Method and device for evaluating influence of X-rays on electrical properties of solid insulating material

Abstract

The invention discloses a method and device for evaluating the influence of X-rays on the electrical properties of a solid insulating material, and the method comprises the steps: irradiating a to-be-tested sample with the X-rays, and obtaining the to-be-tested sample treated at different intensities and different time; measuring the body resistivity and the surface resistivity of the processed to-be-tested sample; removing residual charges on the surface of the to-be-tested sample, applying charges to the surface of the insulator, measuring the attenuation of the central point potential of the to-be-tested sample, and calculating the surface trap distribution of the to-be-tested sample; comparing the body resistivity, the surface resistivity and the surface trap distribution with the performance of the to-be-tested sample before X-ray processing, and determining an evaluation result of the influence of the X-ray on the electrical performance of the insulating material; according to the invention, the influence of X-rays on the electrical properties of the solid insulating material can be evaluated more accurately.

Description

Technical Field

[0001] The present invention relates to the field of high voltage and insulation technology, and in particular to a method and a device for evaluating the influence of X-rays on the electrical properties of solid insulating materials. Background Art

[0002] Gas Insulated Switchgear (GIS) has been widely used in power systems due to its high operating reliability, low maintenance workload, and long maintenance cycle. The average annual growth rate of its installed capacity exceeds 20%. Operating experience shows that although the reliability of GIS equipment is very high, its inevitable internal defects can still cause failures and gradually expand, often leading to major accidents. This has become a problem of great concern to the power sector and a hot topic in this field.

[0003] According to the consensus formed by current research, insulation failure is mainly caused by various defects inside GIS, which distort the electric field inside GIS, causing local electric field concentration and local discharge. From the perspective of defect types, there are mainly serious assembly errors, free conductive particles, metal protrusions, surface and internal defects of insulators, poor electrical or mechanical contact between conductors, etc. Since all equipment components are completely enclosed in a metal casing, it is impossible to rely on human senses to find early signs of faults. The existing conventional live detection technology has different shortcomings in the diagnosis of internal defects of fully enclosed GIS equipment, especially the determination of the degree of defect development is not intuitive. In view of this, researchers proposed to use X-ray detection technology to locate internal fault defects of GIS, realize the "visualization" and rapid diagnosis of internal defects without power outage or disassembly, and improve the location and identification of equipment faults. It is worth noting that X-rays have high transmittance and belong to high-energy rays. Although the efficiency of a single detection is very high and the time is very short, the cumulative impact of long-term use on the electrical properties of solid insulators (such as conductivity characteristics and charge relaxation characteristics) still needs to be evaluated in order to ensure the safe and stable operation of GIS equipment.

[0004] In the related art, the patent application document with publication number CN117269684A proposed a detection device for evaluating the influence of X-rays on the gas-solid insulation system, which is used to simulate the real operating environment of GIS equipment and evaluate the influence of X-rays on the insulation performance of insulating dielectrics. However, the scheme focuses more on evaluating the influence of X-rays on the gas gap and the breakdown characteristics of the insulating sample. The document "The influence of X-rays on the electrical properties of polyethylene materials, master's degree thesis, Lu Zhongxi" proposed to use scanning electron microscopy and X-ray diffraction to characterize the physical surface and crystal structure of polyethylene after radiation, make a preliminary judgment on whether the solid insulating material is affected by radiation, and then measure the insulation parameters such as volume resistivity, surface resistivity, dielectric constant, dielectric loss, etc. of the irradiated polyethylene material, analyze and judge the obtained parameters; however, the scheme uses commercial equipment for measurement, has strict requirements on the volume and thickness of the sample, and is not universal. In addition, the scheme only focuses on insulation parameters such as volume resistivity and surface resistivity, and does not focus on the influence of X-rays on trap distribution, which is an important evaluation index of the surface characteristics of insulating materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to more accurately evaluate the influence of X-rays on the electrical properties of solid insulating materials.

