Three-electrode device for testing dielectric properties of inorganic powder and method of using the same

Abstract

The application discloses a three-electrode device for testing dielectric properties of inorganic powder and a use method thereof, and belongs to the technical field of testing electrical insulation properties of inorganic powder materials. The application solves the technical problem that the existing dielectric property testing device cannot be used for researching dielectric properties of inorganic powder. The application provides a three-electrode system for testing and researching dielectric properties of inorganic powder, which comprises a mechanical part and an electrical measurement part. The mechanical part changes and tests the external pressure of inorganic powder by rotating a lifting bolt and testing pressure by using a pressure sensor. The electrical measurement part comprises a three-electrode system with a special structure, which can complete the testing function of electrical quantities, and also makes the height distance between a standard plate and an inner insulation barrel equal to the height between a high-voltage electrode and a measurement electrode, i.e. the thickness of the powder. The thickness of the powder can be obtained by measuring the height distance between the standard plate and the inner insulation barrel by using a plug gauge.

Description

Technical Field

[0001] This invention relates to a three-electrode device for testing the dielectric properties of inorganic powders and its method of use, belonging to the technical field of testing the electrical insulation properties of inorganic powder materials. Background Technology

[0002] Gas-insulated metal-enclosed transmission lines (GILs) have become increasingly widely used in the field of high-capacity, long-distance power transmission as a potential alternative to overhead lines, power cables, and wall bushings. However, traditional GILs using SF6 as the insulating medium have drawbacks such as high cost, decomposition products that can damage equipment and personnel, certain requirements for the working environment, and environmental hazards. In contrast, some inorganic powders have good insulation and thermal conductivity properties, making them a viable alternative to SF6 gas. Inorganic Powder Insulated Pipelines (IPILs) are a new concept proposed by Professor Li Zhonghua's research group at Harbin University of Science and Technology, which involves replacing part or all of the SF6 gas with inorganic powders.

[0003] Inorganic powders, used as functional additives in the preparation of polymer composite insulation, have improved the mechanical, thermal, and electrical properties of composite materials. This has long been a hot research area in electrical insulation science, with a wide range of research findings and numerous related reports. Due to their high thermal conductivity, high temperature resistance, resistance to thermal aging, non-toxicity, and reusability, inorganic powder dielectric materials offer significant advantages over organic dielectric materials in certain specialized fields, leading to their widespread application, such as in magnesium oxide mineral-insulated cables.

[0004] Whether inorganic powders are added to polymers as fillers or used as insulating media, in-depth research on their dielectric and breakdown properties is essential. However, existing dielectric property testing devices are mostly designed for block or plate materials. Testing powder materials requires pre-fabrication into block or plate shapes, and the test results are affected by the material processing technology. Furthermore, these devices cannot measure the conductivity, polarization, dielectric constant, and dielectric loss of powders under different electric field strengths in different states. Therefore, it is crucial to provide a novel three-electrode device for testing the dielectric properties of inorganic powders. Summary of the Invention

[0005] To address the technical problem that existing dielectric property testing devices cannot perform dielectric property studies on inorganic powders, this invention provides a three-electrode device for testing the dielectric properties of inorganic powders and its usage method.

[0006] The technical solution of this invention:

[0007] One objective of this invention is to provide a three-electrode device for testing the dielectric properties of inorganic powders, comprising an upper cover 1, a lower cover 2, an outer insulating barrel 3, a high-voltage electrode 4, a protective electrode 6, and a measuring electrode 13. The upper cover 1 is detachably fixed above the lower cover 2 by multiple lifting bolts 14 to form a height-adjustable test chamber. The outer insulating barrel 3, the high-voltage electrode 4, the protective electrode 6, and the measuring electrode 13 are placed inside the test chamber. The high-voltage electrode 4 is barrel-shaped and located inside the outer insulating barrel 3, and an inner insulating ring 5 is fixedly fitted inside the high-voltage electrode 4. The protective electrode 6 is barrel-shaped and inverted, installed inside the inner insulating ring 5, and is tightly fitted to the inner insulating ring 5. The measuring electrode 13 is placed inside the protective electrode 6, and the two are electrically insulated from each other by an insulating structure. A standard plate 7 and a pad 8 are placed sequentially above the protective electrode 6, and a pressure sensor 9 is installed on the pad 8.

