Dry-type bushing test method, breakdown test structure and flashover test structure

Abstract

The invention discloses a dry-type bushing test method, a breakdown test structure and a flashover test structure. The dry-type bushing test method comprises the following steps: designing and manufacturing a target test structure corresponding to a dry-type bushing according to a to-be-analyzed target fault of the dry-type bushing; the target test structure is used for testing, and the actual occurrence process of the target fault is simulated, so that the characteristics of the dry-type bushing when the target fault occurs are analyzed. A test structure is designed and manufactured according to the fault of the dry-type bushing, the actual fault occurrence process is simulated through the test, then the state data of the dry-type bushing in the fault process is obtained, the characteristics of the dry-type bushing in the fault process are analyzed, and a basis is provided for fault defense and structure optimization of the dry-type bushing.

Description

Technical Field

[0001] The invention relates to the technical field of transformer bushings, and in particular to a dry bushing test method, a breakdown test structure and a flashover test structure. Background Art

[0002] The operational reliability of bushings is directly related to the operational safety of large power grids. It is one of the key equipment for developing high-voltage power transmission and ensuring the safe and stable operation of power systems. In recent years, oil-immersed paper bushings have experienced many defects such as poor sealing, abnormal oil chromatography, oil leakage, and combustion and explosion accidents, which have seriously affected the safety and stability of the power grid and the reliability of power supply. The operational reliability and combustion and explosion characteristics of bushings have received great attention. As one of the main alternatives to oil-paper bushings, the number and proportion of applications of dry bushings have increased year by year. Although the existing transformer bushings need to undergo a series of tests and verifications before and after installation to ensure that their performance meets the standards and requirements, such as dielectric loss test, insulation resistance test, AC withstand voltage test, DC withstand voltage test, etc., these tests cannot directly and specifically reflect the characteristics of dry bushings when failures occur, and thus cannot provide a scientific basis for bushing fault prevention and structural optimization. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a dry bushing test method, a breakdown test structure and a flashover test structure. The dry bushing test method can simulate the actual fault occurrence process through the test, and then obtain the state data of the dry bushing when the fault occurs, providing a basis for dry bushing fault prevention and structural optimization.

[0004] In order to solve the above technical problems, the present invention provides a dry casing test method, comprising:

[0005] According to the target fault to be analyzed for the dry-type bushing, design and manufacture a corresponding target test structure for the dry-type bushing;

[0006] The target test structure is used to conduct a test to simulate the actual occurrence process of the target fault, thereby analyzing the characteristics of the dry bushing when the target fault occurs.

[0007] In the above-mentioned dry bushing test method, a test structure is designed and manufactured according to the dry bushing fault, and a test is carried out to simulate the actual fault process, so as to obtain the state data of the dry bushing when the fault occurs, analyze the characteristics of the dry bushing when the fault occurs, and provide a basis for dry bushing fault prevention and structural optimization.

[0008] As an improvement of the dry bushing test method of the present invention, when the target fault is radial breakdown of the core, the designing and manufacturing of the corresponding target test structure of the dry bushing according to the target fault to be analyzed of the dry bushing includes:

[0009] On one side of the core of the dry bushing, a conductive wire is passed through the insulating structure of the core along the radial direction of the core to conduct the central guide rod of the core to the outside of the core.

[0010] The central guide rod is connected to the outside of the core through a wire to simulate the radial breakdown of the core of the dry bushing. The current directly passes through the insulating structure to form a conductive channel. The test structure of the dry bushing is ingeniously designed and easy to manufacture.

[0011] Furthermore, on one side of the core of the dry bushing, using a wire to pass through the insulating structure of the core along the radial direction of the core to conduct the central guide rod of the core to the outside of the core includes:

[0012] Remove the upper shed skirt and the lower shed skirt on the outer side of the core from the dry type casing;

[0013] A test hole is opened radially on the core body, and the bottom of the hole is located on the central guide rod;

[0014] One end of the wire is extended to the bottom of the test hole, fixed to the central guide rod and electrically connected, thus completing the design and production of the target test structure corresponding to the radial breakdown of the core.

[0015] By opening holes on the existing dry-type casing products to place the conductors, the design and manufacture are easy and the manufacturing cost and cycle of the test structure are greatly saved.

[0016] Further, the using the target test structure to conduct the test and simulating the actual occurrence process of the target fault includes:

[0017] The other end of the wire and any one end of the central guide rod are respectively connected to the test equipment for testing.

