Flat test piece, liquid-phase dirt settling and smearing method thereof and application of flat test piece and liquid-phase dirt settling and smearing method

Abstract

The invention provides a flat test piece as well as a liquid-phase dirt settling and coating method and application thereof, and relates to the technical field of dirt layer preparation. The method comprises the following steps: placing a suspended dirty solution containing diatomite, sodium chloride and water on the surface of an insulator flat plate by adopting a liquid-phase dirty sedimentation method, standing and naturally settling to form a dirty layer, and obtaining a flat plate test piece; when the insulator flat plate is provided with a hydrophobic interface, the hydrophobicity is damaged before the insulator flat plate is used. According to the method, the pollution degree can be accurately regulated and controlled by changing the dosage of the diatomite and the sodium chloride in the suspended foul solution, and the prepared foul layer is good in uniformity, good in pollution degree quantitation and high in accuracy. Moreover, a liquid-phase dirt sedimentation method is adopted, the method is suitable for hydrophobic, hydrophilic and hydrophobic-hydrophilic mixed interfaces, the application range is wide, and the method is high in universality. According to the method, the pollution degree can be accurately regulated and controlled by changing the dosage of the diatomite and the sodium chloride in the suspended foul solution.

Description

Technical Field

[0001] The invention relates to the technical field of contamination layer preparation, and in particular to a flat test piece and a liquid phase contamination sedimentation and smearing method and application thereof. Background Art

[0002] Pollution flashover voltage (pollution flashover voltage) is an important characteristic of insulators, an indispensable basis for the configuration of external insulation of transmission lines, and the primary assessment indicator for the development of new insulator materials and the study of insulator characteristics. In the laboratory, the pollution flashover voltage of real insulators and flat test pieces is usually determined through artificial pollution tests based on relevant standards. Artificial pollution tests are divided into salt spray method and solid layer method. In the development of new external insulation coatings and the study of pollution flashover characteristics, flat glass and silicone rubber samples are usually used, and the solid layer method is adopted. Among them, coating is an important step in the artificial pollution test of the solid layer method of flat sample. Because the choice of coating method will affect the accuracy and uniformity of the pollution layer. Uneven contamination will lead to local electrical stress concentration in the pollution flashover, resulting in premature formation of dry bands, which in turn affects the accuracy of the pollution flashover voltage. It can be seen that whether the appropriate coating method can be selected and a uniform pollution layer can be prepared determines the success or failure of the artificial pollution test.

[0003] At present, the solid layer coating methods include pouring method, spraying method and quantitative brushing method. Among them, the uniformity of the dirt layer prepared by the pouring method is good, but water marks are prone to appear, and the quantification of the dirtiness (salt density, ash density) is relatively difficult. The dirtiness of the dirt layer prepared by the spraying method is closely related to the variables such as the air output of the spray gun, the air amplitude, the spraying distance, and the spraying time. The dirt layer is prone to agglomeration problems, and the quantification of the dirtiness is also relatively difficult. The quantitative brushing method is the most commonly used coating method. This method has excellent dirtiness quantitative performance, but the brush texture will inevitably be left in the process of brushing the coating with a brush. The uniformity of the dirt layer is not good, which will greatly affect the diffusion of water droplets and the process of the dirt layer being dampened, and then cause the part with sparse brush texture to have a leading hot spot in the dry band formation stage, resulting in difficulties in the study of dry band formation and inaccurate measurement of the flashover voltage. It can be seen that the existing coating methods for flat test pieces often cannot achieve both the quantification of dirtiness and the uniformity of the dirt layer. Therefore, there is an urgent need to propose a coating method for preparing a precise and uniform stain layer. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a flat test piece and a liquid-phase contamination sedimentation and coating method and application thereof. The contamination degree of the contamination layer prepared by the liquid-phase contamination sedimentation and coating method provided by the present invention is quantitatively accurate and the contamination layer has excellent uniformity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for liquid phase contamination sedimentation and smearing of a flat plate test piece, characterized in that it comprises the following steps:

[0007] Mixing diatomaceous earth, sodium chloride and water to obtain a suspended sewage solution;

[0008] Placing the suspended dirty liquid on the surface of the insulator flat plate, allowing it to stand and settle naturally to form a dirt layer, thereby obtaining a flat plate test piece;

[0009] The insulator plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface; when the insulator plate has a hydrophobic interface, the insulator plate is first subjected to hydrophobic destruction before use;

[0010] The insulator plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface; when the insulator plate has a hydrophobic interface or a hydrophobic-hydrophilic mixed interface, the insulator plate is first subjected to hydrophobic destruction before use.

