CN113793739A - Preparation method of surface conductivity gradient coating for direct-current GIL epoxy resin insulator - Google Patents

Preparation method of surface conductivity gradient coating for direct-current GIL epoxy resin insulator Download PDF

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CN113793739A
CN113793739A CN202111097287.0A CN202111097287A CN113793739A CN 113793739 A CN113793739 A CN 113793739A CN 202111097287 A CN202111097287 A CN 202111097287A CN 113793739 A CN113793739 A CN 113793739A
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conductivity
coating
insulator
epoxy resin
gradient
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薛建议
张竹
丁立健
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Hefei University of Technology
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Hefei University of Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/04—Treating the surfaces, e.g. applying coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/14—Conductive material dispersed in non-conductive inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/14—Conductive material dispersed in non-conductive inorganic material
    • H01B1/18—Conductive material dispersed in non-conductive inorganic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
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Abstract

The invention discloses a preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator, which comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into N parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity. Bonding between surface coating and the epoxy insulator is more firm: the invention adopts the normal temperature liquid epoxy resin material which is the same as the base material of the insulator as the matrix of the coating, thus ensuring the adhesiveness between the coating and the epoxy resin insulator; the method can be used for regulating and controlling the surface charge distribution of the GIL epoxy resin insulator under direct current voltage, optimizing the surface electric field distribution and improving the surface electric strength. The preparation scheme of the coating provided by the invention is simple and feasible, has low cost and has wide application prospect.

Description

Preparation method of surface conductivity gradient coating for direct-current GIL epoxy resin insulator
Technical Field
The application relates to the technical field of design and manufacture of high-voltage power equipment, in particular to a preparation method of a surface conductivity gradient coating for a direct-current GIL epoxy resin insulator.
Background
Gas Insulated metal-enclosed transmission Line (GIL) has the advantages of large transmission capacity, small loss, small floor area, environmental friendliness and the like, and is widely applied to power systems. Under the action of long-time direct-current voltage, a large amount of charges accumulated by the insulator are an important reason for causing flashover of the edge surface of the basin-type insulator, so that reasonable inhibition of surface charge accumulation or regulation of surface charge distribution and uniform edge surface electric field distribution are provided, and the method for improving the edge surface electric strength is important for guaranteeing safe and stable operation of the direct-current GIL.
The surface modification is a method which does not change the property of the insulating material body, so the mechanical property of the material is not influenced. The solid insulating surface is the weakest link in insulation, so that the insulating surface can obtain excellent electrical properties by regulating and controlling the electrical parameters of the insulating surface. The existing surface modification methods such as plasma fluorination or direct fluorination have the problem of timeliness and are not completely solved. The epoxy resin-based surface coating method is a method with engineering application prospect, the epoxy resin is used as a substrate in the coating, high-conductivity solid powder particles are used as a filler, and the basin-type insulator is prepared by using the epoxy resin as the substrate, so that the epoxy resin-based surface coating can be firmly adhered to the surface of the basin-type insulator.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present patent application aims to provide a method for preparing a surface conductivity gradient coating for a dc GIL epoxy insulator, which solves the above-mentioned problems of the prior art.
In order to achieve the purpose, the invention provides the following technical scheme:
a preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into N parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity.
Further, the preparation method of the high-conductivity coating comprises the following steps:
s11, preheating the epoxy resin, the high-conductivity filler and the curing agent for 2-3 hours at the temperature of 80-90 ℃;
s12, mixing the epoxy resin and the high-conductivity filler, heating and stirring in an oil bath kettle at the temperature of 60-80 ℃, keeping the temperature for 25-35min, adding the diluent, and continuously stirring for 10-20min to obtain a mixture A;
s13, adding a curing agent and an adhesive into the mixture A prepared in the step S12, and stirring for 8-12min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment at the temperature of 55-65 ℃ for degassing for 25-35min to obtain the high-conductivity coating.
