Environment-friendly 10kv switch cabinet support insulator and preparation method thereof

Abstract

The application discloses an environment-friendly 10kV switch cabinet supporting insulator and a preparation method thereof, and belongs to the technical field of supporting insulators. The supporting insulator comprises an inner circular core, a top supporting column is arranged at the top of the inner circular core, a bottom supporting column is arranged at the bottom of the inner circular core, the top supporting column is provided with a first through hole, the center of the bottom supporting column is provided with a second through hole, the first through hole and the second through hole are used for embedding an insert, and the insert is made of a metal material; at least seven umbrella skirts are arranged in the circumferential direction of the inner circular core and are uniformly arranged between the top supporting column and the bottom supporting column; the inner circular core, the top supporting column, the bottom supporting column and the umbrella skirts are made of a polycarbonate material, and the inner circular core, the top supporting column, the bottom supporting column and the umbrella skirts are integrally formed. The polycarbonate thermoplastic material is used as the main material of the supporting insulator, the supporting insulator has excellent mechanical strength, heat resistance and insulation performance, can be recycled, and the production cost of the supporting insulator and the pollution to the environment are reduced.

Description

Technical Field

[0001] This application relates to an environmentally friendly 10kV switchgear support insulator and its preparation method, belonging to the technical field of support insulators. Background Technology

[0002] 10kV high-voltage switchgear is a crucial component of my country's power transmission and distribution system. Its internal support insulators provide electrical insulation and mechanical load-bearing, playing a vital role in the safe and stable operation of 10kV switchgear. Currently, the raw material used for the support insulators of numerous 10kV switchgear units is primarily epoxy resin-alumina composite material. While epoxy resin possesses excellent electrical, mechanical, and thermal properties, the cross-linked network molecular structure of thermosetting polymer materials prevents them from melting at high temperatures, making them difficult to recycle. After decommissioning, most are only suitable for landfill or incineration, resulting in severe resource waste and environmental pollution. Although methods such as mechanical grinding, high-temperature pyrolysis, and electrical pulse crushing can extract resin particles and / or filler particles / fibers from discarded thermosetting support insulation components for reuse in the manufacture of wind turbine blades, composite panels, or concrete, these methods suffer from high energy consumption during recycling, low added value of recycled products, and performance degradation. Therefore, developing recyclable and environmentally friendly support insulators from a material design perspective is crucial for the "carbon reduction" goals of the power equipment industry.

[0003] Currently, the main technical routes for manufacturing environmentally friendly and recyclable electrical insulation components include the following two types. One is to modify the molecular structure of existing thermosetting epoxy resin materials to construct epoxy resin vitrifiers, giving them biodegradable and recyclable properties. This is mainly achieved by introducing dynamic covalent bond structures into the three-dimensional cross-linked network of thermosetting epoxy resin, generally including transesterification, hindered urea bonds, Diels-Alder reactions, and disulfide bonds. These dynamic covalent bonds are in a reversible equilibrium of breaking and forming, and this dynamic equilibrium is disrupted under external stimuli (such as catalysts, temperature, pH, and ultraviolet irradiation). The breaking of a large number of dynamic covalent bonds leads to the cleavage of the molecular cross-linked network, thereby enabling the recycling of the material.

[0004] Despite this, the method still faces several challenges, and its engineering application prospects remain unclear. First, the preparation process is cumbersome: it typically requires modification of traditional epoxy resins and their curing agents, or the synthesis of novel epoxy oligomers or curing agents containing dynamic covalent bonds. This often necessitates multiple reaction steps. Second, the cost is high: some of the raw materials used in the synthesis are not commonly found in current industrial applications, making them more expensive than traditional epoxy insulation materials. Third, the overall performance of the modified material decreases: due to the low bond energy of some dynamic covalent bonds and the potential presence of catalyst residues in the finished product, the insulation properties (breakdown field strength), mechanical strength, and heat resistance (such as glass transition temperature) of most epoxy resin vitrifiers are currently lower than those of traditional epoxy insulation materials.