[0011] Preferably, the concentration of diatomaceous earth in the suspended sewage is 2.88-9.2 g / L.

[0012] Preferably, the concentration of sodium chloride is 1.8 to 3.6 g / L.

[0013] Preferably, the temperature of the static natural sedimentation is room temperature, and the time is 3 to 5 minutes.

[0014] Preferably, the particle size of the diatomaceous earth is ≥100 mesh.

[0015] Preferably, the particle size of the sodium chloride is ≥100 mesh.

[0016] Preferably, the hydrophobic destruction comprises using diatomaceous earth to cover the hydrophobic interface for hydrophobic destruction.

[0017] The present invention also provides a flat plate test piece obtained by the liquid phase pollution sedimentation and contamination method described in the above technical solution, comprising an insulator flat plate and a contamination layer located on the surface of the insulator flat plate.

[0018] Preferably, the salt density of the contamination layer is 0.02-0.5 mg / cm 2 , ash density is 0.2~5mg / cm 2 .

[0019] The invention also provides application of the flat plate test piece in pollution flashover voltage testing.

[0020] The present invention provides a method for liquid-phase pollution sedimentation and contamination of a flat plate test piece, comprising the following steps: mixing diatomaceous earth, sodium chloride and water to obtain a suspended contaminated liquid; placing the suspended contaminated liquid on the surface of an insulator flat plate, allowing it to settle naturally to form a contaminated layer, and obtaining a flat plate test piece; the insulator flat plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface; when the insulator flat plate has a hydrophobic interface, the insulator flat plate is first subjected to hydrophobic destruction before use. For the insoluble components (ash density) in the contamination layer, the present invention utilizes the characteristics of the suspended contaminated liquid settling naturally to form a uniform diatomaceous earth thin layer on the surface of the insulator flat plate, and the grayscale quantitative property is good. For the soluble components (salt density) in the contamination layer, the sodium chloride aqueous solution dissolved in the suspended contaminated liquid can form a uniform liquid film on the surface of the insulator flat plate. Moreover, since the sodium chloride aqueous solution forms a uniform liquid film on the hydrophilic interface, the hydrophobic interface after the hydrophobicity is destroyed, and the hydrophobic-hydrophilic mixed interface surface, the sodium chloride is evenly dispersed on the surface of the insulator plate, and the salt density is quantitatively good. The present invention can achieve precise control of the degree of contamination by changing the amount of diatomaceous earth and sodium chloride in the suspended sewage, and the prepared contamination layer has good uniformity, good quantitative contamination, and high accuracy. As shown in the test results of the embodiment, the contamination layer prepared by the present invention has good uniformity, the standard deviation of grayscale is 0.0492, the range of grayscale is 0.1371, the standard deviation of salinity is 0.0090, the range of salinity is 0.0273, and the degree of contamination is quantitatively good.

[0021] Moreover, the present invention adopts a liquid phase pollution sedimentation method, which is applicable to hydrophobic, hydrophilic, and hydrophobic-hydrophilic mixed interfaces, has a wide range of applications, and has strong universality. The present invention can achieve precise control of the pollution degree by changing the amount of diatomaceous earth and sodium chloride in the suspended sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a physical picture of the flat test piece prepared in Example 1;

[0023] Figure 2 This is a physical picture of the flat test piece prepared in Example 2;

[0024] Figure 3 This is a physical picture of the flat test piece prepared in Example 3;

[0025] Figure 4 This is a diagram showing the moisture-affected result of the flat test piece prepared in Example 1;

[0026] Figure 5 This is a physical picture of the silicone rubber flat plate test piece prepared in Comparative Example 4;