[0008] Further specifying, the high-voltage electrode 4 has a terminal mounting hole 15 on its side wall.

[0009] Furthermore, one end of the electrode terminal is fixedly connected to the high-voltage electrode 4 through the terminal mounting hole 15, and the other end is connected to the high-voltage electrode lead, with the free end of the high-voltage electrode lead extending outside the test chamber.

[0010] Further, the bottom of the protection electrode 6 is provided with a measuring electrode lead through hole 16, a terminal mounting hole 15 and a plurality of positioning through holes 17, wherein the measuring electrode lead through hole 16 is located at the center of the bottom and the terminal mounting hole 15 is located at the bottom edge.

[0011] Furthermore, one end of the electrode terminal is fixedly connected to the protective electrode 6 through the terminal mounting hole 15, and the other end is connected to the shielding wire, with the free end of the shielding wire extending outside the test chamber.

[0012] Further specified, the first insulating post 10 is tightly fitted to the bottom of the protective electrode 6, and the bottom of the first insulating post 10 is provided with a positioning hole corresponding to the protective electrode 6, and the protective electrode 6 and the first insulating post 10 are fixed by bolts.

[0013] Further defining, the insulation structure includes a first insulating post 10, a second insulating post 11, and an insulating ring 12.

[0014] Furthermore, the measuring electrode 13 is a cylinder with an insulating ring 12 fitted on its outer side. Its bottom surface is connected to the second insulating post 11 and placed inside the protective electrode 6. The second insulating post 11 is in close contact with the first insulating post 10, and the outer walls of the second insulating post 11 and the insulating ring 12 are in close contact with the inner wall of the protective electrode 6.

[0015] Furthermore, the center of both the first insulating post 10 and the second insulating post 11 has a through hole corresponding to the through hole 16 of the measuring electrode lead for the measuring electrode lead to pass through.

[0016] Further, the bottom of the measuring electrode 13 is provided with a terminal mounting hole 15. One end of the electrode terminal is fixedly connected to the measuring electrode 13 through the terminal mounting hole 15, and the other end is connected to the measuring electrode lead. The free end of the measuring electrode lead extends to the outside of the test chamber.

[0017] Furthermore, the total height of the measuring electrode 13, the first insulating post 10, and the second insulating post 11 is the same as the height of the inner wall of the protective electrode 6.

[0018] Furthermore, the height of the outer wall of the protective electrode 6 shall not be less than the height of the inner insulating ring 5.

[0019] Furthermore, the height of the inner insulating ring 5 is greater than the height of the inner wall of the high-voltage electrode 4.

[0020] Furthermore, the height of the insulating ring 12 is the same as the height of the measuring electrode 13.

[0021] Further specified, the inner insulating ring 5, the first insulating post 10, the second insulating post 11, and the insulating ring 12 are made of polytetrafluoroethylene.

[0022] Furthermore, the high-voltage electrode 4, the protective electrode 6, and the measuring electrode 13 are made of brass.

[0023] The second objective of this invention is to use the aforementioned three-electrode device to test the conductivity current, time-domain current, surface potential, dielectric constant, and dielectric loss tangent of inorganic powders under different temperatures, pressures, and humidity conditions.

[0024] Further, the conductivity, polarization intensity, dielectric constant, and dielectric loss of powder under different states and different electric field intensities were measured, thus characterizing the dielectric properties of the powder.

[0025] The third objective of this invention is to provide a method for using the above-mentioned three-electrode device, comprising the following steps:

[0026] Step 1: First, fit the insulating ring 12 onto the outside of the measuring electrode 13. Then, fix one end of the electrode terminal to the measuring electrode 13 through the terminal mounting hole 15, and connect the other end to the measuring electrode lead. The free end of the measuring electrode lead passes through the central through hole of the second insulating post 11, and fix the second insulating post 11 to the measuring electrode 13. Then, install the first insulating post 10 at the bottom of the protective electrode 6, and fix the two with bolts through the positioning through hole 17. Then, the free end of the measuring electrode lead passes through the central through hole of the first insulating post 10 and the measuring electrode lead through hole 16 at the center of the protective electrode 6 in sequence and extends out. The measuring electrode 13, the insulating ring 12, the first insulating post 10, the second insulating post 11, and the inner wall of the protective electrode 6 are tightly fitted together. The top surface of the measuring electrode 13 and the upper edge of the protective electrode 6 are in the same plane. Finally, fix one end of the electrode terminal to the protective electrode 6 through the terminal mounting hole 15, and connect the other end to the shielding wire. The free end of the shielding wire extends out, thus obtaining the protective electrode system.