[0005] Another approach is to directly replace thermosetting materials with thermoplastic materials, using extrusion, injection molding, and other methods to prepare electrical insulation components. This route has received widespread attention from academia and industry due to its advantages such as intrinsic material recyclability, relatively mature technology, and lower cost. Thermoplastic alternatives to cross-linked polyethylene insulated cables and epoxy resin-sealed poles for switchgear have entered the commercial application stage. However, the polypropylene and nylon materials used in these thermoplastic alternatives suffer from low mechanical strength and high hygroscopicity, which can lead to abnormally high dielectric losses, making them difficult to apply to support insulation components that require both high insulation performance and mechanical strength. On the other hand, using traditional injection molding processes to prepare solid structures with complex shapes for support insulators presents problems such as difficulty in melt filling, high residual stress, and a tendency to have bubble defects, limiting the further engineering applications of thermoplastic support insulation components. Summary of the Invention

[0006] To address the aforementioned issues, an environmentally friendly 10kV switchgear support insulator and its manufacturing method are provided. Polycarbonate thermoplastic material is used as the main material for the support insulator, which imparts excellent mechanical strength, heat resistance, and insulation properties. Furthermore, as polycarbonate is a thermoplastic material, the prepared insulator is recyclable, making it an environmentally friendly support insulator suitable for mass production and use, reducing production costs and environmental pollution.

[0007] According to one aspect of this application, an environmentally friendly 10kV switchgear support insulator is provided, comprising:

[0008] The inner core has a top support post at its top and a bottom support post at its bottom. The top support post has a first through hole, and the bottom support post has a second through hole at its center. The first and second through holes are used to embed an insert, which is made of metal.

[0009] At least seven umbrella skirts are arranged circumferentially around the inner core and are evenly distributed between the top support column and the bottom support column;

[0010] The inner core, top support column, bottom support column, and umbrella skirt are made of polycarbonate material, and are integrally formed.

[0011] Polycarbonate has a bisphenol A structure similar to epoxy resin, exhibiting excellent mechanical strength and heat resistance at a low cost. Its tensile strength is approximately 65 MPa, flexural strength approximately 98 MPa, and glass transition temperature approximately 150°C. Furthermore, electrical performance tests have proven its superior properties (see details). Figure 1 Polycarbonate exhibits low dielectric constant and dielectric loss, and its dielectric properties show weak temperature dependence, remaining relatively unchanged within the temperature range of -40℃ to 125℃. Furthermore, polycarbonate possesses high volume resistivity, maintaining a high level of 1×10⁻⁶ even at a high temperature of 125℃. 14 The volume resistivity of polycarbonate is Ω·cm, and its volume resistivity changes very little when the applied electric field increases from 1kV / mm to 8kV / mm; in addition, the breakdown strength of polycarbonate is >40kV / mm. Therefore, the electrical properties of polycarbonate meet the application requirements of electrical insulation materials.

[0012] This application uses an integrally molded polycarbonate inner core, top support column, bottom support column and shed as the main body of the insulator, which can replace the traditional epoxy resin, achieve the purpose of recycling, and the insulator has strong mechanical strength, heat resistance and insulation performance, and can play a long-term role in electrical insulation and mechanical load bearing in 10kV switchgear.

[0013] Optionally, the umbrella skirt has seven sections, and from bottom to top, the bottom support column, the umbrella skirt, and the top support column, together with the inner circular core, respectively form a first rounded corner, a second rounded corner, a third rounded corner, a fourth rounded corner, a fifth rounded corner, a sixth rounded corner, a seventh rounded corner, an eighth rounded corner, a ninth rounded corner, a tenth rounded corner, an eleventh rounded corner, a twelfth rounded corner, a thirteenth rounded corner, a fourteenth rounded corner, a fifteenth rounded corner, and a sixteenth rounded corner.

[0014] The first rounded corner is equal in size to the sixteenth rounded corner, and its radius is 2.2-3.7 mm. The second rounded corner is equal in size to the fifteenth rounded corner, and its radius is 1.1-2.0 mm. The third rounded corner is equal in size to the fourteenth rounded corner, and its radius is 1.4-3.2 mm. The fourth rounded corner is equal in size to the thirteenth rounded corner, and its radius is 1.3-2.2 mm. The fifth rounded corner is equal in size to the twelfth rounded corner, and its radius is 1.5-2.7 mm. The sixth rounded corner is equal in size to the eleventh rounded corner, and its radius is 1.0-1.8 mm.