[0027] Figure 6 This is a physical picture of the glass flat plate test piece prepared in Comparative Example 5;

[0028] Figure 7 This is a physical picture of the RTV flat test piece prepared in Comparative Example 6. DETAILED DESCRIPTION

[0029] The present invention provides a method for liquid phase contamination sedimentation and smearing of a flat plate test piece, comprising the following steps:

[0030] Mixing diatomaceous earth, sodium chloride and water to obtain a suspended sewage solution;

[0031] Placing the suspended dirty liquid on the surface of the insulator flat plate, allowing it to stand and settle naturally to form a dirt layer, thereby obtaining a flat plate test piece;

[0032] The insulator plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface; when the insulator plate has a hydrophobic interface or a hydrophobic-hydrophilic mixed interface, the insulator plate is first subjected to hydrophobic destruction before use.

[0033] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0034] The invention mixes diatomaceous earth, sodium chloride and water to obtain suspended dirty liquid.

[0035] In the present invention, the particle size of the diatomaceous earth is preferably ≥100 mesh.

[0036] In the present invention, the particle size of the diatomaceous earth is preferably ≥100 mesh.

[0037] In the present invention, the purity of the sodium chloride is preferably >97%, more preferably >99.5%.

[0038] In the present invention, the concentration of diatomaceous earth in the suspended sewage is preferably 2.88-9.2 g / L, and in specific embodiments it can be 2.88 g / L, 3 g / L, 3.4 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, 6.5 g / L, 7 g / L, 7.5 g / L, 8 g / L, 8.5 g / L, 9 g / L or 9.2 g / L; the diatomaceous earth is preferably unsilanized diatomaceous earth.

[0039] In the present invention, the concentration of sodium chloride in the suspended sewage is 1.8-3.6 g / L, and in specific embodiments can be 1.8 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L or 3.6 g / L.

[0040] In the present invention, the mixing is preferably carried out under stirring conditions. The present invention has no particular limitation on the rotation speed and time of the stirring, as long as a uniform suspended dirty liquid can be obtained.

[0041] After obtaining the suspended dirty liquid, the present invention places the suspended dirty liquid on the surface of the insulator flat plate, allows it to stand and naturally settle to form a dirt layer, and obtains a flat plate test piece.

[0042] In the present invention, the insulator plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface. In the present invention, the material of the hydrophobic interface preferably includes silicone rubber. In the present invention, the material of the hydrophilic interface preferably includes one or more of glass, ceramic and epoxy resin. In the present invention, the hydrophobic material in the hydrophobic-hydrophilic mixed interface preferably includes silicone rubber, and the material of the hydrophilic interface preferably includes one or more of glass, ceramic and epoxy resin.

[0043] In the present invention, when the insulator plate has a hydrophobic interface or a hydrophobic-hydrophilic mixed interface, the insulator plate is first subjected to hydrophobic destruction before use. In the present invention, the hydrophobic destruction preferably includes using diatomaceous earth to cover the hydrophobic interface for hydrophobic destruction; the temperature of the hydrophobic destruction is preferably room temperature, and the hydrophobic destruction needs to be used within 1 hour; taking the silicone rubber interface as an example, during the hydrophobic destruction process, diatomaceous earth is used to cover the surface of the insulator plate with a layer, and an ear-cleaning bulb is used to blow away the excess diatomaceous earth; the present invention has no special limitation on the thickness of the diatomaceous earth, as long as it can cover the surface of the insulator plate. Water droplets will not spread on the hydrophobic surface and cannot be smeared. The present invention hydrophobically destroys the hydrophobic interface or the hydrophobic-hydrophilic mixed interface before smearing, so that the water droplets can spread.

[0044] In the present invention, the ratio of the thickness of the flat test piece to the height of the suspended dirty liquid is preferably 1:0.1-0.3, and in specific embodiments may be 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3.

[0045] In the present invention, the temperature of the static natural sedimentation is preferably room temperature, and the time is preferably 3 to 5 minutes, and in a specific embodiment, it can be 3 minutes, 4 minutes or 5 minutes; the static natural sedimentation is preferably to place the insulator plate horizontally in a water tank, pour the suspended sewage liquid, stir the suspended sewage liquid evenly, and perform static natural sedimentation. The present invention has no special restrictions on the speed and time of the stirring, as long as a uniform suspended sewage liquid can be obtained.

