A defect size quantification method

Abstract

The present invention belongs to the technical field of non-destructive testing signal processing, and in particular, relates to a defect size quantification method. The defect size quantification method detects the defects of the insulating component to be tested by a rectangular dual-electrode sensing device, and obtains the first-order derivative of the obtained detection signal, so as to accurately judge the length and width parameter size of the defect of the insulating component to be tested. A defect size quantification method includes the following steps: determining the performance parameters of the electrode sensing device used in the defect size quantification method; scanning and detecting the insulating component to be tested along a direction to obtain a one-dimensional line scanning signal; deriving to obtain a first-order derivative signal; scanning and detecting the insulating component to be tested along a direction to obtain a one-dimensional line scanning signal; deriving to obtain a first-order derivative signal; judging whether there is a concave area in the one-dimensional line scanning signal and the one-dimensional line scanning signal.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing signal processing, and in particular relates to a defect size quantification method. Background Art

[0002] Insulating components are widely used in oil and gas exploration, mining, transportation, processing and storage. However, due to factors such as corrosion and wear, insulation component failure is a common problem. Therefore, it is necessary to conduct timely inspections of insulating materials, especially high-attenuation materials.

[0003] Among them, capacitance imaging detection technology is a feasible solution for realizing the detection of insulating components. After further research, the inventor found that in the early stage of the development of capacitance imaging detection technology, due to the limitations of theoretical knowledge and data processing capabilities, only the existence and location of defects in insulating components could be judged. Usually, the capacitance imaging detection data is converted into a data image through a data visualization method, and the existence of defects is judged by drawing an image curve. As for the specific size of the defect, it can only be judged by the experience of technicians, lacking relevant theoretical support and low reliability. However, with the gradual increase in industrial production needs, simply judging the existence and location of defects can no longer meet the needs of industrial applications. The accuracy and efficiency of defect size parameter quantification has gradually become an important technical indicator. When processing data, it is required to quantify the defects of insulating components with high precision. The necessity and importance of developing in the direction of defect size parameter quantification are becoming more and more obvious. Therefore, it is necessary to propose a defect size parameter quantification method that can effectively solve the above-mentioned technical problems. Summary of the invention

[0004] The present invention provides a defect size quantification method, which is based on capacitive imaging technology. The defects of an insulating component to be measured are detected by a rectangular dual-electrode sensing device, and the first-order derivative of the obtained detection signal is calculated; further, by judging the relationship between the maximum point and the minimum point (position) of the first-order derivative and the dual-electrode spacing, the length and width parameter dimensions of the defect of the insulating component to be measured can be accurately judged.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A defect size quantification method comprises the following steps:

[0007] Step S101: determining performance parameters of an electrode sensing device used in a defect size quantification method;

[0008] Step S102: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ;

[0009] Step S103: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ;

[0010] Step S104: Determine the one-dimensional line scanning signal , one-dimensional line scan signal Is there a concave area in the

[0011] Step S105: If the one-dimensional line scan signal , one-dimensional line scan signal If there is no concave area in the test, it is determined that there is no defect in the insulating component to be tested.

[0012] Preferably, in step S104, the one-dimensional line scanning signal is determined , one-dimensional line scan signal Is there a concave area in the process, which can be described as:

[0013] Statistics of one-dimensional line scan signals All signal values ​​in the , the minimum signal value among all signal values ​​is recorded as ;

[0014] Calculate the one-dimensional line scan signal Signal value change rate ; Among them, the one-dimensional line scan signal Signal value change rate ,satisfy: ;

[0015] When the one-dimensional line scan signal Signal value change rate When the one-dimensional line scan signal is not greater than the first preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in the

[0016] Statistics of one-dimensional line scan signals All signal values ​​in the , the minimum signal value among all signal values ​​is recorded as ;

[0017] Calculate the one-dimensional line scan signal Signal value change rate ; Among them, the one-dimensional line scan signal Signal value change rate ,satisfy:

[0018] ;

[0019] When the one-dimensional line scan signal Signal value change rate When the one-dimensional line scan signal is not greater than the second preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in it.