[0015] Preferably, the radius of the first rounded corner is 3.2 mm, the radius of the second rounded corner is 1.3 mm, the radius of the third rounded corner is 1.4 mm, the radius of the fourth rounded corner is 1.5 mm, the radius of the fifth rounded corner is 2.7 mm, and the radius of the sixth rounded corner is 1.2 mm.

[0016] The design of the insulating body supporting the insulator is as follows: Figure 2 As shown, when the supporting insulator is designed with seven skirts, the stress distribution of the supporting insulator under bending force is similar to that of the cantilever beam model. Under concentrated load, the maximum stress of the cantilever beam is mainly concentrated at the root of the cantilever beam, and its value is: 6Wl / (bh) 2 Where W is the concentrated load, l is the beam length, b is the beam width, and h is the beam height. For the 10kV switchgear support insulator of this application, finite element simulation shows that its maximum stress concentration is at the first fillet at the root of the insulator, and the stress concentration point is as follows: Figure 3 As shown.

[0017] For thermoplastic 10kV switchgear support insulators, since the mechanical strength of the polycarbonate material used is slightly lower than that of the commonly used epoxy resin, this application improves its shape design to alleviate local stress and enhance its bending resistance. Because the stress concentration is located at the first rounded corner, a method is adopted to strengthen the structure at the rounded corner: using a fast non-dominated sorting genetic algorithm with an elitist strategy (NSGA-II), the radius of each rounded corner from the first to the sixteenth rounded corner is optimized to obtain an insulator shape that can significantly alleviate stress concentration. The algorithm flowchart is shown below. Figure 4As shown, the supporting insulator is designed with a symmetrical shape, meaning the dimensions of the first fillet and the sixteenth fillet are equal, and so on. According to the algorithm, the radii of the first to sixth fillets are used as the individual vectors in the population. Their initial values ​​are randomly generated by the program, and the maximum first principal stress value when the insulator is subjected to a 2kN bending load is used as the evaluation criterion; the smaller the stress value, the better the individual. Therefore, the optimal numerical range for the first to sixth fillets and the eleventh to sixteenth fillets is calculated.

[0018] Optionally, the radius of the seventh rounded corner is 0.8-1.2mm, the radius of the eighth rounded corner is 0.8-1.2mm, the radius of the ninth rounded corner is 0.8-1.2mm, and the radius of the tenth rounded corner is 0.8-1.2mm.

[0019] Preferably, the radius of the seventh rounded corner is 1.0 mm, the radius of the eighth rounded corner is 1.0 mm, the radius of the ninth rounded corner is 1.0 mm, and the radius of the tenth rounded corner is 1.0 mm.

[0020] Analysis shows that the dimensions of the seventh to tenth fillets have little effect on dispersing the stress of the supporting insulator. However, the algorithm shows that setting the radii of the seventh to tenth fillets within the above range can minimize the stress value of the supporting insulator and facilitate the processing and forming of the supporting insulator.

[0021] Optionally, the diameter of the inner core is 40-50mm, the maximum diameter of the umbrella skirt is 65-70mm, the shortest distance A between adjacent umbrella skirts is 4-5mm, and the longest distance B between adjacent umbrella skirts is 11-13mm. Preferably, the diameter of the inner core is 45mm, the maximum diameter of the umbrella skirt is 68.6mm, the shortest distance A between adjacent umbrella skirts is 4.5mm, and the longest distance B between adjacent umbrella skirts is 12mm.

[0022] The inner core provides support; if its diameter is too small, the mechanical strength of the insulator is reduced; if its diameter is too large, manufacturing costs and processing difficulty increase. The skirts increase the creepage distance along the surface; if the maximum diameter of the skirts is too small, the creepage distance along the surface decreases; if the maximum diameter is too large, manufacturing costs and difficulty increase, and the outer side of the skirts is more susceptible to mechanical damage. If the shortest distance A between adjacent skirts (i.e., the distance between adjacent fillets) is too short, the surface withstand capability decreases; if the shortest distance B between adjacent skirts is too long, a sufficient number of skirts cannot be arranged. If the longest distance between adjacent skirts is too short, the surface flashover voltage decreases; if the longest distance between adjacent skirts is too long, a sufficient number of skirts cannot be arranged, which also leads to a decrease in surface flashover voltage.