[0046] After the natural settling is completed, the present invention preferably further comprises: using a water pump or a drain valve to discharge the excess suspended dirty liquid, and drying the obtained wet flat plate test piece to obtain a flat plate test piece. In the present invention, the drying temperature is preferably 25°C; the drying humidity is preferably 60%RH; and the drying time is preferably 1 hour.

[0047] The present invention also provides a flat plate test piece as described in the above technical solution, comprising an insulator flat plate and a dirt layer located on the surface of the insulator flat plate.

[0048] In the present invention, the salt density of the fouling layer is preferably 0.02 to 0.5 mg / cm 2 , in a specific embodiment, it can be 0.02 mg / cm 2 , 0.05mg / cm 2 , 0.06mg / cm 2 , 0.07mg / cm 2 , 0.08mg / cm 2 , 0.09mg / cm 2 , 0.1mg / cm 2 , 0.15mg / cm 2 , 0.2mg / cm 2 , 0.25mg / cm 2 , 0.3mg / cm 2 , 0.35mg / cm 2 , 0.4mg / cm 2 , 0.45mg / cm 2 or 0.5mg / cm 2 The density of the dirt layer is preferably 0.2 to 5 mg / cm 2 , in a specific embodiment, it can be 0.2 mg / cm 2 , 0.5mg / cm 2 , 0.8mg / cm 2 , 1mg / cm 2 , 1.5mg / cm 2 , 2mg / cm 2 , 2.5mg / cm 2 、3mg / cm 2 、3.5mg / cm 2 , 4mg / cm 2 , 4.5mg / cm 2 or 5mg / cm 2 .

[0049] The present invention has no special limitation on the thickness of the flat test piece, which can be determined according to actual needs, such as 1 to 10 mm, and more preferably 5 mm.

[0050] The present invention also provides the application of the flat test piece described in the above technical solution in the pollution flashover voltage test.

[0051] In order to further illustrate the present invention, the flat test piece and the contamination method and application thereof provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0052] In the following examples, diatomaceous earth (with a median particle size of about 10 μm, unsilanized diatomaceous earth powder) was passed through a 100-mesh sieve, and the portion below the sieve was used.

[0053] Sodium chloride (purity> 99.5%) was passed through a 100-mesh sieve and the portion below the sieve was used.

[0054] Example 1

[0055] The liquid phase dirt sedimentation method was used to prepare the expected ash density of 1.0 mg / cm on the glass surface with a size of 140 mm × 80 mm × 5 mm. 2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the dirt layer are as follows:

[0056] 0.45 g of sodium chloride, 0.85 g of diatomaceous earth and 250 mL of deionized water were stirred and mixed to obtain a uniform suspended sewage solution;

[0057] Place a glass plate in a water tank (25cm×15cm×5cm), and pour the dirty liquid into the water tank, stir the suspended dirty liquid until it is evenly dispersed, let it stand and settle naturally for 5 minutes, use a water pump or a drain valve to drain the excess dirty liquid, use tweezers to lift the sample straight up and take it out smoothly, dry it at a temperature of 25°C and a humidity of 60%, and form a dirty layer on the glass plate to obtain a flat test piece (5mm thick).

[0058] Figure 1 This is a real picture of the flat test piece prepared in Example 1. It can be seen that the uniformity of the dirt layer prepared by the liquid phase dirt sedimentation method of the present invention is very good.

[0059] Example 2

[0060] The liquid phase pollution sedimentation method was used to prepare the expected ash density of 1.0 mg / cm on the surface of an insulator plate (with an epoxy-silicone rubber complex surface) with a size of 140 mm × 80 mm × 5 mm. 2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the dirt layer are as follows:

[0061] 0.45 g of sodium chloride, 0.85 g of diatomaceous earth and 250 mL of deionized water were stirred and mixed to obtain a uniform suspended sewage solution;

[0062] Use diatomaceous earth to cover the surface of the insulator plate, use an ear bulb to blow away the excess diatomaceous earth, put it in a water tank (25cm×15cm×5cm), and pour the dirty liquid into the water tank, stir the suspended dirty liquid until it is evenly dispersed, let it stand and settle naturally for 5 minutes, use a water pump or a drain valve to drain the excess dirty liquid, use tweezers to take out the sample straight up and smoothly, dry it at a temperature of 25°C and a humidity of 60%, form a dirt layer on the glass plate, and obtain a flat test piece (thickness of 5mm).

