Mould for preparing electrical tree sample for resin degradation test

Abstract

The utility model provides a mould for preparing an electrical tree sample for a resin degradation test, which comprises a mould body, the mould body is provided with a gum dipping groove, a fiber groove and a needle electrode groove, the fiber groove and the needle electrode groove transversely penetrate through the mould body and are communicated with the gum dipping groove, and the top surface of the mould body is divided into a first side surface and a second side surface by the gum dipping groove; the fiber groove penetrates through the first side face and the second side face, the needle electrode groove penetrates through the first side face, the width of the first side face is larger than that of the second side face, the fiber groove is used for containing fibers, the needle electrode groove is used for containing high-voltage needle electrodes, and the included angle between the side wall, facing the first longitudinal end of the mold body, of the impregnation groove and the groove bottom of the impregnation groove is an obtuse angle. A slope structure is formed. The inclined surface structure formed by the mold is convenient for sample demolding; by designing a curing grinding tool, the control on experimental interference factors such as an included angle between a needle electrode direction and a fiber direction is realized, so that the interface performance is unique, and a brand new mold is provided for the electrical tree degradation condition and the research on the insulation failure mechanism of a composite material.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage equipment insulation technology, and more specifically, to a mold for preparing electrical tree specimens for resin degradation testing. Background Technology

[0002] In power systems, the insulation performance of high-voltage equipment is one of the key factors in ensuring the safe and stable operation of the power grid. With the further increase in transmission voltage levels and transmission capacity, the insulation problems of high-voltage equipment are becoming increasingly prominent, especially the significant impact of electrical treeing on the reliability and service life of insulation materials.

[0003] In recent years, fiber-reinforced resin composites have been widely used in the field of high-voltage equipment insulation due to their excellent mechanical and insulation properties. However, under the influence of electric fields and external environments, the insulation performance of fiber-reinforced resin composites may gradually decline. Among these factors, electrical treeing is one of the main causes of insulation failure, posing a threat to the safe and stable operation of power systems.

[0004] Electrical treeing degradation is a discharge phenomenon that occurs in insulating materials under the influence of an electric field. When defects exist within the insulating material or when it is affected by external factors (such as temperature, humidity, mechanical stress, etc.), the electric field strength may concentrate in these areas, leading to localized discharge. These discharge channels gradually expand within the material, forming a dendritic structure, ultimately causing a decrease in the material's insulation performance or even its failure.

[0005] Fiber-reinforced resin composites consist of a resin matrix and fiber reinforcements. The resin matrix provides the material with adhesion and basic insulation properties, while the fiber reinforcements provide high strength and high modulus, giving the material better mechanical properties and aging resistance. The interfacial bonding between the fiber and matrix has a significant impact on the electrical treeing degradation phenomenon in composites. When defects exist at the interface, insulation degradation tends to develop rapidly along the interface, exacerbating the insulation failure of the composite material.

[0006] Therefore, research on experimental methods for evaluating the electrical treeing degradation of fiber-reinforced resin interfaces is of great significance for improving the insulation performance of high-voltage equipment and ensuring the safety of power systems. Specific experimental methods are required to assess electrical treeing degradation performance. These methods typically include sample preparation, applying an electric field, and observing and recording discharge phenomena. Sample preparation is a crucial step, requiring that the sample's size, shape, and internal structure meet experimental requirements. Currently, there is a lack of effective experimental methods for evaluating the electrical treeing degradation of fiber-reinforced resin interfaces.

[0007] The current technological bottleneck lies in the preparation of electrical treeing samples from composite materials. Ordinary fiber / resin matrix composite samples are insufficient to meet the requirements of electrical treeing degradation experiments, primarily due to: 1. Numerous influencing factors, making it impossible to eliminate interference from other experimental variables. Typical composite samples contain a large number of fiber / resin matrix interfaces. Factors such as fiber and resin types, fiber volume content, and their arrangement near the needle tip all affect the electrical treeing experimental results, making it impossible to directly evaluate interface performance. 2. Difficulty in observing experimental phenomena. Electrical treeing experiments typically utilize stereomicroscopes for real-time observation of the electrical treeing growth process. However, due to the obstruction of numerous fibers within the composite material (especially opaque fibers such as aramid), the morphology of the electrical trees is difficult to observe. Utility Model Content

[0008] In view of this, the present invention proposes a mold for preparing electrical tree specimens for resin degradation testing, comprising a mold body, wherein the mold body has an impregnation tank and a fiber groove and a needle electrode groove that extend laterally through the mold body and communicate with the impregnation tank. The impregnation tank divides the top surface of the mold body into a first side and a second side. The fiber groove extends through the first side and the second side, and the needle electrode groove extends through the first side. The width of the first side is greater than the width of the second side. The fiber groove is used to place fibers, and the needle electrode groove is used to place high-voltage needle electrodes. The sidewall of the impregnation tank facing the first longitudinal end of the mold body forms an obtuse angle with the bottom of the impregnation tank, forming a sloping structure.

