Bending stress application device for breakdown testing

Abstract

Disclosed is a bending stress application device for breakdown test, wherein a work platform is immersed in insulating oil; a pair of slide rails are vertically connected to the work platform; a high-voltage electrode is supported on the telescopic work platform and located between the pair of slide rails; an insulating support is vertically movably slid between the pair of slide rails; a ground electrode is transversely movably arranged on the insulating support, and the ground electrode and the high-voltage electrode are both immersed in the insulating oil; a sample is connected between the ground electrode and the high-voltage electrode and a predetermined bending stress is applied via the ground electrode.

Description

Technical Field

[0001] This invention belongs to the field of insulation testing technology, and in particular to a bending stress application device for breakdown testing. Background Technology

[0002] The operational status of power equipment is directly related to the safety and stability of the power grid, and the reliability of power equipment largely depends on the performance of its insulation. Once the insulation in power equipment breaks down, it can cause incalculable damage to the entire system. Therefore, the breakdown characteristics of materials are one of the important indicators for evaluating the quality of composite insulation in equipment.

[0003] In the field of insulation, breakdown voltage is one of the four major parameters and is therefore crucial. Thus, breakdown testing is essential for materials. During actual operation, various materials are subjected to different forms of mechanical stress during breakdown, such as tensile stress, compressive stress, and bending stress. Current methods for testing breakdown performance under bending stress involve applying bending stress to the sample, removing the stress, placing the sample between a ground electrode and a high-voltage electrode, immersing the entire system in an insulating medium such as cable oil, applying voltage to the high-voltage electrode, grounding the ground electrode, and slowly increasing the voltage until the material breaks down, thus obtaining its breakdown voltage. However, this method does not reflect real-world applications. To ensure the safe use of materials under actual operating conditions, it is necessary to simulate breakdown testing while applying bending stress.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a bending stress application device for breakdown testing, which can test the breakdown performance while applying bending stress.

[0006] The objective of this invention is achieved through the following technical solution: a bending stress application device for a breakdown test includes:

[0007] The work platform is immersed in insulating oil;

[0008] A pair of slide rails, which are vertically connected to the work platform;

[0009] A high-voltage electrode, which is supported on a telescopic working platform and located between the pair of slide rails;

[0010] An insulating support that is movably slidable in the vertical direction between the pair of slide rails;

[0011] The ground electrode is laterally movable on the insulating support, and both the ground electrode and the high-voltage electrode are immersed in insulating oil;

[0012] The sample is connected between the ground electrode and the high-voltage electrode and a predetermined bending stress is applied through the ground electrode.

[0013] In the bending stress application device for the breakdown test, the ground electrode is rotatably connected to the insulating support.

[0014] In the bending stress application device for the breakdown test, the ground electrode is driven to a force-applying cylinder to apply a predetermined bending stress to the sample.

[0015] In the bending stress application device for the breakdown test, the sample is fixed to the ground electrode via at least one insulating strip.

[0016] In the bending stress application device for the breakdown test, the up-down movement button is connected to the insulating bracket to control its up-down movement distance.

[0017] In the bending stress application device for the breakdown test, the up-and-down movement button is connected to a drive cylinder for up-and-down movement.

[0018] In the bending stress application device for the breakdown test, the left and right movement buttons are connected to the ground electrode to control its lateral movement distance.

[0019] In the bending stress application device for the breakdown test, the left and right movement button is connected to a drive cylinder for lateral movement.

[0020] In the bending stress application device for the breakdown test, the high-voltage electrode is a spherical electrode.

[0021] In the bending stress application device for the breakdown test, the insulating support includes an insulating screw.

[0022] Compared with existing technologies, the present invention has the following advantages: the ground electrode of the bending stress application device for breakdown testing described in the present invention can act as both an electrode and apply bending stress, and this stress is variable and easy to calculate. This allows for testing the breakdown performance of the sample while applying bending stress. Furthermore, the ground electrode is movable, facilitating the testing of breakdown voltage at different locations and increasing material utilization. Attached Figure Description

[0023] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0024] In the attached diagram:

[0025] Figure 1 This is a schematic diagram of the bending stress application device for the breakdown test of the present invention;

[0026] Figure 2 This is a partially enlarged schematic diagram of the bending stress application device for the breakdown test of the present invention during sample bending.

