A method for improving the roughness gradient of insulators to improve the AC / DC surface flashover

Abstract

The present invention discloses a method for modifying the roughness gradient of an insulator for improving the surface flashover of AC / DC, which belongs to the technical field of high-voltage insulating materials, and comprises the following steps: 1) ultrasonically treating and drying a pot-type insulator; 2) selecting a first fine sandpaper with a set mesh number to grind the entire side of the insulator dried in step 1); 3) selecting a first coarse sandpaper with a set mesh number to grind the uncovered part of the insulator obtained in step 2); 4) selecting a second coarse sandpaper with a set mesh number to grind the first gradient of the insulator obtained in step 3); 5) using a roughness tester to frequently measure the roughness of each layer, and uniformly grind the gradient range of each layer to obtain an insulator with a roughness gradient modification. The surface modification treatment method of the roughness gradient of an insulator provided by the present invention can significantly improve the discharge path of the insulator, and provide support for improving the AC / DC surface flashover performance of the insulator.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage insulating materials, and in particular to a method for treating the roughness gradient surface of a pot-type insulator for improving the AC / DC surface flashover voltage. Background Art

[0002] With the continuous development of modern society, my country's demand for electricity has increased year by year, and the pressure on ultra-high voltage AC / DC transmission lines in the power grid has increased. As the key supporting and insulating components of gas-enclosed metal switches (GIS) in ultra-high voltage transmission lines, pot insulators are of great significance to the safe and stable operation of the power grid. However, due to the surface flashover of the gas-solid interface of pot insulators, GIS insulation failure occurs, which seriously threatens the safe and efficient operation of power equipment. Therefore, improving the surface insulation properties of pot insulators has become an urgent problem to maintain the stable operation of high-voltage transmission lines and promote social and economic development.

[0003] In engineering applications, it is inevitable that physical defects such as local tip scratches will appear on basin-type insulators. In a working environment where AC / DC voltage is applied, local electric field distortion will inevitably occur, leading to local discharge. Roughness, as a direct physical modification method to improve surface defects, has the advantages of economical and simple engineering cost, strong operability, and pollution-free modification method. However, a single surface modification technology cannot simultaneously cope with the variable environmental factors of AC / DC in actual engineering. Therefore, the present invention proposes a three-layer uniform gradient modification method based on different roughness surface treatment technologies, which can improve the AC / DC surface flashover characteristics of basin-type insulators by improving the discharge path and reducing surface electric field distortion. Summary of the invention

[0004] The purpose of the present invention is to improve the charge transport characteristics of the basin insulator and increase the AC / DC surface flashover voltage of the insulator in an SF6 atmosphere. The surface treatment technology has low difficulty, obvious improvement effect and strong feasibility.

[0005] To achieve the above object, the method provided by the present invention specifically comprises the following steps:

[0006] 1) Ultrasonic treatment and drying of pot-type insulators using anhydrous ethanol;

[0007] 2) Use the first fine sandpaper with a set mesh number to grind the entire side of the insulator dried in step 1), and use a roughness tester to measure the surface roughness. After reaching the specified roughness range, use stickers to cover the third layer of gradient, that is, the part after grinding and measurement;

[0008] 3) Use a first coarse sandpaper with a set mesh number to grind the uncovered part of the insulator obtained in step 2), and use a roughness tester to measure the surface roughness. After reaching the specified value, use a sticker to cover the second layer of gradient, that is, the part after grinding and measurement, wherein the mesh number of the first coarse sandpaper is smaller than the mesh number of the first fine sandpaper in step 2);

[0009] 4) using a second coarse sandpaper with a set mesh number to grind the first gradient of the insulator obtained in step 3), i.e., the uncovered part, and using a roughness tester to measure the surface roughness so that the roughness reaches a value within a specified range, wherein the mesh number of the second coarse sandpaper is smaller than the mesh number of the first coarse sandpaper;

[0010] 5) Use a roughness tester to frequently measure the roughness of each layer, and polish each gradient range uniformly to obtain an insulator with roughness gradient modification.

