Preparation method of composite iron core for current transformer and composite iron core

Abstract

The invention discloses a preparation method of a composite iron core for a current transformer and the composite iron core. The composite iron core comprises an SMC mould pressing lining, a silicon steel iron core, an amorphous iron core, epoxy resin, a curing agent and silicon powder. Respectively manufacturing a silicon steel iron core, an SMC mould pressing lining and an amorphous iron core; an SMC mould pressing lining is embedded into the silicon steel iron core to form a shell; the amorphous iron core is arranged in the shell; the epoxy resin and the curing agent are put into a stirrer to be stirred and mixed evenly, and a mixture I is obtained; the obtained mixture I is poured into the shell, so that the mixture I completely permeates into the amorphous iron core and covers the amorphous iron core, and then curing is conducted; after curing, the epoxy resin, the curing agent and the silicon powder are put into the stirrer to be stirred and mixed uniformly, and a mixture II is obtained; and pouring the mixture II into the shell, filling the shell with the mixture II, and curing to obtain the composite iron core. The composite iron core coil prepared through the steps is too large in stress, stress is generated, and the output precision and the protection multiple of the current transformer are affected.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical industry, and particularly relates to a preparation method and a composite iron core for a current transformer. Background Art

[0002] The iron core is a core component in electromagnetic equipment, and its function is to concentrate magnetic lines of force and enhance electromagnetic efficiency to achieve energy conversion or signal transmission. However, the existing iron core adopts a stainless steel 304 protective box structure, with the amorphous iron core placed in a stainless steel shell, sealed with 704 silicone rubber, and an epoxy resin ring with an inner diameter, diameter consistent with that of the amorphous iron core and a thickness of 2 mm is placed on it. Finally, it is evenly wound with low-voltage electrical insulating tape. The thickness of the iron core buffer layer reaches 10 mm, the main insulation distance is reduced, affecting the power frequency withstand voltage, and the partial discharge does not meet the technical requirements. Summary of the Invention

[0003] In view of this, the present application provides a preparation method and a composite iron core for a current transformer, which can effectively reduce the buffer layer of the composite iron core, increase the effective distance of the main insulation, improve the power frequency withstand voltage, partial discharge level, measurement accuracy and protection multiple of the current transformer.

[0004] According to one aspect of the present application, a preparation method for a composite iron core for a current transformer is provided. The composite iron core for a current transformer includes an SMC molded inner lining, a silicon steel core and an amorphous iron core. The method includes the following steps: S1: separately manufacture the silicon steel core, the SMC molded inner lining and the amorphous iron core; S2: embed the silicon steel core into the SMC molded inner lining, with a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining to form a shell; S3: place the amorphous iron core into the shell, at this time there is a gap between the amorphous iron core and the inner wall of the silicon steel core, and there is also a gap between the amorphous iron core and the outer wall of the SMC molded inner lining; S4: put epoxy resin and a curing agent into a mixer and stir and mix them to obtain mixture Ⅰ; S5: pour the obtained mixture Ⅰ into the shell, so that the mixture Ⅰ completely penetrates into the gaps between the amorphous iron core and the inner wall of the silicon steel core and between the amorphous iron core and the outer wall of the SMC molded inner lining, and covers the amorphous iron core and then cure it; S6: after curing, put the epoxy resin, the curing agent and silicon powder into a mixer and stir and mix them to obtain mixture Ⅱ; S7: pour mixture Ⅱ into the shell to fill the shell; S8: after filling, cure it to obtain a composite iron core.

[0005] In a possible implementation manner, the mass ratio of the epoxy resin to the curing agent in mixture Ⅰ is 100:25, and after mixture Ⅰ is poured into the shell, the shell is in a non-full state.

[0006] In a possible implementation, the curing duration is not less than 8 hours.

[0007] In a possible implementation, the mass ratio of the epoxy resin, the curing agent and the silica fume in the mixture II is 100:25:300, and the mixture II is poured into the shell until the shell is full.

[0008] In a possible implementation, the SMC molded inner lining is in interference fit with the inner ring of the silicon steel core, and the SMC molded inner lining is 2 mm thick.

[0009] In a possible implementation, the height of the SMC molded inner lining is the same as the height of the inner ring of the silicon steel core.

[0010] In a possible implementation, the height of the amorphous core is 5 mm lower than the height of the shell.

[0011] In a possible implementation, the area ratio of the window of the silicon steel core is 70%, and the area ratio of the window of the amorphous core is 30%.

