Experimental device and method for detecting dielectric strength of insulating cooling medium in various phases

Abstract

An experimental device and method for detecting the dielectric strength of an insulating cooling medium in various phases, the experimental device comprising: a sealed box, one end of which is a voltage-applying end connected to an external dielectric strength tester, and the other corresponding end is a grounding end; a test electrode, comprising a first electrode arranged inside the box and connected to the voltage-applying end, and a second electrode connected to the grounding end, the two electrodes being arranged at a relative distance; an electrode spacing adjustment device, arranged on the outer shell of the box and connected to the first electrode or the second electrode, for adjusting the distance between the two electrodes; an electric heating sleeve, arranged on the first electrode and / or the second electrode, for heating the insulating cooling medium when the insulating cooling medium covers the test electrode; an electric heater, arranged inside the box, for heating the insulating cooling medium when the insulating cooling medium is located below the test electrode. The present invention can detect the dielectric strength data of the insulating cooling medium in the liquid state, the vapor-liquid two-phase state and the vapor state.

Description

Technical Field

[0001] The invention relates to the field of high-voltage electrical equipment, and in particular to an experimental device and method for detecting the dielectric strength of an insulating cooling medium in various phases. Background Art

[0002] Insulating cooling media are widely used in high-voltage electrical equipment. Their role is to insulate and cool the equipment during operation, ensuring the normal and reliable operation of the equipment. Insulating cooling media with phase change characteristics may present various phases during the operation of high-voltage electrical equipment, including liquid, vapor-liquid and vapor. In each phase, the insulating cooling medium must meet the insulation requirements of high-voltage electrical equipment. However, the oil cup for dielectric strength test of insulating cooling media described in the "GB / T507-2002 Method for Determining the Breakdown Voltage of Insulating Oil" is only suitable for dielectric strength test of liquid insulating cooling media at room temperature. Its upper part is open and not sealed, which cannot meet the dielectric strength test of insulating media with phase change characteristics in vapor and vapor-liquid coexistence states. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an experimental device and method for detecting the dielectric strength of an insulating cooling medium in various phases in view of the defects of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: construct an experimental device for detecting the dielectric strength of the insulating cooling medium in various phases, and the experimental device comprises:

[0005] A sealed box, one end of which is a voltage-applying end for connecting to an external dielectric strength tester, and the other end of which is a grounding end;

[0006] The test electrode comprises a first electrode disposed inside the box and connected to the voltage applying end, and a second electrode connected to the ground end, wherein the first electrode and the second electrode are disposed with a relative spacing;

[0007] An electrode spacing adjustment device, disposed on the box shell and connected to the first electrode or the second electrode, for adjusting the spacing between the first electrode and the second electrode;

[0008] An electric heating sleeve, which is sleeved on the first electrode and / or the second electrode, and is used to heat the insulating cooling medium when the insulating cooling medium covers the test electrode and detects the dielectric strength of the insulating cooling medium in a vapor-liquid two-phase state;

[0009] The electric heater is arranged inside the box and is used to heat the insulating cooling medium when the insulating cooling medium is located below the test electrode and the dielectric strength of the insulating cooling medium in the vapor state is detected.

[0010] Preferably, in the dielectric strength experimental device for detecting the insulating cooling medium in various phases described in the present invention, the grounding terminal is grounded through a grounding component arranged on the box.

[0011] Preferably, in the experimental device for detecting the dielectric strength of an insulating cooling medium in various phases of the present invention, the first electrode and the second electrode are connected to the voltage applying end and the grounding end respectively through conductive rods.

[0012] Preferably, in the dielectric strength experimental device for detecting the insulating cooling medium in various phases of the present invention, the electrode spacing adjustment device includes an adjustment knob and a dial;

[0013] The adjustment knob is connected to the conductive rod of the first electrode or the second electrode, and is used to drive the first electrode or the second electrode to move by rotation, adjust the distance between the first electrode and the second electrode, and display the rotation scale of the adjustment knob through the dial.

