Electrical insulation material oil immersion characteristic test system and test method

Abstract

The invention belongs to the technical field of oil-immersed transformers, and relates to an electrical insulation material oil immersion characteristic test system and test method. In the test system, a quartz glass oil tank, an oil heater, a controller, a vacuum pump, an oil conservator, an electrode and a sample are connected through an oil pipeline and a three-way valve, the sample is provided with a temperature sensor, the temperature sensor is connected with an optical fiber temperature monitoring device, and the optical fiber temperature monitoring device is connected with the oil heater and the controller. The testing method comprises the following steps: putting a sample into the quartz glass oil tank, injecting oil into the oil conservator, vacuumizing the quartz glass oil tank, the oil heater, the controller, the oil pump and the transparent oil pipeline, heating the insulating oil, measuring electric parameters, and drawing an oil immersion characteristic curve of the electrical insulating material. According to the invention, the temperature of the electrical insulating material is monitored through the temperature sensor and the electrode device, the insulation resistance value and the dielectric loss value are measured, and the accuracy of the oil immersion characteristic test result of the electrical insulating material is ensured.

Description

Technical Field

[0001] This invention belongs to the technical field of oil-immersed transformers, specifically relating to a testing system and method for testing the oil immersion characteristics of electrical insulation materials. It is mainly used to obtain the relationship between the oil penetration time and the 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 invention provides a testing system and method for testing the oil immersion characteristics of electrical insulation materials. The technical solution of this invention to achieve the above objectives is as follows: A system for testing the oil immersion characteristics of electrical insulation materials includes a cylindrical sealed quartz glass oil tank, an oil heater and controller, a vacuum pump, and an oil storage tank. The quartz glass oil tank has an upper flange cover on its top and upper and lower connection ports on its side walls. The upper connection port is connected to the B1 channel of a three-way valve (or similar) via a transparent oil pipe. The A1 channel of the three-way valve (or similar) is connected to the vacuum pump. The C1 channel of the three-way valve (or similar) is connected to the B2 channel of a three-way valve (or similar) via a transparent oil pipe. The A2 channel of the three-way valve (or similar) is connected to the oil storage tank valve (or similar) via a transparent oil pipe. The C2 channel of the three-way valve (or similar) is connected to the 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 three-way valve (or similar) via a transparent oil pipe. The C3 channel is connected, and the A3 channel of the three-way valve three is connected to the oil tank valve two of the oil tank through a transparent oil pipe. The B3 channel of the three-way valve three is connected to the lower connection port through a transparent oil pipe. The sample is located between the cylindrical upper electrode and the cylindrical lower electrode and placed in the quartz glass oil tank. The cylindrical 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 quartz glass oil tank. The cylindrical lower electrode is grounded. The fiber optic temperature monitoring device located outside the quartz glass 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, the vacuum pump is equipped with a vacuum gauge.

[0007] 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.

[0008] Preferably, the temperature sensor is fixed to the side of the sample by Nomex insulating tape.

[0009] Preferably, the test system is placed in an electromagnetic shielding room, where the background partial discharge is <2pC.