[0009] Preferably, the fiber groove and the needle electrode groove are combined into a first pair of slots that extend through the first side and the second side, and the fiber and the high-pressure needle electrode are both placed in the first pair of slots.

[0010] Preferably, the width of the first pair of slots matches the width of the high-pressure needle electrode.

[0011] Preferably, the first pair of slots includes two slots, one located on the first side and the other on the second side, the fiber is placed in the two slots, and the high-pressure needle electrode is placed in the slot on the first side.

[0012] Preferably, the two grooves are equidistant from the impregnation tank and the longitudinal second end sidewall of the mold body.

[0013] Preferably, the fiber groove is a second pair of grooves that penetrate the first side and the second side, and the needle electrode groove is a third pair of grooves that penetrate the first side. The second pair of grooves and the third pair of grooves are arranged in parallel. When the fiber is placed in the second pair of grooves, it can penetrate the first side and the second side. When the high-pressure needle electrode is placed in the third pair of grooves, it is placed at the position of the first side.

[0014] Preferably, the width of the second pair of slots matches the width of the high-pressure needle electrode.

[0015] Preferably, the width of the third pair of slots matches the width of the high-pressure needle electrode.

[0016] Another aspect of the present invention provides an electrical tree specimen for resin degradation testing, which is prepared from the mold described in any of the above claims.

[0017] Preferably, the electrical tree sample is a three-dimensional trapezoidal resin sample, specifically a right-angled trapezoidal resin sample.

[0018] This invention provides a mold for preparing electrical treeing samples for resin degradation testing, which has the following advantages: the included angle between the bottom of the impregnation tank and one of its sides is an obtuse angle, facilitating sample demolding; by designing a curing mold, experimental interference factors such as the angle between the needle electrode direction and the fiber direction, the number of fibers, and the straight-line distance between the needle and fiber can be controlled during resin preparation, making the resin interface properties of the prepared sample the sole variable; the preparation of needle-plate electrode systems with specific fibers, resin matrix types, and fiber / resin matrix interface states can simulate the internal defects of fiber-reinforced resin materials with different interface compositions and states, providing a novel mold for observing the electrical treeing degradation of fiber-reinforced epoxy composites affected by interface properties and for studying the insulation failure mechanism of composite materials. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0020] Figure 1 A schematic diagram of the overall structure of the mold for preparing electrical tree samples provided in an embodiment of this utility model;

[0021] Figure 2 A sample diagram of a fiber bundle provided for an embodiment of this utility model;

[0022] Figure 3 A sample diagram of a single fiber filament provided for an embodiment of this utility model;

[0023] Figure 4 A sample diagram showing two fiber filaments used in an embodiment of this utility model.

[0024] Figure 5 This is a sample image of the prepared electrical tree sample after polishing, provided in an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the electrical tree morphology of the single-fiber sample in Group A after breakdown, provided in an embodiment of this utility model.

[0026] Figure 7 This is a schematic diagram of the electrical tree morphology of the group B single-fiber sample after breakdown, provided in an embodiment of the present invention.

[0027] Figure 8 The schematic diagrams of the electrical tree development process of the single-fiber samples in Group B provided for the embodiments of this utility model are as follows: 8-1, 0 min; 8-2, 10 min; 8-3, breakdown;

[0028] Figure 9 Schematic diagram of electrical tree morphology of dual-fiber samples with different interface properties provided for embodiments of this utility model;

[0029] In the figure, 1 is the mold body, 2 is the impregnation tank, 3 is the first pair of slots, 4 is the high-pressure needle electrode, 5 is the fiber, 11 is the first side, 12 is the second side, and 21 is the inclined structure. Detailed Implementation