[0023] Optionally, the diameter of the top support column is 60-70mm, the height of the top support column is 16-20mm, the diameter of the first through hole is 20-24mm, and the depth of the first through hole is 18-20mm.

[0024] The diameter of the bottom support column is 60-70mm, the height of the bottom support column is 16-20mm, the diameter of the second through hole is 20-24mm, and the depth of the second through hole is 18-20mm.

[0025] Preferably, the diameter of the top support column is 65mm, the height of the top support column is 18.45mm, the diameter of the first through hole is 22mm, and the depth of the first through hole is 19mm.

[0026] The bottom support column has a diameter of 65mm and a height of 18.45mm. The second through hole has a diameter of 22mm and a depth of 19mm.

[0027] Both the top and bottom support columns serve to resist bending stress and protect the insulator skirts and core. If the diameter of the top support column is too large, it increases costs, makes processing difficult, increases volume and weight, and makes transportation difficult. If the diameter of the top and bottom support columns is too small, they cannot effectively protect the insulator skirts and core. If the height of the top and bottom support columns is less than 16mm, the insulator's bending resistance is reduced. If the height of the top and bottom support columns is greater than 20mm, it encroaches on the skirt space, preventing the skirt from effectively increasing the creepage distance.

[0028] The first and second through holes are for facilitating the insertion of the insert. Therefore, the size of the first and second through holes must not exceed the diameter of the insert. During processing, the first and second through holes can be interference-fitted with the insert. Thus, the diameter of the first and second through holes determines the required diameter of the insert. If the diameter of the first and second through holes is too large, it will increase the difficulty of installing the metal insert and reduce the creepage distance. If the diameter of the first and second through holes is too small, it will be detrimental to the fixing of the insulator (poor fixing stability). The depth of the first and second through holes determines the insertion depth of the insert. If the depth of the first and second through holes is too small, it will be detrimental to the fixing of the insulator, resulting in poor stability of the insulator. If the depth of the first and second through holes is too large, it will be difficult to process and reduce the bending strength of the insulator.

[0029] Optionally, the polycarbonate has a molecular weight of 30,000-100,000. This molecular weight ensures that the supporting insulator has sufficient mechanical strength, electrical properties, and heat resistance, while also reducing the production cost of the supporting insulator. Furthermore, the polycarbonate material can be quickly recycled after heating, and it is less prone to degradation or aging during the use of the supporting insulator, thereby improving the recycling rate and efficiency of the supporting insulator.

[0030] Optionally, the surface roughness of the supporting insulator is no greater than 1.6 μm. This surface roughness ensures that the insulator has sufficient surface dielectric strength.

[0031] According to another aspect of this application, a method for preparing the environmentally friendly 10kV switchgear support insulator as described in any of the above claims is provided, comprising the following steps:

[0032] S1: Select suitable polycarbonate rods;

[0033] S2: Based on finite element simulation and genetic algorithm, design a three-dimensional model of the supporting insulator, and use a CNC lathe to machine the polycarbonate rod to obtain an integral inner core, top support column, umbrella skirt and bottom support column;

[0034] S3: Two inserts are machined using CNC machining. The inserts are heated to 180-260°C and then hot-pressed into the first through hole and the second through hole respectively to obtain the supporting insulator.

[0035] Based on finite element simulation and genetic algorithm design, a three-dimensional model of the supporting insulator can be created. This allows for the analysis of the stress points of the supporting insulator during operation and the optimization of various dimensional parameters. The optimized insulator significantly reduces stress concentration, further improving the mechanical properties of the environmentally friendly supporting insulator and increasing its reliability for safe and stable operation. Furthermore, environmentally friendly 10kV switchgear supporting insulators are fabricated by machining polycarbonate rods. Compared to casting and injection molding processes, this method offers advantages such as simple operation, high precision, short production cycle, and no need for molds. It enables rapid manufacturing of environmentally friendly supporting insulators at a lower cost and is compatible with the rotationally symmetrical structure of the 10kV switchgear supporting insulators, significantly reducing the costs associated with mold manufacturing and facilitating industrial production and manufacturing.