[0010] A method for testing the oil immersion characteristics of electrical insulation materials, using the aforementioned oil immersion characteristic testing system for electrical insulation materials, includes the following steps: Place the dried sample on top of the cylindrical lower electrode, place the temperature sensor on the side of the sample and fix it with Nomex insulating tape, place the cylindrical upper electrode on top of the sample, connect the temperature sensor to the fiber optic adapter box, connect the cylindrical upper electrode to the cable adapter box, and seal the quartz glass tank. Close valve one and valve two of the oil conservator. Inject insulating oil that meets the oil sample standard requirements into the oil conservator. After the insulating oil is injected, connect all transparent oil pipelines. Open the three channels of the three three-way valves, turn on the vacuum pump to evacuate the air from the quartz glass oil tank, oil heater and controller, oil pump and transparent oil pipeline; Close the B2 channel of three-way valve two and the B3 channel of three-way valve three, and continue to evacuate the air and surface moisture of the sample. Open oil tank valve one and oil tank valve two, turn on the oil pump to circulate the oil, turn on the oil heater and controller and set the oil immersion characteristic test temperature to raise the temperature of the insulating oil in the oil tank and pipeline to the set temperature. Open the B3 channel of the three-way valve three, and the insulating oil enters the quartz glass oil tank under the action of pressure difference. When the insulating oil reaches the B1 channel of the three-way valve one, close the A1 channel of the three-way valve one and the vacuum pump, and immerse the sample in the airless insulating oil environment. Connect the analog output cable to the oil heater and controller, and input the set test temperature into the heater and controller to control the temperature of the insulating oil in the quartz glass oil tank. Open the B2 channel of the three-way valve 2 and close the A3 channel of the three-way valve 3. The oil heater and controller are used to heat the insulating oil in the quartz glass oil tank. The transparent oil pipeline between the oil storage tank valve 1 and the A2 channel of the three-way valve 2 and the oil storage tank are used to compensate for changes in the volume of the insulating oil. Perform electrical parameter measurements; Plot the oil-immersion characteristic curves of electrical insulation materials.

[0011] The preferred method for measuring electrical parameters is as follows: The dielectric loss value is obtained by taking three measurements with a dielectric loss tester and averaging them. The insulation resistance value is obtained by taking three measurements with a high resistance meter and averaging them. The AC voltage is output using a high-voltage output and partial discharge monitoring device. The voltage setting of the high-voltage output and partial discharge monitoring device is calculated based on the allowable field strength of electrical insulation materials used in transformers. The voltage is increased by 500V / s, and after reaching the test voltage value, it is held for 60 seconds. The partial discharge quantity is observed during the voltage increase, and then the partial discharge monitoring ends by reducing the voltage.

[0012] The preferred method for plotting the oil immersion characteristic curve of electrical insulation materials is as follows: Based on the electrical parameter measurement results, the oil immersion time value corresponding to each temperature was obtained. The oil immersion time of the electrical insulation material is the partial discharge monitoring time minus the start time of oil immersion. The oil immersion time value of each temperature is the average value of five samples, and the maximum and minimum values ​​of the oil immersion time are recorded. 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.

[0013] Preferably, the dielectric loss value is first measured using a dielectric loss tester, and then the insulation resistance value is measured using a high resistance meter; after the insulation resistance value test is completed, the shielded cable is grounded and kept there for half an hour.

[0014] Preferably, when the difference between the dielectric loss value and insulation resistance value of two adjacent tests does not exceed 2%, a high-voltage output and partial discharge monitoring device is used to monitor the partial discharge. The partial discharge monitoring voltage is the allowable voltage value of the electrical insulation material in the transformer. If the partial discharge does not exceed 3pC, the oil immersion characteristic test at this temperature is completed. If the partial discharge exceeds 3pC, the oil immersion process continues. The partial discharge is tested every two hours until the requirements are met.

[0015] The beneficial effects of this invention are: This invention involves installing a temperature sensor on the surface of an electrical insulating material to measure its temperature during the oil immersion stage. Electrode devices are installed on the upper and lower surfaces of the insulating 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 insulating material. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is an overall layout diagram of the testing system according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the insulating oil preheating of the test system in Embodiment 2 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 Embodiment 2 of the present invention; 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 wire, 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

[0017] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Example 1:

[0019] like Figure 1 As shown, Embodiment 1 of the present invention provides a testing system for the oil immersion characteristics of electrical insulation materials, comprising two components: 1. Insulating oil circulation and temperature control section.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 2. Electrical parameter measurement section of sample 13.

[0026] It consists of an electrode device, a grounding wire 3, a high resistance meter 5, a dielectric loss tester 6, and a high voltage output and partial discharge monitoring device 7. The electrode device 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 wire 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.

