Method for fabricating test sample of rod-shaped composite insulator and auxiliary device for sample fabrication

Abstract

A method for fabricating a test sample of a rod-shaped composite insulator, the fabrication method comprising the following steps: Step 1: After excluding the end fittings of the rod-shaped composite insulator, perform segmented cutting along the direction perpendicular to the axis of the core rod and number them; Step 2: Pretreat the composite insulator segments; Step 3: Clamp both ends of the pretreated composite insulator segments with two metal electrodes, and then use two insulating clamping plates to clamp the upper metal electrode and the lower metal electrode, thereby fabricating an insulation test sample of the composite insulator. The insulation sample sampling of the composite insulator of the present invention can be standardized, avoiding the randomness and arbitrariness of sample sampling. For composite insulators of the same model, the same segmentation and sampling are adopted, and the test results are easy to compare; the lower metal electrode adopts a three-electrode structure, which can make the measurement of the insulation leakage current more accurate and scientific when performing insulation leakage current tests.

Description

Technical Field

[0001] The invention belongs to the technical field of composite insulator fault detection, and in particular relates to a test sample manufacturing method of a rod-shaped composite insulator and a sample manufacturing auxiliary device. Background Art

[0002] Composite insulators have the advantages of light weight, high mechanical strength, excellent resistance to moisture and pollution flashover, and easy installation and maintenance. They have been widely used in China's 110kV and above long-distance overhead transmission lines, and are widely used as the main type of insulator in China's ultra-high voltage AC and DC systems.

[0003] Composite insulators are usually composed of three parts: glass fiber epoxy resin core rod (sometimes also called pull rod), silicone rubber shed, and hardware. Both the core rod and shed are organic composite materials, so insulation aging is prone to occur under the combined effects of external force, dirt accumulation, water absorption, wind, frost, rain and snow. Regular insulation performance sampling and verification of operating composite insulators, as well as fault detection and analysis of faulty composite insulators, require sampling of composite insulators. Insulation leakage current test is also an important item in composite insulator performance test.

[0004] Although the shape of composite insulators actually used in power systems is based on national standards, they are generally very long, making it difficult to directly test the insulation performance of the entire insulator. Therefore, it is common practice for testers to take partial samples of the entire insulator. However, since there are no relevant technical standards and specifications for the sampling of composite insulators and their leakage current testing, the sampling method is very arbitrary, and the test results obtained from different test samples cannot be compared with each other. This is very unfavorable for the long-term insulation performance sampling tracking and comparison of operating composite insulators, as well as the insulation performance detection and judgment of faulty composite insulators, and the long-term accumulated analysis and test data cannot be effectively and fully utilized. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing test samples of rod-shaped composite insulators, so that the composite insulator test samples prepared by the method can be used for various tests such as leakage current, withstand voltage, temperature rise, etc. of composite insulators, promote the normalization and standardization of test samples, so that the test results are obtained under the same sample conditions, which is convenient for unified comparison and analysis.

[0006] The present invention specifically adopts the following technical solutions:

[0007] A method for manufacturing a test sample of a rod-shaped composite insulator, characterized in that the manufacturing method comprises the following steps:

[0008] Step 1: After excluding the end fittings of the rod-shaped composite insulator, perform segmented cutting along the direction perpendicular to the axis of the core rod 8, so that the cutting surface is perpendicular to the axis of the core rod 8;

[0009] Step 2: Pretreat the composite insulator segment to remove the protrusions on the cross-section of the composite insulator segment, the dirt on the surfaces of the sheath 7 and the umbrella skirt 1, and the moisture inside the sheath 7 and the core rod 8;

[0010] Step 3: Clamp the two end cross-sections of the pretreated composite insulator segment with a metal upper electrode 6 and a metal lower electrode respectively, and then clamp the metal upper electrode 6 and the metal lower electrode with an insulating upper clamping plate 2 and an insulating lower clamping plate 5. Tighten and fix between the insulating upper clamping plate 2 and the insulating lower clamping plate 5, thereby making a composite insulator insulation test sample.