[0014] Preferably, the dielectric strength experimental device for detecting the dielectric strength of the insulating cooling medium in various phases of the present invention further comprises:

[0015] A first temperature measuring probe is arranged from the inside of the conductive rod close to the first electrode or the second electrode, and is used to measure the temperature of the insulating cooling medium between the first electrode and the second electrode in a vapor-liquid two-phase state;

[0016] The second temperature measuring probe is arranged below the test electrode and is used to measure the temperature of the insulating cooling medium in liquid state.

[0017] Preferably, in the dielectric strength experimental device for detecting the insulating cooling medium in various phases described in the present invention, it also includes a power terminal arranged on the box body, which is used to connect to the electric heating sleeve wire, and the power terminal is connected to an external power supply.

[0018] Preferably, the dielectric strength experimental device for detecting the insulating cooling medium in various phases of the present invention further includes a liquid injection port with a valve for injecting the insulating cooling medium into the interior of the box or discharging the insulating cooling medium from the interior of the box.

[0019] Preferably, the dielectric strength experimental device for detecting the insulating cooling medium in various phases of the present invention further comprises a pressure gauge connected to the interior of the box body for detecting the pressure inside the box body.

[0020] Preferably, the dielectric strength experimental device for detecting the insulating cooling medium in various phases described in the present invention further includes a pressure release valve connected to the interior of the box, which is used to release pressure by opening when the pressure inside the box exceeds the test requirement value.

[0021] The present invention also constructs an experimental method for detecting the dielectric strength of the insulating cooling medium in various phases using the above-mentioned experimental device, comprising the following steps:

[0022] S1: adjusting the distance between the first electrode and the second electrode to a preset distance;

[0023] S2: An insulating cooling medium with phase change characteristics is placed in the box and the box is kept sealed, so that the insulating cooling medium is in one of the following three states:

[0024] (1) Liquid state, i.e., the state at room temperature and the insulating cooling medium covers the test electrode;

[0025] (2) a vapor-liquid two-phase state, i.e., the insulating cooling medium covers the test electrode, and the insulating cooling medium is heated by the electric heating jacket to generate bubbles between the first electrode and the second electrode;

[0026] (3) Vapor state, i.e., the insulating cooling medium is located below the test electrode and is heated by the electric heater to vaporize the insulating cooling medium;

[0027] S3: For each of the above states, the first electrode is boosted by the dielectric strength tester to cause dielectric breakdown between the first electrode and the second electrode, and the voltage value is recorded by the dielectric strength tester.

[0028] Preferably, in the experimental method for detecting the dielectric strength of the insulating cooling medium in various phases of the present invention, before step S2, the method further includes:

[0029] The box is evacuated to a preset vacuum degree and is kept leak-proof.

[0030] Preferably, in the experimental method for detecting the dielectric strength of the insulating cooling medium in various phases of the present invention, for the vapor-liquid two-phase state and the vapor state, before step S3, the following steps are included:

[0031] Control the experimental temperature and / or pressure to reach the preset experimental requirements.

[0032] By implementing the present invention, the following beneficial effects are achieved:

[0033] The present invention designs a sealed and leak-proof experimental device, heats the liquid insulating cooling medium covering the test electrode through an electric heating sleeve, so that the insulating cooling medium in the middle of the electrode is in a vapor-liquid two-phase state, thereby measuring the dielectric strength data of the insulating cooling medium in the vapor-liquid two-phase state; and heats the insulating cooling medium through an electric heater located below the test electrode, so that the insulating cooling medium in the middle of the electrode is in a vapor state, thereby measuring the dielectric strength data of the insulating cooling medium in the vapor state, thereby providing data support for the design and production of high-voltage electrical equipment and ensuring its safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0035] Figure 1 It is a structural schematic diagram of an experimental device for detecting the dielectric strength of an insulating cooling medium in various phases according to the present invention. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0037] During the operation of high-voltage electrical equipment, the insulating cooling medium with phase change characteristics may be in liquid, vapor-liquid two-phase state or pure vapor state. To ensure the safe operation of high-voltage electrical equipment, the dielectric strength of the insulating cooling medium in liquid, vapor-liquid two-phase state and vapor state must meet the national standards or the operation requirements of high-voltage electrical equipment. Therefore, there must be an experimental device and method to detect the dielectric strength of the insulating cooling medium with phase change characteristics in each phase, to provide data support for the design and production of high-voltage electrical equipment, and to ensure the safe operation of high-voltage electrical equipment.

