Experimental system and method for corona aging process of multiple samples

Abstract

The invention discloses a multi-sample corona aging process experiment system and method, and relates to the technical field of power frequency high-voltage corona resistance tests. The device comprises an insulating supporting plate, electrode assemblies are uniformly arranged on the insulating supporting plate in an array mode, each electrode assembly comprises a support and a column electrode installed on the support, each column electrode is of a column structure, the central axis of each column electrode is perpendicular to the plate face of the insulating supporting plate, one end of each column electrode is a fixed side, and the other end of each column electrode is an experimental side. The fixed side of the column electrode is provided with a micrometer head, and the central axis of the micrometer head is perpendicular to the plate surface of the insulating support plate. The device is convenient to operate and high in retrofit, and researchers in the same field can reproduce the test conveniently.

Description

Technical Field

[0001] The invention relates to the technical field of power frequency high voltage corona resistance testing, and in particular to a precisely distance-controllable electrode system for corona aging of multiple samples. Background Art

[0002] With the rapid development of motor technology, the working environment of electrical insulation materials has become more demanding. Insulation materials, especially epoxy resin insulation materials, are very prone to aging in complex environments under the long-term effects of multiple factors. Electrical aging is an inevitable form of aging for all high-voltage motor insulation materials, and corona aging is one of the most common forms of discharge aging. For corona discharge, its aging effects on polymer insulation materials mainly include direct collision of charged particles, local high temperature, ultraviolet aging, aging of active products, etc. The generation of corona in the motor usually occurs at the position where the local field strength reaches the critical field strength. When the voltage reaches a certain value, even if the average field strength is relatively low, the electric field strength in some parts has reached a very high value. When it exceeds the corona starting voltage, air discharge will occur in such areas, thereby generating corona. The heat generated during this discharge process will cause the motor temperature to be too high, and the temperature increase may cause the epoxy resin insulation glue to deteriorate or even carbonize, which will make the strands loose and affect the motor performance. In this process, chemical reactions will occur, producing ozone products, corroding the insulation system of the motor, seriously damaging the insulation performance of the equipment, causing the main insulation to break down, seriously reducing the reliability of the main insulation of the motor, and shortening the service life of the motor. Based on this, it is necessary to use insulating materials with better insulation performance. After the common development of the insulation field, epoxy resin insulating materials have made different progress in different fields.

[0003] In order to further study the effect of corona discharge on insulating materials, it is necessary to conduct relevant experiments to obtain the effect of corona discharge on the degradation of epoxy-based insulating materials and the corona resistance of epoxy resin materials. In the existing technology, a single needle electrode is usually used to conduct corona experiments on samples. However, the corona intensity generated by a single needle electrode in the needle-plate electrode system is weak and the corona discharge area is limited. The discharge amount is greatly affected by the radius of curvature of the needle tip. The corona intensity of corona discharge for different needle tips is different. This difference will lead to deviations in the results of corona aging resistance tests on epoxy resin insulating materials and affect the evaluation of the corona resistance of epoxy resin materials. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the present invention provides an experimental system for the corona aging process of multiple samples, including an insulating support plate, on which electrode assemblies are evenly arranged in an array, the electrode assembly including a bracket and a column electrode installed on the bracket, the column electrode being a columnar structure, the central axis of the column electrode being perpendicular to the plate surface of the insulating support plate, one end of the column electrode being a fixed side, and the other end being an experimental side, a micrometer head being installed on the fixed side of the column electrode, and the central axis of the micrometer head being perpendicular to the plate surface of the insulating support plate.

[0005] Furthermore, the column electrode and the micrometer head are fixedly connected via an insulating connector.

[0006] Furthermore, the end of the column electrode on the experimental side is chamfered.

[0007] Furthermore, the bracket includes a C-shaped clamp, the C-shaped clamp is connected to the insulating support plate through a threaded fastener, and the C-shaped clamp is connected to the micrometer head through a threaded fastener.