[0030] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] See Figure 1As shown, this is a mold for preparing electrical tree resin samples for resin degradation testing provided by an embodiment of the present invention. It includes a mold body 1, a resin impregnation tank 2, a fiber groove and a needle electrode groove that run transversely through the mold body 1 and communicate with the resin impregnation tank 2. In this embodiment, the fiber groove and the needle electrode groove are combined into a first pair of grooves 3. The resin impregnation tank 2 divides the top surface of the mold body 1 into a first side 11 and a second side 12, and the width of the first side 11 is greater than the width of the second side 12. The first pair of grooves 3 are arranged through the first side 11 and the second side 12. When the fiber 5 is placed, it passes through the two grooves of the first pair of grooves 3 and serves as the fiber groove to carry the fiber. When the high-voltage needle electrode 4 is placed, it is placed at the groove position of the first side 11 and serves as the needle electrode groove to carry the high-voltage needle electrode. The side wall of the resin impregnation tank 2 facing the first longitudinal end of the mold body 1 forms an obtuse angle with the bottom of the resin impregnation tank, forming a sloping structure 21. The electrical resin sample prepared using this mold is easier to demold.

[0032] In this embodiment, the width of the first pair of slots 3 matches the width of the high-pressure needle electrode, which also means that the width of the fiber groove and the needle electrode groove matches the width of the high-pressure needle electrode 4, making it easier to fix the high-pressure needle electrode 4.

[0033] Continue to refer to Figure 1 As shown, the first pair of slots 3 includes two slots, one located on the first side 11 and the other on the second side 12. The fiber 5 is placed in the two slots, and the high-pressure needle electrode 4 is placed in the slot of the first side 11. Since the first side 11 has a large width, it provides a better bearing surface for the placement of the high-pressure needle electrode 4, which facilitates stable placement.

[0034] In this embodiment, the two slots have the same width, and the two slots are equidistant from the impregnation tank 2 toward the longitudinal second end sidewall of the mold body 1.

[0035] In another embodiment of this utility model, the fiber groove is a second pair of slots extending through the first side and the second side, and the needle electrode groove is a third pair of slots extending through the first side. The second and third pairs of slots are arranged parallel to each other. When the fiber is placed in the second pair of slots, it can penetrate through the first and second side. When the high-voltage needle electrode is placed in the third pair of slots, it is positioned on the first side. By setting the fiber groove and needle electrode groove as two parallel pairs of slots, more implementation methods are provided for the placement position and angle of the fiber and the high-voltage needle electrode. The width of the second pair of slots matches the width of the high-voltage needle electrode, and the width of the third pair of slots can also match the width of the high-voltage needle electrode, allowing the positions of the fiber groove and the needle electrode groove to be interchanged. This provides a new arrangement for the placement of the high-voltage needle electrode and the fiber. The electro-resin sample prepared using this mold can form different discharge positions in the discharge laboratory, providing different manifestations of electrical tree degradation.

[0036] This utility model embodiment also discloses an electrical tree specimen for resin degradation testing, which is prepared by the mold disclosed in this utility model embodiment and is an electrical tree specimen prepared from resin.

[0037] The electrical tree specimen is a three-dimensional trapezoidal resin specimen, specifically a right-angled trapezoidal resin specimen.

[0038] This utility model discloses a mold for preparing electrical tree samples from fiber-reinforced resin, which has the following beneficial technical effects: the included angle between the bottom of the impregnation tank and one of its sides is an obtuse angle, which facilitates sample demolding; by designing a curing mold, the experimental interference factors such as the angle between the needle electrode direction and the fiber direction, the number of fibers, and the straight-line distance between the needle and the fiber can be controlled, making the interface performance the only variable; the preparation of needle-plate electrode systems with specific fiber, resin matrix type, and fiber / resin matrix interface state can simulate the internal defects of fiber-reinforced resin materials with different interface composition structures and interface states, providing a brand-new mold for observing the electrical tree degradation of fiber-reinforced epoxy composites affected by interface performance and studying the insulation failure mechanism of composite materials.

[0039] This utility model embodiment also discloses a method for testing the degradation of electrical tree specimens, including the following steps:

[0040] SO1, prepare electrical tree samples of different morphologies, and use multiple molds of different specifications to prepare multiple electrical tree samples with internal fiber and high-voltage needle electrode arrangement that meet the experimental requirements. Specifically, the molds used can make a variety of electrical tree samples with high-voltage needle electrodes and fibers in different positions and angles. Since the molds limit the position of high-voltage needle electrodes and fibers, it is possible to control experimental interference factors such as the angle between the needle electrode direction and the fiber direction, the number of fibers, and the straight distance between the needle and the fiber, so that the interface performance is the only variable.