[0036] After the insert is heated to 180-260℃, it is then embedded into the first through hole and the second through hole by hot pressing. This can achieve a tight fit between the insert and the first and second through holes. During the hot pressing process, residual air should be expelled as much as possible to prevent porosity defects at the junction of the insert and the supporting insulator.

[0037] Optionally, before heating the insert, the surface of the insert is sandblasted and / or coated with conductive adhesive. Sandblasting the surface of the insert can ensure that the insert is tightly installed in the first through hole and the second through hole, improving the overall integrity of the supporting insulator. Coating the surface of the insert with conductive adhesive can eliminate residual stress between the insert and the first through hole and the second through hole.

[0038] Optionally, the pressure of the hot pressing is 0.8-1.5 MPa. Insert installation is achieved through hot pressing, as the melt flow index (MFI) quantitatively reflects the melt flowability of thermoplastic materials. As shown in equation (1), according to the variation law of the melt flow index (MFI) of thermoplastic materials, Ln(MFI) has a linear relationship with temperature T, while Ln(MFI) and the logarithm of the pressure change Ln(ΔP) follow an exponential growth function relationship.

[0039]

[0040] Because the polycarbonate material used has a melt flow index of approximately 18 g / 10 min at 300℃ and a load of 1.2 kg, the metal insert needs to be sanded and coated with adhesive before hot pressing. Then, it must be heated to 180-260℃ and subjected to a uniform and constant pressure of 0.8-1.5 MPa, slowly hot-pressed into the insulator. This hot-pressing pressure ensures that the insert is uniformly embedded into the first and second through holes, guarantees a tight fit, and increases the insertion speed. If the hot-pressing pressure is too low, the insert cannot be fully pressed into place; if the pressure is too high, bubble-like defects may easily form around the insert.

[0041] Furthermore, residual air should be expelled as much as possible during the hot pressing process to prevent porosity defects at the junction of the insert and the insulator.

[0042] Optionally, in step S2, the machining accuracy of the machining process is not less than 0.1 mm. This machining accuracy ensures the precision of each parameter of the supporting insulator body, thereby ensuring that the mechanical strength of the supporting insulator is equal to the calculated values ​​from finite element simulation and genetic algorithm models, thus improving the machining efficiency of the supporting insulator.

[0043] The beneficial effects of this application include, but are not limited to:

[0044] 1. The environmentally friendly 10kV switchgear support insulator of this application uses thermoplastic polycarbonate to replace epoxy resin, which effectively solves the problem that epoxy insulators are difficult to recycle directly. This produces a recyclable and environmentally friendly support insulator, which is conducive to the green and environmentally friendly development of the power system and reduces the production cost of support insulators and environmental pollution.

[0045] 2. According to the environmentally friendly 10kV switchgear support insulator of this application, the shape of the insulator is optimized by using a fast non-dominated sorting genetic algorithm (NSGA-II) with an elite strategy, thereby reasonably controlling the radius of the first rounded corner to the sixteenth rounded corner, so as to alleviate local stress concentration and enhance the bending strength of the insulator.

[0046] 3. According to the environmentally friendly 10kV switchgear support insulator of this application, the insulator shape is optimized by finite element simulation and genetic algorithm, which significantly alleviates the stress concentration problem, further improves the mechanical performance of the environmentally friendly support insulator, and increases its reliability for safe and stable operation.

[0047] 4. According to the method for preparing the environmentally friendly 10kV switchgear support insulator of this application, the environmentally friendly support insulator is manufactured by machining. This manufacturing method has a high degree of automation. Compared with the traditional casting or injection molding process, it does not require molds, which is convenient and fast, and greatly reduces the cost originally caused by the need to manufacture molds. It is conducive to large-scale industrial production and manufacturing. Attached Figure Description

[0048] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0049] Figure 1 This is a test diagram showing the electrical properties of the polycarbonate material involved in this application.

[0050] Figure 2 This is the insulation design drawing of insulator #2 involved in this application.

[0051] Figure 3 This is a stress distribution diagram for a traditional support insulator subjected to bending load, as analyzed by finite element simulation.

[0052] Figure 4 The flowchart of the genetic algorithm for optimizing the shape design of insulators.