[0063] Among them, the preparation method with a complex epoxy-silicone rubber surface is as follows: grooves are machined on the epoxy resin surface and the grooves are filled with room temperature vulcanized silicone rubber.

[0064] Figure 2 This is a real picture of the flat test piece prepared in Example 2. It can be seen that even a complex surface with a mixture of hydrophilic and hydrophobic substances can be evenly stained using the method of the present invention.

[0065] Example 3

[0066] The liquid phase pollution sedimentation method was used to prepare the expected ash density of 3.0 mg / cm on the surface of an insulator plate (with a silicone rubber-glass complex surface) with a size of 90 mm × 50 mm × 2 mm. 2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the pollution layer are as follows:

[0067] 0.85 g of sodium chloride, 1.7 g of diatomaceous earth and 250 mL of deionized water were stirred and mixed to obtain a uniform suspended sewage solution;

[0068] Use diatomaceous earth to cover the surface of the insulator plate, use an ear bulb to blow away the excess diatomaceous earth, put it in a water tank (25cm×15cm×5cm), and pour the dirty liquid into the water tank, stir the suspended dirty liquid until it is evenly dispersed, let it stand and settle naturally for 5 minutes, use a water pump or a drain valve to drain the excess dirty liquid, use tweezers to take out the sample straight up and smoothly, dry it at a temperature of 25°C and a humidity of 60%, form a dirt layer on the glass plate, and obtain a flat test piece (thickness of 5mm).

[0069] Among them, the complex surface of silicone rubber and glass is prepared by mask method, and the silicone rubber interface exists only on the upper side of the insulator plate.

[0070] Figure 3 This is a real picture of the flat test piece prepared in Example 3. It can be seen that a larger dust density and a thicker dirt layer can also be successfully prepared using the method of the present invention.

[0071] Example 4

[0072] The liquid phase pollution sedimentation method is used for 25-120cm 2, the expected ash density is 1.0mg / cm 2 , the expected salt density is 0.1 mg / cm 2 The flat plate test piece was prepared as follows:

[0073] 0.45 g of diatomaceous earth, 0.85 g of diatomaceous earth and 250 mL of deionized water were stirred and mixed to obtain a uniform suspended sewage solution;

[0074] Use diatomaceous earth to cover the silicone rubber interface of the insulator, use an ear bulb to blow away excess diatomaceous earth, place it in a water tank (25cm×15cm×5cm), and pour the dirty liquid into the water tank, stir the suspended dirty liquid until it is evenly dispersed, let it stand and settle naturally for 5 minutes, use a water pump or a drain valve to drain the excess dirty liquid, use tweezers to take out the sample straight up and smoothly, dry it at a temperature of 25°C and a humidity of 60% to obtain a dirty layer, and obtain a flat test piece (thickness of 5 mm).

[0075] Example 5

[0076] The liquid phase pollution sedimentation method is used for 25-120cm 2 , the expected ash density is 3.5mg / cm 2 , the expected salt density is 0.1 mg / cm 2 The preparation of the flat test piece is different from that of Example 2 only in that the amount of sodium chloride used is 0.9 g and the amount of diatomaceous earth used is 2.3 g.

[0077] Example 6

[0078] The liquid phase pollution sedimentation method is used for 25-120cm 2 , the expected ash density is 1.0mg / cm 2 The expected salt density is 0.06 mg / cm 2 The preparation of the flat plate test piece is different from that of Example 2 only in that the amount of sodium chloride used is 0.35 g and the amount of diatomaceous earth used is 0.85 g.