[0041] S02, observe the growth morphology of electric tree branches. Use a microscope to observe the development process of electric tree branches and record the morphological images. The morphology of electric tree branches can be observed intuitively through complete images.

[0042] S03, select node graphs for analysis, select multiple time node graphs for analysis, and select the breakdown graph for analysis, so as to better understand the degradation process of electrical trees and evaluate the resin interface performance.

[0043] In this embodiment, the method for preparing electrical tree samples of various morphologies includes the following steps:

[0044] SO11, Place the fiber. Place the fiber in the fiber groove 3. After controlling the position, attach the two outer ends of the fiber to the outside of the mold body to fix the fiber position.

[0045] S012, Place the high-pressure needle electrode. Clean the pre-polished high-pressure needle electrode to remove impurities, place it in the needle electrode groove, and then seal the needle electrode groove and fiber groove.

[0046] S013, Prepare the sample by pouring the prepared resin into the impregnation tank containing the fiber and electrode, and complete the resin curing according to the designed curing process to prepare the sample for the electrical tree degradation test.

[0047] S014, Grind the sample, grind the bottom of the sample, control the needle-plate distance to meet the preset requirements, ensure good contact between the sample and the ground electrode, attach copper foil to the bottom of the sample, and connect the copper foil to the ground electrode.

[0048] In this embodiment, silicone rubber or other materials are used to seal the fiber groove and needle electrode groove.

[0049] In this embodiment, the prepared electrical trees include single-fiber single-interface electrical trees and double-fiber double-interface electrical trees.

[0050] In practice, the length of the fiber is longer than the length of the mold body.

[0051] In this embodiment, the high-pressure needle electrode is polished to control the tip curvature diameter to be 5±1μm, or to reach a pre-designed diameter range. It should be understood that the tip curvature refers to the curvature of the high-pressure needle tip.

[0052] Meanwhile, the straight-line distance between the high-pressure needle electrode and the fiber is ≤300μm.

[0053] In this embodiment, the fiber used in preparing the electroresin sample is any one of aramid fiber, glass fiber, or polyester fiber, and the fiber morphology is any one of fiber filament, fiber bundle, or fiber cloth.

[0054] In this embodiment, when the fiber morphology is a filament, the number of filaments is a single or double filament.

[0055] When the number of fibers is two, the two fibers are set as the experimental group and the control group, respectively.

[0056] In practice, when cleaning the high-pressure needle electrode, place the polished needle electrode in an ethanol solution and ultrasonically clean it for 30 minutes, or use other cleaning procedures to remove impurities.

[0057] In this embodiment, during sample polishing, the needle-plate distance is controlled to be 1 ± 0.1 mm, or within the designed distance range, while ensuring good contact between the sample and the ground electrode. It should be understood that the needle-plate distance refers to the distance between the high-voltage needle electrode and the ground electrode at the bottom of the electrical tree sample. A 100 μm thick copper foil is adhered to the bottom of the sample and connected to the ground electrode.

[0058] The following describes a specific embodiment of the method for preparing electro-resin samples using a mold disclosed in this utility model to conduct a degradation test, thereby preparing fiber-reinforced resin electrical tree samples and testing the performance of the samples.

[0059] The fiber used in this embodiment is aramid fiber.

[0060] Before sample preparation, the aramid fibers were pretreated to control the interface state of the samples. The aramid fibers were divided into three groups: A, B, and C. Group A was left untreated, Group B underwent 30 minutes of vacuum drying at 100°C in an oven, and Group C underwent 30 minutes of vacuum drying at 100°C followed by 30 seconds of DBD plasma modification in air atmosphere with a plasma discharge power of 73W.