[0012] A composite core for a current transformer, the composite core of the current transformer prepared by the above method; it includes: an SMC molded inner lining, a silicon steel core and an amorphous core; the SMC molded inner lining is a hollow cylindrical structure with openings at both ends, the SMC molded inner lining has a preset height, and one end of the SMC molded inner lining extends outwards to form an extension; the silicon steel core is a hollow cylinder with openings at both ends, the silicon steel core has a preset thickness, and the silicon steel core is sleeved on the outer wall of the SMC molded inner lining, and there is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining, and an interference fit is formed between one end of the silicon steel core and the extension; the amorphous core is also a hollow cylindrical structure with openings at both ends, and the amorphous core is sleeved on the outer wall of the SMC molded inner lining and is located between the silicon steel core and the SMC molded inner lining.

[0013] In a possible implementation, the inner diameter of the SMC molded inner lining is smaller than the inner diameter of the amorphous core, and the inner diameter of the amorphous core is smaller than the inner diameter of the silicon steel core.

[0014] Advantages of the present invention: By providing an SMC molded inner lining, a silicon steel core, an amorphous core, as well as epoxy resin, a curing agent, and silicon powder, and preparing through the following steps: S1: respectively fabricate the silicon steel core, the SMC molded inner lining, and the amorphous core; S2: embed the inner ring of the silicon steel core into the SMC molded inner lining to form a housing composed of the silicon steel and the SMC molded inner lining; S3: place the amorphous core into the housing; S4: put the epoxy resin and the curing agent into a mixer and stir and mix them evenly to obtain mixture I; S5: pour the obtained mixture I into the housing, so that mixture I completely penetrates into the gaps between the amorphous core and the inner wall of the silicon steel core and between the outer wall of the amorphous core and the SMC molded inner lining, and cover the top of the amorphous core and then cure it; S6: after curing, put the epoxy resin, the curing agent, and the silicon powder into a mixer and stir and mix them evenly to obtain mixture II; S7: pour mixture II into the housing and fill the housing; S8: after filling, cure it to obtain a composite core. The obtained composite core is potted with different mixtures to improve its mechanical properties, protect the silicon steel core and the amorphous core from being stressed, effectively reduce the buffer layer of the composite core, increase the effective distance of the main insulation, and improve the power frequency withstand voltage, partial discharge level, measurement accuracy, and protection multiple of the current transformer. Description of the Drawings

[0015] Figure 1 Shows a specific structural cross-sectional view of the composite core of the current transformer according to an embodiment of the present application; Figure 2 Shows a top view of the composite core of the current transformer according to an embodiment of the present application. Detailed Embodiments

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0017] Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference signs denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0018] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention or simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0019] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0020] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "joined", "fixed", "engaged", "hinged", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] As Figures 1 to 2 shown, the preparation method of the composite iron core for the current transformer includes an SMC molded inner liner 100, a silicon steel core 200, an amorphous iron core 300, as well as epoxy resin, a curing agent, and silicon powder, and the mass ratio of the epoxy resin, the curing agent, and the silicon powder is 100:25:300.

[0022] Specifically, SMC molding is adopted because SMC, which is short for Sheet Molding Compound, namely sheet molding compound, is a premix composed of resin, reinforcing materials (such as glass fiber, carbon fiber, etc.), fillers, thickeners, pigments and various additives. The SMC molding process has strong adaptability to molds and can manufacture various products with complex shapes and precise dimensions according to the design requirements of products. SMC products have excellent electrical properties, mechanical properties, thermal stability and chemical corrosion resistance. Application fields: electrical industry, transportation, construction industry, and also include household appliances, electronics, communication, aerospace and other fields. As an excellent composite material, SMC has broad application prospects and market demands. With the progress of technology and continuous improvement of processes, the performance and application fields of SMC will be further expanded.

[0023] The silicon steel core 200 is adopted because of the characteristics of low initial magnetic permeability and high saturation magnetic density of the silicon steel core 200, which can meet the requirements of small current measurement and short circuit or grounding fault. When the composite core changes according to the primary current, it can ensure that the secondary current outputs sufficient power, meet the measurement and reliable operation of the relay protection device, and improve the power supply reliability.

[0024] The amorphous core 300 is adopted because of the characteristics of high initial magnetic permeability and low saturation magnetic density of the amorphous core 300, which can meet the measurement accuracy of the instrument.