[0011] The present invention further adopts the following preferred technical solutions:

[0012] When cutting the rod-shaped composite insulator in the step 1, the length of the rod-shaped composite insulator segment for a line with a voltage not greater than 110 kV is 3 - 4 cm; the length of the rod-shaped composite insulator segment for a line with a voltage greater than 110 kV and not greater than 500 kV is 4 - 5 cm; the length of the rod-shaped composite insulator segment for a line with a voltage greater than 500 kV is 5 - 6 cm.

[0013] When cutting the umbrella skirt 1 part of the rod-shaped composite insulator, each composite insulator segment contains one complete umbrella skirt 1.

[0014] Composite insulators of the same type are cut into composite insulator segments of the same size and numbered in the same way. Thus, when conducting test comparisons, the composite insulator segments at the same numbered positions are taken for comparison.

[0015] The step 2 includes the following steps:

[0016] S201: Grind the two side cross-sections of the composite insulator segment to remove the protrusions on the two side cross-sections of the composite insulator segment;

[0017] S202: Wipe the outer surface of the composite insulator segment;

[0018] S203: Place the composite insulator segment in a vacuum drying oven for 120 minutes;

[0019] S204: Place the composite insulator segment in a constant temperature oven for 240 minutes.

[0020] In the S203, place the composite insulator segment in a vacuum drying oven at 40 °C for 120 minutes;

[0021] In the step S204, the composite insulator segment is statically placed in a constant temperature box with a humidity of 77 - 83% and a temperature of 23 - 27°C for 240 minutes.

[0022] In the step 3, the metal upper electrode 6 is a single integral electrode;

[0023] The diameter of the metal upper electrode 6 is 1.5 - 1.8 times the diameter of the composite insulator segment, and the thickness is 10 - 15 mm.

[0024] The metal lower electrode is a concentric circle three - electrode structure, including an inner electrode 11, an inner ring electrode 9, an outer ring electrode 10, and an insulating bottom plate 12;

[0025] The inner electrode 11, the inner ring electrode 9, and the outer ring electrode 10 are all arranged on the insulating bottom plate 12 and do not make direct contact with each other.

[0026] The diameter of the inner electrode 11 is 1 - 2 mm larger than the diameter of the core rod 8 of the composite insulator segment and not larger than the overall diameter of the composite insulator segment; so that when the composite insulator segment is placed on the metal lower electrode, the range of the inner electrode 11 can cover all the circular areas of the cross - section of the core rod 8, but cannot cover all the circular areas of the overall cross - section of the composite insulator segment.

[0027] The inner - circle diameter of the inner ring electrode 9 is 2 - 3 mm smaller than the overall diameter of the composite insulator segment and not smaller than the diameter of the inner electrode 11;

[0028] The outer - circle diameter of the inner ring electrode 9 is 1 - 2 mm larger than the overall diameter of the composite insulator segment, so that when the composite insulator segment is placed on the metal lower electrode, the edge of the sheath 7 of the composite insulator segment can just be within the range of the inner ring electrode 9.

[0029] The inner - circle diameter of the outer ring electrode 10 is larger than the outer - circle diameter of the inner ring electrode 9, and the difference between them is equal to the difference between the inner - circle diameter of the inner ring electrode 9 and the diameter of the inner electrode 11; the outer - circle diameter of the outer ring electrode 10 is equal to the diameter of the metal upper electrode 6.

[0030] The inner electrode 11 is used to collect the body current of the composite insulator segment and is grounded through a first test resistor;

[0031] The inner ring electrode 9 is used to collect the surface current of the composite insulator segment and is grounded through a second test resistor;

[0032] The outer ring electrode 10 is used to uniform the surface electric field of the composite insulator segment and is directly grounded.