[0027] 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.

[0028] 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.

[0029] Example 2:

[0030] Embodiment 2 of the present invention provides a method for testing the oil immersion characteristics of electrical insulation materials, using the oil immersion characteristic testing system for electrical insulation materials described in Embodiment 1, and includes the following steps: 1. Test procedure for oil immersion characteristics of electrical insulation materials.

[0031] 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.

[0032] 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, in order 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 wire 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.

[0033] 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 monitoring 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.

[0034] The oil immersion time for electrical insulation materials is the partial discharge monitoring time minus the time at which oil immersion begins.

[0035] 2. Sample placement.

[0036] 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.

[0037] 3. Vacuuming and preheating of insulating oil in quartz glass oil tank 1.

[0038] 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.

[0039] 3.2 Open the A1, B1, and C1 channels of three-way valve 12.1, open the A2, B2, and C2 channels of three-way valve 22.2, and open 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.

[0040] 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.

[0041] 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.

[0042] 4. Add oil to the quartz glass oil tank 1.

[0043] 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.

[0044] 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.

[0045] 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 3 As 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.

[0046] 5. Measurement of electrical parameters.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 6. Plotting the oil immersion characteristic curves of electrical insulation materials.

[0051] 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.

[0052] 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.

[0053] In the embodiments of the present invention, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.

[0054] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention 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 within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; 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 the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A system for testing the oil immersion characteristics of electrical insulation materials, comprising a quartz glass oil tank (1) with a cylindrical sealed enclosure structure, an oil heater and controller (8), a vacuum pump (10), and an oil storage tank (11), wherein the top of the quartz glass oil tank (1) is provided with an upper flange cover plate, characterized in that, The quartz glass oil tank (1) has an upper connection port and a lower connection port on its side wall. The upper connection port is connected to the B1 channel of the three-way valve one (12.1) through a transparent oil pipe. The A1 channel of the three-way valve one (12.1) is connected to the vacuum pump (10). The C1 channel of the three-way valve one (12.1) 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 storage tank valve of the oil storage tank (11) through a transparent oil pipe. The first valve (14) is connected, the C2 channel of the second three-way valve (12.2) is connected to the oil pump (9) through a transparent oil pipeline, the oil pump (9) is connected to the oil heater and controller (8) through a transparent oil pipeline, the oil heater and controller (8) is connected to the C3 channel of the third three-way valve (12.3) through a transparent oil pipeline, the A3 channel of the third three-way valve (12.3) is connected to the oil tank valve (15) of the oil tank (11) through a transparent oil pipeline, and the third three-way valve (12.2) is connected to the oil tank valve (15) of the oil tank (11). 3) The B3 channel is connected to the lower connection port through a transparent oil pipe; the sample (13) is located between the cylindrical upper electrode (2.1) and the cylindrical lower electrode (2.2) and placed in the quartz glass oil tank (1). The cylindrical upper electrode (2.1) 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 quartz glass oil tank (1), respectively. The cylindrical lower electrode (2.2) is grounded and located outside the quartz glass oil tank (1). The fiber optic temperature monitoring device (4.3) is connected to the fiber optic adapter box (4.4) via 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-out fiber (4.2). The other end of the lead-out 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) via analog output cable (4.6).

2. The oil immersion characteristic testing system for electrical insulation materials according to claim 1, characterized in that, The vacuum pump (10) is equipped with a vacuum gauge.

3. The oil immersion characteristic testing system for electrical insulation materials according to claim 2, 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.

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

5. A testing system for the oil immersion characteristics of electrical insulation materials according to any one of claims 1-4, characterized in that, The test system is placed in an electromagnetic shielding room, where the background partial discharge is <2pC.

