An electrical insulation material oil immersion characteristic test system

Abstract

The utility model belongs to oil -immersed transformer technical field relates to an electrician insulating material oil immersion characteristic test system, sealed oil tank intercommunication oil storage cabinet, oil storage cabinet intercommunication oil pump, oil pump intercommunication oil heater and controller, oil heater and controller intercommunication sealed oil tank, sample is located between upper electrode and lower electrode and is placed in sealed oil tank, upper electrode connects high resistance meter, dielectric loss tester and high voltage output and partial discharge monitoring device, optical fiber temperature monitoring device passes through optical fiber connection optical fiber adapter box, and optical fiber adapter box is installed on the upper portion of sealed oil tank, and optical fiber adapter box connects temperature sensor one end, and temperature sensor other end passes through temperature sensor fixed connection sample, and optical fiber temperature monitoring device passes through analog output cable connection oil heater and controller. The utility model discloses through temperature sensor and electrode device monitoring electrician insulating material's temperature, measures insulation resistance value and dielectric loss value, has guaranteed electrician insulating material oil immersion characteristic test result's accuracy.

Description

Technical Field

[0001] This utility model belongs to the technical field of oil-immersed transformers, specifically relating to a testing system for the oil immersion characteristics of electrical insulation materials. It is mainly used to obtain the relationship between the oil immersion time and the oil immersion temperature of electrical insulation materials, thereby guiding the formulation of oil immersion process methods for oil-immersed transformer products. Background Technology

[0002] The insulating materials used in oil-immersed transformers can be divided into two types according to their form: solid and liquid. Solid insulating materials are generally called "electrical insulating materials," including various solid forms of insulating materials such as insulating paper, insulating paperboard, laminated paperboard, laminated wood, and aramid paper, with a relative permittivity of generally 3 to 4. Liquid insulating materials include various insulating oils such as mineral oil, natural ester oil, and synthetic ester oil, with a relative permittivity of generally around 2 to 3.

[0003] To ensure the safe, stable, and long-term use of electrical insulation materials within oil-immersed transformers, especially to prevent partial discharge in high-field electromagnetic environments, it is essential to ensure that the electrical insulation materials are thoroughly "impregnated" with insulating oil before the transformer undergoes high-voltage testing at the factory. This means that there should be no gaps or areas in the electrical insulation material that are not impregnated with insulating oil. This process is generally called oil impregnation or insulation treatment. The process involves heating the insulating oil using a vacuum oil filter (different types of insulating oil require different heating temperatures; for example, mineral oil is generally heated to around 55°C). The dried electrical insulation material is then continuously immersed in the hot insulating oil atmosphere for a certain period of time, allowing the hot insulating oil to continuously permeate the material until it is "impregnated." Therefore, the key to the oil impregnation process is the matching of the temperature of the electrical insulation material, the temperature of the insulating oil, and the impregnation time.

[0004] Because laminated paperboard and laminated wood are more difficult to "impregnate" compared to other materials, they are generally chosen as samples. Currently, the main method used in the transformer industry to determine oil impregnation process parameters is as follows: after drying the electrical insulation material sample, it is immersed in hot insulating oil. Samples are taken out at regular intervals and sawn; the color of the oil-impregnated area will darken, and the color change of the sample cross-section is examined to determine the impregnation effect. This method has significant technical shortcomings. Therefore, the oil impregnation characteristics obtained by this method are generally multiplied by 2 to 3 times, or even 4 times, in practical applications to consider equipment safety margins. Its technical shortcomings include not considering the temperature of the electrical insulation material (the temperature of the insulating oil and the temperature of the electrical insulation material are not equivalent; the higher the temperature of the electrical insulation material, the easier it is for oil molecules to penetrate), and the inability to accurately determine the impregnation state through visual observation of the cross-section (the color difference between the non-impregnated and impregnated areas is small, and a single cross-section cannot characterize the entire state of the electrical insulation material). Summary of the Invention