[0033] In the said Step 3, the upper insulating clamping plate 2 and the lower insulating clamping plate 5 are circular ring plates with hollowed-out middles, and there are a plurality of holes in the outer edge part of the circular ring plates for installing the fixing components for fixing the upper insulating clamping plate 2 and the lower insulating clamping plate 5.

[0034] The method for manufacturing a test sample of the rod-shaped composite insulator further includes the following steps:

[0035] Step 4: Place the manufactured composite insulator test sample in a constant temperature oven for storage. The humidity range in the constant temperature oven is 57 - 63%, and the temperature range is 28 - 32°C.

[0036] A sample manufacturing auxiliary device for the method for manufacturing a test sample of the foregoing rod-shaped composite insulator. The device includes a metal upper electrode 6, a metal lower electrode, an upper insulating clamping plate 2, and a lower insulating clamping plate 5, and is characterized in that:

[0037] The metal lower electrode is a concentric circle three-electrode structure, including an inner electrode 11, an inner ring electrode 9, an outer ring electrode 10, and an insulating bottom plate 12;

[0038] The inner electrode 11, the inner ring electrode 9, and the outer ring electrode 10 are all arranged on the insulating bottom plate 12 and do not make direct contact with each other;

[0039] The upper insulating clamping plate 2 and the lower insulating clamping plate 5 are circular ring plates with hollowed-out middles, and there are a plurality of small holes in the outer edge part of the circular ring plates for installing the fixing components for fixing the upper insulating clamping plate 2 and the lower insulating clamping plate 5;

[0040] The metal upper electrode 6 and the metal lower electrode clamp the upper and lower ends of the composite insulator test sample;

[0041] The upper insulating clamping plate 2 is arranged above the metal upper electrode 6, and the lower insulating clamping plate 5 is arranged below the metal lower electrode and is tightened and fixed.

[0042] The diameter of the metal upper electrode 6 is 1.5 - 1.8 times the diameter of the composite insulator section, and the thickness is 10 - 15 mm.

[0043] The diameter of the inner electrode 11 is 1 - 2 mm larger than the diameter of the core rod 8 of the composite insulator section and is not larger than the overall diameter of the composite insulator section.

[0044] The inner circle diameter of the inner ring electrode 9 is 2 - 3 mm smaller than the overall diameter of the composite insulator section and is not smaller than the diameter of the inner electrode 11;

[0045] The outer circle diameter of the inner ring electrode 9 is 1 - 2 mm larger than the overall diameter of the composite insulator section.

[0046] The inner circle diameter of the outer ring electrode 10 is greater than the outer circle diameter of the inner ring electrode 9, and the difference between the two is equal to the difference between the inner circle diameter of the inner ring electrode 9 and the diameter of the inner electrode 11; the outer circle diameter of the outer ring electrode 10 is equal to the diameter of the metal upper electrode 6.

[0047] The inner electrode 11 is grounded through a first test resistor;

[0048] The inner ring electrode 9 is grounded through a second test resistor;

[0049] The outer ring electrode 10 is directly grounded.

[0050] The present invention has the following technical effects:

[0051] (1) The insulation sample sampling of the composite insulator can be standardized, avoiding the randomness and arbitrariness of sample sampling. Composite insulators of the same model adopt the same segmentation and sampling, and the test results are easy to compare.

[0052] (2) The production of the insulation test sample can also be standardized, and the metal lower electrode adopts a three-electrode structure, which can make the measurement of the insulation leakage current more accurate and scientific when conducting the insulation leakage current test.

[0053] (3) The pretreatment and preservation of the insulation test sample can also be standardized. Description of the Drawings

[0054] Figure 1 is a flowchart of the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention.

[0055] Figure 2 is a schematic diagram of the sampling of a composite insulator in the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention.

[0056] Figure 3 is a schematic diagram of the structure of a test sample of a composite insulator in the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention.

[0057] Figure 4 is a top view of the metal lower electrode in the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention.

[0058] Figure 5 is a schematic diagram of the structure of the upper and lower clamping plates in the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention.