[0038] Therefore, if Figure 1 As shown, the present invention constructs an experimental device for detecting the dielectric strength of an insulating cooling medium in various phases, wherein the phases include a liquid state, a vapor-liquid two-phase state, and a vapor state. The experimental device includes: a box 1, a test electrode 2, an electrode spacing adjustment device 3, an electric heating sleeve 4, and an electric heater 5.

[0039] The box 1 is sealed, one end of the box 1 is a voltage-applying terminal 11 for connecting an external dielectric strength tester, and the other end is a grounding terminal 12. In some embodiments, the box is made of insulating and transparent materials except for the voltage-applying terminal 11 and the grounding terminal 12, so that the generation and change process of the insulating cooling medium bubbles can be seen during the experiment. The voltage-applying terminal 11 and the grounding terminal 12 can be the end covers at both ends of the box 1, and the grounding terminal 12 is grounded through a grounding component 6 arranged on the box 1, and the grounding component 6 can be a grounding bolt, etc. In addition, the experimental device is fully sealed and has the ability to withstand a vacuum degree of 1Pa and a positive pressure of 100kPa. Therefore, mechanical strength reinforcing screws 15 are also arranged around the box 1.

[0040] The test electrode 2 includes a first electrode 21 disposed inside the box 1 and connected to the voltage applying terminal 11, and a second electrode 22 connected to the ground terminal 12. The first electrode 21 and the second electrode 22 are arranged at a relative distance. In some embodiments, the first electrode 21 and the second electrode 22 are connected to the voltage applying terminal 11 and the ground terminal 12 respectively through a conductive rod 23. In some embodiments, the shapes of the first electrode 21 and the second electrode 22 can be flat, spherical, or mushroom-shaped. In addition, it should be noted that when the surface of the electrode is damaged or dented, the electrode must be maintainable or replaceable.

[0041] The electrode spacing adjustment device 3 is arranged on the end cover of the box body 1 and connected to the first electrode 21 or the second electrode 22, and is used to adjust the spacing between the first electrode 21 and the second electrode 22. In some embodiments, the electrode spacing adjustment device 3 includes an adjustment knob 31 and a dial 32. The adjustment knob 31 is connected to the conductive rod 23 of the first electrode 21 or the second electrode 22, and is used to drive the first electrode 21 or the second electrode 22 to move by rotation, adjust the spacing between the first electrode 21 and the second electrode 22, and display the rotation scale of the adjustment knob 31 through the dial 32. The spacing between the first electrode 21 and the second electrode 22 can be calculated by the conversion relationship between the rotation scale and the spacing. Preferably, the spacing between the first electrode 21 and the second electrode 22 is adjusted to 2.5 mm. In other embodiments, the spacing can be adjusted according to actual detection requirements, which is not limited here.

[0042] The box 1 can accommodate an insulating cooling medium with phase change characteristics, covering the test electrode 2 or being located below the test electrode 2. The first electrode 21 can undergo dielectric breakdown with the second electrode 22 through the boost of the dielectric strength tester, and the dielectric strength of the insulating cooling medium in each phase can be detected. In some embodiments, the experimental device includes a liquid injection and discharge port 10 with a valve, which is used to inject liquid insulating cooling medium into the box 1 so that the insulating cooling medium covers the test electrode 2, for example, the liquid injection height is 50 mm above the test electrode 2; it can also be used to release the liquid insulating cooling medium in the box 1 so that the liquid level is below the test electrode 2, and the lower end of the test electrode 2 must not be immersed during the entire experiment, for example, the liquid injection height is 40 mm below the test electrode 2; it can also be used to inject vapor insulating cooling medium to cover the test electrode 2; it can also be used to evacuate the box through the liquid injection and discharge port 10 until the vacuum degree inside the box is below 133 Pa.