[0005] To address the aforementioned technical problems, this utility model provides a testing system for the oil immersion characteristics of electrical insulation materials. The technical solution of this utility model to achieve the above objectives is as follows: A system for testing the oil immersion characteristics of electrical insulation materials includes a sealed oil tank, an oil heater and controller, and an oil conservator. The sealed oil tank has an upper flange cover on its top and upper and lower connection ports on its side wall. The upper connection port is connected to the B2 channel of a three-way valve two via a transparent oil pipe. The A2 channel of the three-way valve two is connected to the oil conservator valve one of the oil conservator via a transparent oil pipe. The C2 channel of the three-way valve two is connected to an oil pump via a transparent oil pipe. The oil pump is connected to the oil heater and controller via a transparent oil pipe. The oil heater and controller are connected to the C3 channel of a three-way valve three via a transparent oil pipe. The A3 channel of the three-way valve three is connected via a transparent oil pipe. The oil tank valve 2 is connected to the oil tank, and the B3 channel of the three-way valve 3 is connected to the lower connection port through a transparent oil pipeline; the sample is located between the upper electrode and the lower electrode and placed in the sealed oil tank. The upper electrode is electrically connected to the high resistance meter, dielectric loss tester, and high voltage output and partial discharge monitoring device located outside the sealed oil tank. The lower electrode is grounded. The fiber optic temperature monitoring device located outside the sealed oil tank is connected to the fiber optic adapter box through a fiber optic cable. The fiber optic adapter box is installed on the upper flange cover plate. One end of the fiber optic cable is connected to the fiber optic cable, and the other end of the fiber optic cable is connected to the temperature sensor installed on the sample. The fiber optic temperature monitoring device is electrically connected to the oil heater and controller through an analog output cable.

[0006] Preferably, it also includes a vacuum pump, with the upper connection port connected to the B1 channel of the three-way valve one via a transparent oil pipe, the A1 channel of the three-way valve one connected to the vacuum pump via a transparent oil pipe, and the C1 channel of the three-way valve one connected to the B2 channel of the three-way valve two via a transparent oil pipe.

[0007] Preferably, the vacuum pump is equipped with a vacuum gauge.

[0008] Preferably, the sealed oil tank is a quartz glass oil tank with a cylindrical box structure, the upper electrode is a cylindrical upper electrode, and the lower electrode is a cylindrical lower electrode.

[0009] Preferably, a circular insulating bracket made of quartz glass is welded to the lower surface of the quartz glass tank, and the cylindrical lower electrode is placed on the circular insulating bracket.

[0010] Preferably, the temperature sensor is fixed to the side of the sample by Nomex insulating tape.

[0011] Preferably, the test system is placed in an electromagnetic shielding room, where the background partial discharge is <2pC.

[0012] The beneficial effects of this utility model are: This invention involves installing a temperature sensor on the surface of an electrical insulation material to measure its temperature during the oil immersion stage. Electrode devices are installed on the upper and lower surfaces of the electrical insulation material to measure its insulation resistance under DC voltage, dielectric loss under AC voltage, and partial discharge under high voltage during the oil immersion stage. The changing trends of the insulation resistance and dielectric loss values ​​accurately determine the oil immersion endpoint time, and the partial discharge quantity is then used for final confirmation, ensuring the accuracy and reliability of the oil immersion characteristic test results for the electrical insulation material. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is an overall layout diagram of the testing system according to an embodiment of the present utility model; Figure 2 This is a schematic diagram of the insulating oil preheating of the test system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the oil immersion process of the electrical insulation material in the test system of this utility model embodiment; In the diagram, 1 is a quartz glass oil tank, 2.1 is a cylindrical upper electrode, 2.2 is a cylindrical lower electrode, 2.3 is a shielded electrode lead wire, 2.4 is a shielded cable, 2.5 is a cable junction box, 3 is a grounding point, 4.1 is a temperature sensor, 4.2 is an optical fiber lead, 4.3 is an optical fiber temperature monitoring device, 4.4 is an optical fiber junction box, 4.5 is an optical fiber, 4.6 is an analog output cable, 5 is a high-resistance meter, 6 is a dielectric loss tester, 7 is a high-voltage output and partial discharge monitoring device, 8 is an oil heater and controller, 9 is an oil pump, 10 is a vacuum pump, 11 is an oil tank, 12.1 is a three-way valve one, 12.2 is a three-way valve two, 12.3 is a three-way valve three, 13 is a sample, 14 is an oil tank valve one, and 15 is an oil tank valve two. Detailed Implementation

[0014] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0015] like Figure 1 As shown, this utility model embodiment provides a testing system for the oil immersion characteristics of electrical insulation materials, comprising two components: 1. Insulating oil circulation and temperature control section.