[0018] The other end of the wire and any end of the center rod are used as input and output terminals respectively. Either the input terminal or the output terminal can be used, that is, one is used as the input of high voltage or high current, and the other is grounded. The test equipment has a high voltage or high current output terminal and a ground terminal.

[0019] Preferably, before the other end of the conductor and any one end of the central guide rod are respectively connected to the test equipment for testing, the method further includes: fixing the dry bushing through the flange of the dry bushing.

[0020] Fix the test structure of the dry bushing through the flange. It is best to keep it in the installation state during actual work. This can prevent the test structure from shaking during the test and affect the results, and it is also convenient for test wiring, monitoring and other operations.

[0021] Furthermore, the test hole is opened on a side of the flange of the dry bushing close to the upper terminal.

[0022] Furthermore, one end of the wire is fixed to the central guide rod by a screw, and the wire is fixedly connected to the central guide rod by the screw, so that the fixing and electrical conduction structure of the two are stable and reliable.

[0023] As another improvement of the dry bushing test method of the present invention, when the target fault is a surface flashover, the designing and manufacturing of the corresponding target test structure of the dry bushing according to the target fault to be analyzed of the dry bushing includes:

[0024] On the core surface of the dry bushing, a wire is used to electrically connect the flange of the dry bushing and any end of the central guide rod of the core, and the main body of the wire is arranged on the outer side of the core along the axial direction of the core.

[0025] By laying the conductor on the outer surface of the core along the radial direction of the core and connecting one end of the central guide rod to the flange, the phenomenon of surface flashover of the dry bushing, the gas or liquid dielectric around the core being broken down and discharging along the surface of the core is simulated.

[0026] Furthermore, on the surface of the core of the dry bushing, a wire is used to electrically connect the flange of the dry bushing and any end of the central guide rod of the core, and the main body of the wire is arranged along the axial direction of the core on the outer side of the core, including:

[0027] Remove the upper shed skirt and the lower shed skirt on the outer side of the core from the dry type casing;

[0028] One end of the wire is fixed to the oil-end terminal of the dry bushing and electrically connected, and the other end is fixed to the flange of the dry bushing and electrically connected, and the main body of the wire is laid on the surface of the core along the axial direction of the core; that is, the design and production of the target test structure corresponding to the surface flashover is completed.

[0029] By arranging the conductors on the existing dry-type bushing products, the design and manufacture are easy, and the manufacturing cost and cycle of the test structure are greatly saved.

[0030] Furthermore, the main body of the wire is bonded and fixed to the surface of the core. Preferably, bonding points are evenly spaced along the main body of the wire, and each bonding point is bonded and fixed to the surface of the core by epoxy glue.

[0031] Further, the using the target test structure to conduct the test and simulating the actual occurrence process of the target fault includes:

[0032] Connect any one end of the flange and the center guide rod to the test equipment respectively for testing.

[0033] Either end of the flange and the center guide rod is used as the input and output end respectively, and either end can be used as the input end or the output end, that is, one is used as the input of high voltage or high current, and the other is grounded. The test equipment has a high voltage or high current output end and a ground end.

[0034] Preferably, before the flange and any one end of the central guide rod are respectively connected to the test equipment for testing, the method further includes: fixing the dry sleeve through the flange.

[0035] Fix the test structure of the dry bushing by flange, preferably in the actual working installation state, to prevent the test structure from shaking during the test and affect the results, and also facilitate test wiring, monitoring and other operations.

[0036] As another improvement of the dry bushing test method of the present invention, the using the target test structure to perform the test and simulate the actual occurrence process of the target fault, so as to analyze the characteristics of the dry bushing when the target fault occurs, includes: analyzing the characteristics of the dry bushing when the target fault occurs by recording the state parameters during the dry bushing test.

[0037] Preferably, the state parameters include voltage, current, pressure, temperature, image, etc.

[0038] In order to solve the above technical problems, the present invention provides a breakdown test structure on the other hand, which is used for the above dry bushing test method, including a core body, a conductor, a flange, an upper terminal and an oil-end terminal; the core body includes a central guide rod and an insulating structure sleeved on the central guide rod; a test hole is radially opened on the core body, the test hole passes through the insulating structure, and the bottom of the hole is located on the central guide rod; one end of the conductor extends to the bottom of the test hole, is fixed to the central guide rod and is electrically conductive.