[0006] The present invention solves the above technical problems by the following technical means: The present invention proposes a method for evaluating the influence of X-rays on the electrical properties of solid insulating materials, the method comprising: Use X-rays to irradiate the test sample to obtain the test sample after being treated with different intensities and for different times; Measure the volume resistivity and surface resistivity of the sample to be tested after treatment; After removing the residual charge on the surface of the sample to be tested, a charge is applied to the surface of the insulator, the decay of the potential at the center point of the sample to be tested is measured, and the distribution of surface traps is obtained; Based on the comparison of the volume resistivity, surface resistivity and surface trap distribution with the performance of the test sample before X-ray treatment, an evaluation result of the effect of X-rays on the electrical properties of the insulating material is determined.

[0007] Furthermore, the method of irradiating the test sample with X-rays to obtain the test sample after being treated with different intensities and for different time periods includes: The sample to be tested is placed in an oven to dry for a set period of time, and then its surface is wiped with anhydrous ethanol and placed in a closed cavity on the laboratory table, and the cavity is filled with SF6 gas; Use X-rays to irradiate the sample and obtain the test samples after being treated with different intensities and time.

[0008] Further, the volume resistivity and surface resistivity of the sample to be tested after the measurement process include: The volume resistivity and surface resistivity of the treated sample are measured using a three-electrode system, wherein the volume resistivity of the sample is measured. for:

[0009] Measure the surface resistivity of the sample to be tested for:

[0010] Where: , V is the magnitude of the applied voltage, I V is the body current value flowing through the sample to be tested, d is the thickness of the sample to be tested, d 1 is the diameter of the main electrode 2 in the three-electrode system, g is the distance between the main electrode and the ring electrode in the three-electrode system, I s is the current value flowing through the surface of the test sample.

[0011] Further, after removing the residual charge on the surface of the sample to be tested, applying charge to the surface of the insulator, measuring the attenuation of the potential at the center point of the sample to be tested, and obtaining the distribution of surface traps, comprises: After cleaning the insulator surface with anhydrous ethanol and removing the residual charge on the surface of the sample to be tested with an ion blower, the intrinsic potential measurement platform is used to apply charge to the insulator surface using electrodes; Measuring the decay of the intrinsic potential of the sample to be tested and calculating the density of the electron traps; According to the different processes of carrier detrapping in the trap corresponding to the potential decay on the material surface, a double exponential function is used to fit the measured potential decay curve to obtain a fitting curve; The electron trap energy level distribution of the sample to be tested is calculated according to the fitting curve and the density of the electron trap.

[0012] Furthermore, the measuring of the intrinsic potential decay of the sample to be tested and the calculation of the density of the electron traps include: Assume that the charge is on the surface of the insulator δ The positive and negative charges are evenly distributed in ρ + and ρ - , calculate the potential of the surface of the sample to be tested for:

[0013] The decay of the surface potential over time is calculated as:

[0014] in, , ε 0 is the dielectric constant of vacuum, ε r is the relative permittivity of the sample, q e is the unit charge, L is the thickness of the specimen; Calculate the density of electron traps through the decay curve of surface potential for:

[0015] in, T is the temperature, k B is the Boltzmann constant, f 0 is the initial occupancy of the electron trap.

[0016] Furthermore, according to the different processes of the potential decay corresponding to the detrapping of the carriers in the traps, a double exponential function is used to fit the measured potential decay curve to obtain a fitting curve, including: The traps are divided into deep traps and shallow traps. According to the different processes of carrier detrapping in each trap corresponding to the material surface potential decay, a double exponential function is used to fit the measured potential decay curve, and the fitting curve is:

[0017] In the formula, a 1, b 1, a 2, b 2 is the fitting parameter.

[0018] In addition, the present invention also proposes an evaluation device for the influence of X-rays on the electrical properties of solid insulating materials, the device comprising an X-ray instrument, a test bench, a three-electrode system and an intrinsic potential measurement platform, wherein the intrinsic potential measurement platform comprises a DC power supply 1, a DC power supply 2, a needle electrode, a mesh electrode, a ground electrode, a mobile platform, a mobile track, an electrostatic probe, a motion control mechanism, an electrostatic potentiometer, an oscilloscope and a data acquisition system; The needle electrode is connected to the DC power supply 1, the mesh electrode is connected to the DC power supply 2, the mobile platform is installed on the mobile track, the ground electrode is fixed on the mobile platform, the sample to be tested is fixed on the ground electrode, and the central axes of the needle electrode, the mesh electrode, the sample to be tested, the ground electrode and the mobile platform are in the same straight line; The electrostatic probe is installed on the motion control mechanism and connected to the electrostatic potentiometer, the electrostatic potentiometer is connected to the oscilloscope, the oscilloscope is connected to the data acquisition system, and the data acquisition system is used to collect surface potential data of the sample to be tested.