[0011] Furthermore, step 5) specifically includes:

[0012] 51) Use a roughness tester to measure the insulator obtained in step 4) from different angles for multiple times, use a third coarse sandpaper to grind the uneven roughness part, make the roughness distribution of the first layer of gradient uniform, cover the first layer of gradient with a sticker, and remove the sticker covering the second layer of gradient, wherein the mesh number of the third coarse sandpaper is greater than the mesh number of the second coarse sandpaper;

[0013] 52) Using a roughness tester to measure the insulator obtained in step 51) multiple times from different angles, using a second fine sandpaper to grind the uneven roughness portion, so that the roughness distribution of the second gradient layer is uniform, and then using a sticker to cover the second gradient layer, and removing the sticker covering the third gradient layer, wherein the mesh number of the second fine sandpaper is smaller than the mesh number of the first fine sandpaper, and larger than the mesh number of the second coarse sandpaper;

[0014] 53) Using a roughness tester to measure the insulator obtained in step 52) multiple times from different angles, using a third fine sandpaper to grind the uneven roughness portion to make the third layer of gradient roughness distribution uniform, and then remove all covering stickers, wherein the mesh number of the third fine sandpaper is equal to the mesh number of the first fine sandpaper;

[0015] 54) The insulator obtained in step 53) is immersed in anhydrous ethanol for ultrasonic treatment to remove fine impurities generated by roughness grinding, and then placed in an oven for drying to obtain a roughness gradient modified pot-type insulator.

[0016] Furthermore, in the step 1), the insulator is truncated cone-shaped, with an upper surface diameter of 17.0±0.2 mm, a lower surface diameter of 34.0±0.2 mm, and a height of 17.0±0.2 mm; the ultrasonic power is 99±1 W, and the ultrasonic time is 20±2 min; the drying temperature is 80±5° C., and the drying time is 10±1 h.

[0017] Furthermore, in the step 2), the mesh number of the first fine sandpaper is 500±100 mesh, the roughness is 1±0.1 μm, and the width of the third layer is 8±0.15 mm.

[0018] Furthermore, in step 3), the first coarse sandpaper is 220±100 mesh, with a roughness of 3±0.15 μm, and the width of the second layer is 8±0.1 mm.

[0019] Furthermore, in step 4), the second coarse sandpaper is 60±20 mesh, with a roughness of 5±0.2 μm, and the width of the first layer is 8±0.1 mm.

[0020] Furthermore, in the step 51), the third coarse sandpaper has a mesh size of 100±20, a roughness of 5±0.2 μm, and a first layer width of 8±0.1 mm.

[0021] Furthermore, in the step 52), the mesh number of the second fine sandpaper is 240±20 mesh, the roughness is 3±0.15 μm, and the width of the second layer is 8±0.1 mm.

[0022] Furthermore, in step 53), the third fine sandpaper is 500±100 mesh, with a roughness of 1±0.1 μm, and a third layer width of 8±0.1 mm.

[0023] Furthermore, in step 54), the ultrasonic power is 99±1 W, the ultrasonic time is 40±5 min, the drying temperature is 80±5° C., and the drying time is 10±1 h.

[0024] Therefore, the method of the present invention has the following beneficial effects compared with the existing method:

[0025] (1) The roughness gradient surface treatment method provided by the present invention can increase the decay rate of the surface potential, increase the surface conductivity of the material, reduce the surface charge density of the insulator, and promote the charge dissipation rate, thus laying a foundation for improving the DC surface flashover performance of the insulating material;

[0026] (2) The roughness gradient modification scheme provided by the present invention can significantly improve the relative dielectric constant of the medium, improve the discharge path through gradient modification, reduce the local discharge amplitude, and lay a foundation for improving the AC surface flashover performance of insulating materials;

[0027] (3) The present invention provides a three-layer uniform roughness gradient modification method that simultaneously promotes surface charge dissipation and improves the surface discharge path, and can simultaneously stably increase the AC / DC surface flashover voltage of the insulator;

[0028] (4) The roughness gradient treatment method provided by the present invention has simple and economical tools, obvious surface treatment effect, strong operability of the treatment process, and low operation difficulty.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the insulator roughness gradient modification method of the present invention;

