Method for testing the electrical strength of parallel layers of fiber reinforced epoxy resin insulation tubes

Abstract

The application discloses a kind of parallel layer electrical strength test methods of fiber reinforced epoxy resin insulating pipe, comprising: obtaining the parallel layer sample of multiple fiber reinforced epoxy resin insulating pipes;On each parallel layer sample, a plurality of equal-diameter circular holes are uniformly opened;The parallel layer sample is placed in transformer oil, the transformer oil is heated to preset temperature, and the voltage is gradually increased to the circular hole of the parallel layer sample Breakdown;The median value of the voltage of the circular hole breakdown of multiple parallel layer samples is used as the value of the electrical strength of the parallel layer of the fiber reinforced epoxy resin insulating pipe.Solve the problem that the electrical strength of the fiber reinforced epoxy resin insulating pipe for ultra-high voltage electrical equipment is higher, and the existing standard specifies that the test method is difficult to effectively determine.

Description

Technical Field

[0001] This invention relates to the field of high-voltage equipment, and more specifically to a method for testing the parallel layer electrical strength of fiber-reinforced epoxy resin insulating tubes. Background Technology

[0002] Fiber-reinforced epoxy resin insulating tubes are the basic insulating materials used in ultra-high voltage (UHV) and extra-high voltage (EHV) electrical equipment. They are generally used to manufacture high-performance insulating components such as insulating rods and support insulators in UHV and EHV combined electrical appliances. Among them, insulating rods have harsh operating conditions and high technical requirements, representing the highest level of reinforced epoxy resin insulation components.

[0003] The general manufacturing process of fiber-reinforced epoxy resin insulating tubes is as follows: First, fiber cloth (which can be glass fiber, aramid fiber or polyester fiber) is wound on a metal core rod. Then, epoxy resin is impregnated into the fiber in a vacuum environment. Finally, it is cured under certain temperature conditions.

[0004] Parallel layer electrical strength is a key performance indicator of insulating tubes and is crucial for performance evaluation and quality testing. However, due to the high electrical strength of fiber-reinforced epoxy resin insulating tubes used in ultra-high voltage and extra-high voltage electrical equipment, the test methods specified in existing standards are difficult to effectively measure.

[0005] According to the test methods for the parallel layer breakdown strength of fiber-wound tubes in national standards GB / T5132.2 2009 and GB / T1408.1 2006, three axial length samples of 25±0.2 mm are cut from the insulating tube, and the test is conducted using a circular flat electrode with a diameter of 130 mm. During the test, the samples are placed in No. 25 transformer oil at a temperature of 90℃±2℃, and the test is conducted using a step-by-step voltage increase method. Since this test method ultimately results in surface flashover at the interface of the oil-epoxy fiber-reinforced composite material, it cannot obtain the bulk breakdown characteristics of the material, thus the test method has defects. Therefore, a new test method is needed to determine the bulk electrical strength of the insulating tube. Summary of the Invention

[0006] To address the above problems, this invention provides a method for testing the parallel-layer electrical strength of fiber-reinforced epoxy resin insulating tubes, comprising:

[0007] Obtain multiple parallel layer samples of fiber-reinforced epoxy resin insulating tubes; uniformly open multiple circular holes of equal diameter on each parallel layer sample.

[0008] The parallel layer sample was placed in transformer oil, the transformer oil was heated to a preset temperature, and the voltage was increased to the point where the circular hole of the parallel layer sample broke down using a step-by-step voltage increase method.

[0009] The median value of the breakdown voltage of the circular hole of the plurality of parallel layer samples is taken as the value of the parallel layer electrical strength of the fiber-reinforced epoxy resin insulating tube.

[0010] Further, the plurality of parallel layer samples of the fiber-reinforced epoxy resin insulating tube is at least 3.

[0011] Further, the parallel of the two ends of the parallel layer sample is protected, and the length of the sample is specifically 25 mm.

[0012] Further, a plurality of circular holes with equal diameters are uniformly arranged on each parallel layer sample, and specifically, at least 4 circular holes with equal diameters are uniformly arranged on one side of each parallel layer sample at a preset angle in the circumferential direction, and the bottom of the hole is 3 mm away from the bottom of the sample.

[0013] Further, the preset angle specifically includes 60° and 90°.

[0014] Further, the parallel layer sample is placed in transformer oil, the transformer oil is heated to a preset temperature, and a step-by-step voltage boosting method is used to boost the voltage to the breakdown of the circular hole of the parallel layer sample, including:

[0015] The parallel layer sample is placed in 25# transformer oil, a cylindrical ball head electrode is used as the high-voltage electrode, and a flat electrode is used as the low-voltage electrode to tightly contact the parallel layer sample.

[0016] The transformer oil is heated to 90±2°C, and a 20s step-by-step voltage boosting method is used for testing.