[0039] In the above-mentioned breakdown test structure, the central guide rod is conducted to the outside of the core through a wire to simulate the radial breakdown of the core of the dry bushing. The current directly passes through the insulating structure to form a conductive channel, and then the occurrence of radial breakdown failure of the core can be simulated through test loading. The characteristics of the dry bushing when radial breakdown of the core occurs can be analyzed, providing a basis for fault prevention and structural optimization of the dry bushing. In addition, the breakdown test structure is ingeniously designed and easy to manufacture.

[0040] In order to solve the above technical problems, the present invention also provides a flashover test structure on the one hand, which is used for the above dry bushing test method, including a core body, a conductor, a flange, an upper terminal and an oil end terminal; one end of the conductor is fixed to and electrically connected with the oil end terminal, and the other end is fixed to and electrically connected with the flange, and the main body is laid on the surface of the core body along the axial direction of the core body.

[0041] In the above-mentioned flashover test structure, by laying the conductor on the outer surface of the core along the radial direction of the core, and connecting one end of the central guide rod to the flange, the phenomenon of the gas or liquid dielectric around the core being broken down and discharging along the surface of the core is simulated when the dry bushing has surface flashover. Then, the occurrence of surface flashover can be simulated through test loading, and the characteristics of the dry bushing when surface flashover occurs can be analyzed, providing a basis for fault prevention and structural optimization of the dry bushing. Moreover, the breakdown test structure is cleverly designed and easy to manufacture.

[0042] In summary, by adopting the above-mentioned dry bushing test method, breakdown test structure and flashover test structure, the dry bushing test method can simulate the actual fault occurrence process through the test, and then obtain the state data of the dry bushing during the fault, providing a basis for dry bushing fault prevention and structural optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the attached picture:

[0044] Figure 1 The figure is a flow chart of the dry casing test method of the present invention.

[0045] Figure 2 It is a schematic diagram of the breakdown test structure of the present invention.

[0046] Figure 3 It is a schematic diagram of the flashover test structure of the present invention.

[0047] In the figure, 1. core body; 11. center guide rod; 12. insulation structure; 13. test hole; 2. wire; 3. flange; 4. upper terminal; 5. oil end terminal. DETAILED DESCRIPTION

[0048] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0049] Example 1

[0050] Figure 1 The dry bushing test method of the present invention is shown. The target fault to be analyzed for the dry bushing in this embodiment is radial breakdown of the core, such as Figure 1 As shown, the dry bushing test method includes the following steps S10 and S20.

[0051] Core radial breakdown is a more serious type of transformer failure. Its causes may involve multiple aspects. For example, during the long-term use of transformer bushings, the insulation material will be affected by various environmental factors and self-aging, which greatly reduces the insulation strength. Overvoltage and overcurrent are one of the main causes of transformer bushing breakdown. When the strength of the insulating medium is not enough to withstand the voltage, the arc may pass through the surface of the bushing, causing radial breakdown. For example, when the transformer is affected by external factors such as lightning strikes or operational errors, overvoltage or overcurrent may occur, causing impact on the bushing.

[0052] Step S10: designing and manufacturing a corresponding target test structure of the dry bushing according to the target fault to be analyzed of the dry bushing.

[0053] Combined with Figure 2 First, the target test structure is designed and manufactured, which is required to be able to simulate the radial breakdown of the core of the dry bushing, and the current directly passes through the insulating structure 12 to form a conductive channel. Specifically, it only needs to meet the following structural requirements: on one side of the core 1 of the dry bushing, the conductor 2 passes through the insulating structure 12 of the core 1 along the radial direction of the core 1, and the central guide rod 11 of the core 1 is conducted to the outside of the core 1. There are many structures that meet the above requirements. A feasible design and manufacturing process is given below, including steps a1-a3.

[0054] Step a1: Remove the upper shed and the lower shed from the outer side of the core 1 of the dry casing. Directly take an existing dry casing finished product as the raw material, remove the upper shed and the lower shed, which is convenient for subsequent processing, and these two structures are not needed in the process of simulating the radial breakdown test of the core.

[0055] Step a2: A test hole 13 is opened radially on the core body 1 , with the bottom of the hole located on the central guide rod 11 .

[0056] The test hole 13 is realized by radially passing through the insulating structure 12 of the core 1. The insulating structure 12 is generally a layered structure, including a laminated insulating material layer and a shielding layer. The insulating material includes epoxy resin, glass fiber, resin impregnated paper, etc. The shielding layer is aluminum foil, copper foil, etc. The center guide rod 11 is a copper rod, etc. These structures can be processed by drilling to obtain the test hole 13. Of course, a hole can be directly reserved during the production of the dry bushing as the test hole 13. The diameter of the test hole 13 is as small as possible under the premise of being able to accommodate the conductor 2.

