Flashover characteristic testing device for deep cryogenic temperature region solid-liquid-gas triple point insulating material

Abstract

The application discloses a kind of deep cold temperature zone solid-liquid-gas three-state combination point insulating material flashover characteristic testing device, including test cavity, sample table, pressurization and current monitoring module, temperature control module, gas pressure control module and low-temperature liquid control module;Wherein, sample table is set in test cavity and connects sample table lifting device control test sample height, test cavity is used to provide low-temperature solid-liquid-gas three-state coexistence test environment, pressurization and current monitoring module is used to apply electric field on test sample surface and monitor current change, record flashover current waveform and protect circuit;Temperature control module is used to heat test sample single point and construct temperature gradient, and test sample different position temperature is monitored;Gas pressure control module is used to adjust gas phase environment gas pressure;Low-temperature liquid control module is used to regulate low-temperature liquid liquid level height.Can be carried out to insulating material in deep cold temperature zone solid-liquid-gas three-state combination point different low-temperature liquid, gas pressure, temperature gradient under insulating material surface direct current, alternating current and pulse flashover test.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-temperature extreme environment material surface flashover test, and particularly relates to a deep cold temperature zone solid-liquid-gas three-state junction point insulating material flashover characteristic test device and a test method. BACKGROUND

[0002] Superconducting systems are increasingly applied to superconducting power transmission, deep space exploration, controllable nuclear fusion and other frontier technologies. Liquid nitrogen and liquid helium are the most commonly used cooling sources in superconducting systems at present. However, low-temperature liquids inevitably volatilize due to factors such as temperature fluctuations, and then low-temperature liquids and gases coexist in the superconducting system, forming a solid-liquid-gas three-state junction point with insulating materials. The solid-liquid-gas three-state junction point is often the weak point of insulation in the superconducting system due to complex environment, concentrated electric field and super large temperature gradient. At present, there is no special test device for the flashover characteristics of the solid-liquid-gas three-state junction point in the deep cold temperature zone. Therefore, it is of great significance to design and develop a deep cold temperature zone solid-liquid-gas three-state junction point insulating material flashover characteristic test device that can artificially construct the temperature gradient on the surface of insulating materials and change the gas phase pressure. SUMMARY

[0003] In order to characterize the flashover characteristics of insulating materials at the solid-liquid-gas three-state junction point in the deep cold temperature zone, the purpose of the present application is to provide a deep cold temperature zone solid-liquid-gas three-state junction point insulating material flashover characteristic test device and a test method.

[0004] In order to achieve the above task, the present application adopts the following technical solutions:

[0005] A deep cold temperature zone solid-liquid-gas three-state junction point insulating material flashover characteristic test device, comprising: a test cavity, a sample table and a sample table lifting device, the sample table is arranged in the test cavity and is connected with the sample table lifting device to control the height of the test sample, the test cavity is used to provide a low-temperature solid-liquid-gas three-state coexistence test environment, and the sample table is used to load the test sample and apply a voltage to record the current change, characterized in that it further comprises: a pressure and current monitoring module, a temperature control module, a gas pressure control module and a low-temperature liquid control module, wherein:

[0006] The pressure and current monitoring module is used to apply an electric field to the surface of the test sample and monitor the current change to record the flashover current waveform;

[0007] The temperature control module is used to heat the test sample at a single point to form a temperature gradient and monitor the temperature at different positions of the test sample;

[0008] The gas pressure control module is used to adjust the gas phase environment pressure;

[0009] The low-temperature liquid control module is used to control the liquid level of the low-temperature liquid.

[0010] According to the application, the test cavity is a multilayer adiabatic stainless steel Dewar flask, the top cover of which is internally provided with hard foam plastic with good adiabatic performance to prevent the internal low-temperature liquid from volatilizing, and the test cavity has good overall sealing performance and can be used to build different gas pressure conditions from normal pressure to ultra-high vacuum inside the test cavity.

[0011] The sample table comprises a test sample, a ground electrode and a high-voltage electrode, the test sample is supported by a test sample support to ensure adhesion to the electrodes, the electrode fixing structure is provided with threads to be used to tighten the ground electrode and the high-voltage electrode, and the distance between the ground electrode and the high-voltage electrode can be adjusted through different screw holes provided in the ground electrode and the high-voltage electrode.