[0053] Figure 5 This is a sample diagram of the insulator involved in this application. Detailed Implementation

[0054] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0056] Example 1

[0057] This embodiment relates to a method for preparing an environmentally friendly 10kV switchgear support insulator, comprising the following steps:

[0058] S1: Select suitable polycarbonate rods;

[0059] S2: Based on finite element simulation and genetic algorithm, design a three-dimensional model of the supporting insulator, and use a CNC lathe to machine the polycarbonate rod to obtain an integral inner core, top support column, umbrella skirt and bottom support column;

[0060] S3: Two inserts are CNC machined, sandblasted, and coated with conductive adhesive. The inserts are then heated to 180-260℃ and hot-pressed into the first and second through holes respectively, thus obtaining the supporting insulator. Figure 5 As shown.

[0061] Preferably, the hot pressing pressure is 0.8-1.5 MPa, and in step S2, the machining accuracy of the machining process is greater than 0.1 mm.

[0062] Preferably, before heating the insert, the surface of the insert is sandblasted and / or coated with conductive adhesive.

[0063] The polycarbonate rods used in step S1 of this embodiment are transparent, with a diameter of 80 mm, and their volume resistivity under normal conditions is tested to be approximately 3.2 × 10⁻⁶. 16 The dielectric loss (tanδ) is approximately 0.003 Ω·cm, measured using a three-electrode electrometer. The dielectric loss under normal conditions is approximately 47 kV / mm, measured using a dielectric spectrum analyzer or a Schering bridge. The breakdown strength is approximately 47 kV / mm, measured using 25 mm diameter ball-to-ball electrodes. The sample is completely immersed in pure insulating oil during testing, following GB / T1408 standards.

[0064] According to the above preparation method, insulators 1#-5# were prepared, each with 7 sheds. The specific parameters of the insulators are detailed in Table 1 below. In insulator 1#, the diameter of the inner core is 40mm, the maximum diameter of the sheds is 65mm, the shortest distance A between adjacent sheds is 4mm, the longest distance B between adjacent sheds is 11mm, the diameter of the top support post is 60mm, the height of the top support post is 16mm, the diameter of the first through hole is 20mm, and the depth of the first through hole is 18mm; the diameter of the bottom support post is 60mm, the height of the bottom support post is 16mm, the diameter of the second through hole is 20mm, and the depth of the second through hole is 18mm.

[0065] In insulator #3, the inner core diameter is 50mm, the maximum diameter of the sheds is 70mm, the shortest distance A between adjacent sheds is 5mm, the longest distance B between adjacent sheds is 13mm, the diameter of the top support post is 70mm, the height of the top support post is 20mm, the diameter of the first through hole is 24mm, the depth of the first through hole is 20mm, the diameter of the bottom support post is 70mm, the height of the bottom support post is 20mm, the diameter of the second through hole is 24mm, and the depth of the second through hole is 20mm.

[0066] In insulators #2, #4, and #5, the inner core diameter is 45mm, the maximum diameter of the sheds is 68.6mm, the shortest distance A between adjacent sheds is 4.5mm, and the longest distance B between adjacent sheds is 12mm; the top support post has a diameter of 65mm, a height of 18.45mm, a first through hole diameter of 22mm, and a depth of 19mm; the bottom support post has a diameter of 65mm, a height of 18.45mm, a second through hole diameter of 22mm, and a depth of 19mm.

[0067] Table 1

[0068]

[0069] Test case

[0070] Taking the distribution of the first principal stress of an insulator under a 2kN bending load as an example, the maximum stress points of insulators 1#-5# in Example 1 and the control insulator are analyzed. The stress is mainly concentrated at the first and second rounded corners. The maximum stress data are shown in Table 2 below.

[0071] Table 2

[0072] Insulator #1 45.53 Insulator #2 45.21 Insulator #3 48.03 Insulator #4 49.52 Insulator #5 50.72 Reference insulator 68.90

[0073] It was found that insulator #2 had the lowest maximum stress value. Insulation performance tests were conducted on insulator #2, and the results are shown in Table 3. The test method is as follows:

[0074] Flashover voltage test: Use a high-voltage test transformer (to generate AC high voltage), a voltage divider, and an oscilloscope (to measure AC high voltage); the test conditions are ambient air at normal temperature and pressure; during the test, the voltage is increased at a rate of 1kV / mm until flashover occurs.