6. A method for testing the oil immersion characteristics of electrical insulation materials, characterized in that, The oil immersion characteristic testing system for electrical insulation materials as described in claim 3 includes the following steps: Place the dried sample (13) above the cylindrical lower electrode (2.2), place the temperature sensor (4.1) on the side of the sample (13) and fix it with Nomex insulating tape, place the cylindrical upper electrode (2.1) above the sample (13), connect the temperature sensor (4.1) to the fiber optic adapter box (4.4), connect the cylindrical upper electrode (2.1) to the cable adapter box (2.5), and seal the quartz glass oil tank (1); Close oil tank valve one (14) and oil tank valve two (15), inject insulating oil that meets the oil sample standard requirements into oil tank (11), and connect each transparent oil pipeline after the insulating oil is injected. Open the three channels of the three three-way valves, turn on the vacuum pump (10) to draw a vacuum, and expel the air from the quartz glass oil tank (1), oil heater and controller (8), oil pump (9) and transparent oil pipeline; Close the B2 channel of the three-way valve two (12.2) and the B3 channel of the three-way valve three (12.3), and continue to evacuate the air in the sample (13) and the surface moisture of the sample (13); Open oil tank valve one (14) and oil tank valve two (15), turn on oil pump (9) to circulate oil, turn on oil heater and controller (8) and set oil immersion characteristic test temperature to raise the temperature of insulating oil in oil tank (11) and pipeline to the set temperature. Open the B3 channel of the three-way valve (12.3), and 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), and the sample (13) is immersed in the airless insulating oil environment. 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 control the temperature of the insulating oil in the quartz glass oil tank (1); Open the B2 channel of the three-way valve two (12.2) and close the A3 channel of the three-way valve three (12.3). The oil heater and controller (8) are used to heat the insulating oil in the quartz glass oil tank (1). The transparent oil pipeline between the oil storage tank valve one (14) and the A2 channel of the three-way valve two (12.2) and the oil storage tank (11) are used to compensate for the change in the volume of the insulating oil. Perform electrical parameter measurements; Plot the oil-immersion characteristic curves of electrical insulation materials.

7. The method for testing the oil immersion characteristics of electrical insulation materials according to claim 6, characterized in that, The method for measuring electrical parameters is as follows: The dielectric loss value is obtained by taking the average value of three measurements using a dielectric loss tester (6); The insulation resistance value is obtained by taking the average value of three measurements using a high resistance meter (5); The AC voltage is output by the high voltage output and partial discharge monitoring device (7). 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. The voltage boosting method is 500V / s. After boosting to the test voltage value, it is held for 60 seconds. The partial discharge quantity is observed during the voltage boosting process. Then the voltage is reduced to end the partial discharge monitoring.

8. The method for testing the oil immersion characteristics of electrical insulation materials according to claim 7, characterized in that, The method for plotting the oil-immersion characteristic curves of electrical insulation materials is as follows: Based on the electrical parameter measurement results, the oil immersion time value corresponding to each temperature is obtained. The oil immersion time of the electrical insulation material is the partial discharge monitoring time minus the start time of oil immersion. The oil immersion time value of each temperature is the average value of five samples (13), and the maximum and minimum values ​​of oil immersion time are recorded. 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.

9. The method for testing the oil immersion characteristics of electrical insulation materials according to claim 7, characterized in that, First, use a dielectric loss tester (6) to measure the dielectric loss value, and then use a high resistance meter (5) to measure the insulation resistance value. After the insulation resistance value test is completed, ground the shielded cable (2.4) and keep it for half an hour.

10. A method for testing the oil immersion characteristics of electrical insulation materials according to claim 7, characterized in that, When the difference between the dielectric loss value and insulation resistance value of two adjacent tests does not exceed 2%, the high voltage output and partial discharge monitoring device (7) is used to monitor the partial discharge. The partial discharge monitoring voltage is the allowable voltage value of electrical insulation material in the transformer. If the partial discharge amount does not exceed 3pC, the oil immersion characteristic test at this temperature is over. If the partial discharge amount exceeds 3pC, the oil immersion process continues. The partial discharge amount is tested every two hours until the requirements are met.

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