Preparation method, preparation device and observation platform of electrical treeing experimental sample

Abstract

The application discloses a preparation method and a preparation device of an electrical tree experiment sample and an observation platform. The preparation method comprises the following steps: placing an insulating tape in a glue injection groove, injecting impregnating varnish into the glue injection groove, inserting a needle tip of a needle electrode into the glue injection groove, fixing a needle tail of the needle electrode through a fixing assembly, placing a mold into a vacuum oven, sequentially performing vacuum treatment, heating and curing treatment and cooling and shaping treatment on a sample in the mold, taking out the sample in the mold, and smearing a conductive medium on an end of the sample far away from the needle electrode. The insulating tape is placed in the glue injection groove, the needle electrode is fixed through the fixing assembly, the needle tip of the needle electrode can be kept at a certain distance from the insulating tape, the bubbles in the impregnating varnish can be effectively discharged through the vacuum treatment, the impregnating varnish is cured and shaped through the heating and curing treatment, so that the needle electrode is fixed in the cured impregnating varnish, and the influence of cold and hot mutation on the sample can be avoided through the cooling and shaping treatment.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a method, apparatus and observation platform for preparing experimental samples of electric tree trees. Background Technology

[0002] Currently, the main insulation of the stator windings of variable frequency traction motors mostly adopts a layered composite insulation structure composed of insulating tape and impregnated varnish. During motor manufacturing, weak points in the composite insulation are unavoidable. Furthermore, during motor operation, the insulation structure will continuously withstand the effects of high-frequency repetitive pulse voltages. Electrical trees can initiate and rapidly develop from localized areas of uneven electric field, such as air gaps, pores, and impurity particles, severely damaging the insulation performance of the motor windings and ultimately leading to premature insulation failure. Therefore, it is essential to study the growth characteristics of electrical trees in layered composite insulation materials under different experimental conditions.

[0003] Unlike existing electrical treeing test samples, the preparation of electrical treeing test samples for layered composite insulation materials requires the insulating tape to be cured within an impregnating varnish, and the needle tip of the electrode to be kept at a certain distance from the insulating tape. One existing method for preparing electrical treeing test samples involves embedding the needle electrode into a mold and then injecting insulating liquid into the mold. Clearly, this method is unsuitable for preparing electrical treeing test samples for layered composite insulation materials. Furthermore, this method generates air bubbles during the preparation process, leading to suboptimal sample preparation and consequently affecting the results of the electrical treeing test. Summary of the Invention

[0004] The purpose of this invention is to provide a method, apparatus and observation platform for preparing electrical tree test samples, so as to solve the problem that an existing method for preparing electrical tree test samples cannot be applied to the preparation of electrical tree test samples of layered composite insulating materials, and is prone to generating bubbles, thereby affecting the electrical tree test results.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A method for preparing an electrical tree test sample, comprising a vacuum oven and a mold, wherein the mold has a glue injection groove, and a fixing component is fixedly mounted on the mold, one end of which is fixedly installed on the mold, and the other end is positioned directly above the glue injection groove. The tip of a needle electrode extends into the glue injection groove, and the tail of the needle electrode is fixedly connected to the fixing component. The method for preparing the electrical tree test sample includes:

[0007] The insulating tape is placed in the glue injection tank, and impregnation varnish is injected into the glue injection tank;

[0008] The tip of the needle electrode is inserted into the glue injection groove, and the tail of the needle electrode is fixed by the fixing component;

[0009] The mold is placed in the vacuum oven, and the sample inside the mold is subjected to vacuum treatment, heat curing treatment and cooling and shaping treatment in sequence.

[0010] Remove the sample from the mold and apply a conductive medium to the end of the sample away from the needle electrode.

[0011] As a preferred technical solution for the preparation method of electric tree test samples, the mold includes a base and a mounting base. The base is threadedly connected to the mounting base. The base has a first groove and the mounting base has a first through hole. After the base and the mounting base are threadedly connected in place, the first groove and the first through hole are connected to form the glue injection groove.