Further, the coating process comprises the steps of:
s21, dividing the surface of the insulator into N parts from the high-voltage electrode to the ground electrode, and sequentially recording the N parts as c from the high-voltage end to the low-voltage end1、c2、c3、…、cNA segment wherein N is greater than or equal to 2;
s22, preparing N parts of high-conductivity coating according to the preparation method of the high-conductivity coating, measuring the conductivity of each high-conductivity coating by using a conductivity instrument, and sequentially recording the conductivity from high to low as sigma1、σ2、σ3、…、σN；
S23, mixing1、c2、c3、…、cNSegment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、…、σNThe high-conductivity coating, namely from the high-voltage electrode to the ground electrode, forms gradient distribution with gradually reduced conductivity, and the thickness of each layer of the high-conductivity coating is 0.2 mm.
Further, the insulator surface layer curing comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 75-85 ℃ for solidification for 12h, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
Further, the high-conductivity coating is prepared from the following raw materials in percentage by mass:
Figure BDA0003269535190000031
furthermore, the epoxy resin is one of E44 type epoxy resin or E51 type epoxy resin which is liquid at normal temperature.
Further, the high-conductivity filler is selected from SiC, ZnO and TiO2、BatiO3And carbon black.
Further, 650 portions of polyesteramide is selected as the curing agent.
Further, the diluent is acetone; the binder is fumed silica.
Furthermore, the surface of the insulator is roughened before coating, and the coating mode is spraying or brushing.
Compared with the prior art, the invention has the beneficial effects that:
1. bonding between surface coating and the epoxy insulator is more firm: the invention adopts the normal temperature liquid epoxy resin material which is the same as the base material of the insulator as the matrix of the coating, and the surface of the insulator is firstly subjected to rough treatment before coating, so that the firm adhesion between the epoxy resin material and the epoxy resin insulator can be ensured;
2. the gradient design scheme can actively regulate and control the surface charge distribution, optimize the surface electric field of the insulator and improve the electrical resistance of the edge surface of the insulator;
3. the coating has simple preparation process and lower cost, does not change the mechanical property of the material, is optimized only from the electrical property, and has wide application prospect;
in conclusion, the method can be used for regulating and controlling the surface charge distribution of the GIL epoxy resin insulator under the direct-current voltage, optimizing the surface electric field distribution and improving the surface electric strength. The preparation scheme of the coating provided by the invention is simple and feasible, has low cost and has wide application prospect.
Drawings
FIG. 1 is a schematic view of the design of the surface conductance gradient coating of the insulator of the present invention;
FIG. 2 is a schematic diagram of the surface charge distribution of an insulator under three different surface conductance gradient coating schemes in examples 11-13 of the present invention;
FIG. 3 is a schematic diagram of the Weibull distribution of the positive DC surface flashover voltage of the insulator under three different surface conductance gradient coating schemes in accordance with examples 11-13 of the present invention;
fig. 4 is a schematic view of weibull distribution of dc surface flashover voltage of insulators under three different surface conductance gradient coating schemes in examples 11 to 13 of the present invention.
Detailed Description
The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. The present application is capable of other and different embodiments and its several details are capable of modifications and variations in various respects, all without departing from the spirit of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
Referring to fig. 1-4, the present invention provides the following technical solutions:
a preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into N parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity.
The preparation method of the high-conductivity coating comprises the following steps:
s11, preheating the epoxy resin, the high-conductivity filler and the curing agent for 2-3 hours at the temperature of 80-90 ℃;
s12, mixing the epoxy resin and the high-conductivity filler, heating and stirring in an oil bath kettle at the temperature of 60-80 ℃, keeping the temperature for 25-35min, adding the diluent, and continuously stirring for 10-20min to obtain a mixture A;
s13, adding a curing agent and an adhesive into the mixture A prepared in the step S12, and stirring for 8-12min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment at the temperature of 55-65 ℃ for degassing for 25-35min to obtain the high-conductivity coating.