[0008] Furthermore, the experimental system includes a plate electrode, and the plate electrode is located at the end surface of the experimental side of the column electrode.

[0009] Furthermore, the plate electrode includes an insulating base plate and aluminum foil laid on the insulating base plate, and the aluminum foil is grounded through an electric wire.

[0010] Another aspect of the present invention provides an experimental method for a multi-sample corona aging process, which is implemented based on the experimental system for a multi-sample corona aging process, and includes the following steps:

[0011] An experimental system for the corona aging process of multiple samples is constructed, comprising m insulating support plates, on which n electrode assemblies are evenly arranged in an array;

[0012] Fix the sample on the plate electrode at the port on the experimental side of the column electrode, and adjust the distance between the end surface of the experimental side of the column electrode and the sample;

[0013] Apply a preset voltage to the column electrode and start timing. When s samples are broken down, the experiment ends and the experimental time is recorded.

[0014] Furthermore, the method for applying the preset voltage is: increasing the voltage at a boost speed until the preset voltage value is reached and then maintaining the current voltage.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] The present invention adopts a column electrode to carry out a corona experiment. The column electrode generates a more uniform corona with a higher discharge intensity to accelerate the corona aging of the epoxy resin insulating material, avoids the problem in the prior art that the corona discharge intensity is greatly affected by the curvature radius of the needle tip when a single needle electrode is used, improves the rigor of the corona resistance test, reduces the deviation of multiple corona discharge tests, and provides help for evaluating the epoxy resin insulating material.

[0017] The micrometer head can be used to accurately control the distance between the electrode and the sample, reduce experimental errors, and reduce the dispersion of the corona resistance test. The entire electrode system is simple in material and structure, easy to operate, and highly modifiable, making it easy for researchers in the same field to replicate the experiment. By using multiple electrodes to simultaneously subject the sample to corona aging, the corona resistance life of the sample can be directly obtained, greatly shortening the time previously spent on repeated tests.

[0018] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of an electrode assembly according to a specific embodiment of the present invention;

[0020] Figure 2 for Figure 1 A top view of

[0021] Figure 3 for Figure 1 main view.

[0022] Figure 4 for Figure 1 Right view of .

[0023] Figure 5 It is a schematic diagram of the structure of an experimental system according to a specific embodiment of the present invention;

[0024] Figure 6 It is an experimental circuit principle diagram of an experimental system structure of a specific embodiment of the present invention;

[0025] Figure 7 A physical picture of a breakdown sample of a specific embodiment of the present invention;

[0026] Figure 8 The corona life results of 6 samples measured in a specific embodiment of the present invention are as follows;

[0027] In the figure, 1- hexagonal screw, 2- hexagonal nut, 3- insulating support plate, 4- C-type clamp, 5- micrometer head clamp, 6- column electrode, 7- insulating connector, 8- micrometer head. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] While some exemplary embodiments of the present invention have been described for the purpose of illustration, it should be understood that the present invention may be implemented in other ways not specifically shown in the drawings.

[0030] like Figure 1-5 As shown, in a specific embodiment, an experimental system for a multi-sample corona aging process is provided, including an insulating support plate 3 and a plate electrode. In this embodiment, the insulating support plate 3 is a plate-like structure with a certain thickness, the insulating support is arranged horizontally, and the plate electrode is located at the lower end of the insulating support plate 3, and the plate electrode is also arranged horizontally.

[0031] A number of electrode assemblies are evenly arranged in an array on the insulating support plate 3, and the electrode assembly includes a bracket and a column electrode 6 installed on the bracket. The column electrode 6 is a column structure, and the central axis of the column electrode 6 is perpendicular to the plate surface of the insulating support plate 3. The upper end of the column electrode 6 is a fixed side, and the lower end is an experimental side. The central axis of the micrometer head 8 is perpendicular to the plate surface of the insulating support plate 3. The upper and lower positions of the column electrode 6 are adjusted by adjusting the micrometer head 8, thereby controlling the distance between the end face of the experimental side of the column electrode 6 and the plate electrode.