[0057] In addition, the test hole 13 can be opened at any radial position in theory, because the position where the radial breakdown of the core occurs is also possible at any position. However, for the convenience of actual processing, it can be determined that the test hole 13 is opened on the side of the flange 3 close to the upper terminal 4, and the processing surface is larger, so the distance between the test hole 13 and the flange 3 can be 20-60mm.

[0058] Step a3: Extend one end of the wire 2 to the bottom of the test hole 13, fix it to the central guide rod 11 and make it electrically conductive, thus completing the design and production of the target test structure corresponding to the core radial breakdown.

[0059] In order to achieve a better simulation effect, the smaller the diameter of the wire 2, the better, for example, a copper wire with a diameter of 0.5 mm can be used. In addition, after fixing one end of the wire 2 on the central guide rod 11, the test hole 13 can be filled with insulating material, and it is important to keep the wire 2 in the hole along the radial direction of the core 1.

[0060] In addition, in order to better achieve a fixed connection between one end of the wire 2 and the center guide rod 11, one end of the wire 2 can be fixed with a screw first, and then the screw is inserted into the test hole 13 and tightened to fix it on the center guide rod 11. The operation is convenient, and the fixing and electrical conduction structure is stable and reliable.

[0061] Step S20: Conducting a test using the target test structure to simulate the actual occurrence of the target fault, thereby analyzing the characteristics of the dry bushing when the target fault occurs. Conducting a test using the core radial breakdown fault test structure fabricated above specifically includes the following steps b1 and b2.

[0062] Step b1: Fix the dry bushing through its flange 3. Fix the test structure of the dry bushing through flange 3, preferably keeping the installation state during actual work, to prevent the test structure from shaking during the test and affect the results, and also facilitate test wiring, monitoring and other operations.

[0063] Step b2: Connect the other end of the conductor 2 and any end of the central guide rod 11 to the test equipment respectively for testing.

[0064] Since the other end of the wire 2 and any end of the central guide rod 11 are used as input and output ends respectively, either one can be used as the input end or the output end, that is, one is used as the input of high voltage or high current, and the other is grounded. The test equipment has a high voltage or high current output end and a grounding end. Therefore, the other end of the wire 2 and any end of the central guide rod 11 are connected to the test equipment respectively, and the test can be carried out.

[0065] In addition, to analyze the characteristics of the dry bushing when a core radial breakdown failure occurs, it is necessary to connect the monitoring equipment during the experiment and record the state parameters of the dry bushing test process, such as voltage, current, pressure, temperature, image, etc., in order to analyze the characteristics of the dry bushing when a target failure occurs.

[0066] Example 2

[0067] The target fault to be analyzed for the dry bushing in this embodiment is surface flashover. The dry bushing test method includes the following steps P10 and P20.

[0068] Surface flashover is also a more serious type of transformer failure. Under the action of high voltage, the discharge along the surface of the insulator is called flashover. When the humidity and pollution are serious, the surface discharge flashover of the insulator is the most serious.

[0069] Step P10: According to the target fault to be analyzed of the dry bushing, a corresponding target test structure of the dry bushing is designed and manufactured.

[0070] Combination Figure 3 First, the target test structure is designed and manufactured, which is required to simulate the phenomenon that when the dry bushing has surface flashover, the gas or liquid dielectric around the core 1 is broken down and discharges along the surface of the core 1. Specifically, the following structural requirements are met: on the surface of the core 1 of the dry bushing, the flange 3 of the dry bushing and any end of the central guide rod 11 of the core 1 are electrically connected by the wire 2, and the main body of the wire 2 is arranged on the outer surface of the core 1 along the axial direction of the core 1. There are many structures that meet the above requirements. A feasible design and manufacturing process is given below, including steps c1 and c2.

[0071] Step c1: Remove the upper shed and the lower shed from the outer side of the core 1 of the dry bushing. Directly take an existing dry bushing finished product as the raw material, remove the upper shed and the lower shed, which is convenient for subsequent processing, and these two structures are not needed in the simulated surface flashover test.