[0025] The SMC molded lining 100 is adopted because the function of the SMC molded lining 100 is to increase strength, protect the amorphous core 300 from being stressed, reduce the deformation of the silicon steel core 200, effectively reduce the buffer layer of the composite core, increase the effective distance of the main insulation, and improve the power frequency withstand voltage and partial discharge level of the current transformer.

[0026] In a possible implementation manner, the following steps are included: S1: respectively manufacture the silicon steel core 200, the SMC molded lining 100 and the amorphous core 300; S2: embed the inner ring of the silicon steel core 200 into the SMC molded lining 100 to form a shell composed of the silicon steel and the SMC molded lining 100; S3: put the amorphous core 300 into the shell; S4: put epoxy resin and curing agent into a mixer and stir and mix them to obtain mixture Ⅰ; S5: pour the obtained mixture Ⅰ into the shell, make the mixture Ⅰ completely penetrate into the layers of the amorphous core 300, and cover the amorphous core 300 and then cure it; S6: after curing, put epoxy resin, curing agent and silicon powder into a mixer and stir and mix them to obtain mixture Ⅱ; S7: pour mixture Ⅱ into the shell and fill the shell; S8: after filling, cure it to obtain a composite core. The mixture Ⅰ and the mixture Ⅱ form a mixed solid 400 after curing.

[0027] Among them, the production of the silicon steel core 200, the SMC molded inner lining 100, and the amorphous core 300 respectively are prior arts and will not be described in detail in this application.

[0028] More specifically, the mass ratio of the epoxy resin to the curing agent in the mixture Ⅰ is 100:25. And after the mixture Ⅰ is poured into the shell, the shell is in a non-full state. The mixture Ⅰ is poured into the shell to make the mixture Ⅰ completely penetrate into the layers of the amorphous core 300 and cover the top of the amorphous core 300, and then curing is carried out, and the curing duration is 8 hours. The long curing time of potting produces less stress, which has little impact on the performance of the amorphous core 300.

[0029] Preferably, the mass ratio of the epoxy resin, the curing agent, and the silicon powder in the mixture Ⅱ is 100:25:300. And the mixture Ⅱ is poured into the shell to fill the shell. The potting height is the same as that of the silicon steel core 200, which increases the mechanical strength of the core.

[0030] In a possible implementation manner, the SMC molded inner lining 100 has an interference fit with the inner ring of the silicon steel core 200, and the SMC molded inner lining 100 is 2 mm. The SMC molded inner lining 100 needs to be 2 mm to have sufficient strength. If the thickness is too large, the window area of the amorphous core will decrease, affecting the performance parameters of the core.

[0031] Among them, the height of the SMC molded inner lining 100 is the same as the height of the inner ring of the silicon steel core 200.

[0032] In a possible implementation manner, the height of the amorphous core 300 is 5 mm lower than the height of the shell. Such a setting is because if the height of the amorphous core 300 is 5 mm lower than the height of the shell, the core is prone to being stressed. If it is higher than 5 mm, the window area of the amorphous core will decrease, affecting the performance parameters of the core.

[0033] In a possible implementation manner, the window area of the silicon steel core 200 accounts for 70%, and the window area of the amorphous core 300 accounts for 30%. Such a technical solution setting is considered for economy, effectively controlling costs. The amorphous core mainly meets the detection of small currents, and the silicon steel meets the detection of large currents.

[0034] A composite iron core for a current transformer, and the composite iron core of the current transformer prepared as described above; the SMC molded inner lining is a hollow cylindrical structure with open ends at both ends, the SMC molded inner lining has a preset height, and one end of the SMC molded inner lining extends outward to form an extension part; the silicon steel core is a hollow cylinder with open ends at both ends, the silicon steel core has a preset thickness, and the silicon steel core is sleeved on the outer wall of the SMC molded inner lining, and there is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining, and there is an interference fit between one end of the silicon steel core and the extension part; the amorphous iron core is also a hollow cylindrical structure with open ends at both ends, and the amorphous iron core is sleeved on the outer wall of the SMC molded inner lining and is located between the silicon steel core and the SMC molded inner lining.