[0016] It consists of a quartz glass oil tank 1, a fiber optic temperature measurement and analog output device, an oil heater and controller 8, an oil pump 9, a vacuum pump 10, an oil storage tank 11, a three-way valve, and transparent oil pipelines connected by the three-way valve. The transparent oil pipelines facilitate observation of the insulating oil flow at any time. The temperature control section is used to ensure that the temperature of the insulating oil in the quartz glass oil tank 1 meets the set value. The insulating oil circulation section is used to ensure continuous circulation of the insulating oil. At the same time, the oil storage tank 11 ensures that the insulating oil does not come into contact with oxygen and moisture in the air during heating and circulation, thus preventing oxidation and deterioration of the insulating oil and changes in the water content of the insulating oil.

[0017] The quartz glass oil tank 1 is a cylindrical box with a sealed structure. It is equipped with an upper flange cover plate on the top. The side wall of the quartz glass oil tank 1 is provided with an upper connection port and a lower connection port. The upper connection port is connected to the B1 channel of the three-way valve 12.1 through a transparent oil pipe, and the lower connection port is connected to the B3 channel of the three-way valve 12.3 through a transparent oil pipe. The A1 channel of three-way valve 12.1 is connected to the vacuum pump 10 with a vacuum gauge. The C1 channel of three-way valve 12.1 is connected to the B2 channel of three-way valve 22.2 through a transparent oil pipe. The A2 channel of three-way valve 22.2 is connected to the oil tank valve 14 at the oil inlet below the end of the oil tank 11 through a transparent oil pipe. The C2 channel of three-way valve 22.2 is connected to the oil outlet of the oil pump 9 through a transparent oil pipe. The oil inlet channel of the oil pump 9 is connected to the oil outlet of the oil heater and controller 8 through a transparent oil pipe. The oil inlet of the oil heater and controller 8 is connected to the C3 channel of three-way valve 32.3 through a transparent oil pipe. The A3 channel of three-way valve 32.3 is connected to the oil tank valve 25 at the oil outlet on the side of the oil tank 11 through a transparent oil pipe.

[0018] The fiber optic temperature measurement and analog output device includes a temperature sensor 4.1, an outgoing optical fiber 4.2, a fiber optic temperature monitoring device 4.3, a fiber optic adapter box 4.4, an optical fiber 4.5, and an analog output cable 4.6. The input end of the fiber optic temperature monitoring device 4.3 is connected to the output end of the fiber optic adapter box 4.4 via the optical fiber 4.5. The fiber optic adapter box 4.4 is mounted on the upper flange cover of the quartz glass oil tank 1. The input end of the fiber optic adapter box 4.4 is connected to the temperature sensor 4.1 located inside the quartz glass oil tank 1 via the outgoing optical fiber 4.2. The output end of the fiber optic temperature monitoring device 4.3 is electrically connected to the oil heater and controller 8 via the analog output cable 4.6.

[0019] The heater and controller 8 are existing, mature products, and the GD-40 type pipeline heater can be used. The GD-40 type pipeline heater works by using thermocouples to monitor the oil temperature and control the heater's on / off state: heating stops when the oil temperature exceeds the set value by 2°C, and resumes when the oil temperature falls below the set value by 2°C. The analog output cable 4.6 outputs an analog signal that replaces the original thermocouple temperature value in the oil heater and controller 8 to control the insulating oil temperature in the area where sample 13 is located.

[0020] The high-voltage output and partial discharge monitoring device 7 is an existing mature product. It can use a 150kV AC booster device without partial discharge, a 500pF coupling capacitor without partial discharge, and a TWPD-2F multi-channel digital partial discharge comprehensive analyzer. The high-voltage output and partial discharge monitoring method is an existing mature method.

[0021] 2. Electrical parameter measurement section of sample 13.