[0031] Figure 2 is a schematic structural diagram of the first layer, the second layer and the third layer of the insulator in Embodiment 1 of the present invention;

[0032] Figure 3 It is a graph of the surface potential attenuation of the insulators processed in Comparative Examples 1, 2 and 3 of the present invention;

[0033] Figure 4 It is a graph of the surface conductivity of the insulator obtained by the insulators treated in Comparative Examples 1, 2 and 3 of the present invention;

[0034] Figure 5 1 is a Weibull distribution diagram of the DC surface flashover voltage of the insulators processed in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention;

[0035] Figure 6 is a relative dielectric constant curve diagram of the insulators processed in Comparative Examples 1, 2 and 3 of the present invention;

[0036] Figure 7 It is a comparison diagram of partial discharge amplitudes of insulators processed by Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention;

[0037] Figure 8 It is a Weibull distribution diagram of the AC surface flashover voltage of the insulators processed by Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present application clearer, more thorough and more complete, the technical solutions in the embodiments of the present invention are clearly and completely described below through the drawings and embodiments. The following detailed descriptions are all descriptions of the embodiments, and are intended to provide further detailed descriptions of the present invention. The following detailed descriptions of the embodiments of the present invention provided in the drawings are not intended to limit the scope of the invention claimed for protection, but merely represent selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those commonly understood by ordinary technicians in the field to which the present application belongs.

[0039] The reagents and materials used in the present invention are as follows:

[0040] The insulator is truncated cone-shaped, with an upper surface diameter of 17.0±0.2mm, a lower surface diameter of 34.0±0.2mm, and a height of 17.0±0.2mm. Its main component is epoxy / micron Al2O3 composite material; the roughness tester model is TR-100 integrated small roughness tester.

[0041] As shown in the figure, a method for modifying the roughness gradient of an insulator to improve the AC / DC surface flashover specifically includes: 1) using anhydrous ethanol to ultrasonically treat and dry the pot-type insulator;

[0042] 2) Use the first fine sandpaper with a set mesh number to grind the entire side of the insulator after drying (ultrasonic drying) in step 1), and use a roughness tester to measure the surface roughness. After reaching the specified roughness range, use stickers to cover the third layer of gradient, that is, the part after grinding and measurement;

[0043] 3) Use a first coarse sandpaper with a set mesh number to grind the uncovered part of the insulator obtained in step 2), and use a roughness tester to measure the surface roughness. After reaching the specified value, use a sticker to cover the second gradient layer, wherein the mesh number of the first coarse sandpaper is smaller than the mesh number of the first fine sandpaper in step 2);

[0044] 4) using a second coarse sandpaper with a set mesh number to grind the first gradient of the insulator obtained in step 3), i.e., the uncovered part, and using a roughness tester to measure the surface roughness so that the roughness reaches a value within a specified range, wherein the mesh number of the second coarse sandpaper is smaller than the mesh number of the first coarse sandpaper;

[0045] 5) Use a roughness tester to frequently measure the roughness of each layer, and use sandpaper to evenly polish the gradient range of each layer to obtain an insulator with modified roughness gradient. Specifically include:

[0046] 51) Use a roughness tester to measure the insulator obtained in step 4) from different angles for multiple times, use a third coarse sandpaper to grind the uneven roughness part, make the roughness distribution of the first layer of gradient uniform, cover the first layer of gradient with a sticker, and remove the sticker covering the second layer of gradient, wherein the mesh number of the third coarse sandpaper is greater than the mesh number of the second coarse sandpaper;

[0047] 52) Using a roughness tester to measure the insulator obtained in step 51) multiple times from different angles, using a second fine sandpaper to grind the uneven roughness portion, so that the roughness distribution of the second gradient layer is uniform, and then using a sticker to cover the second gradient layer, and removing the sticker covering the third gradient layer, wherein the mesh number of the second fine sandpaper is smaller than the mesh number of the first fine sandpaper, and larger than the mesh number of the second coarse sandpaper;

