced by at least 13k, or 13 degrees Celsius. Insulation simulations show that the insulation performance meets requirements, for example, meeting GB:12 / 42 / 75kV and IEC:17.5 / 38 / 95kV. Mechanical simulations show that when high current passes through the primary conductor 215, the mechanical properties are stable with sufficient margin, and the maximum stress and material strength meet mechanical requirements.

[0072] Through the solution of the embodiment of the present disclosure, the number of parts can be reduced, thereby reducing material and labor costs; and the insulation performance can be improved, effectively preventing breakdown, leakage and partial discharge.

[0073] In addition, according to an embodiment of the present disclosure, a switch cabinet 200 is provided, including the above-mentioned current transformer 100.

[0074] According to an embodiment of the present disclosure, a method 900 for a current transformer 100 is also provided. Figure 9 Provide a description. Figure 9 A flow chart of a method for manufacturing a current transformer according to some exemplary embodiments of the present disclosure is shown.

[0075] In step 902, secondary conductor 170 is wound around iron core 160 to form secondary winding 180. Secondary conductor 170 may be enameled wire. Enameled wire consists of two parts: a conductor and an insulation layer. The bare wire is annealed and softened, then painted multiple times and baked. The conductor material of the enameled wire can be copper wire, aluminum wire, an alloy, or the like. In some embodiments of the present invention, the conductor material is preferably copper wire.

[0076] In step 904, the secondary winding 180 and the shield 150 are placed in a mold and the relative positions of the secondary winding 180 and the shield 150 are maintained. The relative positions of the secondary winding 180 and the shield 150 can be maintained by some fixing devices, which will not be described in detail.

[0077] In step 906, resin is poured into the mold until the resin fills the cavity of the mold.

[0078] In step 908, the resin is heated to cure. After the resin cures, the secondary winding 180, shield 150, and other components within it are solidified into an integrated structure with the insulating housing 110. The mold is configured to form insulating protrusions on the end surfaces of the insulating housing 110 of the current transformer 100. This allows the resulting current transformer 100 to have insulating protrusions 120, thereby increasing the creepage distance between the primary conductor 215 and the terminal 172.

[0079] In the above embodiments, the manufacturing process of the current transformer can be simplified, a current transformer with reliable performance can be obtained, and breakdown, leakage and partial discharge can be effectively prevented.

[0080] Various embodiments of the present disclosure have been described above. The above descriptions are exemplary and are only optional embodiments of the present disclosure. They are not exhaustive and are not intended to limit the present disclosure. Although the claims in this application have been formulated for specific combinations of features, it should be understood that the scope of the present disclosure also includes any novel feature or any novel combination of features disclosed herein, whether explicitly or implicitly or in any generalization thereof, regardless of whether it relates to the same scheme in any claim currently claimed. The applicant hereby informs that new claims may be formulated to these features and / or combinations of these features during the examination of this application or in any further application derived therefrom.

[0081] The terminology used herein is selected to best explain the principles of the various embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the various embodiments disclosed herein. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure are intended to be included within the scope of protection of this disclosure.

Claims

1. A current transformer (100), comprising: an insulating housing (110), wherein a hole (112) penetrating the insulating housing (110) is provided in the insulating housing (110), and the hole (112) is suitable for a primary conductor (215) of a primary winding to pass therethrough; and A secondary winding (180) is located in the insulating housing (110) and is arranged around the hole (112), and a terminal (172) of a secondary conductor (170) of the secondary winding (180) is arranged outside the insulating housing (110); an insulating protrusion (120) at least partially surrounding the opening of the hole (112) and extending outward from an end surface of the insulating housing (110) so that a creepage distance between the primary conductor (215) and the terminal (172) is greater than an insulation distance threshold between the primary conductor (215) and the terminal (172); as well as A shielding member (150) is configured to be at the same potential as the primary conductor (215), the shielding member (150) being made of a metal material and comprising: a cylindrical portion (152) disposed between the hole (112) and the secondary winding (180); as well as A bent portion (154) extends from an edge of the opening of the cylindrical portion (152) to surround at least a portion of the secondary winding (180).

2. The current transformer (100) according to claim 1, wherein the secondary winding (180) comprises: an iron core (160) having an annular structure and disposed concentrically with the axis of the hole (112); as well as A secondary conductor (170) is wound around the iron core (160).

3. The current transformer (100) according to claim 2, wherein a cross-section of the core (160) extending through an axis of the hole (112) is square.

4. The current transformer (100) according to claim 1, wherein: The insulating protrusion (120) includes a plurality of concentrically arranged insulating ribs (122).

5. The current transformer (100) according to claim 4, wherein: Each of the insulating ribs (122) extends along the axis of the hole (112), and a cross section of each of the insulating ribs (122) along the axis is in a sawtooth shape.

6. The current transformer (100) according to claim 1, wherein a plurality of independent secondary windings (180) are arranged side by side in the insulating housing (110).

7. The current transformer (100) according to claim 1, wherein: The shielding member (150) is made of a metal plate or a metal mesh.

8. The current transformer (100) according to claim 1, further comprising: A support rib (140) is provided on the inner wall of the hole (112), a support member (142) is provided in the support rib (140), and the support member (142) is coupled to the cylindrical portion (152) to support the shielding member (150).

9. The current transformer (100) according to claim 8, wherein: The support member (142) comprises: a support end portion (144), wherein a threaded hole is provided in the support end portion (144), the threaded hole being adapted to cooperate with a fastener (202) to secure the primary conductor (215) to the support rib (140), wherein the fastener (202) is adapted to be provided at an end surface of the insulating housing (110) to clamp a side wall of the primary conductor (215); and A support rod (136) extends from the support end portion (144) in the direction of the axis of the hole (112) to couple with the cylindrical portion (152).

10. The current transformer (100) according to claim 9, wherein: The shielding member (150) is electrically connected to the primary conductor (215) via the support member (142) and the fastener (202).

11. The current transformer (100) according to claim 1, further comprising: A secondary terminal portion (130) is provided in the middle of a side surface of the insulating housing (110), and the terminal (172) of the secondary conductor (170) extends into the secondary terminal portion (130).

12. A switch cabinet comprising the current transformer (100) according to any one of claims 1 to 11.

13. A method for manufacturing a current transformer (100) according to any one of claims 1 to 11, comprising: Winding the secondary conductor onto the core to form a secondary winding; placing the secondary winding and the shielding member into a mold, and maintaining the relative positions of the secondary winding and the shielding member; pouring resin into the mold; as well as heating the resin to cure the resin; The mold is configured to form an insulating protrusion on the end surface of the insulating housing of the current transformer.

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