[0035] Specifically, as Figure 1 shown, the SMC molded inner lining 100, the silicon steel core 200, and the amorphous iron core 300 are all hollow cylinders with open ends at both ends and are hollow cylindrical structures. In order to enable the SMC molded inner lining 100 to be connected to the silicon steel core 200 to form a shell with a preset space, one end of the SMC molded inner lining 100 extends outward by a preset distance to form an extension part. When the silicon steel core 200 is sleeved on the outer wall of the SMC molded inner lining, one end of the silicon steel core 200 is arranged on the extension part and has an interference fit with the extension part. At this time, a space is formed between the inner wall of the silicon steel core 200 and the outer wall of the SMC molded inner lining 100. The amorphous iron core 300 is sleeved on the outer wall of the SMC molded inner lining 100, that is, located in this space. In order to enable the amorphous iron core 300 to be sleeved on the outer wall of the SMC molded inner lining 100 and the silicon steel core 200 to be sleeved on the amorphous iron core 300, the inner diameter of the SMC molded inner lining 100 is smaller than the inner diameter of the amorphous iron core 300, and the inner diameter of the amorphous iron core 300 is smaller than the inner diameter of the silicon steel core 200.

[0036] The following are the examples and comparative examples of this application: Example 1 The composite iron core includes: an SMC molded inner lining, a silicon steel core, an amorphous iron core, as well as epoxy resin, a curing agent, and silicon powder. Moreover, the mass ratio of the epoxy resin to the curing agent is 100:25, and the mass ratio of the epoxy resin, the curing agent, and the silicon powder is 100:25:300.

[0037] The preparation is carried out according to the following steps: S1: Manufacture the silicon steel core, the SMC molded inner lining, and the amorphous iron core respectively; S2: Embed the silicon steel core into the SMC molded inner lining. There is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining to form a shell, and the SMC molded inner lining is 2 mm. S3: Place the amorphous iron core into the shell. At this time, there are gaps between the amorphous iron core and the inner wall of the silicon steel core, and also between the amorphous iron core and the outer wall of the SMC molded inner liner. Moreover, the height of the amorphous iron core is 5 mm lower than the height of the shell. S4: Put epoxy resin and curing agent into a blender and stir evenly to obtain mixture Ⅰ, and the mass ratio of epoxy resin to curing agent is 100:25. S5: Pour the obtained mixture Ⅰ into the shell, so that mixture Ⅰ completely penetrates into the gaps between the amorphous iron core and the inner wall of the silicon steel core and between the amorphous iron core and the outer wall of the SMC molded inner liner, and covers the amorphous iron core and then cures for 8 hours. S6: After curing, put epoxy resin, curing agent and silicon powder into a blender and stir evenly to obtain mixture Ⅱ, and the mass ratio of epoxy resin, curing agent and silicon powder in mixture Ⅱ is 100:25:300. S7: Pour mixture Ⅱ into the shell to fill the shell. S8: After filling, cure to obtain a composite iron core.

[0038] The finished product inspection record of adopting the solution of this invention is shown in Table 1: As can be seen from Table 1, for the composite iron core prepared by this application, the ratio difference at 1% current is -0.14%, the phase difference is 10; at 5% current, the ratio difference is -0.12%, the phase difference is 9; at 20% current, the ratio difference is -0.13%, the phase difference is 9; at 100% current, the ratio difference is -0.14%, the phase difference is 9; at 120% current, the ratio difference is -0.14%, the phase difference is 9.

[0039] Comparative Example 1 The composite iron core includes: SMC molded inner liner, silicon steel core, amorphous iron core, and epoxy resin, curing agent and silicon powder. Moreover, the mass ratio of epoxy resin to curing agent is 100:25, and the mass ratio of epoxy resin, curing agent and silicon powder is 100:25:300.

[0040] Prepare according to the following steps: S1: Manufacture the silicon steel core, SMC molded inner liner and amorphous iron core respectively. S2: Embed the silicon steel core into the SMC molded inner liner. There is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner liner to form a shell, and the SMC molded inner liner is 2 mm. S3: Place the amorphous iron core into the shell. At this time, there are gaps between the amorphous iron core and the inner wall of the silicon steel core, and also between the amorphous iron core and the outer wall of the SMC molded inner liner. Moreover, the height of the amorphous iron core is 5 mm lower than the height of the shell. S4: Put the epoxy resin and the curing agent into a blender and stir to mix evenly to obtain mixture Ⅰ, and the mass ratio of the epoxy resin to the curing agent is 100:25; S5: Pour the obtained mixture Ⅰ into the shell, so that the mixture Ⅰ completely penetrates into the gaps between the inner wall of the amorphous iron core and the silicon steel core and between the outer wall of the amorphous iron core and the SMC molded inner liner, and cover the amorphous iron core and then cure for 4 hours; S6: After curing, put the epoxy resin, the curing agent and the silicon powder into a blender and stir to mix evenly to obtain mixture Ⅱ, and the mass ratio of the epoxy resin, the curing agent and the silicon powder in mixture Ⅱ is 100:25:300; S7: Pour mixture Ⅱ into the shell to fill the shell; S8: After filling, cure to obtain a composite iron core.