Wherein the coating process comprises the steps of:
s21, dividing the surface of the insulator into N parts from the high-voltage electrode to the ground electrode, and sequentially recording the N parts as c from the high-voltage end to the low-voltage end1、c2、c3、…、cNA segment wherein N is greater than or equal to 2;
s22, preparing N parts of high-conductivity coating according to the preparation method of the high-conductivity coating, measuring the conductivity of each high-conductivity coating by using a conductivity instrument, and sequentially recording the conductivity from high to low as sigma1、σ2、σ3、…、σN；
S23, mixing1、c2、c3、…、cNSegment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、…、σNThe high-conductivity coating, namely the gradient distribution with gradually reduced conductivity is formed from the high-voltage electrode to the ground electrode, the coating thickness of each layer of high-conductivity coating is 0.2mm, and the surface of the insulator is subjected to rough treatment before coating, so that the firm adhesion between the insulator and the epoxy resin insulator can be ensured; the coating mode comprises spraying or brushing, and is selected according to the viscosity of the high-conductivity coating.
The insulator surface layer curing method comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 75-85 ℃ for solidification for 12h, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
The high-conductivity coating is prepared from the following raw materials in percentage by mass:
Figure BDA0003269535190000061
Figure BDA0003269535190000071
the epoxy resin is one of E44 type or E51 type epoxy resin which is in a liquid state at normal temperature; the high-conductivity filler is selected from SiC, ZnO and TiO2、BatiO3One of (1); 650 of polyesteramide is selected as the curing agent; the diluent is acetone; the binder is fumed silica.
Example 1
The high-conductivity coating is prepared from the following raw materials in percentage by mass: e44 type epoxy resin 45%, TiO 25%, 650% polyesteramide 35%, acetone 10%, and fumed silica 5%.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 2
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 42 percent of E44 type epoxy resin and TiO 210%, 650% polyesteramide 33%, acetone 10%, and fumed silica 5%.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 3
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 35% of E44 type epoxy resin and TiO220%, 650% polyesteramide 30%, acetone 10%, and fumed silica 5%.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 4
The high-conductivity coating is prepared from the following raw materials in percentage by mass: e44 type epoxy resin 30%, TiO230%, 650% polyesteramide 25%, 10% acetone and 5% fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 5
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 25% of E44 type epoxy resin and TiO240%, 650% polyesteramide 20%, acetone 10%, and fumed silica 5%.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 6
The high-conductivity coating is prepared from the following raw materials in percentage by mass: e44 type epoxy resin 20%, TiO 250%, 650% polyesteramide 15%, 10% acetone, and 5% fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2 hours at the temperature of 80 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 60 deg.C, stirring for 30min, maintaining the temperature, adding acetone, and stirring for 10min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 7
The high-conductivity coating is prepared from the following raw materials in percentage by mass: e44 type epoxy resin 30%, TiO230%, 650% polyesteramide 25%, 10% acetone and 5% fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 2.5 hours at 85 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 70 deg.C, stirring for 25min, maintaining the temperature, adding acetone, and stirring for 15min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 8min at normal temperature to obtain a mixture B;
and S14, placing the mixture B prepared in the step S13 in a vacuum environment at the temperature of 55 ℃ for degassing for 25min to obtain the high-conductivity coating.
Example 8
The high-conductivity coating is prepared from the following raw materials in percentage by mass: e44 type epoxy resin 30%, TiO230%, 650% polyesteramide 25%, 10% acetone and 5% fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, mixing E44 type epoxy resin and TiO2650 of polyesteramide is preheated for 3 hours at the temperature of 90 ℃;
s12, mixing E44 type epoxy resin and TiO2Mixing, heating in an oil bath at 80 deg.C, stirring for 35min, maintaining the temperature, adding acetone, and stirring for 20min to obtain mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring at normal temperature for 12min to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment at the temperature of 65 ℃ for degassing for 35min to obtain the high-conductivity coating.