[0012] The specific steps of placing the insulating tape in the glue injection groove and injecting impregnating varnish into the glue injection groove include: placing the insulating tape over the first groove, leaving a gap between the insulating tape and the first groove so that the impregnating varnish can enter the first groove through the gap; after the base and the mounting seat are threadedly connected in place, the insulating tape is clamped and fixed between the base and the mounting seat; the first through hole and the first groove form the glue injection groove; and the impregnating varnish is injected into the glue injection groove.

[0013] As a preferred technical solution for the preparation method of the electrical tree experimental sample, the fixing component includes a fixing block and a positioning screw. The fixing block is fixedly installed on the mounting base. One end of the fixing block has a U-shaped groove that opens along a first horizontal direction. The U-shaped groove is located directly above the injection groove. The fixing block also has a threaded hole. The axial direction of the threaded hole is parallel to a second horizontal direction, and the second horizontal direction is perpendicular to the first horizontal direction. The threaded hole passes through the U-shaped groove. The positioning screw is threadedly connected to the threaded hole. The needle tail of the needle electrode is fixed by the positioning screw.

[0014] The specific steps of inserting the tip of the needle electrode into the glue injection groove and fixing the tail of the needle electrode by the fixing component include:

[0015] Insert the needle tip into the glue injection groove, so that the distance between the needle tip and the insulating tape is within a first set range value, place the needle tail in the U-shaped groove, and rotate the positioning screw to abut the needle tail against the inner wall of the U-shaped groove.

[0016] As a preferred technical solution for preparing an electric tree test sample, the specific steps for vacuum treatment of the sample within the mold include:

[0017] The heating temperature of the vacuum oven is adjusted to a first temperature value, the heating rate of the vacuum oven is adjusted to a first heating rate, and the vacuum extraction time of the vacuum oven is adjusted to a first time value.

[0018] As a preferred technical solution for preparing electrical tree test samples, the specific steps for heating and curing the sample within the mold include:

[0019] The heating temperature of the vacuum oven is adjusted to a second temperature value, the heating rate of the vacuum oven is adjusted to a second heating rate, the second temperature value is greater than the first temperature value, the second heating rate is greater than the first heating rate, and the heating time of the vacuum oven is adjusted to a second time value.

[0020] As a preferred technical solution for the preparation method of electric tree test samples, the vacuum oven includes a controller, a cooling fan and a temperature sensor. The cooling fan and the temperature sensor are both communicatively connected to the controller. The temperature sensor is used to detect the real-time temperature of the sample and send first temperature information. The controller receives the first temperature information and controls the cooling fan to accelerate, decelerate or stop.

[0021] The specific steps for cooling the sample inside the mold include: receiving the first temperature information; determining whether the first temperature value is greater than the first termination temperature; if yes, controlling the cooling fan to stop; if no, determining whether the cooling rate of the sample is within the first cooling rate range; if yes, the cooling fan operates normally; if no, controlling the cooling fan to accelerate or decelerate.

[0022] An apparatus for preparing an electrical tree test sample, used to implement the above-described method for preparing an electrical tree test sample, the apparatus comprising:

[0023] The vacuum oven and the mold are described. The mold has the glue injection groove and the mold is fixedly provided with the fixing component. One end of the fixing component is fixedly installed on the mold and the other end is located directly above the glue injection groove. The tip of the needle electrode extends into the glue injection groove and the tail of the needle electrode is fixedly connected to the fixing component.

[0024] As a preferred technical solution for the preparation device of electric tree test samples, the mold includes a base and a mounting base. The base is threadedly connected to the mounting base. The base has a first groove and the mounting base has a first through hole. After the base and the mounting base are threadedly connected in place, the first groove and the first through hole communicate to form the glue injection groove.

[0025] As a preferred technical solution for the preparation device of electrical tree test samples, the fixing component includes a fixing block and a positioning screw. The fixing block is fixedly installed on the mounting base. One end of the fixing block has a U-shaped groove that opens along a first horizontal direction. The U-shaped groove is located directly above the injection groove. The fixing block also has a threaded hole. The axis of the threaded hole is parallel to a second horizontal direction, and the second horizontal direction is perpendicular to the first horizontal direction. The threaded hole passes through the U-shaped groove. The positioning screw is threadedly connected to the threaded hole. The needle tail of the needle electrode is fixed by the positioning screw.