[0019] Further, the three-electrode system comprises a main electrode 1, a main electrode 2 and an annular electrode, the main electrode 2 and the annular electrode are arranged concentrically and on the same horizontal plane, the sample to be tested is placed on the plane formed by the main electrode 2 and the annular electrode, the main electrode 1 is placed on the sample to be tested, and the sample to be tested is in close contact with the main electrode 1, the main electrode 2 and the annular electrode; When measuring the volume resistivity of the insulating material, the DC high voltage is connected to the main electrode 1, the annular electrode is grounded, and the main electrode 2 is grounded through an electrometer; When measuring the surface resistivity of the insulating material, a DC high voltage is connected to the annular electrode, the first main electrode is grounded, and the second main electrode is grounded through an electrometer.

[0020] Furthermore, a closed cavity is arranged on the experimental table, and a support table for placing the sample to be tested is provided in the cavity; and SF6 gas is filled in the cavity.

[0021] Furthermore, the device also includes an ion blower for removing residual charges on the surface of the sample to be tested.

[0022] The advantages of the present invention are: (1) The present invention measures the bulk conductivity, surface conductivity and surface trap distribution of solid insulating materials after X-ray irradiation, and can be used to evaluate the effect of X-ray irradiation on the charge relaxation dynamics and conduction mechanism of solid insulating materials, so as to realize the engineering application of X-ray detection technology in fault identification of power transmission and distribution equipment such as GIS; and the present invention takes the trap distribution of insulating materials as an important indicator, which can indicate the effect of X-rays on the surface breakdown characteristics of insulating materials, making the evaluation result of the effect of X-rays on the electrical properties of solid insulating materials more accurate.

[0023] (2) The present invention can measure samples of different sizes and thicknesses through a self-built three-electrode system, has better universal thickness, is more flexible to use, and is closer to the insulators in actual GIS equipment.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1It is a flow chart of a method for evaluating the influence of X-rays on the electrical properties of solid insulating materials proposed in one embodiment of the present invention; Figure 2 is a schematic diagram of an X-ray treated insulating material in one embodiment of the present invention; Figure 3 is a schematic diagram of a three-electrode structure in one embodiment of the present invention; Figure 4 is a schematic diagram of a surface trap measurement platform in one embodiment of the present invention; Figure 5 is a graph showing the change trend of the electrical conductivity of the insulating material after irradiation for different time periods in one embodiment of the present invention; Figure 6 is a graph showing a change trend of the surface conductivity of an insulating material after irradiation for different time periods in one embodiment of the present invention; Figure 7 is a diagram of the decay process of the surface potential of the insulating material after being irradiated for different time periods in one embodiment of the present invention; Figure 8 is a trend diagram of the influence of traps on the surface of insulating materials at different times in one embodiment of the present invention; Fig. 9 is a graph showing the change trend of the electrical conductivity of the insulating material after being irradiated with different intensities in one embodiment of the present invention; Fig.10 is a graph showing a change trend of the surface conductivity of an insulating material after being irradiated with different intensities in one embodiment of the present invention; Fig.11 is a diagram of the attenuation process of the surface potential of an insulating material after being irradiated with different intensities in one embodiment of the present invention; Fig.12 This is a trend diagram of the influence of different intensities on surface traps of insulating materials in one embodiment of the present invention.

[0026] In the figure: 1-X-ray instrument, 2-sealed cavity, 3-sample to be tested, 4-support table, 5-main electrode 1, 6-main electrode 2, 7-ring electrode, 8-DC power supply 1, 9-DC power supply 2, 10-needle electrode, 11-screen electrode, 12-electrostatic potentiometer, 13-oscilloscope, 14-data acquisition system, 15-motion control mechanism, 16-electrostatic probe, 17-ground electrode, 18-movable platform, 19-movable track. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0028] like Figure 1 As shown, the first embodiment of the present invention discloses a method for evaluating the influence of X-rays on the electrical properties of solid insulating materials, the method comprising the following steps: S10, irradiating the test sample with X-rays to obtain the test sample after being treated with different intensities and for different time periods; It should be noted that, in this embodiment, the X-rays emitted by the X-ray device can be used to irradiate the sample to be tested, X-rays of different intensities can be selected to process the sample to be tested, and the sample to be tested with different processing times can be obtained.