[0043] The electric heating sleeve 4 is sleeved on the first electrode 21 and / or the second electrode 22, and is used to heat the insulating cooling medium when the liquid insulating cooling medium covers the test electrode 2 and measures the dielectric strength of the insulating cooling medium in the vapor-liquid two-phase state. Preferably, the electric heating sleeve 4 is sleeved on the second electrode 22. In some embodiments, the box body 1 is also provided with a power terminal 9 connected to the wire of the electric heating sleeve 4, and the power terminal 9 is connected to an external power supply.

[0044] Specifically, when the liquid insulating cooling medium covers the test electrode 2 and the dielectric strength of the insulating cooling medium in the vapor-liquid two-phase state is detected, the electric heating sleeve 4 can be energized to generate heat and conduct it to the electrode, thereby heating the insulating cooling medium between the first electrode 21 and the second electrode 22, so that bubbles are generated between the first electrode 21 and the second electrode 22. Through the voltage boost of the dielectric strength tester, the first electrode 21 can then undergo dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in the vapor-liquid two-phase state.

[0045] The electric heater 5 is arranged inside the box body 1 and connected to an external power supply, and is used to heat the insulating cooling medium when the insulating cooling medium in liquid state is below the test electrode 2 and the dielectric strength of the insulating cooling medium in vapor state is measured. Alternatively, it is used to heat the insulating cooling medium when the insulating cooling medium in liquid state covers the test electrode 2 and the dielectric strength of the insulating cooling medium in liquid state at various temperatures is measured. Specifically, when the insulating cooling medium is located below the test electrode 2 and the dielectric strength of the insulating cooling medium in vapor state is detected, the insulating cooling medium is heated to vaporize it, and then the first electrode 21 can undergo dielectric breakdown with the second electrode 22 through the voltage boost of the dielectric strength tester, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in vapor state. Alternatively, when the liquid insulating cooling medium covers the test electrode 2 and the dielectric strength of the liquid insulating cooling medium at various temperatures is detected, the insulating cooling medium is heated, and then the first electrode 21 can undergo dielectric breakdown with the second electrode 22 through the voltage boost of the dielectric strength tester, and the final voltage value is recorded, thereby detecting the dielectric strength of the liquid insulating cooling medium at various temperatures.

[0046] The experimental device also includes: a first temperature measuring probe 7, a second temperature measuring probe 8 and a pressure gauge 14. The first temperature measuring probe 7 is set from the inside of the conductive rod 23 close to the first electrode 21 or the second electrode 22, and is used to measure the temperature of the insulating cooling medium between the first electrode 21 and the second electrode 22 in a vapor-liquid two-phase state. When the temperature reaches the preset experimental temperature, the control signal of the first temperature measuring probe 7 can be used to control the electric heating sleeve 4 to disconnect the power supply and accurately control the experimental temperature. In some embodiments, the experimental device drills a hole inside the conductive rod 23 of the second electrode 22, and the first temperature measuring probe 7 penetrates into a position about 2 mm close to the surface of the second electrode 22 to accurately measure the temperature of the insulating cooling medium between the electrodes in a vapor-liquid two-phase state and in a vapor state.

[0047] The second temperature probe 8 is arranged below the test electrode 2 to measure the temperature of the insulating cooling medium in liquid state. When the temperature reaches the preset test temperature, the control signal of the second temperature probe 8 can be used to control the electric heater 5 to disconnect the power supply and accurately control the test temperature.

[0048] The pressure gauge 13 is connected to the inside of the box 1 and is used to detect the pressure inside the box 1. In some embodiments, the experimental device also includes a pressure release valve 14 connected to the inside of the box 1, which is used to control the pressure release valve 14 to release pressure through the signal contact of the pressure gauge 13 when the pressure gauge 13 detects that the pressure inside the box 1 exceeds the preset experimental pressure value, adjust the experimental pressure and ensure that the pressure inside the experimental device is within a safe range. In some embodiments, the power supply of the electric heating sleeve 4 and the electric heater 5 can also be controlled by the signal contact of the pressure gauge 13 to accurately control the experimental pressure.