[0020] Preferably, the method further includes: Step S106: if the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect length ,satisfy: Formula (1);

[0021] In formula (1), is the first-order derivative signal The distance between the maximum and minimum points; It is the distance between adjacent electrode plates in the electrode sensing device.

[0022] Preferably, the method further includes: Step S107: if the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect width ,satisfy: Formula (2);

[0023] In formula (2), is the first-order derivative signal The distance between the maximum and minimum points.

[0024] Preferably, the electrode sensing device used in step S101 is composed of two rectangular electrodes with the same size parameters;

[0025] Among them, the width of the rectangular electrode Not less than , the length of the rectangular electrode Select as , the spacing between adjacent electrode plates Select as .

[0026] Preferably, the electrode sensing device further comprises: a shielding layer arranged between adjacent rectangular electrodes;

[0027] The shielding layer is grounded to shield signal interference between adjacent rectangular electrodes.

[0028] The present invention provides a defect size quantification method, which includes the following steps: step S101: determining the performance parameters of the electrode sensor device used in the defect size quantification method; step S102: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S103: along The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S104: Determine the one-dimensional line scanning signal , one-dimensional line scan signal Step S105: If the one-dimensional line scanning signal , one-dimensional line scan signal If there is no concave area in the one-dimensional line scanning signal, it is determined that there is no defect in the insulating component to be tested; Step S106: If the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect length ,satisfy: Formula (1); Step S107: If the one-dimensional line scan signal If there is a concave area in the insulating component to be tested, the defect width ,satisfy: Formula (2).

[0029] A defect size quantification method having the above-mentioned step characteristics has at least the following technical advantages compared with the prior art:

[0030] 1) It fills the technical gap in the existing detection technology for defect size quantification and can accurately calculate the length and width of the defect;

[0031] 2) It can realize real-time and rapid in-situ detection of the insulating components to be tested and quantification of defect size parameters without destroying the insulating component samples to be tested for sampling;

[0032] 3) It has strong anti-interference ability, high reliability, good on-site adaptability, and the defect calculation results are less affected by factors such as the lift-off effect, which can effectively reduce the error in the defect size parameter quantification process;

[0033] 4) The defect size quantification process has a wide range of applications. It can detect open defects or hidden defects, and can also detect defects in both length and width directions at the same time without being affected by lift-off. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the following drawings:

[0035] Figure 1 A schematic diagram of the process of the defect size quantification method provided by the present invention;

[0036] Figure 2 It is a schematic diagram for reference of the structure of a rectangular electrode in an electrode sensing device;

[0037] Figure 3 A reference schematic diagram of the scanning direction and scanning position of the electrode sensing device;

[0038] Figure 4 It is a structural reference schematic diagram of the electrode sensing device;

[0039] Figure 5 It is a structural schematic diagram of the insulating component sample to be tested;

[0040] Figure 6 For electrode sensing devices Schematic diagram of one-dimensional line scan signal detected by direction;

[0041] Figure 7 For electrode sensing devices Schematic diagram of the first derivative of the one-dimensional line scan signal detected in the direction;

[0042] Figure 8 The distance between the plates is When the electrode sensing device is Schematic diagram of one-dimensional line scan signal detected by direction;

[0043] Fig. 9 The distance between the plates is When the electrode sensing device is Schematic diagram of the first derivative of the one-dimensional line scan signal detected in the direction;

[0044] Fig.10 For electrode sensing devices Schematic diagram of one-dimensional line scan signal detected by direction;

[0045] Fig.11 For electrode sensing devices Schematic diagram of the first derivative of the one-dimensional line scan signal detected in the direction;

[0046] Fig.12 For electrode sensing devices Direction and Directional first-order derivative signal , Schematic diagram of the situation where there is no concave area;

[0047] Fig.13 for Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction Schematic diagram of

[0048] Fig.14 for Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction The first derivative signal of Schematic diagram of

[0049] Fig.15 for Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction Schematic diagram of

[0050] Fig.16 for Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction The first derivative signal of Schematic diagram of .