[0012] The sample table lifting device is connected to the sample table at one end and is a control end at the other end, is arranged outside the top end of the test cavity and is used to adjust the height of the sample table and change the depth of the test sample immersed in the low-temperature liquid.

[0013] The pressurization and current monitoring module comprises a high-voltage source and a current monitoring system, both of which are arranged outside the test cavity and are connected to the ground electrode and the high-voltage electrode in the test cavity through wires, the high-voltage source is used to provide direct current, alternating current or pulse voltage, a high electric field is formed on the surface of the test sample through the ground electrode and the high-voltage electrode, the current monitoring system is used to monitor the current change on the surface of the test sample, record the flashover current waveform and timely disconnect the high-voltage power supply after flashover occurs.

[0014] The temperature control module comprises a heating device, a heating wire, a temperature monitoring device and a temperature measurement array, the heating wire is arranged at the connection between the upper end of the sample table and the sample table lifting device to achieve the purpose of single-point heating, and the temperature measurement array is arranged at the upper part of the test sample, the middle part of the gas phase of the test sample, the liquid surface of the low-temperature liquid and the middle part of the liquid phase of the test sample to monitor the temperature gradient on the surface of the test sample.

[0015] The gas pressure control module comprises a gas pressure gauge, a gas pressure monitoring device, a vacuum pump, a gas feeding device and compressed gas.

[0016] The gas pressure gauge and the gas pressure monitoring device are used to monitor the gas phase pressure in the test cavity, and the vacuum pump, the gas feeding device and the compressed gas are used to build the gas environment in the test cavity and adjust the gas pressure.

[0017] The low-temperature liquid control module comprises a liquid level monitoring device, a low-temperature liquid feeding system and low-temperature liquid, the liquid level monitoring device is used to monitor the liquid level of the low-temperature liquid, and the low-temperature liquid feeding system feeds low-temperature liquid into the test cavity when the liquid level does not reach the specified height to keep the liquid level stable.

[0018] Specifically, the test sample is a flat and insulating material in the form of a sheet, and the thickness thereof ranges from 1 μm to 1 cm.

[0019] Further, the compressed gas is mainly compressed nitrogen or compressed helium, corresponding to the type of low-temperature liquid.

[0020] Further, the low-temperature liquid is mainly liquid nitrogen or liquid helium.

[0021] The test method of the deep cooling temperature zone solid-liquid-gas triple point insulation material flashover characteristic test device has the characteristics that the following steps are performed:

[0022] Step 1: Install the test sample on the sample table, tighten the test sample support, adjust the electrode spacing, tighten the electrode fixing structure, and then install the sample table on the cover top sample table lifting device.

[0023] Step 2: Inject a small amount of low-temperature liquid into the test chamber several times, gradually reduce the temperature of the tank, and the amount of low-temperature liquid added during the cooling process should be less than the final low-temperature liquid amount, then install the test chamber cover top, and fix it;

[0024] Step 3: Adjust the height of the sample table to the specified position, and fix the sample table lifting device;

[0025] Step 4: Set the test gas phase environment, the gas type should correspond to the selected low-temperature liquid, open the vacuum pump to pump out part of the gas in the test chamber, close the vacuum pump valve, open the gas feeding device valve, feed the specified gas to 1 standard atmosphere, then close the gas feeding device valve, open the vacuum pump valve to pump out part of the gas in the test chamber, close the vacuum pump valve, open the gas feeding device valve, feed the specified gas to 1 standard atmosphere, repeat the above steps 2~3 times, until the gas in the test sample chamber is replaced by the specified gas, then close the feeding device valve, open the vacuum pump, and reach the specified gas pressure;

[0026] Step 5: Set the height of the low-temperature liquid level, which should be located between the two electrodes, open the low-temperature liquid control module, and feed the low-temperature liquid to the specified height;

[0027] Step 6: Set the surface temperature gradient of the test sample, set the temperature of the heating wire to the required maximum temperature of the sample surface, and monitor the temperature gradient of the sample surface using the temperature array;

[0028] Step 7: Open the pressurization and current monitoring module, set the high voltage (which can be alternating, direct current or pulse voltage) waveform applied to the sample surface, and monitor and record the output current waveform at the same time until flashover occurs;

[0029] Step 8: Check the low-temperature liquid level, atmospheric conditions and temperature conditions, if they meet the test requirements, repeat step 7, if they do not meet the requirements, repeat steps 4-6 to restore the test conditions to the original settings, and then repeat step 7 test;

[0030] Step 9: repeat step 8, according to the test insulation material setting, repeat 10-100 times, until the flashover test is completed;

[0031] Step 10: close the pressure and current monitoring module, close the temperature control module, open the gas feeding device to the test cavity, and restore the gas pressure to normal pressure; open the test cavity, replace the sample, repeat the test steps 1-9, or complete the test and close the test system.