[0026] As a preferred technical solution for the preparation device of electric tree test samples, the vacuum oven includes a controller, a cooling fan and a temperature sensor. The cooling fan and the temperature sensor are both communicatively connected to the controller. The temperature sensor is used to detect the real-time temperature of the sample and send first temperature information. The controller receives the first temperature information and controls the cooling fan to accelerate, decelerate or stop.

[0027] An observation platform for electric tree test samples, used to observe samples prepared by the above-described method for preparing electric tree test samples, includes a sample box, a voltage generator, a microscope, a CDD camera, and a computer. The sample is placed in the sample box. The positive terminal of the voltage generator is connected to the tail of the needle electrode, and the negative terminal of the voltage generator is connected to the conductive medium of the sample. The objective lens of the microscope is aimed at the sample, and the CDD camera is aimed at the eyepiece of the microscope. The CDD camera is connected to the computer via a data cable.

[0028] As a preferred technical solution for the observation platform of the electric tree test sample, the observation platform of the electric tree test sample further includes an insulating vessel containing insulating oil, the sample box being placed inside the insulating vessel and immersed in the insulating oil.

[0029] The beneficial effects of this invention are as follows:

[0030] This invention provides a method for preparing an electrical tree test sample. The method specifically includes: placing an insulating tape in a glue-filling tank and injecting impregnating varnish into the tank; inserting the tip of a needle electrode into the glue-filling tank, with the needle tail fixed by a fixing component; placing a mold in a vacuum oven and sequentially performing vacuum treatment, heat curing treatment, and cooling and shaping treatment on the sample within the mold; removing the sample from the mold and applying a conductive medium to the end of the sample furthest from the needle electrode. Placing the insulating tape in the glue-filling tank and fixing the needle electrode with the fixing component ensures a certain distance between the needle electrode and the insulating tape, meeting experimental requirements; vacuum treatment effectively removes air bubbles from the impregnating varnish, ensuring the sample meets experimental requirements; heat curing treatment solidifies and shapes the impregnating varnish, fixing the needle electrode within the solidified varnish; and cooling and shaping treatment avoids the effects of sudden temperature changes on the sample, ensuring the sample meets experimental requirements.

[0031] This invention also provides an apparatus for preparing electrical tree test samples, specifically including a vacuum oven and a mold. The mold has a glue injection groove, and a fixing component is fixedly installed on the mold. One end of the fixing component is fixedly installed on the mold, and the other end is positioned directly above the glue injection groove. The tip of the needle electrode extends into the glue injection groove, and the tail of the needle electrode is fixedly connected to the fixing component. The mold is used to fix the needle electrode in the impregnation solution and to maintain a certain distance between the needle electrode and the insulating tape. The vacuum oven is used to perform vacuum treatment, heat curing treatment, and cooling treatment. This apparatus for preparing electrical tree test samples is used to implement the above-described method for preparing electrical tree test samples to produce samples that meet the experimental requirements.

[0032] This invention also provides an observation platform for electrical treeing experiments, specifically including a sample box, a voltage generator, a microscope, a CDD camera, and a computer. The sample is placed inside the sample box. The positive terminal of the voltage generator is connected to the tail of the needle electrode, and the negative terminal of the voltage generator is connected to the conductive medium of the sample. The objective lens of the microscope is aimed at the sample, and the CDD camera is aimed at the eyepiece of the microscope. The CDD camera is connected to the computer via a data cable. Electrical treeing experiments are performed on the sample using the voltage generator. The electrical treeing within the sample is observed in real time using the microscope, CDD camera, and computer, and photographs are taken and recorded, providing image data for subsequent research and analysis. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the apparatus for preparing electrical tree experimental samples provided in an embodiment of the present invention; and a schematic diagram of the observation platform.

[0034] Figure 2 yes Figure 1 Schematic diagram of the middle base;

[0035] Figure 3This is a schematic diagram of the structure of a sample provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the observation platform for the electric tree experimental sample provided in an embodiment of the present invention.