[0051] Reference numerals: 1-shielding layer; 2-electrode sensing device during scanning Direction; 3-electrode sensing device scanning direction; 4-insulating component sample to be tested; 5-defects in the insulating component sample to be tested; 6-scanning position of the electrode sensing device in step S102; 7-scanning position of the electrode sensing device in step S103; 8-scanning position of the electrode sensing device in step S104 9-The electrode sensing device in step S104 is Scan position in the direction. DETAILED DESCRIPTION

[0052] The present invention provides a defect size quantification method, which is based on capacitive imaging technology. The defects of an insulating component to be measured are detected by a rectangular dual-electrode sensing device, and the first-order derivative of the obtained detection signal is calculated; further, by judging the relationship between the maximum point and the minimum point (position) of the first-order derivative and the dual-electrode spacing, the length and width parameter dimensions of the defect of the insulating component to be measured can be accurately judged. Embodiment 1

[0053] The present invention provides a defect size quantification method, such as Figure 1 As shown, the following steps are included:

[0054] Step S101: Determine the performance parameters of the electrode sensing device used in the defect size quantification method.

[0055] Specifically, as a preferred embodiment of the present invention, the electrode sensing device is composed of two rectangular electrodes with the same size parameters, such as Figure 2 Preferably, the parameters of the electrode sensing device include at least the width of the rectangular electrode. , the length of the rectangular electrode , the spacing between adjacent electrode plates .

[0056] It should be noted that the width of the rectangular electrode It will affect the minimum width of the defect that can be correctly quantified. However, a too small rectangular electrode width will result in a smaller detected signal strength. Therefore, the width of the rectangular electrode Not less than . Select here to set the width of the rectangular electrode for .

[0057] Length of rectangular electrode The distance between adjacent electrode plates This will affect the penetration depth of the electrode sensing device and the strength of the detection signal. For example, the length of the rectangular electrode The longer the electrode plates are, the stronger the signal strength collected by the electrode sensor device will be. However, if the length of the electrode sensor device is too long, the overall size of the electrode sensor device will become larger. The larger the value, the deeper the penetration depth of the electrode sensing device, but at the same time it will reduce the intensity of the detected defect signal. Therefore, the length of the rectangular electrode needs to be reasonably set. The distance between adjacent electrode plates Here, the length of the rectangular electrode Select as (More preferably ), the spacing between adjacent electrode plates Select as (More preferably ).

[0058] In addition, as a more preferred embodiment, Figure 2 As shown, the electrode sensor device also includes a shielding layer 1. The shielding layer 1 is arranged between adjacent rectangular electrodes and is grounded, and is specifically used to shield signal interference between adjacent rectangular electrodes. Here, it is preferred to set the shielding layer thickness of the electrode sensor device to .

[0059] Step S102: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal .

[0060] After completing step S101, continue to implement step S102: For details, refer to Figure 3 As shown, Figure 3 The electrode sensing device is shown in direction and scan position.

[0061] It should be noted that, in order to facilitate those skilled in the art to understand the defect size quantification method provided by the present invention, an electrode sensor device structure is provided as a reference. Specifically, the electrode sensor device structure is shown as follows: Figure 4 As shown, it includes a rectangular sensor module, an excitation signal generating module, a signal processing module and an acquisition card. Among them, the rectangular sensor module further includes: a housing, a substrate and a coplanar rectangular electrode pair. The coplanar rectangular electrode pair is printed on the substrate through a printed circuit board process and is connected to the detection circuit through a coaxial cable. One of the coplanar rectangular electrodes is used as an excitation electrode, and the other is used as a detection electrode. The excitation electrode and the detection electrode form an electromagnetic coupling relationship. As shown Figure 5 As shown, a schematic diagram of the structure of an insulating component (sample) to be tested is further provided. Specifically, the insulating component sample to be tested is composed of an organic glass plate (with a hole defect arranged thereon), and the organic glass plate is thick. , the defect on the plexiglass plate is ,depth square hole.