[0032] The deep cold temperature zone solid-liquid-gas triple point insulation material flashover characteristic testing device provided by the application is the first to target the special environment of the deep cold temperature zone solid-liquid-gas triple point, and can artificially construct a temperature gradient, and can perform direct current, alternating current and pulse flashover tests on the surface of the insulation material under different low-temperature liquids, different gas pressures and different temperature gradients.

[0033] Compared with the prior art, the technical innovation brought by the application is that:

[0034] (1) the deep cold temperature zone solid-liquid-gas triple point environment is directly constructed in the test cavity, and the surface flashover characteristics of the insulation material under this special environmental condition are characterized;

[0035] (2) the temperature gradient on the surface of the material can be artificially constructed and monitored to simulate the possible super-large temperature gradient on the insulation material in the superconducting system;

[0036] (3) the gas pressure in the test cavity can be adjusted according to the needs. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The deep cold temperature zone solid-liquid-gas triple point insulation material flashover characteristic testing device system structure block diagram of the application;

[0038] Figure 2 The deep cold temperature zone solid-liquid-gas triple point insulation material flashover characteristic testing device structure schematic diagram constructed by the inventor according to Figure 1

[0039] Figure 3 The electrode structure top view;

[0040] Figure 4 The electrode structure sectional view.

[0041] ​1, test chamber, 2, sample stage, 3, sample stage lifting device, 4, pressure and current monitoring module, 5, temperature control module, 6, gas pressure control module, 7, low-temperature liquid control module, 8, high-voltage source, 9, current monitoring system, 10, heating device, 11, heating wire, 12, temperature monitoring device, 13, temperature measurement array, 14, manometer, 15, gas pressure monitoring device, 16, vacuum pump, 17, gas feeding device, 18, compressed gas, 19, liquid level monitoring device, 20, low-temperature liquid feeding system, 21, low-temperature liquid, 22, sample, 23, ground electrode, 24, high-voltage electrode, 25, sample support, 26, electrode fixing structure.

[0042] The application will be further described in detail below with reference to the drawings and examples. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of the purpose, advantages and technical solutions of the present application, the following examples are only used to explain the present application, and the present application is not limited to the following examples. In the following description, the directions such as up, down, left, right, front and back, as well as top and bottom, are described with reference to the drawings, and when the placement of the device changes, the corresponding directions and the description of top and bottom will also change according to the change of the placement. Figure 2 、 Figure 3 and Figure 4

[0044] Example 1

[0045] The present embodiment provides a flashover characteristic testing device for a cryogenic temperature zone insulating material-liquid nitrogen-nitrogen gas triple-state combination point, which comprises a test chamber 1, a sample stage 2 and a sample stage lifting device 3, the sample stage 2 is arranged in the test chamber 1 and is connected with the sample stage lifting device 3 to control the height of the sample; wherein the test chamber 1 is used to provide a low-temperature solid-liquid-gas triple-state coexistence test environment, and the sample stage 2 is used to load a sample 22 and apply a voltage to record the current change; further comprising a pressure and current monitoring module 4, a temperature control module 5, a gas pressure control module 6 and a low-temperature liquid control module 7.

[0046] The pressure and current monitoring module 4 is used to apply an electric field on the surface of the sample and monitor the current change, record the flashover current waveform and protect the circuit;

[0047] The temperature control module 5 is used to heat the sample at a single point to form a temperature gradient and monitor the temperature at different positions of the sample;

[0048] The gas pressure control module 6 is used to adjust the gas pressure of the gas phase environment;

[0049] The low-temperature liquid control module 7 is used to control the liquid level of the low-temperature liquid.