[0079] Example 7

[0080] The liquid phase pollution sedimentation method is used for 25-120cm 2 , the expected ash density is 0.8mg / cm 2 , the expected salt density is 0.05 mg / cm 2 The preparation of the flat test piece is different from that of Example 2 only in that the amount of sodium chloride used is 0.3 g and the amount of diatomaceous earth used is 0.72 g.

[0081] Comparative Example 1

[0082] The pouring method was used to prepare the glass surface with a size of 140 mm × 80 mm × 5 mm. The expected ash density was 1.0 mg / cm2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the pollution layer are as follows:

[0083] 6g of sodium chloride, 50g of diatomaceous earth and 1L of deionized water were stirred and mixed to obtain a dirty liquid; the dirty liquid was placed in a small plastic basin. The sample was tightly clamped with tweezers, moved left and right in the dirty liquid, and stirred the dirty liquid for about 10 times. The sample was placed horizontally immediately after the dirty liquid was taken out vertically, and dried at 25°C and 60% RH to obtain a dirty layer, and a flat test piece was obtained.

[0084] Comparative Example 2

[0085] The smearing method was used to prepare the glass surface with a size of 140 mm × 80 mm × 5 mm. The expected ash density was 1.0 mg / cm 2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the pollution layer are as follows:

[0086] 3 g of sodium chloride, 32 g of diatomaceous earth and 500 mL of deionized water were stirred and mixed evenly to obtain a dirty liquid; a spraying system consisting of an Iwata W-71 spray gun and an air compressor was used, the spray gun was placed vertically, 15 to 20 cm away from the glass surface, the spray gun was moved left and right, and sprayed evenly for 20 seconds. During the spraying process, the dirty liquid in the spray gun tank was stirred all the time to prevent the diatomaceous earth from settling, and the dirty layer was obtained by drying at 25° C. and 60% RH to obtain a flat test piece.

[0087] Comparative Example 3

[0088] The quantitative brushing method was used to prepare the glass surface with a size of 140 mm × 80 mm × 5 mm. The expected ash density was 1.0 mg / cm 2 , the expected salt density is 0.1 mg / cm 2 The preparation steps of the pollution layer are as follows:

[0089] Based on the sample surface area, i.e. 112cm 2 , the required diatomaceous earth mass is calculated to be: 112cm 2 ×1mg / cm 2 =112mg. The mass of NaCl is: 112cm 2 ×0.1mg / cm 2 =11.2mg.

[0090] Prepare sodium chloride solution: 1.6g sodium chloride is dissolved in 100mL deionized water. Use a 1 / 1000 balance to weigh 112mg diatomaceous earth, transfer the diatomaceous earth to the glass surface, use a pipette to absorb 0.7mL sodium chloride solution, and drop it on the sample, use a brush to evenly apply the diatomaceous earth on the sample surface with the sodium chloride solution. Considering the problem of residual dirt on the brush, wipe off the dirt layer after the first two applications, and use the dirt layer after the third application as the prepared dirt layer. Dry the obtained dirt layer at 25°C and 60% RH to obtain a flat test piece.

[0091] Comparative Example 4

[0092] The flat test piece prepared in the literature (Wei Xu, Zhou Zhicheng, Dai Hanqi, Zhao Chenlong, Wang Liming. Research on the surface contamination method of high temperature vulcanized silicone rubber specimens [J]. High Voltage Electrical Appliances, 2015, 51(2): 51–56.) is shown in the actual picture. Figure 5 .

[0093] Comparative Example 5

[0094] The flat specimen prepared in the literature (ANDOH MA, GBAH K, VOLAT C. Development of a Simple Experimental Setup for the Study of the Formation of Dry Bands on Composite Insulators [J]. Energies, Multidisciplinary Digital Publishing Institute, 2022, 15 (14): 5108.) is shown in the figure. Figure 6 .

[0095] Comparative Example 6

[0096] The flat test piece prepared in the literature (Wei Xu, Zhou Zhicheng, Dai Hanqi, Zhao Chenlong, Wang Liming. Research on the surface contamination method of high temperature vulcanized silicone rubber specimens [J]. High Voltage Electrical Appliances, 2015, 51(2): 51–56.) is shown in the actual picture. Figure 7 .