[0049] In addition, most of the components of the experimental device are arranged at the grounding end, ensuring the safety of components and personnel during the experiment.

[0050] Completely, before the experiment, first check the sealing performance of the experimental device to ensure that the sealing of the experimental device is reliable and leak-free. Adjust the spacing between the first electrode 21 and the second electrode 22 to preferably 2.5 mm by adjusting the knob 31, evacuate the box body through the liquid injection port 10 until the vacuum degree inside the box body is below 133 Pa, and then inject liquid insulating cooling medium into the box body 1 through the liquid injection port 10, so that the insulating cooling medium covers the top of the test electrode 2. When detecting the dielectric strength of the insulating cooling medium in liquid state at room temperature, the electric heating sleeve 4 is not energized, and the electric heater 5 is energized. Through the boost of the dielectric strength tester, the first electrode 21 can undergo dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in liquid state at room temperature.

[0051] When detecting the dielectric strength of the insulating cooling medium in liquid state at various temperatures, the electric heater 5 is powered on, and then the temperature of the insulating cooling medium is measured by the second temperature measuring probe 8. When the temperature reaches the preset experimental temperature, the electric heater 5 is controlled to disconnect the power supply and stop working. The boosted first electrode 21 of the dielectric strength tester can cause dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in liquid state at various temperatures.

[0052] When the liquid insulating cooling medium covers the test electrode 2 and the dielectric strength of the insulating cooling medium in the vapor-liquid two-phase state is detected, the insulating cooling medium can be heated by the electric heating sleeve 4 to generate bubbles between the first electrode 21 and the second electrode 22, and then the temperature of the insulating cooling medium in the vapor-liquid two-phase state between the first electrode 21 and the second electrode 22 is measured by the first temperature measuring probe 7, and the pressure inside the box 1 is detected by the pressure gauge 13. When the temperature and pressure reach the preset experimental temperature and pressure, the electric heating sleeve 4 is controlled to disconnect the power supply and stop working. Finally, through the voltage boost of the dielectric strength tester, the first electrode 21 can undergo dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in the vapor-liquid two-phase state.

[0053] When detecting the dielectric strength of the insulating cooling medium in vapor state, the liquid insulating cooling medium in the box body 1 is discharged through the liquid injection port 10, so that the liquid insulating cooling medium is located below the test electrode 2. At this time, the insulating cooling medium is heated by the electric heater 5 to vaporize it, and then the pressure inside the box body 1 is detected by the pressure gauge 13. When the pressure reaches the preset test pressure, the electric heater 5 is controlled to disconnect the power supply and stop working. Through the voltage boost of the dielectric strength tester, the first electrode 21 can undergo dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in vapor state.

[0054] In addition, the dielectric strength of the insulating cooling medium in a vapor state at room temperature can also be measured. Before the experiment, the sealing performance of the experimental device is first tested to ensure that the experimental device is sealed reliably and leaks not. The spacing between the first electrode 21 and the second electrode 22 is adjusted to preferably 2.5 mm by adjusting the knob 31. The vacuum is drawn through the liquid injection port 10 until the vacuum degree inside the box is below 133 Pa. Then, the insulating cooling medium in a vapor state at room temperature is injected into the box body 1 through the liquid injection port 10. According to the reading of the pressure gauge 13, the valve of the liquid injection port 10 is closed after reaching the preset experimental pressure. Through the voltage increase of the dielectric strength tester, the first electrode 21 can undergo dielectric breakdown with the second electrode 22, and the final voltage value is recorded, thereby detecting the dielectric strength of the insulating cooling medium in a vapor state at room temperature under the pressure.