[0041] The finished product inspection record using this scheme is shown in Table 2: As can be seen from Table 2, for the composite iron core prepared by this application, the ratio difference at 1% current is -3.5%, the phase difference is 50, the ratio difference at 5% current is -3.1%, the phase difference is 40, the ratio difference at 20% current is -2.5%, the phase difference is 32, the ratio difference at 100% current is -2.0%, the phase difference is 30, and the ratio difference at 120% current is -2.1%, the phase difference is 30.

[0042] Comparative Example 2 The composite iron core includes: SMC molded inner liner, silicon steel core, amorphous iron core, and epoxy resin, curing agent and silicon powder, and the mass ratio of the epoxy resin to the curing agent is 100:25, and the mass ratio of the epoxy resin, the curing agent and the silicon powder is 100:25:300.

[0043] The preparation is carried out according to the following steps: S1: Manufacture the silicon steel core, SMC molded inner liner and amorphous iron core respectively; S2: Embed the silicon steel core into the SMC molded inner liner, and there is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner liner to form a shell, and the SMC molded inner liner is 2 mm; S3: Put the amorphous iron core into the shell. At this time, there is a gap between the amorphous iron core and the inner wall of the silicon steel core, and there is also a gap between the amorphous iron core and the outer wall of the SMC molded inner liner, and the height of the amorphous iron core is 5 mm lower than the height of the shell; S4: Put the epoxy resin and the curing agent into a blender and stir to mix evenly to obtain mixture Ⅰ, and the mass ratio of the epoxy resin to the curing agent is 100:25; S5: Pour the obtained mixture Ⅰ into the shell, allowing the mixture Ⅰ to fully penetrate into the gaps between the amorphous iron core and the inner wall of the silicon steel core and between the amorphous iron core and the outer wall of the SMC molded lining, covering the top of the amorphous iron core and then curing for 6 hours; S6: After curing, put epoxy resin, curing agent and silicon powder into a blender and stir evenly to obtain mixture Ⅱ, and the mass ratio of epoxy resin, curing agent and silicon powder in mixture Ⅱ is 100:25:300; S7: Pour mixture Ⅱ into the shell and fill the shell; S8: After filling, cure to obtain a composite iron core.

[0044] The finished product inspection record using this scheme is shown in Table 3: As can be seen from Table 3, for the composite iron core prepared by this application, the ratio difference at 1% current is -3.1%, the phase difference is 38, the ratio difference at 5% current is -3.0%, the phase difference is 35, the ratio difference at 20% current is -2.0%, the phase difference is 30, the ratio difference at 100% current is -1.8%, the phase difference is 29, and the ratio difference at 120% current is -1.91%, the phase difference is 28.

[0045] Comparative Example 3 The composite iron core includes: SMC molded lining, silicon steel core, amorphous iron core, and epoxy resin, curing agent and silicon powder, and the mass ratio of epoxy resin to curing agent is 100:25, and the mass ratio of epoxy resin, curing agent and silicon powder is 100:25:300.

[0046] The preparation is carried out according to the following steps: S1: Manufacture the silicon steel core, SMC molded lining and amorphous iron core respectively; S2: Embed the silicon steel core into the SMC molded lining, with a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded lining to form a shell, and the SMC molded lining is 2 mm; S3: Put the amorphous iron core into the shell. At this time, there are gaps between the amorphous iron core and the inner wall of the silicon steel core and between the amorphous iron core and the outer wall of the SMC molded lining, and the height of the amorphous iron core is 3 mm lower than the height of the shell; S4: Put epoxy resin and curing agent into a blender and stir evenly to obtain mixture Ⅰ, and the mass ratio of epoxy resin to curing agent is 100:25; S5: Pour the obtained mixture Ⅰ into the shell, allowing the mixture Ⅰ to fully penetrate into the gaps between the amorphous iron core and the inner wall of the silicon steel core and between the amorphous iron core and the outer wall of the SMC molded lining, covering the top of the amorphous iron core and then curing for 8 hours; S6: After curing, put epoxy resin, curing agent and silicon powder into a blender and stir evenly to obtain mixture II, and the mass ratio of epoxy resin, curing agent and silicon powder in mixture II is 100:25:300; S7: Pour mixture II into the shell and fill the shell; S8: After filling, cure to obtain a composite iron core.