[0072] Step c2: fix one end of the conductor 2 to the oil terminal 5 of the dry bushing and make it electrically connected, and fix the other end to the flange 3 of the dry bushing and make it electrically connected, and the main body of the conductor 2 is laid on the surface of the core body 1 along the axial direction of the core body 1; that is, the design and production of the target test structure corresponding to the surface flashover is completed.

[0073] Specifically, one end of the wire 2 can be fixed to the oil terminal 5 by screwing, and the other end can be fixed to the flange 3 by welding; during the laying process of the wire 2, epoxy glue is used to bond and fix at a certain interval. In order to have a better simulation effect, the smaller the diameter of the wire 2, the better, for example, a copper wire with a diameter of 0.5 mm can be used.

[0074] Step P20: Conducting a test using the target test structure to simulate the actual occurrence of the target fault, thereby analyzing the characteristics of the dry bushing when the target fault occurs. Conducting a test using the above-made surface flashover fault test structure specifically includes the following steps d1 and d2.

[0075] Step d1: Fix the dry bushing through flange 3. Fix the test structure of the dry bushing through flange 3, preferably keeping the installation state during actual work, to prevent the test structure from shaking during the test and affect the results, and also facilitate test wiring, monitoring and other operations.

[0076] Step d2: Connect any end of the flange 3 and the center guide rod 11 to the test equipment respectively for testing.

[0077] Since the other end of the wire 2 is connected to the flange 3, any end of the flange 3 and the center guide rod 11 can be used as the input and output ends respectively. Specifically, either one can be used as the input end or the output end, that is, one can be used as the input of high voltage or high current, and the other can be grounded. The test equipment has a high voltage or high current output end and a grounding end. Therefore, the test can be carried out by connecting any end of the flange 3 and the center guide rod 11 to the test equipment.

[0078] In addition, to analyze the characteristics of dry bushing when a surface flashover fault occurs, it is necessary to connect a monitoring device during the experiment to record the state parameters of the dry bushing during the test, such as voltage, current, pressure, temperature, image, etc., in order to analyze the characteristics of the dry bushing when a target fault occurs.

[0079] Example 3

[0080] Figure 2 The present invention shows a breakdown test structure for the dry bushing test method of the above-mentioned embodiment 1, including a core body 1, a conductor 2, a flange 3, an upper terminal 4 and an oil terminal 5; the core body 1 includes a central guide rod 11 and an insulating structure 12 sleeved on the central guide rod 11; a test hole 13 is radially opened on the core body 1, the test hole 13 passes through the insulating structure 12, and the bottom of the hole is located on the central guide rod 11; one end of the conductor 2 extends to the bottom of the test hole 13, fixed to the central guide rod 11 and electrically connected. The two ends of the central guide rod 11 are electrically connected to the upper terminal 4 and the oil terminal 5 respectively.

[0081] During the test, the other end of the conductor 2 and any end of the central guide rod 11 are connected to the test equipment respectively, and the monitoring equipment is connected to obtain the voltage, current, pressure, temperature, image and other state parameters of the dry bushing. Then, high voltage or high current is loaded through the test equipment to simulate the radial breakdown failure of the core of the dry bushing, obtain the state parameters of the actual process, and then analyze the characteristics of the dry bushing when the core is radially broken down, so as to provide a basis for the fault prevention and structural optimization of the dry bushing.

[0082] Example 4

[0083] Figure 3The present invention shows a flashover test structure for the dry bushing test method of the above-mentioned embodiment 2, comprising a core 1, a conductor 2, a flange 3, an upper terminal 4 and an oil terminal 5; one end of the conductor 2 is fixed and electrically connected to the oil terminal 5, and the other end is fixed and electrically connected to the flange 3, and the main body is laid on the surface of the core 1 along the axial direction of the core 1. The core 1 comprises a central guide rod 11 and an insulating structure 12 sleeved on the central guide rod 11, and the two ends of the central guide rod 11 are electrically connected to the upper terminal 4 and the oil terminal 5 respectively.

[0084] During the test, any end of the flange 3 and the center guide rod 11 are connected to the test equipment respectively, and the monitoring equipment is connected to obtain the voltage, current, pressure, temperature, image and other state parameters of the dry bushing. Then, high voltage or high current is loaded through the test equipment to simulate the surface flashover failure of the dry bushing, obtain the state parameters of the actual process, and then analyze the characteristics of the dry bushing when the surface flashover occurs, so as to provide a basis for the fault prevention and structural optimization of the dry bushing.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A dry casing test method, characterized in that: include: According to the target fault to be analyzed for the dry-type bushing, design and manufacture a corresponding target test structure for the dry-type bushing; The target test structure is used to conduct a test to simulate the actual occurrence process of the target fault, thereby analyzing the characteristics of the dry bushing when the target fault occurs.