[0037] In the picture:

[0038] 1. Mold; 11. Base; 111. First groove; 12. Mounting base; 121. First through hole;

[0039] 2. Fixing components; 21. Fixing block; 211. U-shaped groove; 22. Positioning screw;

[0040] 3. Sample; 31. Needle electrode; 32. Insulating tape;

[0041] 4. Sample box; 41. Elastic clamping structure;

[0042] 5. Voltage generator;

[0043] 6. Microscope; 61. LED cold light source;

[0044] 7. CDD camera;

[0045] 8. Computer;

[0046] 9. Insulating containers. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0048] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0051] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0052] like Figure 1 , Figure 2 As shown in the figure, an embodiment of the present invention provides an apparatus for preparing an electric tree experimental sample, specifically including a vacuum oven and a mold 1.

[0053] Specifically, the mold 1 has a glue injection groove, and a fixing component 2 is fixedly installed on the mold 1. One end of the fixing component 2 is fixedly installed on the mold 1, and the other end is located directly above the glue injection groove. The tip of the needle electrode 31 extends into the glue injection groove, and the tail of the needle electrode 31 is fixedly connected to the fixing component 2. More specifically, the mold 1 includes a base 11 and a mounting base 12. The base 11 and the mounting base 12 are threadedly connected. The base 11 has a first groove 111, and the mounting base 12 has a first through hole 121. After the base 11 and the mounting base 12 are threadedly connected, the first groove 111 and the first through hole 121 communicate to form a glue injection groove. Preferably, multiple glue injection grooves are provided, and correspondingly, multiple sets of fixing components 2 are configured so that the device for preparing electrical tree experimental samples 3 can prepare multiple samples 3 simultaneously, improving the preparation efficiency of samples 3. Specifically, the depth of the first groove 111 ranges from 0.3 mm to 0.7 mm, preferably 0.5 mm.

[0054] In detail, the fixing component 2 includes a fixing block 21 and a positioning screw 22. The outer contour of the fixing block 21 is "L" shaped. One end of the fixing block 21 is fixedly installed on the mounting base 12. The other end of the fixing block 21 has a U-shaped groove 211 that opens along the first horizontal direction. The U-shaped groove 211 is located directly above the injection groove. The fixing block 21 also has a threaded hole. The axis of the threaded hole is parallel to the second horizontal direction, and the second horizontal direction is perpendicular to the first horizontal direction. The threaded hole passes through the U-shaped groove 211. The positioning screw 22 is threadedly connected to the threaded hole. The needle tail of the needle electrode 31 is fixed by the positioning screw 22.

[0055] Optionally, a measuring scale is provided on the periphery of the U-shaped groove 211, and the distance of the needle electrode 31 extending into the glue injection groove can be precisely adjusted by the measuring scale.

[0056] For example, the length direction of the mounting base 12 is taken as the first horizontal direction, and the width direction of the mounting base 12 is taken as the second horizontal direction.

[0057] Specifically, the vacuum oven has the functions of vacuuming and heating. In addition, the vacuum oven also includes a controller, a cooling fan and a temperature sensor. The cooling fan and the temperature sensor are all connected to the controller. The temperature sensor is used to detect the real-time temperature of sample 3 and send the first temperature information. The controller receives the first temperature information and controls the cooling fan to accelerate, decelerate or stop.

[0058] Embodiments of the present invention also provide a method for preparing an electrical tree experimental sample, specifically including:

[0059] S100. Place the insulating tape 32 into the glue injection tank and inject impregnation varnish into the glue injection tank.

[0060] Among them, insulating tape 32 and impregnating varnish correspond to insulating tape 32 and impregnating varnish in the layered composite insulation structure of existing motor stator windings, respectively. Impregnating varnish has good insulation properties and is mainly used to impregnate the coils of motors and electrical appliances.

[0061] S200, Insert the tip of the needle electrode 31 into the glue injection groove, and fix the tail of the needle electrode 31 by the fixing component 2.

[0062] The lower end of the needle electrode 31 can be stably immersed in the impregnation varnish by the fixing component 2, and the needle electrode 31 can be kept at a certain distance from the insulating tape 32 to simulate artificial defects.

[0063] S300. Place mold 1 into a vacuum oven and perform vacuum treatment, heating and curing treatment and cooling and shaping treatment on sample 3 inside mold 1 in sequence.