[0047] The finished product inspection record using this solution is shown in Table 4.

[0048] As can be seen from Table 4, for the composite iron core prepared by this application, the ratio difference at 1% current is -3.2%, the phase difference is 60; at 5% current, the ratio difference is -3.1%, the phase difference is 44; at 20% current, the ratio difference is -3%, the phase difference is 34; at 100% current, the ratio difference is -2.8%, the phase difference is 32; at 120% current, the ratio difference is -2.8%, the phase difference is 32.

[0049] From the above experimental data, it can be seen that compared with Comparative Examples 1, 2, and 3, the iron core performance of the composite iron core prepared in Example 1 is the best.

[0050] The composite iron core prepared by this application through the above steps solves the problem that the wire package is subjected to excessive force, generates stress, and affects the output accuracy and protection multiple of the current transformer.

[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the scope disclosed by the present invention, according to the technical solution and concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a composite iron core for a current transformer, characterized in that: The composite core for the current transformer includes an SMC molded inner lining, a silicon steel core, and an amorphous core; The method includes the following steps: S1: respectively fabricate the silicon steel core, the SMC molded inner lining, and the amorphous core; S2: embed the silicon steel core into the SMC molded inner lining, with a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining, to form a shell; S3: place the amorphous core into the shell, at this time there is a gap between the amorphous core and the inner wall of the silicon steel core, and there is also a gap between the amorphous core and the outer wall of the SMC molded inner lining; S4: put epoxy resin and a curing agent into a blender and stir and mix them evenly to obtain mixture I; S5: pour the obtained mixture I into the shell, so that mixture I completely penetrates into the gaps between the amorphous core and the inner wall of the silicon steel core and between the amorphous core and the outer wall of the SMC molded inner lining, and cover the top of the amorphous core and then cure it; S6: after curing, put the epoxy resin, the curing agent, and silicon powder into a blender and stir and mix them evenly to obtain mixture II; S7: pour mixture II into the shell to fill the shell; S8: after filling, cure it to obtain a composite core.

2. The preparation method of the composite iron core for a current transformer according to claim 1, wherein: The mass ratio of the epoxy resin and the curing agent in mixture I is 100:25, and after mixture I is poured into the shell, the shell is in a non-full state.

3. The preparation method of the composite iron core for a current transformer according to claim 2, characterized in that: In step S5, the curing duration is not less than 8 hours.

4. The preparation method of the composite iron core for a current transformer according to claim 3, characterized in that: The mass ratio of the epoxy resin, the curing agent, and the silicon powder in mixture II is 100:25:300, and mixture II is poured into the shell to fill the shell.

5. The preparation method of the composite iron core for a current transformer according to claim 3, characterized in that: The SMC molded inner lining is in interference fit with the inner circle of the silicon steel core, and the SMC molded inner lining is 2 mm.

6. The preparation method of the composite iron core for a current transformer according to claim 5, characterized in that: The height of the SMC molded inner lining is the same as the height of the inner circle of the silicon steel core.

7. The preparation method of the composite iron core for a current transformer according to claim 6, characterized in that: The height of the amorphous core is 5 mm lower than the height of the shell.

8. The preparation method of the composite iron core for a current transformer according to claim 7, characterized in that: The window area ratio of the silicon steel core is 70%, and the window area ratio of the amorphous core is 30%.

9. A composite core for a current transformer, characterized in that, A composite core for a current transformer prepared by any one of claims 1-8; It includes: an SMC molded inner lining, a silicon steel core, and an amorphous core; The SMC molded inner lining is a hollow cylindrical structure with both ends open, the SMC molded inner lining has a preset height, and one end of the SMC molded inner lining extends out an extension part; The silicon steel core is a hollow cylinder with both ends open, the silicon steel core has a preset thickness, and the silicon steel core is sleeved on the outer wall of the SMC molded inner lining, there is a preset distance between the inner wall of the silicon steel core and the outer wall of the SMC molded inner lining, and one end of the silicon steel core is in interference fit with the extension part; The amorphous core is also a hollow cylindrical structure with both ends open, and the amorphous core is sleeved on the outer wall of the SMC molded inner lining, located between the silicon steel core and the SMC molded inner lining.

10. The composite iron core for a current transformer according to claim 9, characterized in that, The inner diameter of the SMC molded inner liner is smaller than the inner diameter of the amorphous iron core, and the inner diameter of the amorphous iron core is smaller than the inner diameter of the silicon steel iron core.

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