[0059] In the figure: 1 shed, 2 insulating upper clamping plate, 3 insulating nut, 4 insulating bolt, 5 insulating lower clamping plate, 6 upper electrode, 7 sheath, 8 core rod, 9 inner ring electrode, 10 outer ring electrode, 11 inner electrode, 12 insulating bottom plate. Detailed Embodiments

[0060] The present invention will be described in more detail below with the aid of embodiments. However, the following embodiments are merely illustrative, and the protection scope of the present invention is not limited by these embodiments.

[0061] Figure 1 It is a flowchart of a method for fabricating a test sample of a rod-shaped composite insulator according to the present invention; Figure 2 It is a schematic diagram of sampling a composite insulator in a method for fabricating an insulation test sample of a rod-shaped composite insulator according to the present invention; Figure 3 It is a schematic structural diagram of a composite insulator test sample in a method for fabricating an insulation test sample of a rod-shaped composite insulator according to the present invention as Figures 1 - 3 As shown, the method for fabricating a test sample of a rod-shaped composite insulator according to the present invention specifically includes the following steps.

[0062] Step 1: Assume that the total length of the composite insulator excluding the end fittings is L. Cut it into segments along the direction perpendicular to the axis of the core rod 8, making the cutting surface perpendicular to the axis of the core rod 8. And along the direction from low voltage to high voltage when the composite insulator is hung and operated on the power grid, number each cut composite insulator segment, denoted as 1, 2, 3, ……, N respectively.

[0063] When cutting a rod-shaped composite insulator, the length of the rod-shaped composite insulator segment for a line with a voltage not greater than 110 kV is 3 - 4 cm; the length of the rod-shaped composite insulator segment for a line with a voltage greater than 110 kV and not greater than 500 kV is 4 - 5 cm; the length of the rod-shaped composite insulator segment for a line with a voltage greater than 500 kV is 5 - 6 cm. When cutting the umbrella skirt 1 part, try to ensure that each segment contains a complete umbrella skirt 1. And, composite insulators of the same type are cut into composite insulator segments of the same size, numbered in the same way, and when conducting a test comparison, take the composite insulator segments at the same numbered positions for comparison.

[0064] In an embodiment of the present invention, the FXBW4-110 / 100 type rod-shaped suspension composite insulator commonly used in the power system transmission line is removed from the end fittings at both ends and cut into N segments. Since the operating voltage of the FXBW4-110 / 100 type composite insulator is 110 kV, the length of each cut segment is 4.5 cm.

[0065] In another embodiment of the present invention, when sampling a rod-shaped composite insulator for a line with a voltage not greater than 110 kV, the length of the sample insulator segment is taken as 3.5 cm.

[0066] In yet another embodiment of the present invention, when sampling a rod-shaped composite insulator for a line with a voltage greater than 500 kV, the length of the sample insulator segment is taken as 5.5 cm.

[0067] Step 2: Pre-treat the cut composite insulator segments to remove obvious rough protrusions on the cross-sections of the composite insulator segments, dirt on the surfaces of the sheath 7 and the umbrella skirts 1, and moisture inside the sheath 7 and the core rod 8. The pre-treatment specifically includes the following steps:

[0068] S201: Sand the two cross-sections of the composite insulator segment with sandpaper to remove obvious rough protrusions;

[0069] S202: Wipe the outer surface of the composite insulator segment clean with a lint-free cloth dipped in anhydrous alcohol;

[0070] S203: Place the composite insulator segment in a vacuum drying oven at 40 °C for 120 minutes;

[0071] S204: Place the composite insulator segment in a constant temperature oven with a humidity of 80 ± 3% and a temperature of 25 ± 2 °C for 240 minutes.

[0072] By implementing a set of standard pre-treatment processes, the initial states of the composite insulator samples are made as consistent as possible before subsequent insulation tests, reducing or eliminating the interference caused by uncertain factors such as uneven cross-sections during cutting, dirt and impurities contained in the samples themselves, and moisture, thereby ensuring the accuracy and reliability of the test results.