[0050] ​In this embodiment, the test cavity 1 is a multi-layered stainless steel Dewar with good heat insulation, and the top is covered with hard foam plastic with good heat insulation to prevent the evaporation of the low-temperature liquid inside. During the manufacturing process, the overall sealing of the test cavity 1 is ensured to be good, and different gas pressure conditions from normal pressure to ultra-high vacuum can be built inside.

[0051] The sample stage 2 includes a test sample 22, a ground electrode 23, and a high-voltage electrode 24. The test sample 22 is supported by a test sample support 25 to ensure that the test sample 22 is in close contact with the ground electrode 23 and the high-voltage electrode 24. The ground electrode 23 and the high-voltage electrode 24 are positioned using an electrode fixing structure 26, which has threads and can be used to tighten the ground electrode 23 and the high-voltage electrode 24. By using different screw holes on the ground electrode 23 and the high-voltage electrode 24, the distance between the ground electrode 23 and the high-voltage electrode 24 can be adjusted.

[0052] The sample stage lifting device 3 is connected to the sample stage 2 at one end and is a control end at the other end. It is set outside the top of the test cavity 1 and is used to adjust the height of the sample stage 2 and change the depth of the test sample 22 immersed in liquid nitrogen.

[0053] The pressure and current monitoring module 4 includes a high-voltage source 8 and a current monitoring system 9, both of which are set outside the test cavity 1 and connected to the electrodes 23 and 24 inside the test cavity 1 through wires. The high-voltage source 8 is used to provide direct current, alternating current, or pulse voltage to form a high electric field on the surface of the test sample 22 through the electrodes. The current monitoring system 9 is used to monitor the current change on the surface of the test sample 22, record the flashover current waveform, and disconnect the high-voltage source 8 in time after flashover occurs to protect subsequent circuit components.

[0054] The temperature control module 5 includes a heating device 10, a heating wire 11, a temperature monitoring device 12, and a temperature measurement array 13. The heating wire 11 is set at the connection between the upper end of the sample stage 2 and the sample stage lifting device 3 to achieve single-point heating. The temperature measurement array 13 is set at the upper part of the test sample 22, the middle part of the gas phase of the test sample 22, the liquid surface of the low-temperature liquid, and the middle part of the liquid phase of the test sample 22 to monitor the temperature gradient on the surface of the test sample 22.

[0055] The gas pressure control module 6 includes a gas pressure gauge 14, a gas pressure monitoring device 15, a vacuum pump 16, a gas feeding device 17, and compressed gas 18. The gas pressure gauge 14 and the gas pressure monitoring device 15 are used to monitor the gas phase pressure inside the test cavity 1. The vacuum pump 16, the gas feeding device 17, and the compressed gas 18 are used to build a nitrogen environment inside the test cavity 1 and adjust the nitrogen pressure.

[0056] The low-temperature liquid regulating module 7 comprises a liquid level monitoring device 19 for monitoring the liquid nitrogen level, a low-temperature liquid feeding system 20 for feeding liquid nitrogen into the test chamber 1 when the liquid level does not reach a specified height, and low-temperature liquid 21.

[0057] In this embodiment, the sample 22 is a flat sheet of insulating material with a thickness ranging from 1 μm to 1 cm.

[0058] The compressed gas 18 is compressed nitrogen.

[0059] The low-temperature liquid 21 is liquid nitrogen.

[0060] The test method of the above-described flashover characteristic test device for insulating materials at the triple-point of solid-liquid-gas in a cryogenic temperature range is performed according to the following steps:

[0061] Step 1: Install the sample 22 to be tested on the sample stage 2, tighten the sample support 25, adjust the distance between the ground electrode 23 and the high-voltage electrode 24, tighten the electrode fixing structure 26, and then install the sample stage 2 on the cover-top sample stage lifting device 3.

[0062] Step 2: Inject a small amount of liquid nitrogen into the test chamber 1 multiple times, gradually lower the temperature of the tank, and the amount of liquid nitrogen added during the cooling process should be less than the final amount of liquid nitrogen. Then install the test chamber cover-top and fix it.

[0063] Step 3: Adjust the height of the sample stage 2 to the specified position and fix the sample stage lifting device 3.