[0062] Based on this, the following explanation is given for step S102. The sample is scanned in the direction to obtain a one-dimensional line scan signal ,like Figure 6Then, the one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ,like Figure 7 As shown. Among them, the scanning step length of the electrode sensing device is .

[0063] Specifically, the one-dimensional line scan signal The calculation formula can be referred to as:

[0064] ;

[0065] in, is the real output signal of the capacitance mode in the detection result; It is the imaginary output signal of the capacitance mode in the detection result.

[0066] Then, find the first-order derivative signal (From one-dimensional line scan signal Specifically, the central difference method, the forward difference method and the backward difference method are used for numerical derivation. During the acquisition process, 30 sets of one-dimensional line scan signals were collected. Data, so its calculation formula satisfies:

[0067] ;

[0068] ;

[0069] ;

[0070] in, is the first-order derivative signal No. values, One-dimensional line scan signal No. value.

[0071] Step S103: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal .

[0072] After completing step S102, continue to implement step S103: wherein the step S103 mentioned Direction and scanning position reference Figure 3 As shown, the electrode sensing device structure and the sample to be tested used are consistent with those in step S102.

[0073] Based on this, step S103 is further explained as follows. The sample is scanned in the direction to obtain a one-dimensional line scan signal ,like Fig.10 As shown. For a one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ,like Fig.11 As shown. Among them, the one-dimensional line scanning signal The calculation method of the first-order derivative is similar to the one-dimensional line scan signal The calculation method for the first-order derivative is the same, so I will not go into details here.

[0074] Step S104: Determine the one-dimensional line scanning signal , one-dimensional line scan signal Is there a concave area in the

[0075] As a preferred embodiment of the present invention, the one-dimensional line scanning signal is determined in step S104. , one-dimensional line scan signal Is there a concave area in the process, which can be described as:

[0076] Statistics of one-dimensional line scan signals All signal values ​​in the , the minimum signal value among all signal values ​​is recorded as ;

[0077] Calculate the one-dimensional line scan signal Signal value change rate ; Among them, the one-dimensional line scan signal Signal value change rate ,satisfy:

[0078] ;

[0079] When the one-dimensional line scan signal Signal value change rate When the one-dimensional line scan signal is not greater than the first preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in it.

[0080] Statistics of one-dimensional line scan signals All signal values ​​in the , the minimum signal value among all signal values ​​is recorded as ;

[0081] Calculate the one-dimensional line scan signal Signal value change rate ; Among them, the one-dimensional line scan signal Signal value change rate ,satisfy:

[0082] ;

[0083] When the one-dimensional line scan signal Signal value change rate When the one-dimensional line scan signal is not greater than the second preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in it.

[0084] It is worth noting that the first preset parameter and the second preset parameter are both empirical parameters, which are specifically affected by factors such as the material and density of the insulating component to be measured during the quantification process, and can be determined by technical personnel based on statistical data derived from multiple experiments. For the sample composed of the organic glass plate, the first preset parameter and the second preset parameter can be selected as .

[0085] Step S105: If the one-dimensional line scan signal , one-dimensional line scan signal If there is no concave area in the test, it is determined that there is no defect in the insulating component to be tested.

[0086] As a preferred embodiment of the present invention, a defect size quantification method provided by the present invention further includes: Step S106: if the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect length ,satisfy: Formula (1);

[0087] In formula (1), is the first-order derivative signal The distance between the maximum and minimum points; It is the distance between adjacent electrode plates in the electrode sensing device.

[0088] Step S107: If the one-dimensional line scan signal If there is a concave area in the insulating component to be tested, the defect width ,satisfy: Formula (2);

[0089] In formula (2), is the first-order derivative signal The distance between the maximum and minimum points.