[0075] Partial discharge initiation voltage test: A high-voltage test transformer (generating AC high voltage) and a partial discharge detector (detecting partial discharge signals) are used. The test method involves step-by-step voltage increases (after increasing the voltage to a certain value, it is held for 60 seconds, and the number of partial discharge occurrences is counted to determine whether the partial discharge initiation voltage has been reached). Specifically, when the voltage is close to the partial discharge initiation voltage, a step size of 0.2kV is used to ensure measurement accuracy. When more than 10 partial discharge signals are detected within 60 seconds, the applied voltage at this time is recorded as the partial discharge initiation voltage.

[0076] The instrument used for the power frequency withstand voltage test is a high-voltage test transformer, and the method is shown in Table 3; the instrument used for the lightning withstand voltage test is an impulse transformer, and the method is shown in Table 3.

[0077] The partial discharge test under rated operating voltage is similar to the partial discharge initiation voltage test. The main instruments are a high-voltage test transformer (to generate AC high voltage) and a partial discharge detector (to detect partial discharge signals). The test method is to detect the discharge amount of partial discharge under rated operating voltage for 300 seconds. The test results show that no partial discharge signal greater than 1 pC was detected.

[0078] Table 3

[0079]

[0080] Tests showed that the electrical performance of insulator #2 met the national and industry standards for 10kV high-voltage switchgear, such as DL / T 404, proving that it has excellent mechanical properties and insulation capabilities.

[0081] Example 2

[0082] This embodiment relates to a method for preparing environmentally friendly 10kV switchgear support insulators. Based on the preparation method for insulator #2 in Embodiment 1, insulators #6-#12 are prepared, as detailed below:

[0083] Insulator #6

[0084] Compared to insulator #2, the inner core diameter is 55mm, and the other parameters are the same as insulator #2, resulting in insulator #6. The increased inner core diameter of insulator #6 leads to an increase in the mass and volume of the insulator, resulting in higher costs and increased manufacturing difficulty.

[0085] Insulator #7

[0086] Compared to insulator #2, the maximum diameter of the shed is 63mm, and the other parameters are the same as those of insulator #2, resulting in insulator #7. The maximum diameter of the shed in insulator #7 is smaller, which causes the insulation distance along the surface of the insulator to decrease, leading to a decrease in insulation performance.

[0087] Insulator #8

[0088] Compared to insulator #2, the shortest distance A between adjacent sheds is 3mm, and all other parameters are the same as insulator #2, resulting in insulator #8. In insulator #8, the shorter shortest distance A between adjacent sheds leads to a smaller shed spacing, shortening the insulation distance and causing a decrease in insulation performance. This smaller shed spacing also makes it difficult to increase the corner radius, resulting in a higher maximum stress value and making it impossible to improve the stress concentration problem.

[0089] Insulator #9

[0090] Compared to insulator #2, the longest distance B between adjacent sheds is 15mm, and the other parameters are the same as insulator #2, resulting in insulator #9. In insulator #9, the longest distance B between adjacent sheds is larger, which can easily cause uneven distribution of sheds and lead to a decrease in the insulation performance of the insulator.

[0091] Insulator #10

[0092] Compared to insulator #2, the diameter of the top support column is 55mm, the diameter of the bottom support column is 55mm, and the other parameters are the same as those of insulator #2, resulting in insulator #10. The smaller diameter of the top and bottom support columns in insulator #10 leads to a decrease in the bending strength of the insulator, resulting in an increase in the maximum stress value and making the insulator more susceptible to mechanical damage.

[0093] Insulator #11

[0094] Compared to insulator #2, the diameter of the first through hole is 18mm, the diameter of the second through hole is 18mm, and the other parameters are the same as those of insulator #2, resulting in insulator #11. The smaller diameter of the first and second through holes in insulator #11 leads to a smaller diameter of the screws used for fixing, resulting in poorer stability when the insulator is fixed in the switch cabinet.

[0095] Insulator #12

[0096] Compared to insulator #2, the depth of the first through hole is 15mm, the depth of the second through hole is 15mm, and the other parameters are the same as those of insulator #2, resulting in insulator #12. The reduced depth of the first and second through holes in insulator #12 leads to a reduction in the length of the screws used for fixing, resulting in poorer stability when the insulator is fixed in the switch cabinet.