[0048] 53) Using a roughness tester to measure the insulator obtained in step 52) multiple times from different angles, using a third fine sandpaper to grind the uneven roughness portion to make the third layer of gradient roughness distribution uniform, and then remove all covering stickers, wherein the mesh number of the third fine sandpaper is equal to the mesh number of the first fine sandpaper;

[0049] 54) The insulator obtained in step 53) is immersed in anhydrous ethanol for ultrasonic treatment to remove fine impurities (such as debris, powder and other impurities of hundreds of microns) generated by roughness grinding, and then placed in an oven for drying (ultrasonic drying) to obtain a roughness gradient modified pot insulator. Example 1

[0050] This embodiment provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with three layers of uniform surface roughness gradient treatment, which specifically includes the following steps:

[0051] 1) The pot-type insulator was immersed in anhydrous ethanol and ultrasonically treated at 99W for 20 min, and then dried in an oven at 80℃ for 10 h.

[0052] 2) Use 500-grit sandpaper to grind the 8 mm width of the third layer of the pot-type insulator dried in step 1), and use a roughness tester to test different positions of the third layer several times. When the roughness value is 1 μm (such as Figure 2 As shown), cover the third layer with a sticker with a width of 8 mm.

[0053] 3) Use 220-grit sandpaper to grind the 8 mm width range of the second layer of the pot-type insulator obtained in step 2), and use a roughness tester to test different positions of it multiple times. When the roughness display value is 3 μm, cover the second layer with a sticker with a width of 8 mm.

[0054] 4) Use 60-grit sandpaper to grind the 8 mm width range of the first layer of the pot-type insulator obtained in step 3), and use a roughness tester to test different positions of the first layer multiple times until the roughness shows a value of 5 μm.

[0055] 5) Use a roughness tester to measure the pot-type insulator obtained in step 4) at different angles for multiple times. When a large deviation in the roughness value appears, use 100-grit sandpaper to grind the measuring range. After the roughness measurement values ​​of the first layer are uniform, cover the first layer with a sticker with a width of 8 mm and remove the second layer of sticker.

[0056] 6) Use a roughness tester to measure the pot-type insulator obtained in step 5) at different angles for multiple times. When a large deviation in the roughness value appears, use 240-grit sandpaper to grind the measurement range. After the roughness measurement values ​​of the second layer are uniform, cover the second layer with a sticker with a width of 8 mm and remove the third layer of sticker.

[0057] 7) Use a roughness tester to measure the pot-type insulator obtained in step 6) at different angles for multiple times. When a large deviation in the roughness value appears, use 500-grit sandpaper to grind the measuring range. After the roughness measurement value of the third layer is uniform, remove the stickers of the first and second layers.

[0058] 8) The pot-type insulator obtained in step 7) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 99 W for 40 min, and then placed in an oven at 80° C. for drying for 10 h to obtain a three-layer pot-type insulator with uniform roughness gradient treatment. Example 2

[0059] This embodiment provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with three layers of uniform surface roughness gradient treatment, which specifically includes the following steps:

[0060] 1) The pot-type insulator was immersed in anhydrous ethanol and ultrasonically treated at 98W for 18 min, and then dried in an oven at 75℃ for 9 h.

[0061] 2) Use 400-grit sandpaper to grind the 7.9 mm width range of the third layer of the pot-type insulator dried in step 1), and use a roughness tester to test different positions of the third layer for multiple times. When the roughness display value is 0.9 μm, cover the third layer with a sticker with a width of 7.9 mm.

[0062] 3) Use 120-grit sandpaper to grind the 7.9 mm width range of the second layer of the pot-type insulator obtained in step 2), and use a roughness tester to test different positions of it multiple times. When the roughness display value is 2.85 μm, cover the second layer with a sticker with a width of 7.9 mm.

[0063] 4) Use 40-grit sandpaper to grind the 7.9 mm width range of the first layer of the pot-type insulator obtained in step 3), and use a roughness tester to test different positions of the first layer multiple times until the roughness value displayed is 4.8 μm.

[0064] 5) Use a roughness tester to measure the pot insulator obtained in step 4) at different angles for multiple times. When a large deviation in the roughness value appears, use 80-grit sandpaper to grind the measuring range. After the roughness measurement values ​​of the first layer are uniform, cover the first layer with a sticker with a width of 7.9 mm and remove the second layer of sticker.