[0073] Step 3: Clamp the two cross-sections of the pre-treated composite insulator segment with a metal upper electrode 6 and a metal lower electrode respectively, and then clamp the metal upper electrode 6 and the metal lower electrode with an insulating upper clamping plate 2 and an insulating lower clamping plate 5, and tighten and fix the upper clamping plate 2 and the lower clamping plate 5 through insulating bolts 4 and insulating nuts 3, thereby fabricating a composite insulator test sample.

[0074] The metal upper electrode 6 is a single integral electrode with a chamfered cylindrical edge. The diameter of the metal upper electrode 6 is 1.5 - 1.8 times the diameter of the composite insulator segment, and the thickness is 10 - 15 mm.

[0075] Figure 4 is the top view of the metal lower electrode of a method for fabricating an insulation test sample of a rod-shaped composite insulator according to the present invention. As Figure 4 shown, the metal lower electrode has a concentric circle three-electrode structure, including an inner electrode 11, an inner ring electrode 9, an outer ring electrode 10, and an insulating bottom plate 12. The inner electrode 11, the inner ring electrode 9, and the outer ring electrode 10 are all arranged on the insulating bottom plate 12 and do not come into direct contact with each other.

[0076] Specifically, the diameter of the inner electrode 11 is 1-2 mm larger than the diameter of the core rod 8 of the composite insulator segment and not larger than the overall diameter of the composite insulator segment; such that when the composite insulator segment is placed on the metal lower electrode, the range of the inner electrode 11 can cover the entire circular area of the cross-section of the core rod 8, but cannot cover the entire circular area of the overall cross-section of the composite insulator segment.

[0077] The inner diameter of the inner ring electrode 9 is 2-3 mm smaller than the overall diameter of the composite insulator segment and not smaller than the diameter of the inner electrode 11. The outer diameter of the inner ring electrode 9 is 1-2 mm larger than the overall diameter of the composite insulator segment; such that when the composite insulator segment is placed on the metal lower electrode, the edge of the sheath 7 of the composite insulator segment can just be within the range of the inner ring electrode 9.

[0078] The inner diameter of the outer ring electrode 10 is larger than the outer diameter of the inner ring electrode 9, and the difference between the two is equal to the difference between the inner diameter of the inner ring electrode 9 and the diameter of the inner electrode 11; the outer diameter of the outer ring electrode 10 is equal to the diameter of the metal upper electrode 6.

[0079] In an embodiment of the present invention, the diameter of the core rod 8 of the FXBW4-110 / 100 type composite insulator is 37 mm, the thickness of the sheath 7 is 5 mm, and the overall diameter is 47 mm. According to the relationship between the diameter of the electrode and the sample, the diameter of the metal upper electrode 6 is 70 mm, which is a cylindrical shape with a chamfered edge, and the chamfer radius is 1 mm.

[0080] The diameter of the inner electrode 11 is 39 mm, the inner diameter of the inner ring electrode 9 is 43 mm, the outer diameter is 49 mm, the inner diameter of the outer ring electrode 10 is 53 mm, and the outer diameter is 70 mm.

[0081] When performing the insulation leakage current test, the inner electrode 11 is grounded through the test resistor R1, which is used to collect the body current of the sample and the leakage current at the interface between the core rod 8 and the sheath 7; the inner ring electrode 9 is grounded through the test resistor R2, which is used to collect the surface leakage current of the sample; the outer ring electrode 10 is directly grounded, which is used to uniform the surface electric field of the sample. The test resistors R1 and R2 are both standard non-inductive resistors of 1 kΩ.