[0064] Step 4: Set the test gas environment, select nitrogen as the gas, start the vacuum pump 16 to pump out part of the gas in the test chamber 1, close the vacuum pump 16 valve, open the gas feeding device 17 valve, feed nitrogen to 1 standard atmosphere, then close the gas feeding device 17 valve, open the vacuum pump 16 valve to pump out part of the gas in the test chamber 1, close the vacuum pump 16 valve, open the gas feeding device 17 valve, feed nitrogen to 1 standard atmosphere, repeat the above steps 2-3 times until the gas in the sample chamber 1 is replaced by nitrogen, then close the feeding device 17 valve and open the vacuum pump 16 to the specified gas pressure.

[0065] Step 5: Set the liquid nitrogen level, which should be between the two electrodes (ground electrode 23 and high-voltage electrode 24), open the low-temperature liquid regulating module, and feed liquid nitrogen to the specified height.

[0066] Step 6: Set the surface temperature gradient of the sample 22 to be tested, set the temperature of the heating wire 11 to the required maximum temperature of the sample surface, and use the temperature measurement array 13 to monitor the surface temperature gradient of the sample 22.

[0067] Step 7: Turn on the pressurization and current monitoring module 4, set the high voltage (may be AC, DC or pulse voltage) waveform applied to the surface of the sample, while monitoring and recording the output current waveform until flashover occurs;

[0068] Step 8: Check the liquid nitrogen liquid level, atmospheric conditions and temperature conditions, if it meets the test requirements, repeat step 7, if it does not meet the requirements, repeat steps 4-6 to restore the test conditions to the original settings, and then repeat step 7 test;

[0069] Step 9: Repeat step 8, repeat 10-100 times according to the test insulation material settings, until the flashover test is completed;

[0070] Step 10: Turn off the pressurization and current monitoring module 4, turn off the temperature control module 5, turn on the gas feeding device 17 to restore the pressure in the test chamber 1 to normal pressure, turn on the test chamber 1, replace the sample 22 and repeat the test steps 1-9, or complete the test and turn off the test system.

[0071] Example 2:

[0072] This embodiment gives a kind of deep cold temperature zone insulation material-liquid helium-helium three-state combination point insulation material flashover characteristic testing device, including: test chamber 1, sample table 2 and sample table lifting device 3, the sample table 2 is set in test chamber 1 and is connected with sample table lifting device 3 to control the height of test sample, the test chamber 1 is used to provide low-temperature solid-liquid-gas three-state coexistence test environment, the sample table 2 is used to load test sample 22 and apply voltage to record current change;It also includes pressurization and current monitoring module 4, temperature control module 5, gas pressure control module 6 and low-temperature liquid control module 7, wherein:

[0073] The pressurization and current monitoring module 4 is used to apply electric field to the surface of the test sample and monitor the current change, record the flashover current waveform and protect the circuit;

[0074] The temperature control module 5 is used to heat the test sample at a single point to form a temperature gradient, and monitor the temperature at different positions of the test sample;

[0075] The gas pressure control module 6 is used to adjust the gas phase environment pressure;

[0076] The low-temperature liquid control module 7 is used to adjust the liquid level of low-temperature liquid.

[0077] In this embodiment, the test chamber 1 is a multi-layer adiabatic stainless steel Dewar pot, the top cover contains hard foam plastic with good adiabatic performance inside, to prevent internal low-temperature liquid evaporation, and the whole test chamber 1 should be sealed well during manufacturing, to build different gas pressure conditions from normal pressure to ultra-high vacuum inside it;

[0078] The sample stage 2 includes a test sample 22, a ground electrode 23, a high voltage electrode 24, the test sample 22 is pressed by a test sample support 25 to ensure the test sample 22 is attached to the ground electrode 23 and the high voltage electrode 24, the ground electrode 23 and the high voltage electrode 24 are positioned by an electrode fixing structure 26, the electrode fixing structure 26 is threaded and can be used to tighten the ground electrode 23 and the high voltage electrode 24, the distance between the ground electrode 23 and the high voltage electrode 24 can be adjusted by using different screw holes on the ground electrode 23 and the high voltage electrode 24.

[0079] The sample stage lifting device 3 is connected to the sample stage 2 at one end and is a control end, is arranged outside the top end of the test chamber 1 and is used to adjust the height of the sample stage 2 and change the depth of the test sample 22 immersed in liquid helium.