[0022] It consists of an electrode assembly, a grounding point 3, a high-resistance meter 5, a dielectric loss tester 6, and a high-voltage output and partial discharge monitoring device 7. The electrode assembly includes a cylindrical upper electrode 2.1, a cylindrical lower electrode 2.2, a shielded electrode lead-out wire 2.3, a shielded cable 2.4, and a cable adapter box 2.5. The high-resistance meter 5, dielectric loss tester 6, and high-voltage output and partial discharge monitoring device 7 are all separate testing systems and are existing products. According to the test procedure, for each electrical parameter measurement, one of the high-resistance meter 5, dielectric loss tester 6, or high-voltage output and partial discharge monitoring device 7 is electrically connected to the output end of the cable adapter box 2.5 through the shielded cable 2.4 to complete the electrical parameter measurement. The cable adapter box 2.5 is installed on the upper flange cover plate of the quartz glass oil tank 1. The input end of the cable adapter box 2.5 is electrically connected to the cylindrical upper electrode 2.1 located inside the quartz glass oil tank 1 through the shielded wire 2.3 led out by the electrode. The sample 13 is placed below the cylindrical upper electrode 2.1, and the cylindrical lower electrode 2.2 is placed below the sample 13. The cylindrical lower electrode 2.2 is led out from the quartz glass oil tank 1 through the shielded wire 2.3 led out by the electrode, and then grounded through the grounding point 3. One end of the optical fiber 4.2 is connected to the optical fiber adapter box 4.4, and the other end of the optical fiber 4.2 is connected to the temperature sensor 4.1. The temperature sensor 4.1 is fixed to the side of the sample 13 with Nomex insulating tape. The shielded cable 2.4 is used to output voltage to the cylindrical upper electrode 2.1 and also to transmit measurement data.

[0023] A circular insulating bracket is welded to the lower surface of the quartz glass oil tank 1. The circular insulating bracket is also made of quartz glass. The cylindrical lower electrode 2.2 rests directly on the circular insulating bracket.

[0024] To ensure the accuracy of partial discharge monitoring, the entire testing system is placed in an electromagnetic shielding room, where the background partial discharge is <2pC.

[0025] The operation and use steps of the oil immersion characteristic testing system for electrical insulation materials are as follows: 1. Test procedure for oil immersion characteristics of electrical insulation materials.

[0026] 1.1 Based on the type of insulating oil used in the transformer, with a temperature gradient of 5℃, the test temperature range for the oil immersion characteristics of electrical insulation materials using mineral insulating oil is 40~60℃, and the test range for the oil immersion characteristics of electrical insulation materials using non-mineral insulating oil is 60~80℃. For the oil immersion characteristic test of electrical insulation materials, a total of five samples (13 samples) were tested under each temperature condition, and the average value was taken to eliminate the influence of material dispersion.

[0027] 1.2 After the electrical insulation material has been immersed in oil for one hour, electrical parameter measurements are started. The dielectric loss tester 6 and the high resistance meter 5 are used to measure the dielectric loss value and the insulation resistance value first, to avoid the residual charge affecting the dielectric loss value test when the insulation resistance value test is performed under DC voltage first. After the insulation resistance value test is completed, the shielded cable 2.4 is grounded through the grounding point 3, and the grounding time is maintained for half an hour to completely eliminate the residual DC charge. Subsequently, the dielectric loss value and insulation resistance value are measured every hour.

[0028] 1.3 As the oil impregnation process of the electrical insulation material continues, the dielectric loss value of the electrical insulation material gradually decreases and tends to stabilize, while the insulation resistance value gradually increases and tends to stabilize. When the difference between the dielectric loss value and insulation resistance value of two consecutive tests does not exceed 2%, partial discharge monitoring is performed using the high-voltage output and partial discharge monitoring device 7. The partial discharge test voltage is the allowable voltage value of the electrical insulation material in the transformer. If the partial discharge quantity does not exceed 3pC, the oil impregnation characteristic test at that temperature is considered complete. If the partial discharge quantity exceeds 3pC, the oil impregnation process continues, and the partial discharge quantity is tested every two hours until the requirements are met.

[0029] The oil immersion time for electrical insulation materials is the partial discharge test time minus the time at which the oil immersion begins.

[0030] 2. Sample placement.