Example 9
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 30% of E44 type epoxy resin, 30% of ZnO, 25% of 650 type polyesteramide, 10% of acetone and 5% of fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, preheating E44 type epoxy resin, ZnO and 650 type polyesteramide at 80 ℃ for 2 hours;
s12, mixing the E44 type epoxy resin and ZnO, heating and stirring in an oil bath kettle at 60 ℃, keeping the temperature for 30min, then adding acetone, and continuing stirring for 10min to obtain a mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Example 10
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 30% of E51 type epoxy resin, 30% of SiC, 25% of 650 type polyesteramide, 10% of acetone and 5% of fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, preheating E51 type epoxy resin, SiC and 650 type polyesteramide at 80 ℃ for 2 hours;
s12, mixing E51 type epoxy resin and SiC, heating and stirring in an oil bath kettle at 60 ℃, keeping the temperature for 30min, then adding acetone, and continuing stirring for 10min to obtain a mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the high-conductivity coating.
Comparative example 1
The high-conductivity coating is prepared from the following raw materials in percentage by mass: 50% of E44 type epoxy resin, 35% of 650 polyesteramide, 10% of acetone and 5% of fumed silica.
The preparation method of the high-conductivity coating comprises the following steps:
s11, preheating E44 type epoxy resin and 650 type polyesteramide at 80 ℃ for 2 hours;
s12, heating and stirring the E44 epoxy resin in an oil bath kettle at 60 ℃, keeping the temperature for 30min, adding acetone, and continuing stirring for 10min to obtain a mixture A;
s13, adding 650 parts of polyesteramide and fumed silica into the mixture A prepared in the step S12, and stirring for 10min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment with the temperature of 60 ℃ for degassing for 30min to obtain the coating.
Wherein, the same materials and reaction conditions are selected in the examples 1 to 6, all by TiO2Is a high conductivity filler, with the difference that TiO is used in each example2The percentage of the total amount is different; examples 4, 7 and 8 were made of the same material, and the percentage of each material was the same, except that the reaction conditions in the manufacturing process of each example were different; examples 4, 9 and 10 differ in the selection of the high conductivity filler in each example, and the other conditions are consistent.
The high-conductivity coating materials prepared in the above examples were tested for bulk conductivity and surface conductivity under the same conditions, and the results are shown in table 1.
TABLE 1 bulk and surface conductivity of the coating
High conductivity filler Volume conductivity/10-13 Sm-1 Surface conductivity/10-16S
Example 1 TiO2(5％) 0.95 1.36
Example 2 TiO2(10％) 1.87 2.81
Example 3 TiO2(20％) 2.66 4.16
Example 4 TiO2(30％) 4.28 6.65
Example 5 TiO2(40％) 7.65 9.86
Example 6 TiO2(50％) 9.46 12.98
Example 7 TiO2(30％) 4.26 6.53
Example 8 TiO2(30％) 4.32 6.59
Example 9 ZnO(30％) 4.22 6.48
Example 10 SiC(30％) 4.18 6.39
Comparative example 1 Is free of 0.14 0.58
From the data analysis shown in Table 1, it can be seen from the results of examples-6 that the bulk conductivity and surface conductivity of the high conductivity coating are dependent on TiO2The proportion in the high-conductivity coating is increased obviously; from the results of examples 4, 7 and 8, it can be seen that the bulk conductivity and surface conductivity of the high conductivity coating do not change much under a certain range of conditions; from the results of examples 4, 9 and 10, it can be seen that different high conductivity fillers have little effect on the bulk conductivity and surface conductivity of the high conductivity coating under the same reaction conditions.
Example 11
A preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into 4 parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity.
Wherein the coating process comprises the steps of:
s21, dividing the surface of the 56mm long insulator into 4 parts from the high-voltage electrode to the ground electrode, and sequentially recording the parts as c from the high-voltage end to the low-voltage end1、c2、c3、c4A segment, and c1From the starting end of the insulator to the high-voltage endThe distance is 6.5 mm;
s22, selecting the high-conductivity coating prepared in the examples 2, 3, 4 and 6, the conductivity is sequentially recorded as sigma from high to low1、σ2、σ3、σ4；
S23, mixing1、c2、c3、c4Segment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、σ4The high-conductivity coating, i.e., the coating from the high-voltage electrode to the ground electrode, as shown in fig. 1, forms a gradient distribution in which the conductivity gradually decreases, and each layer of the high-conductivity coating is coated to a thickness of 0.2 mm.