[0032] In this embodiment, the micrometer head 8 is a mechanical micrometer head, made of manganese steel, with a measuring range of 0-13mm, a measuring accuracy of 0.1mm, an installation diameter of 9.5mm, a rotating head with friction lines at the top, a diameter of 13mm, and a metal column with a diameter of 5mm at the bottom. The clamp part of the micrometer head clamp 5 is rubber-coated to ensure that the micrometer head 8 is perpendicular to the insulating upper plate, the clamp controllable range is 9-10mm, and the measuring hole diameter is 4mm.

[0033] In this embodiment, the column electrode 6 is made of copper and is a cylindrical structure with a length of 30 mm and a diameter of a circular cross section of 6 mm. The upper end face of the column electrode 6 is a plane, which is convenient for bonding with the insulating connector 7. In order to reduce the electric field concentration and thus generate corona more evenly, the edge of the lower end face of the column electrode 6 is set to a 1 mm chamfered structure, and the bottom diameter after chamfering is 4 mm.

[0034] The fixed side of the column electrode 6 is fixedly connected to the micrometer head 8 through an insulating connector 7. The insulating connector 7 in this embodiment is made of epoxy resin, which bonds the lower end of the micrometer head 8 and the upper end surface of the column electrode 6 together.

[0035] As shown in the figure, the bracket includes a C-type clamp 4, and the C-type clamp 4 is connected to the insulating support plate 3 through a threaded fastener. The C-type clamp 4 is connected to the micrometer head 8 through a threaded fastener. The threaded fastener includes a stud and a bolt. The C-type clamp 4 is made of 304 stainless steel and has a circular opening on it for fixing the hexagonal screw 1 and the hexagonal nut 2 on the insulating support plate 3. There are circular openings on the side for the hexagonal screw 1 and the hexagonal nut 2 to connect the micrometer head clamp 5. The opening of the C-type clamp 4 is 25mm, the controllable range is 0-220mm, the plate width is 25mm, the edge length is 27mm, and the diameter of the upper hole and the side hole is 4mm.

[0036] The plate electrode includes an insulating base plate and an aluminum foil paper laid on the insulating base plate, and the aluminum foil paper is grounded through an electric wire. The insulating base plate is also a glass fiber board with a thickness of 20 mm and a bottom surface of 450 mm×640 mm. The insulating support plate 3 is a glass fiber board with a thickness of 15 mm, a width of 50 mm, and a length of 200 mm.

[0037] Based on the experimental system implementation of a multi-sample corona aging process, in a specific embodiment, an experimental method for a multi-sample corona aging process is provided, comprising the following steps:

[0038] S1. Build an experimental system for the corona aging process of multiple samples, including three insulating support plates 3, on which three electrode assemblies are evenly arrayed. Before the formal measurement begins, connect the nine column electrodes 6 to a protective resistor with a resistance value of 1 megohm with experimental wires, and the protective resistor is connected to a transformer. The aluminum foil laid on the insulating bottom plate is grounded by the experimental wires.

[0039] One insulating upper plate can use three electrode systems. At this time, the total length of the insulating support plate 3 is 640mm. The side of the insulating support plate 3 is supported by a rectangular support column, so that there is an experimental space between the insulating support plate 3 and the plate motor. The height of the rectangular column is 65mm. The size of the plate electrode is 20mm×50mm, and its material is the same as the insulating support plate 3. In order to ensure the safety of the experiment and the influence of the placement of each column electrode 6, the spacing between each measuring column electrode 6 system is more than 200mm, and the spacing between the three insulating support plates 3 is 100mm.

[0040] S2. Fix the sample to be tested on the plate electrode at the end of the experimental side of the column electrode 6, and adjust the distance between the end surface of the experimental side of the column electrode 6 and the sample.