[0082] Figure 5 Schematic diagram of the upper and lower clamping plates 5 shown in the present invention, as Figure 5 shown, the upper clamping plate 2, the lower clamping plate 5, the insulating bolt 4 and the insulating nut 3 are all made of epoxy resin. The upper clamping plate 2 and the lower clamping plate 5 are circular ring plates with a hollow middle part, and there are a plurality of small holes at the outer edge part of the circular ring plate, which are used to install the insulating bolt 4 and the insulating nut 3.

[0083] Step 4: Place the fabricated composite insulator test sample in a constant temperature oven with a humidity of 60±3% and a temperature of 30±2°C for storage, so that it can be directly taken for insulation testing. After the insulation test, if the sample needs to be stored, it is also placed in a constant temperature oven with a humidity of 60±3% and a temperature of 30±2°C for storage.

[0084] In the present invention, when fabricating an insulator test sample, a sample fabrication auxiliary device is used, which includes a metal upper electrode 6, a metal lower electrode, an insulating upper clamping plate 2, and an insulating lower clamping plate 5.

[0085] The metal upper electrode 6 is a single integral electrode, which is a cylindrical electrode with chamfered edges. And the diameter of the metal upper electrode 6 is 1.5 - 1.8 times the diameter of the composite insulator segment, and the thickness is 10 - 15 mm.

[0086] The metal lower electrode is a concentric circle three - electrode structure, including an inner electrode 11, an inner ring electrode 9, an outer ring electrode 10, and an insulating bottom plate 12. The inner electrode 11, the inner ring electrode 9, and the outer ring electrode 10 are all arranged on the insulating bottom plate 12 and do not come into direct contact with each other.

[0087] Specifically, the diameter of the inner electrode 11 is 1 - 2 mm larger than the diameter of the core rod 8 of the composite insulator segment and not larger than the overall diameter of the composite insulator segment.

[0088] The inner - circle diameter of the inner ring electrode 9 is 2 - 3 mm smaller than the overall diameter of the composite insulator segment and not smaller than the diameter of the inner electrode 11. The outer - circle diameter of the inner ring electrode 9 is 1 - 2 mm larger than the overall diameter of the composite insulator segment.

[0089] The inner - circle diameter of the outer ring electrode 10 is larger than the outer - circle diameter of the inner ring electrode 9, and the difference between them is equal to the difference between the inner - circle diameter of the inner ring electrode 9 and the diameter of the inner electrode 11; the outer - circle diameter of the outer ring electrode 10 is equal to the diameter of the metal upper electrode 6.

[0090] The inner electrode 11 is used to collect the body current of the composite insulator segment and is grounded through a first test resistor;

[0091] The inner ring electrode 9 is used to collect the surface current of the composite insulator segment and is grounded through a second test resistor;

[0092] The outer ring electrode 10 is used to uniform the surface electric field of the composite insulator segment and is directly grounded.

[0093] The insulating upper clamping plate 2 and the insulating lower clamping plate 5 are circular ring plates with hollowed - out middles, and there are multiple small holes in the outer edge part of the circular ring plates for installing insulating bolts 4 and insulating nuts 3.

[0094] The insulation sample sampling of the composite insulator of the present invention can be standardized, avoiding the randomness and arbitrariness of sample sampling. For composite insulators of the same model, the same segmentation and sampling are adopted, and the test results are easy to compare. The production of insulation test samples can also be standardized, and the metal lower electrode adopts a three-electrode structure, which can make the measurement of insulation leakage current more accurate and scientific when conducting insulation leakage current tests. The pretreatment and preservation of insulation test samples can also be standardized.

[0095] The above is only the preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the drawings. Therefore, all equivalent or modified implementations completed without departing from the spirit disclosed by the present invention fall within the protection scope of the present invention.