The insulator surface layer curing method comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 80 ℃ for solidification for 12 hours, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
Example 12
A preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into 5 parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity.
Wherein the coating process comprises the steps of:
s21, dividing the surface of the 56mm long insulator into 5 parts from the high-voltage electrode to the ground electrode, and sequentially recording the parts as c from the high-voltage end to the low-voltage end1、c2、c3、c4、c5A segment, and c1The distance between the starting end of the insulator and the high-voltage end of the insulator is 6.5 mm;
s22, selecting the high-conductivity coating prepared in the examples 2, 3, 4, 5 and 6, wherein the conductivity is sequentially recorded as sigma from high to low1、σ2、σ3、σ4、σ5；
S23, mixing1、c2、c3、c4、c5Segment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、σ4、σ5The high-conductivity coating, i.e., the coating from the high-voltage electrode to the ground electrode, as shown in fig. 1, forms a gradient distribution in which the conductivity gradually decreases, and each layer of the high-conductivity coating is coated to a thickness of 0.2 mm.
The insulator surface layer curing method comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 80 ℃ for solidification for 12 hours, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
Example 13
A preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator comprises the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into 6 parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and forming the insulator with gradient distribution and gradually reduced conductivity through curing.
Wherein the coating process comprises the steps of:
s21, equally dividing the surface of the 56mm long insulator into 6 equal parts from the high-voltage electrode to the ground electrode, and sequentially recording the parts as c from the high-voltage end to the low-voltage end1、c2、c3、c4、c5、c6A segment, and c1The distance between the starting end of the insulator and the high-voltage end of the insulator is 6.5 mm;
s22, selecting the high-conductivity coating prepared in the examples 2, 3, 4 and 6, the conductivity is sequentially recorded as sigma from high to low1、σ2、σ3、σ4、σ5、σ6；
S23, mixing1、c2、c3、c4、c5、c6Segment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、σ4、σ5、σ6The high-conductivity coating, i.e., the coating from the high-voltage electrode to the ground electrode, as shown in fig. 1, forms a gradient distribution in which the conductivity gradually decreases, and each layer of the high-conductivity coating is coated to a thickness of 0.2 mm.
The insulator surface layer curing method comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 80 ℃ for solidification for 12 hours, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
The design of the gradient coating for the insulators of examples 11-13 is shown in table 2.
TABLE 2 gradient coating design for insulators
Figure BDA0003269535190000171
Figure BDA0003269535190000181
According to the insulators with gradient distribution and gradually reduced conductivity prepared in the embodiments 11 to 13, the surface charge and flashover voltage tests under direct current voltage are carried out in the mixed gas of 0.1MPa 15% SF6/N2, the surface charge distribution result is shown in FIG. 2, the Weibull distribution of the flashover voltage test result is shown in FIGS. 3 and 4, and the flashover voltage value corresponding to the flashover probability of 63.2% is taken as the insulator along-surface flashover voltage test result according to the International Standard IEC 62539-2007.
According to the distribution spectrogram of the surface charge density of the insulator under different surface conductance gradient coating schemes, homopolar charges near the high-voltage electrode and random charges at other positions are distributed on the surface of an untreated insulator, and after the surface conductance gradient coating is adopted for treatment, the surface charges of the insulator are mainly concentrated near the high-voltage electrode and are statistical, and in other areas of the surface of the insulator, the surface charge density is-1 pC/mm2～1pC/mm2It is considered that there is substantially no charge accumulation, which indicates that the surface conductance gradient coating insulator can effectively suppress the surface charge accumulation, and thus can reduce the occurrence of flashover along the surface due to the surface charge accumulation.
Under the scheme of obtaining three gradient coatings by measurement, the insulator positive polarity flashover voltage sequentially comprises from 4 layers to 6 layers: 61.14kV, 62.32kV and 62.89kV, the flashover voltage of negative polarity is from 4 layers to 6 layers: -65.74kV, -66.29kV, -66.60 kV. The positive polarity surface flashover voltage of the untreated insulator is 59.14kV, and the negative polarity flashover voltage is-63.20 kV. Compared with an untreated insulator, the flashover voltage of the insulator with the surface conductivity gradient coating from 4 layers to 6 layers is improved, and the flashover voltage of the surface is improved, which shows that the surface conductivity gradient coating method can improve the electric strength of the surface of the insulator.