[0080] The pressurization and current monitoring module 4 includes a high voltage source 8 and a current monitoring system 9, both of which are arranged outside the test chamber 1 and are connected to the ground electrode 23 and the high voltage electrode 24 in the test chamber 1 through wires, the high voltage source 8 is used to provide direct current, alternating current or pulse voltage, a high electric field is formed on the surface of the test sample 22 through the ground electrode 23 and the high voltage electrode 24, the current monitoring system 9 is used to monitor the current change on the surface of the test sample, record the flashover current waveform and disconnect the high voltage source 8 in time after flashover occurs.

[0081] The temperature control module 5 includes a heating device 10, a heating wire 11, a temperature monitoring device 12 and a temperature measurement array 13, the heating wire 11 is arranged at the connection between the upper end of the sample stage 2 and the sample stage lifting device 3 to achieve the purpose of single-point heating. The temperature measurement array 13 is arranged at the upper part of the test sample 22, the middle part of the gas phase of the test sample 22, the liquid surface of the low-temperature liquid and the middle part of the liquid phase of the test sample 22 respectively to monitor the temperature gradient on the surface of the test sample 22.

[0082] The gas pressure control module 6 includes a gas pressure gauge 14, a gas pressure monitoring device 15, a vacuum pump 16, a gas feeding device 17 and compressed gas 18, the gas pressure gauge 14 and the gas pressure monitoring device 15 are used to monitor the gas phase pressure in the test chamber 1, the vacuum pump 16, the gas feeding device 17 and the compressed gas 18 are used to build a helium gas environment in the test chamber 1 and adjust the pressure of the helium gas.

[0083] The low-temperature liquid control module 7 includes a liquid level monitoring device 19, a low-temperature liquid feeding system 20 and a low-temperature liquid 21, the liquid level monitoring device 19 is used to monitor the liquid level of liquid helium, when the liquid level does not reach the specified height, the low-temperature liquid feeding system 20 feeds liquid helium into the test chamber 1 to keep the liquid level stable.

[0084] In this embodiment, the test sample 22 is a flat sheet of insulating material with a thickness ranging from 1 μm to 1 cm.

[0085] The compressed gas 18 is compressed helium gas.

[0086] The low-temperature liquid 21 is liquid helium.

[0087] The test method of the above-mentioned deep cooling temperature zone solid-liquid-gas triple point insulating material flashover characteristic test device is executed according to the following steps:

[0088] Step 1: Install the sample 22 to be tested on the sample table 2, tighten the sample support 25, adjust the distance between the ground electrode 23 and the high-voltage electrode 24, tighten the electrode fixing structure 26, and then install the sample table 2 on the cover-top sample table lifting device 3.

[0089] Step 2: Inject liquid helium into the test cavity 1 in small amounts multiple times, gradually lower the tank temperature, and the amount of liquid helium added during the cooling process should be less than the final amount of liquid helium. Then install the test cavity cover and fix it.

[0090] Step 3: Adjust the height of the sample table 2 to the specified position and fix the sample table lifting device 3.

[0091] Step 4: Set the test gas phase environment, select helium as the gas, open the vacuum pump 16 to pump out part of the gas in the test cavity 1, close the vacuum pump 16 valve, open the gas feeding device 17 valve, feed helium to 1 standard atmosphere, then close the gas feeding device 17 valve, open the vacuum pump 16 valve to pump out part of the gas in the test cavity 1, close the vacuum pump 16 valve, open the gas feeding device 17 valve, feed helium to 1 standard atmosphere, repeat the above steps 2-3 times until the gas in the sample cavity 1 is replaced by helium, then close the feeding device 17 valve, open the vacuum pump 16, and reach the specified gas pressure.

[0092] Step 5: Set the liquid helium liquid level height, which should be between the two electrodes (ground electrode 23 and high-voltage electrode 24), open the low-temperature liquid control module, and feed liquid helium to the specified height.

[0093] Step 6: Set the sample 22 surface temperature gradient, set the temperature of the heating wire 11 to the required maximum temperature of the sample surface, and monitor the sample 22 surface temperature gradient using the temperature measurement array 13.

[0094] Step 7: Open the pressure and current monitoring module 4, set the high voltage (which can be alternating, direct or pulsed voltage) waveform applied to the surface of the sample 22, and simultaneously monitor and record the output current waveform until flashover occurs.

[0095] Step 8: Check the liquid helium liquid level height, gas atmosphere conditions and temperature conditions, if they meet the test requirements, repeat step 7, if they do not meet the requirements, repeat steps 4-6 to restore the test conditions to the original settings, and then repeat step 7.