[0064] Vacuum treatment effectively removes air bubbles from the impregnating varnish, ensuring that sample 3 meets experimental requirements. Subsequently, heat curing is used to solidify the impregnating varnish, fixing the needle electrode 31 within the cured varnish. Cooling and solidification processes prevent sudden temperature changes from affecting sample 3, ensuring it meets experimental requirements.

[0065] S400. Remove sample 3 from mold 1 and apply a conductive medium to the end of sample 3 furthest from needle electrode 31. Specifically, during the electric tree experiment, needle electrode 31 is used to connect to the positive terminal of the high-voltage power supply, and the conductive medium is used to connect to the negative terminal of the high-voltage power supply or to ground. Preferably, the conductive medium is silver.

[0066] Specifically, the sample prepared by the above preparation method is as follows: Figure 3 As shown in the image.

[0067] Specifically, the steps of placing the insulating tape 32 in the glue injection tank and injecting impregnating varnish into the glue injection tank include: placing the insulating tape 32 on top of the first groove 111, leaving a gap between the insulating tape 32 and the first groove 111, allowing the impregnating varnish to enter the first groove 111 through the gap; after the base 11 and the mounting base 12 are threadedly connected in place, the insulating tape 32 is clamped and fixed between the base 11 and the mounting base 12; the first through hole 121 and the first groove 111 form the glue injection tank, and the impregnating varnish is injected into the glue injection tank.

[0068] In detail, in this embodiment, the insulating tape 32 and the first groove 111 are arranged in a cross shape on top of the first groove 111, leaving a gap between the insulating tape 32 and the first groove 111, allowing the impregnating varnish to enter the first groove 111 through the gap. More specifically, the depth of the first groove 111 is the distance between the insulating tape 32 and the conductive medium. Optionally, multiple sets of first grooves 111 with different depths can be provided on the base 11 as a control group for the electrical tree experiment. Further specifically, in this embodiment, the depth of the first groove 111 is 0.5 mm, that is, the distance between the insulating tape 32 and the conductive medium is 0.5 mm.

[0069] Specifically, the steps for inserting the tip of the needle electrode 31 into the glue injection groove and fixing the tail of the needle electrode 31 by the fixing component 2 include:

[0070] Insert the needle tip into the glue injection groove, ensuring the distance between the needle tip and the insulating tape 32 is within the first set range. Position the needle tail in the U-shaped groove 211 and rotate the positioning screw 22 to abut the needle tail against the inner wall of the U-shaped groove 211.

[0071] Specifically, the first set range is 1mm to 2mm. More specifically, in this embodiment, the thickness of the mounting base 12 can be measured, that is, the depth of the first through hole 121 is known, the height of the fixing block 21 can be measured, and the length of the needle electrode 31 can also be measured. Based on this, with the assistance of a measuring ruler, the distance between the needle tip and the insulating tape 32 can be precisely adjusted. Furthermore, multiple sets of fixing components 2 can be used to simultaneously prepare multiple samples 3 with different distances between the needle tip and the insulating tape 32 as experimental control groups.

[0072] Specifically, the specific steps for vacuum treatment of sample 3 inside mold 1 include:

[0073] Adjust the heating temperature of the vacuum oven to the first temperature value, adjust the heating rate of the vacuum oven to the first heating rate, and adjust the vacuum extraction time of the vacuum oven to the first time value.

[0074] Specifically, the first temperature value is any value between 40°C and 80°C to ensure that the impregnating varnish is in a low viscosity state, which can better remove air bubbles; the first heating rate is less than or equal to 10°C / min; and the first time value is any value between 20min and 40min. Preferably, in order to fully remove air bubbles from the impregnating varnish, the above-described vacuum treatment steps are repeated multiple times in actual operation.

[0075] Specifically, the steps for heat curing sample 3 inside mold 1 include:

[0076] Adjust the heating temperature of the vacuum oven to the second temperature value, adjust the heating rate of the vacuum oven to the second heating rate, the second temperature value is greater than the first temperature value, the second heating rate is greater than the first heating rate, and adjust the heating time of the vacuum oven to the second time value.

[0077] Specifically, the second temperature value is any value between 100°C and 200°C to ensure better curing of the impregnation varnish, the first heating rate is greater than 10°C / min and less than or equal to 15°C / min, and the second time value is any value between 6h and 10h.