[0055] An experimental method for detecting the dielectric strength of the insulating cooling medium in various phases using the above experimental device is also constructed, comprising the following steps:

[0056] S1: adjusting the distance between the first electrode 21 and the second electrode 22 to a preset distance;

[0057] S2: An insulating cooling medium with phase change characteristics is placed in the box 1 and the box 1 is kept sealed, so that the insulating cooling medium is in one of the following three states:

[0058] 1. Liquid state, i.e., the state at room temperature and with the insulating cooling medium covering the test electrode 2;

[0059] 2. A vapor-liquid two-phase state, i.e., a liquid insulating cooling medium covers the test electrode 2, and the insulating cooling medium is heated by the electric heating jacket 4 to generate bubbles between the first electrode 21 and the second electrode 22;

[0060] 3. Vapor state, i.e., the liquid insulating cooling medium is located below the test electrode 2, and the insulating cooling medium is heated by the electric heater 5 to vaporize it;

[0061] S3: For each of the above states, the first electrode 21 is boosted by a dielectric strength tester to cause dielectric breakdown between the first electrode 21 and the second electrode 22, and the voltage value is recorded by the dielectric strength tester.

[0062] Before step S1, the following steps are included: cleaning and drying the box 1 containing the insulating cooling medium, installing various components and grounding wires; testing the sealing performance of the experimental device to ensure that the sealing of the experimental device is reliable and leak-free;

[0063] Step S1 includes: adjusting the distance between the first electrode 21 and the second electrode 22 to 2.5 mm by adjusting the knob 31. In other embodiments, the distance can be adjusted according to actual detection requirements, which is not limited here.

[0064] Before step S2, the process also includes: the box 1 is evacuated to a preset vacuum degree and kept leak-proof. In some embodiments, for example, the box is evacuated through the liquid injection port 10 until the vacuum degree inside the box is below 133 Pa.

[0065] For the vapor-liquid two-phase state and the vapor state, before step S3, it includes: controlling the experimental temperature and / or pressure to reach the preset experimental required value. In some embodiments, when the insulating cooling medium is in the vapor-liquid two-phase state, the temperature of the insulating cooling medium in the vapor-liquid two-phase state between the first electrode 21 and the second electrode 22 is measured by the first temperature measuring probe 7, and the pressure inside the box 1 is detected by the pressure gauge 13. When its temperature and pressure reach the preset experimental temperature and pressure, the electric heating sleeve 4 is controlled to disconnect the power supply and stop working. And when the insulating cooling medium is in the vapor state, the pressure inside the box 1 is detected by the pressure gauge 13. When its pressure reaches the preset experimental pressure, the electric heater 5 is controlled to disconnect the power supply and stop working.

[0066] Step S3 includes: the dielectric strength tester boosts the first electrode 21 at a uniform boost speed to cause dielectric breakdown with the second electrode 22, and the dielectric strength tester records the voltage value, pauses for a period of time according to a preset time period after breakdown, repeats the step, and takes the voltage average. In some embodiments, the dielectric strength tester uniformly presses the first electrode 21 at a boost speed of 2kV / s (or 3kV / s) ±0.2kV / s until dielectric breakdown occurs with the second electrode 22, pauses for at least 2 minutes after breakdown, and then pressurizes again, repeats 6 times, and takes the average value of 6 times.

[0067] By implementing the present invention, the following beneficial effects are achieved:

[0068] The present invention designs a sealed and leak-proof experimental device, heats the liquid insulating cooling medium covering the test electrode through an electric heating sleeve, so that the insulating cooling medium in the middle of the electrode is in a vapor-liquid two-phase state, thereby measuring the dielectric strength data of the insulating cooling medium in the vapor-liquid two-phase state; and heats the insulating cooling medium through an electric heater located below the test electrode, so that the insulating cooling medium in the middle of the electrode is in a vapor state, thereby measuring the dielectric strength data of the insulating cooling medium in the vapor state, thereby providing data support for the design and production of high-voltage electrical equipment and ensuring its safe operation.