[0090] Specifically, if the one-dimensional line scan signal There is a concave area in the test, indicating that there is a defect in the insulating component to be tested. The length of the defect is the first-order derivative signal The distance between two extreme points Minus the plate spacing ,Right now .

[0091] It is worth noting that, as a preferred embodiment of the present invention, in step S102, according to the one-dimensional line scanning signal When there are defects in the length direction of the shape judgment equipment: Figure 6 As shown, the one-dimensional line scan signal If there is a concave area, it proves that there is a defect in the insulating component to be tested. At this time, first calculate the first-order derivative signal The distance between the maximum and minimum points in . References Figure 7 As shown, Figure 7 The distance between the maximum and minimum points is marked in , and then get the spacing between adjacent electrode plates (Here, ), the length of the defect can be calculated as .

[0092] In addition, the inventor further provides another example for illustration, assuming that: the spacing between adjacent electrode plates is set to Greater than , such as choosing to set the plate spacing for , electrode sensing equipment The direction and scanning position remain the same Figure 3 As shown, the capacitance imaging detection device and the sample to be tested are the same as those in step S102, except that the length and width of the defect are changed to At this time, when testing the insulating component sample to be tested, the one-dimensional line scanning signal There will be a convex area in the middle, refer to Figure 8 Since the defect length can be calculated using the above method, technicians can actually ignore the first-order derivative signal. The maximum and minimum points corresponding to the upper convex area (influence), but only the first-order derivative signal The first-order derivative signal corresponding to the concave area The maximum and minimum points can be, such as Fig. 9 shown.

[0093] Similarly, the first-order derivative signal is obtained in step S103 According to its shape, it can be judged whether there are defects in the width direction of the insulating component to be tested: Fig.10 As shown, the first-order derivative signal If there is a concave area in the test, it proves that there is a defect in the width direction of the insulating component to be tested. If there is a defect in the width direction of the insulating component to be tested, the calculation process can be referred to as follows: Calculate the first-order derivative signal The distance between the maximum and minimum points is . References Fig.11 As shown, Fig.11 The distance between the maximum and minimum points is marked in Defect width .

[0094] So far, the present invention provides a defect size quantification method, which calculates the length and width data of the defect in the insulating component to be tested based on the one-dimensional line scanning signal and the first-order derivative signal (the distance between the maximum point and the minimum point) obtained by derivation, thereby realizing the quantification of the defect length and width size. Embodiment 2

[0095] Embodiment 2 includes all the technical features of Embodiment 1. In addition, Embodiment 2 further adds a lift-off height in the quantification process, thereby proving that a defect size quantification method provided by the present invention is indeed effective.

[0096] Specifically, in the second embodiment, the scanning detection process of the insulating component sample to be tested is realized by a variable lift-off method. Among them, lift-off means that there is a certain distance between the probe and the sample to be tested during scanning detection, and variable lift-off means changing the lift-off height during the scanning detection process. It should be noted that the electrode sensing equipment used in this embodiment is the same as that in the first embodiment, and the only difference is that the lift-off height is changed.

[0097] Fig.13 and Fig.14 They are Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction And the first-order derivative signal It can be found that Fig.14 The distance between the maximum point and the minimum point remains unchanged and does not change with the change of lift-off, which further verifies the feasibility of the defect size quantification method provided by the present invention.

[0098] Fig.15 and Fig.16 They are Figure 5 The sensor is in the case of variable lift-off of the sample to be tested One-dimensional line scan signal obtained from the direction And the first-order derivative signal It can be found that Fig.16 The distance between the maximum point and the minimum point remains unchanged and does not change with the change of lift-off, which further verifies the feasibility of the defect size quantification method provided by the present invention.