[0078] Specifically, the specific steps for cooling the sample 3 inside the mold 1 include: receiving first temperature information, determining whether the first temperature value is greater than the first termination temperature, if so, controlling the cooling fan to stop, if not, determining whether the cooling rate of the sample 3 is within the first cooling rate range, if so, the cooling fan to work normally, if not, controlling the cooling fan to accelerate or decelerate.

[0079] More specifically, if the cooling rate of sample 3 is less than the first cooling rate, the fan is controlled to accelerate; if the cooling rate of sample 3 is greater than the first cooling rate, the fan is controlled to decelerate. Specifically, the first termination temperature is room temperature, or optionally 25°C. The first cooling rate ranges from 8°C / min to 10°C / min.

[0080] Furthermore, after removing sample 3 from mold 1 and applying a conductive medium to the end of sample 3 furthest from needle electrode 31, the following step is performed: sanding sample 3 with sandpaper. This operation increases the transparency of sample 3, thereby making the images acquired during the electrical tree experiment clearer.

[0081] like Figure 4 As shown, embodiments of the present invention also provide an observation platform for electric tree test samples, specifically including a sample box 4, a voltage generator 5, a microscope 6, a CDD camera 7, and a computer 8. The sample 3 is placed in the sample box 4. The positive terminal of the voltage generator 5 is connected to the needle tail of the needle electrode 31, and the negative terminal of the voltage generator 5 is connected to the conductive medium of the sample 3. The objective lens of the microscope 6 is aligned with the sample 3, and the CDD camera 7 is aligned with the eyepiece of the microscope 6. The CDD camera 7 is connected to the computer 8 via a data cable.

[0082] Preferably, the observation platform for the electric tree experiment sample 3 also includes an LED cold light source 61, which is located below the sample box 4.

[0083] More specifically, the sample box 4 is a semi-circular shell made of plastic, and it has good light transmittance. Furthermore, an elastic clamping structure 41 is provided inside the sample box 4 to press the sample 3 firmly into the sample box 4, thereby ensuring good observation results.

[0084] Preferably, the observation platform for the electrical tree experimental sample 3 further includes an insulating vessel 9 containing insulating oil. The sample box 4 is placed inside the insulating vessel 9 and immersed in the insulating oil. Specifically, the insulating vessel 9 is made of transparent glass. The insulating oil serves two purposes: firstly, it prevents surface flashover and external discharge during the experiment; secondly, it fills in the tiny lines generated during the polishing process of the sample 3, making the electrical tree image captured by the CDD camera 7 clearer and smoother, facilitating subsequent research and analysis.

[0085] More specifically, the operating steps of the observation platform for sample 3 in the electric tree experiment are as follows:

[0086] Sample 3 is fixedly installed in sample box 4, and microscope 6 and CCD camera 7 are adjusted. Specifically, the microscope 6 of this invention is a Zeiss Stemi 508 stereo microscope with a magnification range of 1x to 100x, and the CCD camera 7 has a magnification of 1x. The lens of the CCD camera 7 is aligned with the eyepiece of microscope 6.

[0087] Place the sample box 4 in the insulating container 9 and immerse it in the insulating oil. Adjust the position of the sample box 4 until the tip of the needle electrode 31 is visible. Adjust the position of the LED cold light source 61 so that the light emitted by the LED cold light source 61 shines directly on the tip of the needle electrode 31 to clearly observe the internal condition of the sample 3.

[0088] The CCD camera 7 is connected to the computer 8, and the computer 8 observes the morphology of the electrical tree inside the sample 3 in real time and takes pictures to record it.

[0089] The aging study and analysis of layered composite insulation materials can be conducted using the recorded images.