[0096] Step 9: repeat step 8, repeat 10~100 times according to the test insulation material settings until the completion of the flashover test;

[0097] Step 10: close the pressurization and current monitoring module 4, close the temperature control module 5, open the gas feeding device 17 to restore the pressure in the test chamber 1 to normal pressure, open the test chamber 1, replace the test sample 22, repeat the test steps 1-9, or complete the test and close the test system.

[0098] In summary, the deep cold temperature zone solid-liquid-gas triple point insulation material flashover characteristic test device given in the above embodiment can solve the problem of the formation of insulation weak points at the solid-liquid-gas triple point caused by the evaporation of the low-temperature liquid in the cold source of the superconducting device. It can perform direct current, alternating current, and pulse flashover tests on the surface of the insulation material under different low-temperature liquids, different gas pressures, and different temperature gradients in the special environment at the deep cold temperature zone solid-liquid-gas triple point, and can artificially construct a temperature gradient. It fills the gap in the surface flashover test technology of materials in extreme low-temperature environments.

Claims

1. A device for testing the flashover characteristics of an insulating material at the triple point of solid-liquid-gas in the cryogenic temperature region, characterized in that The device comprises a test cavity (1), a sample table (2) and a sample table lifting device (3), wherein: The sample table (2) is arranged in the test cavity (1) and connected to the sample table lifting device (3) to control the height of the test sample, the test cavity (1) is used to provide a low-temperature solid-liquid-gas three-phase coexistence test environment, and the sample table (2) is used to load the test sample (22) and apply a voltage to record the current change, characterized in that it further comprises a pressurization and current monitoring module (4), a temperature control module (5), a gas pressure control module (6) and a low-temperature liquid control module (7), wherein: The pressurization and current monitoring module (4) is used to apply an electric field to the surface of the test sample and monitor the current change to record the flashover current waveform; The temperature control module (5) is used to heat the test sample at a single point to form a temperature gradient and monitor the temperature at different positions of the test sample; The gas pressure control module (6) is used to adjust the gas phase environment pressure; The low-temperature liquid control module (7) is used to adjust the liquid level of the low-temperature liquid; The test cavity (1) is a multi-layer adiabatic stainless steel Dewar pot, and the top cover contains hard foam plastic with good adiabatic performance inside; The sample table (2) comprises a test sample (22), a ground electrode (23) and a high-voltage electrode (24) on the test sample (22), and the test sample (22) is pressed by a test sample support (25) to ensure that the test sample (22) is tightly attached to the ground electrode (23) and the high-voltage electrode (24), the ground electrode (23) and the high-voltage electrode (24) are positioned by using an electrode fixing structure (26), and the electrode fixing structure (26) has threads for tightening the ground electrode (23) and the high-voltage electrode (24), and the distance between the ground electrode (23) and the high-voltage electrode (24) is adjusted by different screw holes provided on the ground electrode (23) and the high-voltage electrode (24); The sample table lifting device (3) is connected to the sample table (2) at one end and is a control end at the other end, is arranged outside the top end of the test cavity (1) and is used to adjust the height of the sample table (3) to change the depth of the test sample (22) immersed in the low-temperature liquid; The pressurization and current monitoring module (4) comprises a high-voltage source (8) and a current monitoring system (9), both of which are arranged outside the test cavity (1) and connected to the ground electrode (23) and the high-voltage electrode (24) in the test cavity (1) through wires, the high-voltage source (8) is used to provide a direct current, alternating current or pulse voltage to form a high electric field on the surface of the test sample (22) through the ground electrode (23) and the high-voltage electrode (24), and the current monitoring system (9) is used to monitor the current change on the surface of the test sample, record the flashover current waveform and timely disconnect the high-voltage source (8) after flashover occurs; The temperature control module (5) comprises a heating device (10), a heating wire (11), a temperature monitoring device (12) and a temperature measurement array (13), the heating wire is arranged at the connection between the upper end of the sample table (2) and the sample table lifting device (3) to achieve the purpose of single-point heating, and the temperature measurement array (13) is arranged at the upper part of the test sample (22), the middle part of the gas phase of the test sample (22), the liquid level of the low-temperature liquid and the middle part of the liquid phase of the test sample (22) to monitor the temperature gradient on the surface of the test sample (22). The gas pressure control module (6) comprises a gas pressure gauge (14), a gas pressure monitoring device (15), a vacuum pump (16), a gas feeding device (17) and compressed gas (18), the gas pressure gauge (14) and the gas pressure monitoring device (15) are used to monitor the gas phase pressure inside the test chamber (1), the vacuum pump (16), the gas feeding device (17) and the compressed gas (18) are used to build the gas environment in the test chamber (1) and adjust the gas pressure; The low-temperature liquid control module (7) comprises a liquid level monitoring device (19), a low-temperature liquid feeding system (20) and a low-temperature liquid (21), the liquid level monitoring device (19) is used to monitor the liquid level of the low-temperature liquid, when the liquid level does not reach the specified height, the low-temperature liquid feeding system (20) feeds the low-temperature liquid into the test chamber (1) to keep the liquid level stable.