[0065] 6) Use a roughness tester to measure the pot insulator obtained in step 5) at different angles for multiple times. When a large deviation in the roughness value appears, use 220-grit sandpaper to grind the measuring range. After the roughness measurement values ​​of the first layer are uniform, cover the second layer with a sticker with a width of 7.9 mm and remove the third layer of sticker.

[0066] 7) Use a roughness tester to measure the pot-type insulator obtained in step 6) at different angles for multiple times. When a large deviation in the roughness value appears, use 400-grit sandpaper to grind the measurement range. After the third layer of roughness measurement values ​​are uniform, remove the first and second layers of stickers.

[0067] 8) The pot-type insulator obtained in step 7) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 98 W for 35 min, and then placed in an oven at 75° C. for drying for 9 h to obtain a three-layer pot-type insulator with uniform roughness gradient treatment. Example 3

[0068] This embodiment provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with three layers of uniform surface roughness gradient treatment, which specifically includes the following steps:

[0069] 1) Immerse the pot insulator in anhydrous ethanol and treat it with 100W ultrasonic wave for 22 min, and then dry it in an oven at 85℃ for 11h.

[0070] 2) Use 600-grit sandpaper to grind the 8.1 mm width range of the third layer of the pot-type insulator dried in step 1), and use a roughness tester to test different positions of the third layer for multiple times. When the roughness display value is 1.1 μm, cover the third layer with a sticker with a width of 8.1 mm.

[0071] 3) Use 320-grit sandpaper to grind the 8.1 mm width range of the second layer of the pot-type insulator obtained in step 2), and use a roughness tester to test different positions of it multiple times. When the roughness display value is 3.15 μm, cover the second layer with a sticker with a width of 8.1 mm.

[0072] 4) Use 80-grit sandpaper to grind the 8.1 mm width range of the first layer of the pot-type insulator obtained in step 3), and use a roughness tester to test different positions of the first layer multiple times until the roughness display value is 5.2 μm.

[0073] 5) Use a roughness tester to measure the pot insulator obtained in step 4) at different angles for multiple times. When a large deviation in the roughness value appears, use 120-grit sandpaper to grind the measuring range. After the roughness measurement values ​​of the first layer are uniform, cover the first layer with a sticker with a width of 8.1 mm and remove the second layer of sticker.

[0074] 6) Use a roughness tester to measure the pot insulator obtained in step 5) at different angles for multiple times. When a large deviation in the roughness value appears, use 260-grit sandpaper to grind the measuring range. After the roughness measurement values ​​of the first layer are uniform, cover the second layer with a sticker with a width of 8.1 mm and remove the third layer of sticker.

[0075] 7) Use a roughness tester to measure the pot-type insulator obtained in step 6) at different angles for multiple times. When a large deviation in the roughness value appears, use 600-grit sandpaper to grind the measuring range. After the roughness measurement value of the third layer is uniform, remove the stickers of the first and second layers.

[0076] 8) The pot-type insulator obtained in step 7) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 100 W for 45 min, and then placed in an oven at 80° C. for 11 h to obtain a three-layer pot-type insulator with uniform roughness gradient treatment.

[0077] Comparative Example 1

[0078] This comparative example provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with a 1 μm single-layer surface roughness gradient treatment, which specifically includes the following steps:

[0079] 1) Immerse the pot-type insulator in anhydrous ethanol and treat it with ultrasound at 99 W for 20 min, and then dry it in an oven at 80°C for 11 h;

[0080] 2) using 500-grit sandpaper to polish the entire side surface of the pot-type insulator dried in step 1);

[0081] 3) Using a roughness tester, measure the pot-type insulator obtained in step 2) at different angles for multiple times. When a roughness value deviates greatly from 1 μm, use 500-grit sandpaper to polish the measuring range to make the surface roughness of the pot-type insulator uniform.

[0082] 4) The pot-type insulator obtained in step 3) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 99 W for 40 min, and then placed in an oven at 80° C. for drying for 10 h to obtain a 1 μm single-layer roughness gradient-treated pot-type insulator.