[0029] S20, measuring the volume resistivity and surface resistivity of the sample to be tested after treatment; S30, after removing the residual charge on the surface of the sample to be tested, applying a charge to the surface of the insulator, measuring the attenuation of the potential at the center point of the sample to be tested, and obtaining the distribution of surface traps; S40, comparing the volume resistivity, surface resistivity and surface trap distribution with the performance of the test sample before X-ray treatment, and determining an evaluation result of the effect of X-rays on the electrical properties of the insulating material.

[0030] This embodiment measures the bulk conductivity, surface conductivity and surface trap distribution of the solid insulating material after X-ray irradiation, which can be used to evaluate the effect of X-ray irradiation on the charge relaxation dynamics and conduction mechanism of the solid insulating material, so as to realize the engineering application of X-ray detection technology in fault identification of power transmission and distribution equipment such as GIS; and the present invention uses the trap distribution of the insulating material as an important indicator, which can indicate the effect of X-rays on the surface breakdown characteristics of the insulating material, so that the evaluation result of the effect of X-rays on the electrical properties of the solid insulating material is more accurate.

[0031] In one embodiment, the step S10 of irradiating the sample to be tested with X-rays to obtain the sample to be tested after being treated with different intensities and for different times specifically includes: Before the experiment, the test sample was placed in an oven to dry for 24 hours, and its surface was wiped with anhydrous ethanol and placed on a support table in a closed cavity. The X-ray instrument was turned on and the sample was irradiated with X-rays to obtain the test samples after treatment with different intensities and different times. The cavity was filled with 0.4~0.6MPa SF6 gas to simulate the actual GIS working environment.

[0032] It should be noted that, in order to simulate the actual operation of GIS pot-type insulators, the test sample 3 in this embodiment uses an alumina epoxy composite material with the same formula as the pot-type insulator. Figure 2 The structure shown uses X-rays to process the insulating material.

[0033] In one embodiment, in the step S20, a three-electrode system is used to measure the volume resistivity and surface resistivity of the sample to be tested after processing, wherein the three-electrode system includes a main electrode 1 5, a main electrode 2 6 and an annular electrode 7, the main electrode 2 6 and the annular electrode 7 are arranged concentrically and on the same horizontal plane, the sample to be tested 3 is placed on the plane formed by the main electrode 2 6 and the annular electrode 7, the main electrode 1 5 is placed on the sample to be tested 3, and the sample to be tested 3 is in close contact with the main electrode 1 5, the main electrode 2 6 and the annular electrode 7.

[0034] When measuring the volume resistivity of the insulating material, the DC high voltage is connected to the main electrode 1 5, the annular electrode is grounded, and the main electrode 2 6 is grounded through an electrometer to measure the volume resistivity of the test sample 3. for:

[0035] When measuring the surface resistivity of the insulating material, the DC high voltage is connected to the annular electrode 7, the main electrode 1 5 is grounded, and the main electrode 2 6 is grounded through an electrometer to measure the surface resistivity of the test sample 3. for:

[0036] Where: , V is the magnitude of the applied voltage, I V is the body current value flowing through the test sample 3, d is the thickness of the sample 3 to be tested, d 1 is the diameter of the main electrode 2 6, g is the distance between the main electrode 2 6 and the annular electrode 7, I s is the current value flowing through the surface of the test sample 3.

[0037] It should be noted that the existing measurement schemes are mostly measured through relatively mature commercial instruments. Due to the volume of the relevant equipment, they can generally only measure samples with smaller thicknesses. However, this embodiment uses a self-built three-electrode system, which can measure samples of different sizes and thicknesses, and has better flexibility and universality.