[0097] Test Case

[0098] The flat test piece was subjected to moisture in a 40cm×40cm×40cm artificial fog chamber at 25°C, 100% RH, and a fog volume of 300mL / h. Figure 4 It can be seen that the dirt layer prepared by the liquid phase dirt sedimentation method of the present invention forms a uniform liquid film after being dampened, and has all the conditions for dry band formation and dirt flashover.

[0099] The contamination degree of the flat test piece prepared in Example 1 was measured according to the method of GB / T 4585-2004. The results are shown in Table 1.

[0100] Table 1 The results of the pollution degree test of the pollution layer prepared by the liquid phase pollution sedimentation method

[0101]

[0102] As can be seen from Table 1, the dirtiness of the dirt layer prepared by the liquid phase dirt sedimentation method of the present invention is very accurate, while the dirtiness accuracy of the dirt layer prepared by the pouring method, the spraying method and the quantitative brushing method is worse than the liquid phase dirt sedimentation method provided by the present invention.

[0103] In summary, when the mass of diatomaceous earth, the volume of suspended dirty liquid, and the area of ​​the water tank are certain, the mass of diatomaceous earth precipitated on the surface of the insulator plate is also certain, and the ash density is quantitatively good. When the mass of sodium chloride and the volume of suspended dirty liquid are certain, the mass of the liquid film formed on the surface of the flat sample is also certain, and thus the salt density is quantitatively good. The present invention can achieve precise control of the degree of contamination by changing the amount of diatomaceous earth and sodium chloride in the suspended dirty liquid, and the prepared dirt layer has good uniformity, good quantitative contamination, and high accuracy. Moreover, the present invention adopts a liquid phase contamination sedimentation method, which is suitable for hydrophobic, hydrophilic, and hydrophobic-hydrophilic mixed interfaces, has a wide range of applications, and has strong universality. The present invention can achieve precise control of the degree of contamination by changing the amount of diatomaceous earth and sodium chloride in the suspended dirty liquid.

[0104] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for sedimentation and smearing of liquid contamination on a flat test piece, characterized in that: The following steps are involved: Mixing diatomaceous earth, sodium chloride and water to obtain a suspended sewage solution; Placing the suspended dirty liquid on the surface of the insulator flat plate, allowing it to stand and settle naturally to form a dirt layer, thereby obtaining a flat plate test piece; The insulator plate has a hydrophobic interface, a hydrophilic interface or a hydrophobic-hydrophilic mixed interface; when the insulator plate has a hydrophobic interface or a hydrophobic-hydrophilic mixed interface, the insulator plate is first subjected to hydrophobic destruction before use.

2. The liquid phase pollution sedimentation and smearing method according to claim 1, characterized in that: The concentration of diatomaceous earth in the suspended sewage is 2.88-9.2 g / L.

3. The liquid phase pollution sedimentation and smearing method according to claim 1, characterized in that: The concentration of sodium chloride is 1.8-3.6 g / L.

4. The liquid phase pollution sedimentation and smearing method according to any one of claims 1 to 3, characterized in that: The temperature of the static natural sedimentation is room temperature, and the time is 3 to 5 minutes.

5. The liquid phase pollution sedimentation and smearing method according to claim 1 or 2, characterized in that: The particle size of the diatomaceous earth is ≥100 meshes.

6. The liquid phase pollution sedimentation and smearing method according to claim 1 or 3, characterized in that: The particle size of the sodium chloride is ≥100 meshes.

7. The liquid phase pollution sedimentation and smearing method according to claim 1, characterized in that: The hydrophobic destruction comprises using diatomaceous earth to cover the hydrophobic interface to perform the hydrophobic destruction.

8. The flat plate test piece obtained by the liquid phase pollution sedimentation and contamination method according to any one of claims 1 to 7 comprises an insulator plate and a contamination layer located on the surface of the insulator plate.

9. The flat test piece according to claim 8, characterized in that: The salt density of the dirt layer is 0.02-0.5 mg / cm 2 , ash density is 0.2~5mg / cm 2 .

10. Use of the flat test piece according to claim 8 or 9 in pollution flashover voltage testing.

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