[0097] The above tests show that the dimensions of the first to sixteenth fillets can affect the maximum stress value of the insulator and its insulation performance. The dimensions of the insulator's inner core, sheds, top support column, bottom support column, first through hole, and second through hole also affect the maximum stress value and insulation performance of the insulator.

[0098] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. An environmentally friendly 10kV switchgear support insulator, characterized in that, include: The inner core has a top support post at its top and a bottom support post at its bottom. The top support post has a first through hole, and the bottom support post has a second through hole at its center. The first and second through holes are used to embed an insert, which is made of metal. At least seven umbrella skirts are arranged circumferentially around the inner core and are evenly distributed between the top support column and the bottom support column; The inner core, top support column, bottom support column, and umbrella skirt are made of polycarbonate material, and the inner core, top support column, bottom support column, and umbrella skirt are integrally formed. The umbrella skirt consists of seven parts. From bottom to top, the bottom support column, the umbrella skirt, and the top support column, together with the inner circular core, form a first rounded corner, a second rounded corner, a third rounded corner, a fourth rounded corner, a fifth rounded corner, a sixth rounded corner, a seventh rounded corner, an eighth rounded corner, a ninth rounded corner, a tenth rounded corner, an eleventh rounded corner, a twelfth rounded corner, a thirteenth rounded corner, a fourteenth rounded corner, a fifteenth rounded corner, and a sixteenth rounded corner, respectively. The first rounded corner is equal in size to the sixteenth rounded corner, and its radius is 2.2-3.7 mm. The second rounded corner is equal in size to the fifteenth rounded corner, and its radius is 1.1-2.0 mm. The third rounded corner is equal in size to the fourteenth rounded corner, and its radius is 1.4-3.2 mm. The fourth rounded corner is equal in size to the thirteenth rounded corner, and its radius is 1.3-2.2 mm. The fifth rounded corner is equal in size to the twelfth rounded corner, and its radius is 1.5-2.7 mm. The sixth rounded corner is equal in size to the eleventh rounded corner, and its radius is 1.0-1.8 mm.

2. The environmentally friendly 10kV switchgear support insulator according to claim 1, characterized in that, The radius of the seventh rounded corner is 0.8-1.2mm, the radius of the eighth rounded corner is 0.8-1.2mm, the radius of the ninth rounded corner is 0.8-1.2mm, and the radius of the tenth rounded corner is 0.8-1.2mm.

3. The environmentally friendly 10kV switchgear support insulator according to claim 1, characterized in that, The inner core has a diameter of 40-50mm, the umbrella skirt has a maximum diameter of 65-70mm, the shortest distance A between adjacent umbrella skirts is 4-5mm, and the longest distance B between adjacent umbrella skirts is 11-13mm.

4. The environmentally friendly 10kV switchgear support insulator according to claim 1, characterized in that, The diameter of the top support column is 60-70mm, the height of the top support column is 16-20mm, the diameter of the first through hole is 20-24mm, and the depth of the first through hole is 18-20mm. The diameter of the bottom support column is 60-70mm, the height of the bottom support column is 16-20mm, the diameter of the second through hole is 20-24mm, and the depth of the second through hole is 18-20mm.

5. The environmentally friendly 10kV switchgear support insulator according to claim 1, characterized in that, The polycarbonate has a molecular weight of 30,000-100,000.

6. The environmentally friendly 10kV switchgear support insulator according to claim 1, characterized in that, The surface roughness of the supporting insulator is no greater than 1.6 μm.

7. The method for preparing the environmentally friendly 10kV switchgear support insulator according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Select suitable polycarbonate rods; S2: Based on finite element simulation and genetic algorithm, design a three-dimensional model of the supporting insulator, and use a CNC lathe to machine the polycarbonate rod to obtain an integral inner core, top support column, umbrella skirt and bottom support column; S3: Two inserts are machined using CNC machining. The inserts are heated to 180-260°C and then hot-pressed into the first through hole and the second through hole respectively to obtain the supporting insulator. Before the insert is heated, the surface of the insert is sandblasted and / or coated with conductive adhesive. The pressure of the hot pressing is 0.8-1.5 MPa.

8. The preparation method according to claim 7, characterized in that, In step S2, the machining accuracy of the machining process is not less than 0.1 mm.

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