[0017] The voltage is boosted to the breakdown of the circular hole of the parallel layer sample, and the breakdown voltage of the circular hole of the parallel layer sample is obtained.

[0018] Further, the step-by-step voltage boosting method is applied to the parallel layer sample at 40% of the predicted short-time breakdown voltage.

[0019] If the parallel layer sample can withstand the current breakdown voltage without breakdown, the voltage is increased step by step until the breakdown of the circular hole of the parallel layer sample occurs.

[0020] Further, the breakdown of the circular hole of the parallel layer sample has at least 4 breakdown points.

[0021] The parallel layer electrical strength test method of the fiber-reinforced epoxy resin insulating tube provided by the application can effectively determine the parallel layer electrical strength of the fiber-reinforced epoxy resin insulating tube, improve the test efficiency of the electrical strength, and save sample materials and provide more test data by arranging a plurality of holes on each sample. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flowchart of a parallel layer electrical strength test method of a fiber reinforced epoxy resin insulating tube provided by an embodiment of the present application;

[0023] Figure 2 is a cross-sectional view of a round hole opened in a fiber reinforced epoxy resin insulating tube related to an embodiment of the present application;

[0024] Figure 3 is a plan view of a fiber reinforced epoxy resin insulating tube related to an embodiment of the present application;

[0025] Figure 4 is a high-voltage electrode shape related to an embodiment of the present application. DETAILED DESCRIPTION

[0026] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods have not been described in detail in order to avoid obscuring the present application.

[0027] Figure 1 is a flowchart of a parallel layer electrical strength test method of a fiber reinforced epoxy resin insulating tube provided by an embodiment of the present application, and the following will be described in combination with Figure 1 The method provided by the present application will be described in detail.

[0028] In step S101, a plurality of parallel layer samples of fiber reinforced epoxy resin insulating tubes are obtained; and a plurality of round holes with equal diameters are uniformly opened on each parallel layer sample.

[0029] A YG3X type hard alloy cutter is used to cut a sample from the insulating tube, the two ends of the sample are kept parallel, and the sample length is 25 mm. The YG3X type hard alloy cutter has high strength and toughness, and good thermal conductivity, which is beneficial to dissipating cutting heat from the cutter tip, reducing cutting temperature, and facilitating cutting. At the same time, the cutter edge is excellent in grindability, easy to grind sharp edges, and conducive to improving the surface quality of machined parts.

[0030] A polishing machine is used to polish the two sections of the sample smooth, and no surface defects such as pores and impurities are checked and confirmed. The parallel layer sample of the fiber reinforced epoxy resin insulating tube is at least 3.

[0031] A metal drill is used to drill holes on one side of the insulating tube, and the holes can be uniformly drilled at a certain angle (such as 60°, 90°) along the circumferential direction, and there are at least 4 round holes with equal diameters, as shown in Figure 2 The bottom of the hole is 3 mm away from the bottom of the sample, as shown in Figure 3 .

[0032] Step S102, the parallel layer sample is placed in transformer oil, the transformer oil is heated to a preset temperature, and a step-by-step voltage boosting method is used to boost the voltage to the round hole of the parallel layer sample to cause breakdown.

[0033] The parallel layer sample is placed in 25# transformer oil, the high-voltage electrode adopts a columnar ball head electrode, the shape of the high-voltage electrode is as shown in Figure 4 The low-voltage electrode adopts a flat electrode in close contact with the parallel layer sample.

[0034] The transformer oil is heated to 90±2℃, and the test is performed by using a 20s step-by-step voltage boosting method.

[0035] The voltage is boosted to the round hole of the parallel layer sample to cause breakdown, and the voltage at which the round hole of the parallel layer sample causes breakdown is obtained.

[0036] The step-by-step voltage boosting method is used to apply a 40% expected short-time breakdown voltage to the parallel layer sample. If the expected value of the short-time breakdown voltage is unknown, the short-time (rapid voltage boosting) test method is used to obtain it. If the parallel layer sample can withstand the current breakdown voltage and does not cause breakdown, the voltage is increased step by step by the increment specified in Table 1 until the round hole of the parallel layer sample causes breakdown.

[0037] Table 1: Increment of voltage increase (kV, peak / √2)

[0038] Starting voltage / kV Increment / kV ≤1.0 10% of starting voltage ＞1.0～2.0 0.1 ＞2.0～5.0 0.2 ＞5.0～10 0.5 ＞10～20 1.0 ＞20～50 2.0 ＞50～100 5.0 ＞100～200 10.0 ＞200 20.0

[0039] Step S103, the median value of the breakdown voltages of the round holes of the plurality of parallel layer samples is taken as the value of the parallel layer electrical strength of the fiber-reinforced epoxy resin insulating pipe.