[0031] Remove the upper flange cover of the quartz glass oil tank 1. Place the dried sample 13 on top of the cylindrical lower electrode 2.2, aligning the center of sample 13 with the center of the cylindrical lower electrode 2.2. Place the temperature sensor 4.1 on the side of sample 13 and secure it with Nomex insulating tape. Then, place the cylindrical upper electrode 2.1 on top of sample 13, aligning the center of the cylindrical upper electrode 2.1 with the center of sample 13. Connect the temperature sensor 4.1 to the fiber optic adapter box 4.4 via the lead-out optical fiber 4.2. Connect the cylindrical upper electrode 2.1 to the cable adapter box 2.5 via the lead-out shielded wire 2.3. Install the upper flange cover of the quartz glass oil tank 1 and reseal the quartz glass oil tank 1.

[0032] 3. Vacuuming and preheating of insulating oil in quartz glass oil tank 1.

[0033] 3.1 An oil inlet is provided at the top of the oil storage tank 11. Close oil storage tank valve 14 and oil storage tank valve 2 15, and inject insulating oil that meets the oil sample standard requirements into the oil storage tank 11. After the insulating oil is injected, connect each transparent oil pipeline.

[0034] 3.2 Open the A1, B1, and C1 channels of three-way valve 12.1, the A2, B2, and C2 channels of three-way valve 22.2, and the A3, B3, and C3 channels of three-way valve 32.3. Turn on vacuum pump 10 and evacuate to 100 Pa (read directly by vacuum gauge) to expel air from the quartz glass oil tank 1, oil heater and controller 8, oil pump 9, and transparent oil pipeline. Vacuuming can prevent air from entering the entire oil flow system during the oil immersion process, thereby avoiding any impact on the stability of the measurement results.

[0035] 3.3 Close the B2 channel of three-way valve 2 12.2 and the B3 channel of three-way valve 3 12.3; continue to evacuate for three hours to remove air and surface moisture from sample 13.

[0036] 3.4. Open oil conservator valve 14 and oil conservator valve 25, start oil pump 9 to circulate the oil, turn on oil heater and controller 8 and set the oil immersion characteristic test temperature to raise the temperature of the insulating oil in oil conservator 11 and pipelines to the set temperature. The circulation path of the insulating oil at this time is as follows: Figure 2 As indicated by the arrow.

[0037] 4. Add oil to the quartz glass oil tank 1.

[0038] 4.1 Open the B3 channel of the three-way valve 12.3. The insulating oil enters the quartz glass oil tank 1 under the action of pressure difference. When the insulating oil reaches the B1 channel of the three-way valve 12.1, close the A1 channel of the three-way valve 12.1 and the vacuum pump 10. At this time, the sample 13 is completely immersed in the airless insulating oil environment.

[0039] 4.2 Connect the analog output cable 4.6 to the oil heater and controller 8, and input the set test temperature into the heater and controller 8 to accurately control the temperature of the insulating oil in the quartz glass oil tank 1.

[0040] 4.3 Open the B2 channel of three-way valve 2 (12.2) and close the A3 channel of three-way valve 3 (12.3). At this time, the oil heater and controller 8 will mainly be used to heat the insulating oil in the quartz glass oil tank 1. The oil circulation path at this time is as follows: Figure 3As indicated by the arrow. The transparent oil pipeline between valve 14 and the A2 channel of three-way valve 12.2, and the oil reservoir 11, are used to compensate for changes in the volume of insulating oil and prevent overpressure in the transparent oil pipeline.

[0041] 5. Measurement of electrical parameters.

[0042] 5.1 The test voltage of the dielectric loss tester 6 is set to 200V, the measurement frequency is set to 1Hz, and the average value is taken after three measurements to obtain the dielectric loss value.

[0043] 5.2 The high resistance meter 5 outputs a DC voltage. The test voltage of the high resistance meter 5 is set to 500V. The insulation resistance value is obtained by taking the average value of three measurements.

[0044] 5.3 The high-voltage output and partial discharge monitoring device 7 outputs AC voltage. The voltage setting of the high-voltage output and partial discharge monitoring device 7 is calculated based on the allowable field strength of electrical insulation materials used in transformers, generally not exceeding 2.5kV / mm. The test voltage value is 2.5kV / mm multiplied by the thickness of the sample 13. The voltage boosting method is 500V / s, and after boosting to the test voltage value, it is held for 60 seconds. During the voltage boosting process, the partial discharge quantity is observed, and then the voltage is reduced to end the partial discharge monitoring.