[0099] The present invention provides a defect size quantification method, which includes the following steps: step S101: determining the performance parameters of the electrode sensor device used in the defect size quantification method; step S102: The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S103: along The insulating component to be tested is scanned in the direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S104: Determine the one-dimensional line scanning signal , one-dimensional line scan signal Step S105: If the one-dimensional line scanning signal , one-dimensional line scan signal If there is no concave area in the one-dimensional line scanning signal, it is determined that there is no defect in the insulating component to be tested; Step S106: If the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect length ,satisfy: Formula (1); Step S107: If the one-dimensional line scan signal If there is a concave area in the insulating component to be tested, the defect width ,satisfy: Formula (2).

[0100] A defect size quantification method having the above-mentioned step characteristics has at least the following technical advantages compared with the prior art:

[0101] 1) It fills the technical gap in the existing detection technology for defect size quantification and can accurately calculate the length and width of the defect;

[0102] 2) It can realize real-time and rapid in-situ detection of the insulating components to be tested and quantification of defect size parameters without destroying the insulating component samples to be tested for sampling;

[0103] 3) It has strong anti-interference ability, high reliability, good on-site adaptability, and the defect calculation results are less affected by factors such as the lift-off effect, which can effectively reduce the error in the defect size parameter quantification process;

[0104] 4) The defect size quantification process has a wide range of applications. It can detect open defects or hidden defects, and can also detect defects in both length and width directions at the same time without being affected by lift-off.

[0105] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A defect size quantification method, characterized in that: The steps include: Step S101: determining performance parameters of an electrode sensing device used in a defect size quantification method; Step S102: Scan and detect the insulating component to be tested along the x direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S103: Scan and detect the insulating component to be tested along the y direction to obtain a one-dimensional line scanning signal ; For one-dimensional line scan signal Find the first-order derivative and get the first-order derivative signal ; Step S104: Determine the one-dimensional line scanning signal , one-dimensional line scan signal Is there a concave area in the Step S105: If the one-dimensional line scan signal , one-dimensional line scan signal If there is no concave area in the test, it is determined that there is no defect in the insulating component to be tested; In step S104, the one-dimensional line scanning signal is determined , one-dimensional line scan signal Is there a concave area in the process, which can be described as: Statistics of one-dimensional line scan signals All signal values ​​in the above table are recorded as V. 1_ini , the minimum signal value among all signal values ​​is recorded as V 1_min ; Calculate the one-dimensional line scan signal Signal value change rate V 1_ratio ; Among them, the one-dimensional line scan signal Signal value change rate V 1_ratio ,satisfy: ； When the one-dimensional line scan signal Signal value change rate V 1_ratio When the one-dimensional line scan signal is not greater than the first preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in the Statistics of one-dimensional line scan signals All signal values ​​in the above table are recorded as V. 2_ini , the minimum signal value among all signal values ​​is recorded as V 2_min ; Calculate the one-dimensional line scan signal Signal value change rate V 2_ratio ; Among them, the one-dimensional line scan signal Signal value change rate V 2_ratio ,satisfy: ； When the one-dimensional line scan signal Signal value change rate V 2_ratio When the one-dimensional line scan signal is not greater than the second preset parameter, There is no concave area in the ; otherwise, it is determined that the one-dimensional line scan signal There is a concave area in the The method also includes: Step S106: If the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect length ,satisfy: Formula (1); In formula (1), is the first-order derivative signal The distance between the maximum and minimum points; is the distance between adjacent electrode plates in the electrode sensing device; The method also includes: Step S107: if the one-dimensional line scanning signal If there is a concave area in the insulating component to be tested, the defect width ,satisfy: Formula (2); In formula (2), is the first-order derivative signal The distance between the maximum and minimum points; The electrode sensing device used in step S101 is composed of two rectangular electrodes with the same size parameters; The width b of the rectangular electrode is not less than 0.5 mm, the length h of the rectangular electrode is selected to be 8 mm to 10 mm, and the spacing a between adjacent electrode plates is selected to be 2 mm to 5 mm; The electrode sensing device also includes: a shielding layer arranged between adjacent rectangular electrodes; The shielding layer is grounded to shield signal interference between adjacent rectangular electrodes.

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