[0040] The number of parallel layer samples should be no less than 3, and the effective breakdown points (holes) on each sample should be at least 4. The average value of the 4 breakdown points on each sample is taken as the breakdown voltage of the sample. The median value of the breakdown voltage results of all samples is taken as the value of the electrical strength, expressed in kV / mm.

[0041] The specific application implementation is as follows:

[0042] In the circumferential direction of the polyester fiber-reinforced pipe with an inner diameter of φ35mm, an outer diameter of φ42mm, and a thickness of 25mm, 8 round holes with a diameter of φ3mm are uniformly formed by using a round drill bit.

[0043] The electrical breakdown voltages measured at the 4 positions of sample A are 41.91kV, 39.16kV, 40.02kV, and 43.24kV, respectively. The breakdown strength V1 of sample A is (41.91kV+39.16kV+40.02kV+43.24kV) / 3mm / 4=13.69kV / mm.

[0044] The electrical breakdown voltage of sample B measured at four positions is 45.35 kV, 40.19 kV, 38.67 kV, and 41.38 kV, respectively, and the breakdown strength V2 of sample B is (45.35 kV+40.19 kV+38.67 kV+41.38 kV) / 3mm / 4=13.80 kV / mm.

[0045] The electrical breakdown voltage of sample C measured at four positions is 36.92 kV, 40.88 kV, 38.65 kV, and 41.31 kV, respectively, and the breakdown strength V3 of sample C is (36.92 kV+40.88 kV+38.65 kV+41.31 kV) / 3mm / 4=13.15 kV / mm.

[0046] The median of the breakdown strengths of sample A, sample B, and sample C is taken as the electrical strength of the insulating tube, i.e., 13.69 kV / mm.

[0047] The parallel-layer electrical strength testing method of the fiber-reinforced epoxy resin insulating tube provided by the application can effectively determine the parallel-layer electrical strength of the fiber-reinforced epoxy resin insulating tube, and meanwhile, the testing efficiency of the electrical strength is improved. The mode of opening several holes on each sample can save sample materials and provide more test data.

[0048] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can adopt a computer program product in the form of being implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0049] The application is described with reference to flowcharts and / or block diagrams according to the methods, devices (systems), and computer program products of the embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one flow or multiple flows and / or blocks. Figure 1 The device that implements the functions specified in one block or multiple blocks.

[0050] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0051] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for testing the parallel-layer electrical strength of a fiber-reinforced epoxy resin insulating tube, characterized in that, include: Obtain multiple parallel layer samples of fiber-reinforced epoxy resin insulating tubes; uniformly open multiple circular holes of equal diameter on each parallel layer sample. The parallel layer sample was placed in transformer oil, the transformer oil was heated to a preset temperature, and the voltage was increased to the point where the circular hole of the parallel layer sample broke down using a step-by-step voltage increase method. The median voltage at which the circular holes of multiple parallel-layered samples break down is taken as the value of the parallel-layered electrical strength of the fiber-reinforced epoxy resin insulating tube. On each parallel layer sample, multiple circular holes of equal diameter are uniformly opened. Specifically, on one side cross section of each parallel layer sample, holes are uniformly opened at a preset angle along the circumference. Specifically, at least 4 circular holes of equal diameter are opened, and the bottom of the holes is 3mm away from the bottom of the sample. The parallel layer sample is placed in transformer oil, the transformer oil is heated to a preset temperature, and the voltage is increased to the point where the circular hole of the parallel layer sample breaks down using a step-by-step voltage increase method, including: The parallel layer sample was placed in 25# transformer oil. The high voltage electrode was a columnar ball-head electrode, and the low voltage electrode was a flat plate electrode. The electrodes were in close contact with the parallel layer sample. The transformer oil was heated to 90±2℃, and the test was conducted using a 20s step-by-step voltage increase method. The voltage is increased until the circular hole of the parallel layer sample breaks down, and the voltage at which the circular hole of the parallel layer sample breaks down is obtained.

2. The method according to claim 1, characterized in that, The number of parallel layer samples of the plurality of fiber-reinforced epoxy resin insulating tubes shall be at least three.

3. The method according to claim 1, characterized in that, The two ends of the parallel layer sample are kept parallel, and the sample length is 25 mm.

4. The method according to claim 1, characterized in that, The preset angles specifically include 60° and 90°.

5. The method according to claim 1, characterized in that, The step-up voltage method applies 40% of the expected short-time breakdown voltage to the parallel layer sample; If the parallel layer sample withstands the current breakdown voltage without breakdown, the voltage is increased incrementally until the circular hole of the parallel layer sample breaks down.

6. The method according to claim 1, characterized in that, The circular holes of the parallel layer sample were broken down, and there were at least four breakdown points.

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