[0038] In one embodiment, the step S30: applying charge to the surface of the insulator after removing residual charge on the surface of the sample to be tested, measuring the attenuation of the potential at the center point of the sample to be tested, and obtaining the surface trap distribution thereof, comprises the following steps: S31. After cleaning the surface of the insulator with anhydrous ethanol and removing the residual charge on the surface of the sample to be tested with an ion blower, an intrinsic potential measurement platform is used to apply charge to the surface of the insulator with electrodes; Specifically, Figure 4 As shown, the intrinsic potential measurement platform includes a DC power supply 1 8, a DC power supply 2 9, a needle electrode 10, a mesh electrode 11, a ground electrode 17, a mobile platform 18, a mobile track 19, an electrostatic probe 16, a motion control mechanism 15, an electrostatic potentiometer 12, an oscilloscope 13 and a data acquisition system 14; wherein the needle electrode 10 is connected to the DC power supply 1 8, the mesh electrode 11 is connected to the DC power supply 2 9, the mobile platform 18 is installed on the mobile track 19, and can slide horizontally on the mobile track 19, the ground electrode 17 is fixed on the mobile platform 18, the test sample 3 is fixed on the ground electrode 17, and the central axes of the needle electrode 10, the mesh electrode 11, the test sample 3, the ground electrode 17 and the mobile platform 18 are in the same straight line; the electrostatic probe 16 is installed on the motion control mechanism 15 and is connected to the electrostatic potentiometer 12, the electrostatic potentiometer 12 is connected to the oscilloscope 13, and the oscilloscope 13 is connected to the data acquisition system 14, for collecting the dynamic changes of the surface potential data of the test sample 3.

[0039] During the experiment, a DC high voltage of the same polarity is applied to the needle electrode 10 and the mesh electrode 11. After the test sample 3 is charged by the "needle-mesh" electrode, the charge is evenly distributed on its surface. Turn off the DC power supply 1 8 and the DC power supply 2 9, move the mobile platform 18 to the measurement position, and control the electrostatic probe 16 to move to the center point of the test sample 3 through the motion control mechanism 15 to measure the dissipation characteristics of its surface potential.

[0040] According to the "double injection" model, after unipolar corona charging, charges with the same polarity as the needle voltage are distributed on the upper surface of the test sample 3, with an injection depth of about 1~2μm, and charges with opposite sign to the polarity of the applied corona voltage are injected on the lower surface of the sample close to the ground electrode 17.

[0041] S32, measuring the decay of the intrinsic potential of the sample to be tested, and calculating the density of the electron traps; Specifically, assume that the charge is at a distance δ The positive and negative charges are evenly distributed in ρ + and ρ - , which are approximately equal in size, are recorded as ρ , the charge density in the central area is very small and can be ignored. Therefore, the potential on the surface of the sample to be tested can be expressed as:

[0042] Solving the above integral, we get the expression for the surface potential:

[0043] The carriers escape from the traps to form current, which is manifested externally as the decay of surface potential over time. The relationship between them can be expressed as:

[0044] According to the isothermal current decay (ICD) theory, the total number of electrons emitted from the upper half of the bandgap to the conduction band is:

[0045] Therefore, the density of electron traps N ( E T ) can be obtained from the surface potential decay curve:

[0046] In the formula, ε 0 is the dielectric constant of vacuum, ε r is the relative permittivity of the sample, q e is the unit charge, L is the thickness of the specimen, T is the temperature, k B is the Boltzmann constant, f 0 is the initial occupancy of the electron trap.

[0047] It should be noted that due to f 0 is difficult to measure experimentally. To simplify the calculation, we assume f 0≈1, that is, the initial occupancy of the trap is 100%, then the density of the trap is also the density of the trapped charge.

[0048] S33, according to the different processes of carrier detrapping in the trap corresponding to the potential decay of the material surface, a double exponential function is used to fit the measured potential decay curve to obtain a fitting curve; Specifically, traps are divided into deep traps and shallow traps according to the different trap energy levels of the trapped carriers. The carrier detrapping in the two traps corresponds to different processes of the material surface potential decay. Therefore, the measured potential decay curve can be fitted with a double exponential function:

[0049] In the formula, a 1, b 1, a 2, b 2 is the fitting parameter.

[0050] S34, calculating the electron trap energy level distribution of the sample to be tested according to the fitting curve and the density of the electron traps.