2. A dry casing test method according to claim 1, characterized in that: In the case where the target fault is radial breakdown of the core, the designing and manufacturing of the corresponding target test structure of the dry bushing according to the target fault to be analyzed of the dry bushing includes: On one side of the core (1) of the dry bushing, a conductor (2) is used to pass through the insulating structure (12) of the core (1) along the radial direction of the core (1) to conduct the central guide rod (11) of the core (1) to the outside of the core (1).

3. A dry casing test method according to claim 2, characterized in that: The method of using a conductive wire (2) to pass through an insulating structure (12) of the core (1) along the radial direction of the core (1) on one side of the core (1) of the dry bushing to conduct the central guide rod (11) of the core (1) to the outside of the core (1) comprises: The dry-type casing is removed from the upper shed skirt and the lower shed skirt on the outer side of the core (1); A test hole (13) is opened radially on the core body (1), and the bottom of the hole is located on the central guide rod (11); One end of the wire (2) is extended to the bottom of the test hole (13), fixed to the central guide rod (11) and electrically connected thereto.

4. A dry casing test method according to claim 3, characterized in that: The testing using the target test structure to simulate the actual occurrence process of the target fault includes: The other end of the wire (2) and any one end of the central guide rod (11) are respectively connected to the test equipment to carry out the test.

5. A dry casing test method according to claim 3, characterized in that: The test hole (13) is opened on a side of the flange (3) of the dry bushing close to the upper connection terminal (4).

6. A dry casing test method according to claim 1, characterized in that: In the case where the target fault is a surface flashover, the designing and manufacturing of a corresponding target test structure of the dry bushing according to the target fault to be analyzed of the dry bushing includes: On the surface of the core (1) of the dry bushing, a wire (2) is used to electrically connect the flange (3) of the dry bushing and any one end of the central guide rod (11) of the core (1), and the main body of the wire (2) is arranged along the axial direction of the core (1) and in close contact with the outer surface of the core (1).

7. A dry casing test method according to claim 6, characterized in that: The dry-type bushing core (1) is provided with a conductive wire (2) electrically conducting the flange (3) of the dry-type bushing and any one end of the central guide rod (11) of the core (1), and the main body of the conductive wire (2) is arranged in close contact with the outer surface of the core (1) along the axial direction of the core (1), and comprises: The dry-type casing is removed from the upper shed skirt and the lower shed skirt on the outer side of the core (1); One end of the wire (2) is fixed to and electrically connected with the oil-end terminal (5) of the dry bushing, and the other end is fixed to and electrically connected with the flange (3) of the dry bushing. The main body is laid on the surface of the core body (1) along the axial direction of the core body (1).

8. A dry casing test method according to claim 7, characterized in that: The testing using the target test structure to simulate the actual occurrence process of the target fault includes: Any one end of the flange (3) and the center guide rod (11) is connected to the test equipment to carry out the test.

9. A dry casing test method according to claim 1, characterized in that: The method of using the target test structure to test and simulate the actual occurrence process of the target fault, thereby analyzing the characteristics of the dry bushing when the target fault occurs, includes: By recording the state parameters during the dry bushing test, the characteristics of the dry bushing when the target fault occurs are analyzed.

10. A breakdown test structure, used in the dry bushing test method according to any one of claims 2 to 5, characterized in that: The invention comprises a core body (1), a conductor (2), a flange (3), an upper terminal (4) and an oil terminal (5); the core body (1) comprises a central guide rod (11) and an insulating structure (12) sleeved on the central guide rod (11); a test hole (13) is radially opened on the core body (1), the test hole (13) passes through the insulating structure (12), and the bottom of the hole is located on the central guide rod (11); one end of the conductor (2) extends to the bottom of the test hole (13), is fixed to the central guide rod (11) and is electrically connected.

11. A flashover test structure, used in the dry bushing test method according to any one of claims 6 to 8, characterized in that: It comprises a core body (1), a conductor (2), a flange (3), an upper wiring terminal (4) and an oil-end wiring terminal (5); one end of the conductor (2) is fixed to and electrically connected with the oil-end wiring terminal (5), and the other end is fixed to and electrically connected with the flange (3); and the main body is laid on the surface of the core body (1) along the axial direction of the core body (1).

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