[0061] By designing a curing mold, the direction of the high-pressure needle electrode can be controlled to be parallel to the fiber direction during sample preparation. The needle-fiber straight-line distance is approximately 280 μm, which is the shortest distance between the high-pressure needle tip and the fiber. By changing the position and width of the needle electrode groove and fiber groove, the needle-fiber straight-line distance and the angle between the needle electrode direction and the fiber direction can be controlled. To ensure that the electrical tree grows to the interface, it is recommended that the needle-fiber straight-line distance not exceed 300 μm. The mold used in this experiment is as follows: Figure 1 As shown, the mold includes a rectangular mold body and a first pair of slots 1 on it, which serve as fiber slots and needle electrode slots. The mold body has an impregnation tank, which can be used to prepare electrical tree samples with dimensions of 5 mm thick, 15 mm wide, and 20 mm long. The impregnation tank 2 divides the top surface of the mold body 1 into a first side 11 and a second side 12, and the thickness of the first side 11 is greater than the thickness of the second side 12. The two slots of the first pair of slots are both 400 μm wide and 3 mm deep, and can be used as needle electrode slots and fiber slots at the same time to place fibers and high-voltage needle electrodes. The fibers 5 are placed through the first pair of slots 3 (i.e., fiber slots) and the impregnation tank 2. The high-voltage needle electrode 4 is placed in the slot of the first side 11, and its needle electrode diameter is 400 μm, which matches the width of the two slots. The bottom and sidewall of the impregnation tank 2 form a slope structure 21, which facilitates the demolding of the electrical tree samples prepared therein. In addition, in specific applications, a preparation mold with more slots can be selected, which can separate the fiber and the high-voltage needle electrode. The different positional relationships between the two can form different discharge positions when the electro-resin sample prepared by the mold is discharged, providing different manifestations of the degradation of electrical trees.

[0062] Single fiber samples were prepared using fibers from groups A and B, respectively. That is, only one fiber was placed in each sample.

[0063] Dual-fiber samples were prepared using group A and group C fibers. Specifically, one group A fiber and one group C fiber were placed simultaneously in each sample, positioned at the two corners of the lower edge of the needle electrode groove. This allowed for comparative observation of experimental phenomena under two different interfacial properties in a single electrical treeing degradation experiment.

[0064] The sample preparation process is as follows:

[0065] 1. Place the fiber into the designed fiber groove of the mold, ensuring the fiber is longer than the mold. After controlling the position, attach the outer ends of the fiber to the outside of the mold to fix the fiber's position.

[0066] 2. Grind one high-voltage needle electrode with sandpaper, controlling the tip curvature diameter to be 5±1μm. Place the ground needle electrode in an ethanol solution and ultrasonically clean it for 30 minutes. Place the cleaned high-voltage needle electrode into the designed mold needle electrode groove, and then seal the fiber groove and needle electrode groove with silicone rubber.

[0067] 3. Pour the prepared resin into a mold containing fibers and electrodes, and cure the resin according to the designed curing process to prepare an experimental sample for electrical tree degradation.

[0068] The epoxy resin formulation is as follows: bisphenol A epoxy resin: methyltetrahydrophthalic anhydride: 2-ethyl-4-methylimidazole = 100:85:0.5.

[0069] The curing process is as follows: ① Mix epoxy resin, methyltetrahydrophthalic anhydride, and 2-ethyl-4-methylimidazolium, heat at 60℃ for 30 minutes, stir evenly, and then degas under vacuum for 30 minutes. ② After pouring, maintain a constant temperature of 80℃ for 30 minutes, 120℃ for 1 hour, and 140℃ for 1 hour.

[0070] 4. Grind the bottom of the sample with sandpaper, controlling the needle-plate distance to 1±0.1mm, while ensuring good contact between the sample and the ground electrode. Then, attach a 100μm thick copper foil to the bottom of the sample, connecting the copper foil to the ground electrode.

[0071] 5. Connect the high-voltage needle electrode and the ground electrode to the high-voltage power supply and the ground wire, respectively, and apply a 16kV power frequency voltage until breakdown occurs. Then, observe the growth of electrical trees inside the device using a microscope.

[0072] 6. Statistical analysis of characteristic parameters such as electrical tree growth rate, morphology, and breakdown time was conducted to evaluate the fiber / resin matrix interface properties.

[0073] Table 1 is a statistical table of breakdown time for single-fiber electrical tree samples.

[0074]

[0075] As can be seen from Table 1, after vacuum drying and dehumidification treatment, the breakdown time of the aramid fiber / epoxy resin sample was prolonged and the interfacial properties were improved.

[0076] Figure 6 and Figure 7 These are schematic diagrams of the electrical tree morphology after breakdown of samples A and B, respectively. It can be seen that, compared to the untreated samples, the aramid fiber / epoxy resin samples treated with vacuum drying and dehumidification exhibit different electrical tree morphologies: the electrical trees have more branches, are darker in color, and the breakdown channels are more uniform in thickness. The difference in electrical tree morphology reflects changes in interfacial properties.