[0051] In addition, if Figures 2 to 4 As shown, the second embodiment of the present invention further discloses an evaluation device for the influence of X-rays on the electrical properties of solid insulating materials, the device comprising an X-ray instrument 1, a test bench, a three-electrode system and an intrinsic potential measurement platform, wherein the intrinsic potential measurement platform comprises a DC power supply 1 8, a DC power supply 2 9, a needle electrode 10, a mesh electrode 11, a ground electrode 17, a moving platform 18, a moving track 19, an electrostatic probe 16, a motion control mechanism 15, an electrostatic potentiometer 12, an oscilloscope 13 and a data acquisition system 14; The needle electrode 10 is connected to the DC power supply 1 8, the mesh electrode 11 is connected to the DC power supply 2 9, the mobile platform 18 is installed on the mobile track 19, the ground electrode 17 is fixed on the mobile platform 18, the test sample 3 is fixed on the ground electrode 17, and the central axes of the needle electrode 10, the mesh electrode 11, the test sample 3, the ground electrode 17 and the mobile platform 18 are on the same straight line; The electrostatic probe 16 is installed on the motion control mechanism 15 and connected to the electrostatic potentiometer 12 , the electrostatic potentiometer 12 is connected to the oscilloscope 13 , the oscilloscope 13 is connected to the data acquisition system 14 , and the data acquisition system 14 is used to collect surface potential data of the sample 3 to be tested.

[0052] Specifically, during the experiment, the test sample 3 is placed on the experimental table, the X-ray instrument 1 is turned on, and the sample is irradiated with X-rays to obtain the test sample 3 after being processed with different intensities and different times; then the X-ray instrument 1 is turned off, and the volume conductivity of the test sample 3 after processing is measured using a three-electrode system, and then the wiring of the three-electrode system is changed to measure the surface conductivity of the test sample 3; finally, after applying a charge to the surface of the insulator using an intrinsic potential measurement platform, the attenuation of the potential at the center point of the test sample 3 is measured, and its surface trap distribution is obtained.

[0053] It should be noted that the model of the X-ray instrument 1 is Ruixin PTX-225HP / 11. In order to consider the cumulative effect caused by X-rays, X-rays of different intensities are selected in the experiment to process the test sample 3, and the test sample 3 with different processing times is obtained.

[0054] In one embodiment, the three-electrode system includes a main electrode 1 5, a main electrode 2 6 and an annular electrode 7, the main electrode 2 6 and the annular electrode 7 are arranged concentrically and on the same horizontal plane, the sample to be tested 3 is placed on the plane formed by the main electrode 2 6 and the annular electrode 7, the main electrode 1 5 is placed on the sample to be tested 3, and the sample to be tested 3 is in close contact with the main electrode 1 5, the main electrode 2 6 and the annular electrode 7; When measuring the resistivity of the insulating material, the DC high voltage is connected to the main electrode 1 5, the annular electrode is grounded, and the main electrode 2 6 is grounded through an electrometer; When measuring the surface resistivity of the insulating material, a DC high voltage is connected to the annular electrode 7, the main electrode 1 5 is grounded, and the main electrode 2 6 is grounded through an electrometer.

[0055] In one embodiment, when the test sample 3 is charged using the intrinsic potential measurement platform, a DC high voltage of the same polarity is applied to the needle electrode 10 and the mesh electrode 11. After the test sample 3 is charged by the "needle-mesh" electrode, the charge is evenly distributed on its surface. Then, the DC power supply 1 8 and the DC power supply 2 9 are turned off, the mobile platform 18 is moved to the measurement position, and the electrostatic probe 16 is controlled by the motion control mechanism 15 to move to the center point of the test sample 3 to measure the dissipation characteristics of its surface potential.

[0056] According to the "double injection" model, after unipolar corona charging, charges with the same polarity as the needle voltage are distributed on the upper surface of the test sample 3, with an injection depth of about 1~2μm, and charges with opposite sign to the polarity of the applied corona voltage are injected on the lower surface of the sample close to the ground electrode 17.

[0057] In one embodiment, a closed cavity 2 is arranged on the experimental table, and a support table 4 for placing a test sample 3 is provided in the cavity 2; 0.4~0.6MPa SF6 gas is filled in the cavity 2 to simulate the actual GIS working environment.

[0058] In one embodiment, the device further comprises an ion blower, which is a white light BK5600 type, for removing residual charges on the surface of the sample 3 to be tested.