2. The deep-cool temperature region solid-liquid-gas triple point junction insulating material flashover characteristic testing device of claim 1, wherein, The sample (22) is a flat sheet of insulating material, with a thickness ranging from 1 μm to 1 cm.

3. The deep-cool temperature triple point solid-liquid-gas junction dielectric flashover property test apparatus of claim 1, wherein, The compressed gas (18) is compressed nitrogen or compressed helium, corresponding to the type of low-temperature liquid.

4. The deep-cool temperature triple point solid-liquid-gas junction dielectric flashover property test apparatus of claim 1, wherein, The low-temperature liquid (21) is liquid nitrogen or liquid helium.

5. The test method of the test device for the flashover characteristics of insulating materials at the solid-liquid-gas three-state junction in the cryogenic temperature range as described in any one of claims 1-4, characterized in that, The following steps are performed: Step 1: Install the sample (22) on the sample stage (2), tighten the sample support (25), adjust the distance between the ground electrode (23) and the high-voltage electrode (24), tighten the electrode fixing structure (26), and then install the sample stage (2) on the cover-top sample stage lifting device; Step 2: Inject a small amount of low-temperature liquid into the test chamber (1) several times, gradually lower the temperature in the test chamber (1), and the amount of low-temperature liquid added during the cooling process should be less than the final amount of low-temperature liquid, then install the test chamber cover and fix it; Step 3: Adjust the height of the sample stage (2) to the specified position and fix the sample stage lifting device (3); Step 4: Set the test gas environment, the gas type should correspond to the selected low-temperature liquid, turn on the vacuum pump (16) to extract part of the gas in the test chamber (1), close the vacuum pump (16) valve, open the gas feeding device (17) valve, feed the specified gas to 1 standard atmosphere, then close the gas feeding device (17) valve, open the vacuum pump (16) valve to extract part of the gas in the test chamber (1), close the vacuum pump (16) valve, open the gas feeding device (17) valve, feed the specified gas to 1 standard atmosphere, repeat the above steps 2-3 times until the gas in the sample chamber (1) is replaced by the specified gas, then close the feeding device (17) valve and open the vacuum pump (16) to the specified gas pressure; Step 5: Set the liquid level of the low-temperature liquid, the height should be between the two electrodes, turn on the low-temperature liquid control module, and feed the low-temperature liquid to the specified height; Step 6: Set the temperature gradient of the sample (22) surface, set the temperature of the heating wire (11) to the required maximum temperature of the sample surface, and monitor the temperature gradient of the sample surface using the temperature measurement array (13); Step 7: Turn on the pressure and current monitoring module (4), set the high voltage waveform applied to the sample surface, the high voltage is alternating current, direct current or pulse voltage, and monitor and record the output current waveform simultaneously until flashover occurs. Step 8: Check the low-temperature liquid liquid level, atmosphere conditions and temperature conditions, if meet the test requirements, repeat step 7, if not meet the requirements, repeat steps 4-6 to make the test conditions back to the original settings, then repeat step 7 test; Step 9: Repeat step 8, according to the test insulation material settings repeat 10-100 times, until the completion of flashover test; Step 10: Close the pressure and current monitoring module (4), close the temperature control module (5), open the gas feeding device (17) to the test chamber (1) to restore the atmospheric pressure; open the test chamber (1), replace the sample (22), repeat the test steps 1-9, or complete the test and close the test system.

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