[0083] Comparative Example 2

[0084] This comparative example provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with a single-layer surface roughness gradient of 3 μm, which specifically includes the following steps:

[0085] 1) Immerse the pot insulator in anhydrous ethanol and treat it with 99W ultrasonic wave for 20 min, and then dry it in an oven at 80℃ for 10 h;

[0086] 2) using 220-grit sandpaper to polish the entire side surface of the pot-type insulator dried in step 1);

[0087] 3) Using a roughness tester, measure the pot-type insulator obtained in step 2) at different angles for multiple times. When a roughness value deviates greatly from 3 μm, use 240-grit sandpaper to grind the measuring range to make the surface roughness of the pot-type insulator uniform.

[0088] 4) The pot-type insulator obtained in step 3) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 99 W for 40 min, and then placed in an oven at 80° C. for 10 h to obtain a 3 μm single-layer roughness gradient-treated pot-type insulator.

[0089] Comparative Example 3

[0090] This comparative example provides a method for treating a basin-type insulator with a roughness gradient surface to improve the AC / DC surface flashover voltage, and obtains a basin-type insulator with a single-layer surface roughness gradient of 5 μm, which specifically includes the following steps:

[0091] 1) Immerse the pot insulator in anhydrous ethanol and treat it with 99W ultrasonic wave for 20 min, and then dry it in an oven at 80℃ for 10 h;

[0092] 2) using 60-grit sandpaper to polish the entire side surface of the pot-type insulator dried in step 1);

[0093] 3) Using a roughness tester, measure the pot-type insulator obtained in step 2) at different angles for multiple times. When the roughness value deviates greatly from 5 μm, use 100-grit sandpaper to polish the measuring range to make the surface roughness of the pot-type insulator uniform.

[0094] 4) The pot-type insulator obtained in step 3) is immersed in anhydrous ethanol, subjected to ultrasonic treatment at 99 W for 40 min, and then placed in an oven at 80° C. for drying for 10 h to obtain a 5 μm single-layer roughness gradient treated pot-type insulator.

[0095] Experimental Testing (one)

[0097] The surface potential decay test was conducted on Comparative Examples 1, 2 and 3 (Comparative Examples 1, 2 and 3 are conventional practices) of basin insulators with different roughness treatments, with a needle voltage of -10 kV and a charging time of 10 min. The surface potential test device was Trek-542A, the measurement time was 20000s, the sampling time was 1s, and the experimental test temperature was 27°C. Figure 3 This is the potential attenuation diagram of the insulator surface treated with different roughness (the ordinate is voltage, the unit is V, the abscissa is time, the unit is s).

[0098] from Figure 3 It can be concluded that the surface potential decreases with time, and the surface potential decay rate becomes faster as the surface roughness of the basin insulator increases, indicating that roughness treatment can effectively reduce the surface charge density and promote charge dissipation. (two)

[0100] The surface conductivity of Comparative Example 1, Comparative Example 2 and Comparative Example 3 of pot-type insulators with different roughness treatments was tested. The test voltage was 1 kV. The test used a Keithley 6517B Keithley electrometer as an ammeter. The samples were placed in an 8009 resistance box. Each group of samples was tested 5 times, and the average value was taken as the final surface conductivity. Figure 4 This is the surface conductivity diagram of different roughness treatments (the ordinate is surface conductivity, the unit is S, and the abscissa is roughness, the unit is μm).

[0101] Depend on Figure 4It can be seen that after the roughness grinding treatment, the surface conductivity of the insulator increased from 10-14S to 10-13S, and the surface conductivity increased by 1 order of magnitude, which is a significant effect. Due to the increase in surface conductivity, the electron migration rate in the insulating material will be accelerated, thereby accelerating the dissipation rate of the surface charge. Figure 3 The surface potential decay rate decreases significantly with the roughness. (three)

[0103] Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of pot-type insulators with different numbers of roughness gradients were subjected to a DC surface flashover test. The test atmosphere was 0.1 MPa SF6 gas. The test adopted a step-by-step voltage increase method with a voltage increase rate of 1 kV / s. Three samples of each example were tested and each sample was tested 5 times. Figure 5 The Weibull distribution diagram of the DC surface flashover voltage of the pot-type insulator with different number of layers of roughness gradient treatment (the ordinate is the surface flashover probability, the abscissa is the DC flashover voltage, the unit is kV). Table 1 is the DC surface flashover test data.