[0069] The present invention is described by specific embodiments, and it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or specific circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. An experimental device for detecting the dielectric strength of an insulating cooling medium in various phases, characterized in that: The experimental setup includes: A sealed box (1), one end of the box (1) being a voltage-applying end (11) for connecting to an external dielectric strength tester, and the other end being a grounding end (12); The test electrode (2) comprises a first electrode (21) disposed inside the box (1) and connected to the voltage applying terminal (11), and a second electrode (22) connected to the ground terminal (12), wherein the first electrode (21) and the second electrode (22) are disposed at a relative distance; An electrode spacing adjustment device (3), arranged on the outer shell of the box (1) and connected to the first electrode (21) or the second electrode (22), and used for adjusting the spacing between the first electrode (21) and the second electrode (22); an electric heating sleeve (4), which is sleeved on the first electrode (21) and / or the second electrode (22), and is used to heat the insulating cooling medium when the insulating cooling medium covers the test electrode (2) to detect the dielectric strength of the insulating cooling medium in a vapor-liquid two-phase state; an electric heater (5), arranged inside the box (1), and used to heat the insulating cooling medium when the insulating cooling medium is located below the test electrode (2) and the dielectric strength of the insulating cooling medium in a vapor state is detected; Wherein, the grounding terminal (12) is grounded via a grounding component (6) arranged on the box (1); The first electrode (21) and the second electrode (22) are connected to the voltage applying end (11) and the grounding end (12) respectively through a conductive rod (23); The electrode spacing adjustment device (3) comprises an adjustment knob (31) and a dial (32); The adjusting knob (31) is connected to the conductive rod (23) of the first electrode (21) or the second electrode (22), and is used to drive the first electrode (21) or the second electrode (22) to move by rotation, adjust the distance between the first electrode (21) and the second electrode (22), and display the rotation scale of the adjusting knob (31) through the dial (32); The experimental setup also includes: A first temperature measuring probe (7) is arranged inside the conductive rod (23) close to the first electrode (21) or the second electrode (22) and is used to measure the temperature of the insulating cooling medium between the first electrode (21) and the second electrode (22) when the insulating cooling medium is in a vapor-liquid two-phase state; The second temperature measuring probe (8) is arranged below the test electrode (2) and is used to measure the temperature of the insulating cooling medium in liquid state.

2. The experimental device for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 1 is characterized in that: It also includes a power supply terminal (9) arranged on the box body (1) and used for connecting to the wire of the electric heating sleeve (4), and the power supply terminal (9) is connected to an external power supply.

3. The experimental device for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 1 is characterized in that: It also comprises a liquid injection or discharge port (10) having a valve, which is used to inject the insulating cooling medium into the interior of the box (1) or to discharge the insulating cooling medium in the interior of the box (1).

4. The experimental device for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 1 is characterized in that: It also includes a pressure gauge (13) connected to the interior of the box (1) and used to detect the pressure inside the box (1).

5. The experimental device for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 4 is characterized in that: It also comprises a pressure release valve (14) which is in communication with the interior of the box (1) and is used for releasing pressure by opening when the pressure inside the box (1) exceeds the test requirement value.

6. An experimental method for detecting the dielectric strength of an insulating cooling medium in various phases using the experimental device according to claim 1, characterized in that: The following steps are involved: S1: adjusting the distance between the first electrode (21) and the second electrode (22) to a preset distance; S2: An insulating cooling medium having phase change characteristics is placed in the box (1) and the box (1) is kept sealed, so that the insulating cooling medium is in one of the following three states: (1) Liquid state, i.e., a state at room temperature and in which the insulating cooling medium covers the test electrode (2); (2) a vapor-liquid two-phase state, i.e., the insulating cooling medium covers the test electrode (2), and the insulating cooling medium is heated by the electric heating sleeve (4) to generate bubbles between the first electrode (21) and the second electrode (22); (3) Vapor state, i.e., the insulating cooling medium is located below the test electrode (2) and is heated by the electric heater (5) to vaporize the insulating cooling medium; S3: For each of the above states, the first electrode (21) is boosted by the dielectric strength tester to cause dielectric breakdown between the first electrode (21) and the second electrode (22), and the voltage value is recorded by the dielectric strength tester.

7. The experimental method for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 6, characterized in that: Before step S2, the following steps are also included: The box (1) is evacuated to a preset vacuum degree and is kept leak-proof.

8. The experimental method for detecting the dielectric strength of the insulating cooling medium in each phase according to claim 6, characterized in that: For the vapor-liquid two-phase state and the vapor state, the step before S3 includes: Control the experimental temperature and / or pressure to reach the preset experimental requirements.

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