[0090] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing samples for electrical tree experiments, characterized in that, The apparatus for preparing electrical tree test samples includes a vacuum oven and a mold (1). The mold (1) has a glue injection groove. A fixing component (2) is fixedly installed on the mold (1). One end of the fixing component (2) is fixedly installed on the mold (1), and the other end is located directly above the glue injection groove. The tip of the needle electrode (31) extends into the glue injection groove, and the tail of the needle electrode (31) is fixedly connected to the fixing component (2). The method for preparing the electrical tree experimental sample includes: Place the insulating tape (32) into the glue injection tank and inject impregnation varnish into the glue injection tank; The tip of the needle electrode (31) is inserted into the glue injection groove, and the tail of the needle electrode (31) is fixed by the fixing component (2); The mold (1) is placed in the vacuum oven, and the sample (3) inside the mold (1) is subjected to vacuum treatment, heating and curing treatment and cooling and shaping treatment in sequence. Take out the sample (3) from the mold (1) and apply a conductive medium to the end of the sample (3) away from the needle electrode (31); The mold (1) includes a base (11) and a mounting base (12). The base (11) and the mounting base (12) are threaded together. The base (11) has a first groove (111), and the mounting base (12) has a first through hole (121). After the base (11) and the mounting base (12) are threaded together, the first groove (111) and the first through hole (121) are connected to form the glue injection groove. The specific steps of placing the insulating tape (32) in the glue injection groove and injecting impregnating paint into the glue injection groove include: placing the insulating tape (32) above the first groove (111), leaving a gap between the insulating tape (32) and the first groove (111), allowing the impregnating paint to enter the first groove (111) through the gap; after the base (11) and the mounting seat (12) are threadedly connected in place, the insulating tape (32) is clamped and fixed between the base (11) and the mounting seat (12); the first through hole (121) and the first groove (111) form the glue injection groove; and injecting impregnating paint into the glue injection groove. The needle tip is inserted into the glue injection groove, so that the distance between the needle tip and the insulating tape (32) is within a first set range value, the first set range value being 1mm to 2mm.

2. The method for preparing an electrical tree experimental sample according to claim 1, characterized in that, The fixing component (2) includes a fixing block (21) and a positioning screw (22). The fixing block (21) is fixedly installed on the mounting base (12). One end of the fixing block (21) has a U-shaped groove (211) that opens along a first horizontal direction. The U-shaped groove (211) is located directly above the glue injection groove. The fixing block (21) also has a threaded hole. The axis of the threaded hole is parallel to a second horizontal direction, and the second horizontal direction is perpendicular to the first horizontal direction. The threaded hole passes through the U-shaped groove (211). The positioning screw (22) is threadedly connected to the threaded hole. The needle tail of the needle electrode (31) is fixed by the positioning screw (22). The specific steps for inserting the tip of the needle electrode (31) into the glue injection groove and fixing the tail of the needle electrode (31) by the fixing component (2) include: Insert the needle tip into the glue injection groove, so that the distance between the needle tip and the insulating tape (32) is within a first set range value, place the needle tail in the U-shaped groove (211), and rotate the positioning screw (22) to abut the needle tail against the inner wall of the U-shaped groove (211).

3. The method for preparing an electrical tree experimental sample according to claim 1, characterized in that, The specific steps for vacuum treatment of the sample (3) inside the mold (1) include: The heating temperature of the vacuum oven is adjusted to a first temperature value, the heating rate of the vacuum oven is adjusted to a first heating rate, and the vacuum extraction time of the vacuum oven is adjusted to a first time value.

4. The method for preparing an electrical tree test sample according to claim 3, characterized in that, The specific steps for heat curing the sample (3) inside the mold (1) include: The heating temperature of the vacuum oven is adjusted to a second temperature value, the heating rate of the vacuum oven is adjusted to a second heating rate, the second temperature value is greater than the first temperature value, the second heating rate is greater than the first heating rate, and the heating time of the vacuum oven is adjusted to a second time value.

5. The method for preparing an electrical tree test sample according to any one of claims 1-4, characterized in that, The vacuum oven includes a controller, a cooling fan, and a temperature sensor. The cooling fan and the temperature sensor are both connected to the controller. The temperature sensor is used to detect the real-time temperature of the sample (3) and send first temperature information. The controller receives the first temperature information and controls the cooling fan to accelerate, decelerate, or stop. The specific steps for cooling the sample (3) inside the mold (1) include: receiving the first temperature information; determining whether the first temperature value is greater than the first termination temperature; if yes, controlling the cooling fan to stop; if no, determining whether the cooling rate of the sample (3) is within the first cooling rate range; if yes, the cooling fan operates normally; if no, controlling the cooling fan to accelerate or decelerate.

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