[0077] Figure 8This is a schematic diagram of the electrical tree development process in the single-fiber samples of group B.

[0078] Table 2 shows the shear strength of the fiber-epoxy resin interface in groups B and C.

[0079]

[0080] As can be seen from Table 2, the C group fibers have better interfacial properties after plasma treatment.

[0081] Figure 9 This is a schematic diagram of the electrical tree morphology after breakdown of a dual-fiber sample. The fibers below the needle electrode are group B fibers, and the fibers above the needle electrode are group C fibers. It can be seen that in the same sample, electrical trees tend to grow and break down along the interface of the less efficient group B fibers / resin. The breakdown path of the electrical trees reflects the quality of the interface.

[0082] In summary, the degradation test method for electrical treeing samples prepared from fiber-reinforced resin disclosed in this invention has the following advantages: By designing a curing mold, experimental interference factors such as the angle between the needle electrode direction and the fiber direction, the number of fibers, and the straight-line distance between the needle and fiber can be controlled during the sample preparation process, making the interface properties of the prepared resin the sole variable; by preparing a needle-plate electrode system with specific fibers, resin matrix types, and fiber / resin matrix interface states, the internal defects of fiber-reinforced resin materials under different interface compositions and states can be simulated, providing a novel method for observing the electrical treeing degradation of fiber-reinforced epoxy composites affected by interface properties and for studying the insulation failure mechanism of composite materials; by using fibers and matrices of different materials and fibers of different diameters, the interface composition can be controlled; by pre-fabricating different interface defects and using different modification methods to pre-treat the fibers, the interface state can be controlled, and the provided mold can meet the experimental requirements.

[0083] It should be noted that in the description of this utility model, the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this utility model.

[0084] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0085] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A mold for preparing electrical tree specimens for resin degradation testing, characterized in that, The mold includes a mold body, which has an impregnation tank and a fiber groove and a needle electrode groove that run horizontally through the mold body and communicate with the impregnation tank. The impregnation tank divides the top surface of the mold body into a first side and a second side. The fiber groove passes through the first side and the second side, and the needle electrode groove passes through the first side. The width of the first side is greater than the width of the second side. The fiber groove is used to place fibers, and the needle electrode groove is used to place high-pressure needle electrodes. The sidewall of the impregnation tank facing the first longitudinal end of the mold body forms an obtuse angle with the bottom of the impregnation tank, forming a sloping structure.

2. The mold for preparing electrical tree specimens for resin degradation testing according to claim 1, characterized in that, The fiber groove and the needle electrode groove are combined into a first pair of slots that extend through the first side and the second side, and the fiber and the high-pressure needle electrode are placed in the first pair of slots.

3. The mold for preparing electrical tree specimens for resin degradation testing according to claim 2, characterized in that, The width of the first pair of slots matches the width of the high-pressure needle electrode.

4. The mold for preparing electrical tree specimens for resin degradation testing according to claim 2, characterized in that, The first pair of slots includes two slots, one located on the first side and one located on the second side. The fiber is placed in the two slots, and the high-pressure needle electrode is placed in the slot on the first side.

5. The mold for preparing electrical tree specimens for resin degradation testing according to claim 4, characterized in that, The two grooves are equidistant from the dip tank and the longitudinal second end sidewall of the mold body.

6. The mold for preparing electrical tree specimens for resin degradation testing according to claim 1, characterized in that, The fiber groove is a second pair of slots that penetrate the first side and the second side. The needle electrode groove is a third pair of slots that penetrate the first side and the second side. The second pair of slots and the third pair of slots are arranged in parallel. When the fiber is placed in the second pair of slots, it can penetrate the first side and the second side. When the high-pressure needle electrode is placed in the third pair of slots, it is placed at the position of the first side.

7. The mold for preparing electrical tree specimens for resin degradation testing according to claim 6, characterized in that, The width of the second pair of slots matches the width of the high-pressure needle electrode.

8. The mold for preparing electrical tree specimens for resin degradation testing according to claim 6, characterized in that, The width of the third pair of slots matches the width of the high-pressure needle electrode.

9. An electrical tree specimen for resin degradation testing, characterized in that, It is prepared from the mold described in any one of claims 1-8.

10. The electrical tree specimen for resin degradation testing according to claim 9, characterized in that, The electrical tree specimen is a three-dimensional trapezoidal resin specimen, specifically a right-angled trapezoidal resin specimen.

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