[0027] In the figure: 1-slide rail, 2-sample, 3-insulating tape, 4-ground electrode, 5-up / down movement button, 6-left / right movement button, 7-high voltage electrode, 8-working platform, 9-insulating support.

[0028] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0029] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention can 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 invention and to fully convey the scope of the invention to those skilled in the art.

[0030] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0031] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0032] For better understanding, in one embodiment, such as Figure 1 As shown, in a bending stress application device for a breakdown test,

[0033] Work platform 8 is immersed in insulating oil;

[0034] A pair of slide rails 1 are vertically connected to the work platform 8;

[0035] High-voltage electrode 7 is supported on telescopic working platform 8 and located between the pair of slide rails 1;

[0036] An insulating bracket 9 is movably slidable in the vertical direction between the pair of slide rails 1;

[0037] The ground electrode 4 is laterally movably mounted on the insulating support 9. Both the ground electrode 4 and the high-voltage electrode 7 are immersed in insulating oil.

[0038] Sample 2 is connected between the ground electrode 4 and the high-voltage electrode 7 and a predetermined bending stress is applied via the ground electrode 4.

[0039] In a preferred embodiment of the bending stress application device for breakdown testing, the ground electrode 4 is rotatably connected to the insulating support 9.

[0040] In a preferred embodiment of the bending stress application device for the breakdown test, the ground electrode 4 is driven to a force-applying cylinder to apply a predetermined bending stress to the specimen 2.

[0041] In a preferred embodiment of the bending stress application device for the breakdown test, the sample 2 is fixed to the ground electrode 4 via at least one insulating strip 3.

[0042] In a preferred embodiment of the bending stress application device for the breakdown test, the up-down movement button 5 is connected to the insulating bracket 9 to control its up-down movement distance.

[0043] In a preferred embodiment of the bending stress application device for the breakdown test, the up-and-down movement button 5 is connected to a drive cylinder for up-and-down movement.

[0044] In a preferred embodiment of the bending stress application device for the breakdown test, the left and right movement button 6 is connected to the ground electrode 4 to control its lateral movement distance.

[0045] In a preferred embodiment of the bending stress application device for the breakdown test, the left and right movement button 6 is connected to a drive cylinder for lateral movement.

[0046] In a preferred embodiment of the bending stress application device for the breakdown test, the high-voltage electrode 7 is a spherical electrode.

[0047] In a preferred embodiment of the bending stress application device for the breakdown test, the insulating support 9 includes an insulating screw.

[0048] In one embodiment, the bending stress application device for the breakdown test includes a slide rail 1, a sample 2, an insulating strip 3, a ground electrode 4, a vertical movement button 5, a horizontal movement button 6, a high-voltage electrode 7, a working platform 8, and an insulating support 9. The insulating strip 3 is used to fix the sample 2, the high-voltage electrode 7, and the ground electrode 4 for the breakdown test. The ground electrode 4 acts as an electrode while also applying bending stress and can move vertically, horizontally, and vertically, rotating at the insulating support 9 to facilitate changing the material to different positions for the breakdown test. The insulating support 9 is used to fix the electrode structure. Preferably, the upper electrode can act as an electrode and apply a variable bending stress, and this force is calculable.

[0049] In one embodiment, the ground electrode 4 serves as an electrode while also applying bending stress, and can move up, down, left, and right, and rotate at the insulating support 9, facilitating the material to be tested at different locations. The insulating support 9 is used to fix the electrode structure.

[0050] The entire electrode system is placed in insulating oil, ensuring the oil completely covers the ground electrode 4. The high-voltage electrode 7 is a spherical electrode, fixed with a bracket. The sample 2 is secured to the ground electrode 4 with insulating straps. The ground electrode 4 can move up, down, left, right, and rotate. This allows for different locations on the material to be tested for breakdown voltage after each measurement, improving experimental efficiency, increasing material utilization, and reducing waste. The high-voltage electrode 7 is a solid metal spherical electrode, and the ground electrode 4 is an aluminum tube used to fix the sample 2.