Claims

1. A method for fabricating a test sample of a rod-shaped composite insulator, characterized in that, The manufacturing method includes the following steps: Step 1: After excluding the end fittings of the rod-shaped composite insulator, perform segmented cutting along the direction perpendicular to the axis of the core rod (8) so that the cutting surface is perpendicular to the axis of the core rod (8); Step 2: Pretreat the composite insulator segment to remove the protrusions on the cross-section of the composite insulator segment, the dirt on the surfaces of the sheath (7) and the umbrella skirt (1), and the moisture inside the sheath (7) and the core rod (8); Step 3: Clamp the two end cross-sections of the pretreated composite insulator segment with a metal upper electrode (6) and a metal lower electrode respectively, and then clamp the metal upper electrode (6) and the metal lower electrode with an insulating upper clamping plate (2) and an insulating lower clamping plate (5). The insulating upper clamping plate (2) and the insulating lower clamping plate (5) are tightened and fixed to manufacture a composite insulator insulation test sample; The insulating upper clamping plate (2) and the insulating lower clamping plate (5) are circular plates with a hollow middle, and there are a plurality of small holes at the outer edge of the circular plate for installing insulating bolts (4) and insulating nuts (3); The metal lower electrode is a concentric circle three-electrode structure, including an inner electrode (11), an inner ring electrode (9), an outer ring electrode (10), and an insulating bottom plate (12); The inner electrode (11), the inner ring electrode (9), and the outer ring electrode (10) are all arranged on the insulating bottom plate (12) and do not come into direct contact with each other; The diameter of the inner electrode (11) is 1-2 mm larger than the diameter of the core rod (8) of the composite insulator segment and not larger than the overall diameter of the composite insulator segment; The inner circle diameter of the inner ring electrode (9) is 2-3 mm smaller than the overall diameter of the composite insulator segment and not smaller than the diameter of the inner electrode (11); The outer circle diameter of the inner ring electrode (9) is 1-2 mm larger than the overall diameter of the composite insulator segment; The inner circle diameter of the outer ring electrode (10) is larger than the outer circle diameter of the inner ring electrode (9), and the difference between the two is equal to the difference between the inner circle diameter of the inner ring electrode (9) and the diameter of the inner electrode (11); the outer circle diameter of the outer ring electrode (10) is equal to the diameter of the metal upper electrode (6).

2. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1, characterized in that: When cutting the rod-shaped composite insulator in Step 1, the length of the rod-shaped composite insulator segment for a line not greater than 110 kV is 3-4 cm; the length of the rod-shaped composite insulator segment for a line greater than 110 kV and not greater than 500 kV is 4-5 cm; the length of the rod-shaped composite insulator segment for a line greater than 500 kV is 5-6 cm.

3. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, characterized in that: When cutting the umbrella skirt (1) part of the rod-shaped composite insulator, each composite insulator segment contains one complete umbrella skirt (1).

4. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, characterized in that: Composite insulators of the same model are cut into composite insulator segments of the same size and numbered in the same way, so that when conducting test comparisons, the composite insulator segments at the same numbered positions are taken for comparison.

5. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, characterized in that: Step 2 includes the following steps: S201: Grind the two side cross-sections of the composite insulator segment to remove the protrusions on the two side cross-sections of the composite insulator segment; S202: Wipe the outer surface of the composite insulator segment; S203: Place the composite insulator segment statically in a vacuum drying oven for 120 minutes; S204: Place the composite insulator segment statically in a constant temperature oven for 240 minutes.

6. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 5, characterized in that: In S203, place the composite insulator segment statically in a vacuum drying oven at 40 °C for 120 minutes; In S204, place the composite insulator segment statically in a constant temperature oven with a humidity of 77 - 83% and a temperature of 23 - 27 °C for 240 minutes.

7. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, characterized in that: In step 3, the metal upper electrode (6) is a single integral electrode; The diameter of the metal upper electrode (6) is 1.5 - 1.8 times the diameter of the composite insulator segment, and the thickness is 10 - 15 mm.

8. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1, characterized in that: So that when the composite insulator segment is placed on the metal lower electrode, the range of the inner electrode (11) can cover the entire circular area of the cross-section of the core rod (8), but cannot cover the entire circular area of the cross-section of the composite insulator segment.

9. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1, wherein: So that when the composite insulator segment is placed on the metal lower electrode, the edge of the sheath (7) of the composite insulator segment can just be within the range of the inner ring electrode (9).

10. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1, wherein: The inner electrode (11) is used to collect the body current of the composite insulator segment and is grounded through a first test resistor; The inner ring electrode (9) is used to collect the surface current of the composite insulator segment and is grounded through a second test resistor; The outer ring electrode (10) is used to uniform the surface electric field of the composite insulator segment and is directly grounded.

11. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, wherein: In step 3, the insulating upper clamping plate (2) and the insulating lower clamping plate (5) are circular ring plates with a hollow middle part, and there are a plurality of holes in the outer edge part of the circular ring plate for installing the fixing components of the insulating upper clamping plate (2) and the insulating lower clamping plate (5).

12. The method for fabricating a test sample of a rod-shaped composite insulator according to claim 1 or 2, wherein: The method for manufacturing the test sample of the rod-shaped composite insulator further includes the following steps: Step 4: Place the manufactured composite insulator test sample in a constant temperature oven for storage, and the humidity range in the constant temperature oven is 57 - 63% and the temperature range is 28 - 32 °C.

13. A sample fabrication auxiliary device for the method for fabricating a test sample of a rod-shaped composite insulator according to any one of claims 1 - 12, the device comprising a metal upper electrode (6), a metal lower electrode, an insulating upper clamping plate (2), and an insulating lower clamping plate (5), wherein: The metal lower electrode is a concentric circle three-electrode structure, including an inner electrode (11), an inner ring electrode (9), an outer ring electrode (10), and an insulating bottom plate (12); The inner electrode (11), the inner ring electrode (9), and the outer ring electrode (10) are arranged at intervals on the insulating bottom plate (12); The insulating upper clamping plate (2) and the insulating lower clamping plate (5) are circular ring plates with a hollow middle part, and there are a plurality of holes in the outer edge part of the circular ring plate, and the fixing components of the insulating upper clamping plate (2) and the insulating lower clamping plate (5); The metal upper electrode (6) and the metal lower electrode clamp the upper and lower ends of the composite insulator test sample; The insulating upper clamping plate (2) is arranged above the metal upper electrode (6), and the insulating lower clamping plate (5) is arranged below the metal lower electrode and is tightened and fixed.

14. The sample fabrication auxiliary device according to claim 13, wherein: The diameter of the metal upper electrode (6) is 1.5 - 1.8 times the diameter of the composite insulator segment, and the thickness is 10 - 15 mm.

15. The sample fabrication auxiliary device according to claim 13, wherein: The diameter of the inner electrode (11) is 1 - 2 mm larger than the diameter of the core rod (8) of the composite insulator segment and is not larger than the diameter of the cross-section of the composite insulator segment.

16. The sample fabrication auxiliary device according to any one of claims 13 - 15, wherein: The inner circle diameter of the inner ring electrode (9) is 2-3 mm less than the overall diameter of the composite insulator section and not less than the diameter of the inner electrode (11); The outer circle diameter of the inner ring electrode (9) is 1-2 mm greater than the overall diameter of the composite insulator section.

17. The sample fabrication auxiliary device according to any one of claims 13 - 15, wherein: The inner circle diameter of the outer ring electrode (10) is greater than the outer circle diameter of the inner ring electrode (9), and the difference between the two is equal to the difference between the inner circle diameter of the inner ring electrode (9) and the diameter of the inner electrode (11); the outer circle diameter of the outer ring electrode (10) is equal to the diameter of the metal upper electrode (6).

18. The sample fabrication auxiliary device according to any one of claims 13 - 15, wherein: The inner electrode (11) is used to collect the body current of the composite insulator section and is grounded through a first test resistor; The inner ring electrode (9) is used to collect the surface current of the composite insulator section and is grounded through a second test resistor; The outer ring electrode (10) is used to uniform the surface electric field of the composite insulator section and is directly grounded.

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