[0059] Furthermore, the following two experimental examples illustrate the influence of X-rays on the electrical properties of insulating materials: In this embodiment 1, the effects of different irradiation times on the electrical properties of the insulating material were measured: The parameters of the X-ray instrument 1 are: tube voltage 225kV, current 2.8mA, and irradiation time distribution of 10min, 2h, 4h, and 10h. 0.4MPa SF6 gas is introduced into the closed cavity 2, and the test sample 3 is a 1mm thick alumina epoxy composite flat material with a relative dielectric constant of 5.87. The voltage of the needle electrode 10 is set to -9kV, the voltage of the mesh electrode 11 is set to -7kV, the distance between the needle electrode 10 and the mesh electrode 11 is 10mm, and the distance between the mesh electrode 11 and the test sample 3 is 2mm. After applying the voltage for 3min, turn off the DC power supply 18 and the DC power supply 29, the experimental temperature is 27℃, and the relative humidity is 34%RH.

[0060] The influence of different irradiation times on the electrical properties of insulating materials Figure 5-Figure 8 As shown in the figure. As can be seen from the figure, with the increase of irradiation time, the volume resistivity of the insulating material does not change much, and the surface resistivity gradually increases. The test sample 3 obtained with different processing times was measured, and the corresponding surface trap characteristics were obtained. When X-ray irradiation was not used, the surface traps of the insulator were mainly deep traps, and there were fewer shallow traps, indicating that the charges were difficult to dissipate when accumulated on the surface of the insulating material. As the irradiation time increased, the number of deep traps and shallow traps gradually decreased, indicating that it was difficult for charges to accumulate on the surface of the insulator, and the dissipation rate increased, which greatly enhanced and significantly improved the surface characteristics of the insulating material.

[0061] In this embodiment 2, the effects of different irradiation intensities on the electrical properties of insulating materials were measured: The irradiation intensity of X-rays is changed by changing the tube voltage and current of the X-ray instrument 1. In this embodiment, the working conditions of the X-ray instrument 1 are: 225 kV and 2.8 mA, 100 kV and 6.3 mA, and 50 kV and 12.6 mA, and the irradiation time distribution is 2 hours. Other conditions are consistent with those in the first embodiment.

[0062] The influence of different radiation intensities on the electrical properties of insulating materials Figure 9-12 As shown in the figure, X-rays have almost no effect on the volume resistivity of the insulating material, while the surface resistivity gradually increases with the increase of the tube voltage. The test sample 3 obtained with different treatment intensities was measured, and the corresponding surface trap characteristics were obtained. As the irradiation time increases, the number of deep traps and shallow traps gradually decreases, indicating that it is difficult for charges to accumulate on the surface of the insulator and the dissipation rate increases.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0065] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the effect of X-rays on the electrical properties of solid insulating materials, characterized in that: The method comprises: Use X-rays to irradiate the test sample to obtain the test sample after being treated with different intensities and for different times; Measure the volume resistivity and surface resistivity of the sample to be tested after treatment; After removing the residual charge on the surface of the sample to be tested, a charge is applied to the surface of the insulator, the decay of the potential at the center point of the sample to be tested is measured, and the distribution of surface traps is obtained; Based on the comparison of the volume resistivity, surface resistivity and surface trap distribution with the performance of the test sample before X-ray treatment, an evaluation result of the effect of X-rays on the electrical properties of the insulating material is determined.

2. The method for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 1, characterized in that: The method of using X-rays to irradiate the test sample to obtain the test sample after being processed with different intensities and for different times includes: The sample to be tested is placed in an oven to dry for a set period of time, and then its surface is wiped with anhydrous ethanol and placed in a closed cavity on the laboratory table, and the cavity is filled with SF6 gas; Use X-rays to irradiate the sample and obtain the test samples after being treated with different intensities and time.

3. The method for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 1, characterized in that: The measuring of the volume resistivity and surface resistivity of the sample to be tested after the processing comprises: The volume resistivity and surface resistivity of the treated sample are measured using a three-electrode system, wherein the volume resistivity of the sample is measured. for: Measure the surface resistivity of the sample to be tested for: Where: , V is the magnitude of the applied voltage, I V is the body current value flowing through the sample to be tested, d is the thickness of the sample to be tested, d 1 is the diameter of the main electrode 2 in the three-electrode system, g is the distance between the main electrode 2 and the annular electrode in the three-electrode system, I s is the current value flowing through the surface of the test sample.