[0041] Each sample in this embodiment is a uniform sample with a thickness of 0.2 mm and a diameter of 60 mm. Before the experiment, the sample to be tested needs to be cleaned with alcohol and deionized water to ensure that there is no stain on the surface of the sample. The 9 samples to be tested are placed directly under the 9 column electrodes 6, and the edges of the samples are covered with glass sheets to ensure that the positions of the samples remain unchanged during the experiment. Then, the micrometer head 88 is adjusted clockwise until the column electrode 66 just touches the surface of the sample, and then the micrometer head 8 is adjusted in the opposite direction. When the experimental distance between the sample and the column electrode 6 reaches the experimental distance value, it stops. In this embodiment, the experimental distance value is set to 0.1 mm, and this value can be flexibly set and adjusted as needed.

[0042] S3. Increase the voltage at a certain rate until it reaches a preset voltage value and then start timing. When 5 samples are broken down, the experiment ends and the experimental time is recorded.

[0043] In this embodiment, the voltage of the power frequency AC transformer is controlled by the voltage regulator. The power frequency AC transformer can output a voltage of 0-40kV. The circuit principle is as follows: Figure 6 As shown. During the measurement, the voltage regulator is controlled to boost the power frequency AC transformer to 4kV at a boost speed of 0.5kV / s. After the boost is completed, the timer is turned on to start timing. The 9 samples are placed under the 9-column electrode 6 respectively. When the 5th sample breaks down, the timing is stopped and the experimental time is recorded. Repeating the above steps, the breakdown samples and corona resistance life results of the 6 materials can be finally obtained as shown in Figure 7 and Figure 8 shown.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An experimental system for multi-sample corona aging process, characterized in that: It includes an insulating support plate, on which electrode assemblies are evenly arranged in an array, the electrode assembly includes a bracket and a column electrode installed on the bracket, the column electrode is a column structure, the central axis of the column electrode is perpendicular to the plate surface of the insulating support plate, one end of the column electrode is a fixed side, and the other end is an experimental side, a micrometer head is installed on the fixed side of the column electrode, and the central axis of the micrometer head is perpendicular to the plate surface of the insulating support plate.

2. The experimental system for the multi-sample corona aging process according to claim 1, characterized in that: The column electrode and the micrometer head are fixedly connected via an insulating connector.

3. The experimental system for corona aging process of multiple samples according to claim 1, characterized in that: The end of the pillar electrode on the experimental side is chamfered.

4. The experimental system for the corona aging process of multiple samples according to claim 1, characterized in that: The bracket includes a C-shaped clamp, the C-shaped clamp is connected to the insulating support plate through a threaded fastener, and the C-shaped clamp is connected to the micrometer head through a threaded fastener.

5. The experimental system for corona aging process of multiple samples according to claim 1, characterized in that: The experimental system comprises a plate electrode, which is located at the end surface of the experimental side of the column electrode.

6. The experimental system for corona aging process of multiple samples according to claim 5, characterized in that: The plate electrode comprises an insulating base plate and aluminum foil paper laid on the insulating base plate, and the aluminum foil paper is grounded through an electric wire.

7. An experimental method for the corona aging process of multiple samples, characterized in that: The experimental system for the corona aging process of multiple samples according to any one of claims 1 to 5 is implemented, comprising the following steps: An experimental system for the corona aging process of multiple samples is constructed, comprising m insulating support plates, on which n electrode assemblies are evenly arranged in an array; Fix the sample on the plate electrode at the port on the experimental side of the column electrode, and adjust the distance between the end surface of the experimental side of the column electrode and the sample; Apply a preset voltage to the column electrode and start timing. When s samples are broken down, the experiment ends and the experimental time is recorded.

8. The experimental method for corona aging process of multiple samples according to claim 7, characterized in that: The method for applying the preset voltage is: increasing the voltage at a boost speed until the preset voltage value is reached and maintaining the current voltage.

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