[0051] Calculation of bending stress: A magnified view of a portion of specimen 2 during bending is shown below. Figure 2 As shown. Assuming PQ is a longitudinal fiber on the neutral layer, the radius of curvature of the neutral layer after deformation of sample 2 is ρ, and the angle between the neutral layer and PQ is dθ. The distance from any longitudinal fiber to the neutral layer is h. Then, the length of this longitudinal fiber after bending deformation of sample 2 is (ρ+h)dθ, and its original length should be equal to that of the longitudinal fiber on the neutral layer with unchanged length, i.e., ρdθ. Therefore, the linear strain of the longitudinal fiber at a distance h from the neutral layer is:

[0052]

[0053] In the formula, ρ is independent of h and is a constant. The above formula shows that the linear strain of the longitudinal fiber at each point on the cross-section is proportional to the distance h from the fiber to the neutral layer.

[0054] When longitudinal fibers are subjected to axial tension or compression, and the stress does not exceed the proportional limit of the material, the stress and strain obey Hooke's Law, that is:

[0055] σ=Eε (2)

[0056] Substituting formula (2) into formula (1), we get:

[0057]

[0058] If the thickness of sample 2 is d, and the outer diameter of the aluminum tube is D, since D >> d, it can be assumed that the bending normal stress on the material used in the experiment is equal at all points on the cross-section. The above formula can be simplified to:

[0059]

[0060] In the formula, E is the flexural modulus of the material, which is determined by the sample 2 used in the experiment.

[0061] The bending stress can be calculated from the above formula.

[0062] In one embodiment, an imaging unit is further included for photographing the specimen 2, which obtains bending stress data through image information.

[0063] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A bending stress application device for a breakdown test, characterized in that, It includes, The work platform is immersed in insulating oil; A pair of slide rails, which are vertically connected to the work platform; A high-voltage electrode, which is supported on a telescopic working platform and located between the pair of slide rails; An insulating support that is movably slidable in the vertical direction between the pair of slide rails; The ground electrode is laterally movable on the insulating support, and both the ground electrode and the high-voltage electrode are immersed in insulating oil; The sample is connected between the ground electrode and the high-voltage electrode, and a predetermined bending stress is applied through the ground electrode. The ground electrode is rotatably connected to the insulating support. PQ is a longitudinal fiber on the neutral layer. After the sample is deformed, the radius of curvature of the neutral layer is ρ, and the angle between it and PQ is dθ. The distance from any longitudinal fiber to the neutral layer is h. Then, the length of the longitudinal fiber after the sample is bent and deformed is (ρ+h)dθ. Its original length should be equal to that of the longitudinal fiber on the neutral layer with unchanged length, i.e., ρdθ. The linear strain of the longitudinal fiber at a distance h from the neutral layer is: （1） In the formula, ρ is independent of h. When longitudinal fibers are subjected to axial tension or compression, their stress and strain obey Hooke's Law, that is: （2） Substituting formula (2) into formula (1), we get: （3） If the sample thickness is d, the outer diameter of the aluminum tube is D, and the bending normal stress on the material at all points along the cross-section is equal, the above formula simplifies to: （4） In the formula, E is the flexural modulus of the material.

2. The bending stress application device for breakdown testing according to claim 1, characterized in that, The ground electrode is connected to a force-applying cylinder to apply a predetermined bending stress to the specimen.

3. The bending stress application device for breakdown testing according to claim 1, characterized in that, The sample is fixed to the ground electrode via at least one insulating tape.

4. The bending stress application device for breakdown testing according to claim 1, characterized in that, The up / down movement button is connected to the insulating bracket to control its up / down movement distance.

5. The bending stress application device for breakdown testing according to claim 4, characterized in that, The up / down movement button is connected to a drive cylinder for up / down movement.

6. The bending stress application device for breakdown testing according to claim 1, characterized in that, The left and right movement buttons are connected to the ground electrode to control its lateral movement distance.

7. The bending stress application device for breakdown testing according to claim 6, characterized in that, The left and right movement buttons are connected to a drive cylinder for lateral movement.

8. The bending stress application device for breakdown testing according to claim 1, characterized in that, The high-voltage electrode is a spherical electrode.

9. The bending stress application device for breakdown testing according to claim 1, characterized in that, The insulating support includes an insulating screw.

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