[0104] Table 1 DC surface flashover data

[0105]

[0106] From Table 1 and Figure 5 It can be seen that after three-layer uniform gradient roughness treatment, the surface flashover voltage of the pot-type insulator is significantly improved. Compared with the pot-type insulators treated with 1 μm single-layer roughness gradient, 3 μm single-layer roughness gradient and 5 μm single-layer roughness gradient, the DC surface flashover voltage increases by 19.99%, 9.37% and 5.05%, respectively. (Four)

[0108] The relative dielectric constants of Comparative Examples 1, 2 and 3 of the basin-type insulators with different numbers of layers of roughness gradient treatment were tested. Figure 6 This is a diagram of the relative dielectric constant of insulators with different roughness treatments (the ordinate is the dielectric constant, the abscissa is the frequency, and the unit is Hz). Since the dielectric constant is a body test and the roughness grinding only modifies the surface of the sample, the dielectric constant changes very little. It can be concluded from the figure that with the increase of roughness, the relative dielectric constant increases. (five)

[0110] The partial discharge amplitude test was conducted on Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the pot-type insulators with different number of layers of roughness gradient treatment. The test environment was air and the applied voltage was 10 kV. Figure 7The figure shows the partial discharge amplitude of insulators with different roughness treatments (the ordinate is voltage, the unit is V, the abscissa is time, the unit is s). It can be concluded from the figure that the discharge amplitude is as follows: 5 μm single-layer roughness gradient treated pot-type insulator, 3 μm single-layer roughness gradient treated pot-type insulator, 1 μm single-layer roughness gradient treated pot-type insulator, three-layer uniform roughness gradient modified pot-type insulator, and the three-layer uniform roughness uniform modification can effectively improve the discharge amplitude of the pot-type insulator under AC voltage. (six)

[0112] Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of pot-type insulators with different numbers of roughness gradients were subjected to AC surface flashover tests. The test atmosphere was 0.1 MPa SF6 gas. The test adopted a step-by-step voltage increase method with a voltage increase rate of 1 kV / s. Three samples of each example were tested and each sample was tested 5 times. Figure 8 The Weibull distribution diagram of the AC surface flashover voltage of the pot-type insulator with different number of layers of roughness gradient treatment (the ordinate is the surface flashover probability, the abscissa is the DC flashover voltage, the unit is kV). Table 2 is the AC surface flashover test data.

[0113] Table 2 AC surface flashover data

[0114]

[0115] From Table 2 and Figure 8 It can be seen that after three-layer uniform gradient roughness treatment, the surface flashover voltage of the pot-type insulator is significantly improved. Compared with the pot-type insulators treated with 1 μm single-layer roughness gradient, 3 μm single-layer roughness gradient and 5 μm single-layer roughness gradient, the AC surface flashover voltage increases by 3.62%, 9.41% and 13.26%, respectively.

[0116] Therefore, the roughness gradient surface treatment method for pot-type insulators for improving the AC / DC surface flashover voltage provided by the present invention can improve the charge dissipation efficiency of the insulator surface, reduce the local discharge amplitude, improve the surface discharge path, and thus improve the AC / DC surface flashover voltage of the insulator in SF6 atmosphere; the roughness gradient treatment method has simple and economical tools and instruments, the surface treatment effect is obvious and stable, the implementation difficulty is low, and the operability is strong.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for improving the roughness gradient of an insulator to improve AC / DC surface flashover, characterized in that: The specific steps include: 1) Ultrasonic treatment and drying of pot-type insulators using anhydrous ethanol; 2) Use the first fine sandpaper with a set mesh number to grind the entire side of the insulator dried in step 1), and use a roughness tester to measure the surface roughness. After reaching the specified roughness range, use stickers to cover the third layer of gradient, that is, the part after grinding and measurement; 3) Use a first coarse sandpaper with a set mesh number to grind the uncovered part of the insulator obtained in step 2), and use a roughness tester to measure the surface roughness. After reaching the specified value, use a sticker to cover the second layer of gradient, that is, the part after grinding and measurement, wherein the mesh number of the first coarse sandpaper is smaller than the mesh number of the first fine sandpaper in step 2); 4) using a second coarse sandpaper with a set mesh number to grind the first gradient of the insulator obtained in step 3), i.e., the uncovered part, and using a roughness tester to measure the surface roughness so that the roughness reaches a value within a specified range, wherein the mesh number of the second coarse sandpaper is smaller than the mesh number of the first coarse sandpaper; 5) Use a roughness tester to frequently measure the roughness of each layer, and polish each gradient range uniformly to obtain an insulator with roughness gradient modification.

2. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 1, characterized in that: Step 5) specifically includes: 51) Use a roughness tester to measure the insulator obtained in step 4) from different angles for multiple times, use a third coarse sandpaper to grind the uneven roughness part, make the roughness distribution of the first layer of gradient uniform, cover the first layer of gradient with a sticker, and remove the sticker covering the second layer of gradient, wherein the mesh number of the third coarse sandpaper is greater than the mesh number of the second coarse sandpaper; 52) Using a roughness tester to measure the insulator obtained in step 51) multiple times from different angles, using a second fine sandpaper to grind the uneven roughness portion, so that the roughness distribution of the second gradient layer is uniform, and then using a sticker to cover the second gradient layer, and removing the sticker covering the third gradient layer, wherein the mesh number of the second fine sandpaper is smaller than the mesh number of the first fine sandpaper, and larger than the mesh number of the second coarse sandpaper; 53) Using a roughness tester to measure the insulator obtained in step 52) multiple times from different angles, using a third fine sandpaper to grind the uneven roughness portion to make the third layer of gradient roughness distribution uniform, and then remove all covering stickers, wherein the mesh number of the third fine sandpaper is equal to the mesh number of the first fine sandpaper; 54) The insulator obtained in step 53) is immersed in anhydrous ethanol for ultrasonic treatment to remove fine impurities generated by roughness grinding, and then placed in an oven for drying to obtain a roughness gradient modified pot-type insulator.

3. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 1, characterized in that: In the step 1), the insulator is truncated cone-shaped, with an upper surface diameter of 17.0±0.2 mm, a lower surface diameter of 34.0±0.2 mm, and a height of 17.0±0.2 mm; the ultrasonic power is 99±1 W, the ultrasonic time is 20±2 min; the drying temperature is 80±5° C., and the drying time is 10±1 h.

4. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 1, characterized in that: In the step 2), the mesh number of the first fine sandpaper is 500±100 mesh, the roughness is 1±0.1 μm, and the width of the third layer is 8±0.15 mm.

5. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 1, characterized in that: In step 3), the first coarse sandpaper has a mesh size of 220±100 and a roughness of 3±0.15 μm, and the width of the second layer is 8±0.1 mm.

6. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 1, characterized in that: In the step 4), the second coarse sandpaper has a mesh size of 60±20, a roughness of 5±0.2 μm, and a first layer width of 8±0.1 mm.

7. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 2, characterized in that: In the step 51), the mesh number of the third coarse sandpaper is 100±20, the roughness is 5±0.2 μm, and the width of the first layer is 8±0.1 mm.

8. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 2, characterized in that: In the step 52), the mesh number of the second fine sandpaper is 240±20 mesh, the roughness is 3±0.15 μm, and the width of the second layer is 8±0.1 mm.

9. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 2, characterized in that: In step 53), the third fine sandpaper is 500±100 mesh, with a roughness of 1±0.1 μm, and a third layer width of 8±0.1 mm.

10. The method for modifying the roughness gradient of an insulator to improve AC / DC surface flashover according to claim 2, characterized in that: In the step 54), the ultrasonic power is 99±1 W, the ultrasonic time is 40±5 min, the drying temperature is 80±5° C., and the drying time is 10±1 h.

Images