The above-described embodiments are merely illustrative of the principles and utilities of the present patent application and are not intended to limit the present patent application. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of this patent application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.

Claims (10)

1. A preparation method of a surface conductivity gradient coating for a direct current GIL epoxy resin insulator is characterized by comprising the following steps: firstly, dividing the surface of an insulator from a high-voltage electrode to a ground electrode into N parts, then sequentially coating high-conductivity coating on the surface of the insulator from the high-voltage electrode to the ground electrode according to the conductivity from high to low, and curing to form the insulator with gradient distribution and gradually reduced conductivity.
2. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator as claimed in claim 1, wherein the method for preparing the high conductivity coating comprises the steps of:
s11, preheating the epoxy resin, the high-conductivity filler and the curing agent for 2-3 hours at the temperature of 80-90 ℃;
s12, mixing the epoxy resin and the high-conductivity filler, heating and stirring in an oil bath kettle at the temperature of 60-80 ℃, keeping the temperature for 25-35min, adding the diluent, and continuously stirring for 10-20min to obtain a mixture A;
s13, adding a curing agent and an adhesive into the mixture A prepared in the step S12, and stirring for 8-12min at normal temperature to obtain a mixture B;
s14, placing the mixture B prepared in the step S13 in a vacuum environment at the temperature of 55-65 ℃ for degassing for 25-35min to obtain the high-conductivity coating.
3. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator as claimed in claim 2, wherein the coating process comprises the steps of:
s21, dividing the surface of the insulator into N parts from the high-voltage electrode to the ground electrode, and sequentially recording the N parts as c from the high-voltage end to the low-voltage end1、c2、c3、…、cNA segment wherein N is greater than or equal to 2;
s22, preparing N parts of high-conductivity coating according to the preparation method of the high-conductivity coating, measuring the conductivity of each high-conductivity coating by using a conductivity instrument, and sequentially recording the conductivity from high to low as sigma1、σ2、σ3、…、σN；
S23, mixing1、c2、c3、…、cNSegment-by-segment coating having an electrical conductivity of σ1、σ2、σ3、…、σNThe high-conductivity coating, namely from the high-voltage electrode to the ground electrode, forms gradient distribution with gradually reduced conductivity, and the thickness of each layer of the high-conductivity coating is 0.2 mm.
4. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to any one of claims 1 to 3, wherein the curing of the surface layer of the insulator comprises the following steps:
s31, firstly, placing the insulator coated with the high-conductivity coating on the surface in a room temperature environment for curing for 12 hours;
s32, placing the insulator which is not completely solidified in the step S31 in an environment of 75-85 ℃ for solidification for 12h, and obtaining the insulator with gradient distribution and gradually reduced conductivity.
5. The preparation method of the surface conductivity gradient coating for the direct current GIL epoxy resin insulator as claimed in claim 2, wherein the high conductivity coating is prepared from the following raw materials in percentage by mass:
Figure FDA0003269535180000021
6. the method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to claim 5, wherein the method comprises the following steps: the epoxy resin is one of E44 type or E51 type epoxy resin which is liquid at normal temperature.
7. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to claim 5, wherein the method comprises the following steps: the high-conductivity filler is selected from SiC, ZnO and TiO2、BatiO3And carbon black.
8. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to claim 5, wherein the method comprises the following steps: 650 portions of polyesteramide is selected as the curing agent.
9. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to claim 5, wherein the method comprises the following steps: the diluent is acetone; the binder is fumed silica.
10. The method for preparing the surface conductivity gradient coating for the direct current GIL epoxy resin insulator according to claim 5, wherein the method comprises the following steps: the surface of the insulator is roughened before coating, and the coating mode is spraying or brushing.
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