[0045] 6. Plotting the oil immersion characteristic curves of electrical insulation materials.

[0046] 6.1. Based on the electrical parameter measurement results, the oil immersion time value corresponding to each temperature is obtained. The oil immersion time value for each temperature is the average value of five samples 13, and the maximum and minimum values ​​of the oil immersion time are recorded.

[0047] 6.2 Plot the oil immersion characteristic curve of electrical insulation material with immersion time as the x-axis and temperature as the y-axis. Each data point is temperature / immersion time, and the maximum and minimum immersion time of each data point are marked and represented by error bars.

[0048] In this embodiment of the utility model, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.

[0049] Finally, it should be noted that the above embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model.

Claims

1. A system for testing the oil immersion characteristics of electrical insulation materials, comprising a sealed oil tank, an oil heater and controller (8), and an oil storage tank (11), wherein the top of the sealed oil tank is provided with an upper flange cover, characterized in that, The sealed oil tank has an upper connection port and a lower connection port on its side wall. The upper connection port is connected to the B2 channel of the three-way valve two (12.2) through a transparent oil pipe. The A2 channel of the three-way valve two (12.2) is connected to the oil tank valve one (14) of the oil tank (11) through a transparent oil pipe. The C2 channel of the three-way valve two (12.2) is connected to the oil pump (9) through a transparent oil pipe. The oil pump (9) is connected to the oil heater and controller (8) through a transparent oil pipe. The oil heater and controller (8) is connected to the C3 channel of the three-way valve three (12.3) through a transparent oil pipe. The A3 channel of the three-way valve three (12.3) is connected to the oil tank valve two (15) of the oil tank (11) through a transparent oil pipe. The B3 channel of the three-way valve three (12.3) is connected to the oil tank valve two (15) of the oil tank (11) through a transparent oil pipe. The pipeline is connected to the lower connection port; the sample (13) is located between the upper electrode and the lower electrode and placed in the sealed oil tank. The upper electrode is electrically connected to the high resistance meter (5), dielectric loss tester (6) and high voltage output and partial discharge monitoring device (7) located outside the sealed oil tank, respectively. The lower electrode is grounded. The fiber optic temperature monitoring device (4.3) located outside the sealed oil tank is connected to the fiber optic adapter box (4.4) through the fiber optic cable (4.5). The fiber optic adapter box (4.4) is installed on the upper flange cover plate. The fiber optic adapter box (4.4) is connected to one end of the lead fiber (4.2). The other end of the lead fiber (4.2) is connected to the temperature sensor (4.1) installed on the sample (13). The fiber optic temperature monitoring device (4.3) is electrically connected to the oil heater and controller (8) through the analog output cable (4.6).

2. The oil immersion characteristic testing system for electrical insulation materials according to claim 1, characterized in that, It also includes a vacuum pump (10), the upper connection port of which is connected to the B1 channel of the three-way valve (12.1) through a transparent oil pipe, the A1 channel of the three-way valve (12.1) is connected to the vacuum pump (10) through a transparent oil pipe, and the C1 channel of the three-way valve (12.1) is connected to the B2 channel of the three-way valve (12.2) through a transparent oil pipe.

3. The oil immersion characteristic testing system for electrical insulation materials according to claim 2, characterized in that, The vacuum pump (10) is equipped with a vacuum gauge.

4. The oil immersion characteristic testing system for electrical insulation materials according to claim 1, characterized in that, The sealed oil tank is a quartz glass oil tank with a cylindrical box structure (1), the upper electrode is a cylindrical upper electrode (2.1), and the lower electrode is a cylindrical lower electrode (2.2).

5. The oil immersion characteristic testing system for electrical insulation materials according to claim 4, characterized in that, The lower surface of the quartz glass oil tank (1) is welded with a circular insulating support made of quartz glass, and the cylindrical lower electrode (2.2) is placed on the circular insulating support.

6. The oil immersion characteristic testing system for electrical insulation materials according to claim 1, characterized in that, The temperature sensor (4.1) is fixed to the side of the sample (13) by Nomex insulating tape.

7. A testing system for the oil immersion characteristics of electrical insulation materials according to any one of claims 1-6, characterized in that, The test system is placed in an electromagnetic shielding room, where the background partial discharge is <2pC.

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