4. The method for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 1, characterized in that: After removing the residual charge on the surface of the sample to be tested, applying charge to the surface of the insulator, measuring the attenuation of the potential at the center point of the sample to be tested, and obtaining the surface trap distribution, including: After cleaning the insulator surface with anhydrous ethanol and removing the residual charge on the surface of the sample to be tested with an ion blower, the intrinsic potential measurement platform is used to apply charge to the insulator surface using electrodes; Measuring the decay of the intrinsic potential of the sample to be tested and calculating the density of the electron traps; According to the different processes of carrier detrapping in the trap corresponding to the potential decay on the material surface, a double exponential function is used to fit the measured potential decay curve to obtain a fitting curve; The electron trap energy level distribution of the sample to be tested is calculated according to the fitting curve and the density of the electron trap.

5. The method for evaluating the influence of X-rays on the electrical properties of solid insulating materials according to claim 4, characterized in that: The step of measuring the decay of the intrinsic potential of the sample to be tested and calculating the density of electron traps comprises: Assume that the charge is on the surface of the insulator δ The positive and negative charges are evenly distributed in ρ + and ρ - , calculate the potential of the surface of the sample to be tested for: The decay of the surface potential over time is calculated as: in, , ε 0 is the dielectric constant of vacuum, ε r is the relative permittivity of the sample, q e is the unit charge, L is the thickness of the specimen; Calculate the density of electron traps through the decay curve of surface potential for: in, T is the temperature, k B is the Boltzmann constant, f 0 is the initial occupancy of the electron trap.

6. The method for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 4, characterized in that: According to the different processes of the potential decay corresponding to the detrapping of the carriers in the trap, a double exponential function is used to fit the measured potential decay curve to obtain a fitting curve, including: The traps are divided into deep traps and shallow traps. According to the different processes of carrier detrapping in each trap corresponding to the material surface potential decay, a double exponential function is used to fit the measured potential decay curve, and the fitting curve is: In the formula, a 1, b 1, a 2, b 2 is the fitting parameter.

7. An evaluation device for the effect of X-rays on the electrical properties of solid insulating materials, characterized in that: The device includes an X-ray instrument, a test bench, a three-electrode system and an intrinsic potential measurement platform, wherein the intrinsic potential measurement platform includes a DC power supply 1, a DC power supply 2, a needle electrode, a mesh electrode, a ground electrode, a mobile platform, a mobile track, an electrostatic probe, a motion control mechanism, an electrostatic potentiometer, an oscilloscope and a data acquisition system; The needle electrode is connected to the DC power supply 1, the mesh electrode is connected to the DC power supply 2, the mobile platform is installed on the mobile track, the ground electrode is fixed on the mobile platform, the sample to be tested is fixed on the ground electrode, and the central axes of the needle electrode, the mesh electrode, the sample to be tested, the ground electrode and the mobile platform are in the same straight line; The electrostatic probe is installed on the motion control mechanism and connected to the electrostatic potentiometer, the electrostatic potentiometer is connected to the oscilloscope, the oscilloscope is connected to the data acquisition system, and the data acquisition system is used to collect surface potential data of the sample to be tested.

8. The device for evaluating the effect of X-rays on the electrical properties of solid insulating materials as claimed in claim 7, characterized in that: The three-electrode system comprises a main electrode 1, a main electrode 2 and an annular electrode, wherein the main electrode 2 and the annular electrode are arranged concentrically and on the same horizontal plane, the sample to be tested is placed on the plane formed by the main electrode 2 and the annular electrode, the main electrode 1 is placed on the sample to be tested, and the sample to be tested is in close contact with the main electrode 1, the main electrode 2 and the annular electrode; When measuring the volume resistivity of the insulating material, the DC high voltage is connected to the main electrode 1, the annular electrode is grounded, and the main electrode 2 is grounded through an electrometer; When measuring the surface resistivity of the insulating material, a DC high voltage is connected to the annular electrode, the first main electrode is grounded, and the second main electrode is grounded through an electrometer.

9. The device for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 7, characterized in that: A closed cavity is arranged on the experimental table, and a support table for placing the sample to be tested is arranged in the cavity; and SF6 gas is filled in the cavity.

10. The device for evaluating the effect of X-rays on the electrical properties of solid insulating materials according to claim 7, characterized in that: The device also includes an ion fan for removing residual charges on the surface of the sample to be tested.

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