[0027] Step 2: First, install the inner insulating ring 5 inside the high-voltage electrode 4, ensuring that the outer wall of the inner insulating ring 5 is tightly fitted to the inner wall of the high-voltage electrode 4. Then, fix one end of the electrode terminal to the high-voltage electrode 4 through the terminal mounting hole 15, and connect the other end to the high-voltage electrode lead. The free end of the high-voltage electrode lead extends out, thus obtaining the high-voltage electrode system.

[0028] Step 3: First, place the outer insulating bucket 3 on the lower cover 2. Then, place the protective electrode system obtained in step 1 upside down inside the high-voltage electrode system obtained in step 2, ensuring that the outer wall of the protective electrode 6 is tightly fitted to the inner wall of the inner insulating ring 5. Place the entire assembly inside the outer insulating bucket 3. Then, place the standard plate 7 above the protective electrode 6, ensuring that the measuring electrode lead extends out. Place the pad 8 on top of the standard plate 7, on which the pressure sensor 9 is installed. Fix the upper cover 1 with the lifting bolt 14, so that the upper cover 1 contacts the pressure sensor 9, and ensure that the standard plate 7 is fitted to the edge of the inner insulating ring 5. Correct the distance between the two to obtain a specific pressure value.

[0029] Step 4: First, separate the protective electrode system and the high-voltage electrode system. Inject the inorganic powder to be tested into the inner insulating ring 5 and spread it evenly. Then, place the protective electrode system inside the high-voltage electrode system. Next, place the standard plate 7 above the protective electrode 6, ensuring that the measuring electrode lead extends out. Place the pad 8 with the pressure sensor 9 installed on it above the standard plate 7. Fix the upper cover 1 with the lifting bolt 14 so that the upper cover 1 contacts the pressure sensor 9. Adjust the lifting bolt 14 so that the pressure value is the same as the pressure value in step 3. Use a feeler gauge to measure the distance between the standard plate 7 and the inner insulating ring 5. This distance value is the thickness value of the inorganic powder (sample 18 to be tested) and also the distance value between the measuring electrode 13 and the high-voltage electrode 4.

[0030] Step 5: First, connect the high-voltage test lead of the testing instrument to the free end of the high-voltage electrode lead, connect the measuring lead of the testing instrument to the free end of the measuring electrode lead, and connect the ground wire of the testing instrument to the free end of the shield wire. To avoid external electromagnetic interference during testing, shielded wires and RF connectors are used for the measurement wiring to achieve accurate testing of small currents.

[0031] Step 6: Calculate the voltage applied to the powder according to the requirements of the test electric field strength, and complete the test of conduction current, time-domain current, surface potential, dielectric constant and dielectric loss tangent under different electric field conditions.

[0032] Step 7: Calculate the conductivity, polarization intensity, dielectric constant and dielectric loss of the powder under different electric field strengths based on the results obtained in Step 6, so as to characterize the dielectric properties of the powder.

[0033] Furthermore, by changing the type, particle size, packing state, and temperature of the inorganic powder, or by adjusting the pressure applied to the sample 18 by the lifting bolt 14, the influence of different conditions on the dielectric properties of the inorganic powder can be characterized.

[0034] This invention proposes a three-electrode system for testing the dielectric properties of inorganic powders. The system comprises a mechanical part and an electrical measurement part. The mechanical part consists of a pressure sensor, an upper cover, a lower cover, and a pad, which are connected and fixed by lifting bolts passing through through holes in the upper and lower covers. By rotating the lifting bolts and measuring the pressure using the pressure sensor, the pressure is displayed on a monitor, thus changing and testing the external pressure of the inorganic powder and simultaneously altering its packing state. The electrical measurement part includes a specially structured three-electrode system that performs electrical quantity testing while also containing the powder and transmitting mechanical pressure to it. Furthermore, the ingenious structural design ensures that the height distance between the standard plate and the inner insulating container is equal to the height distance between the high-voltage electrode and the measuring electrode, i.e., the powder thickness. The powder thickness can be obtained by measuring the height distance between the standard plate and the inner insulating container using a feeler gauge. Compared with existing technologies, this system also has the following advantages:

[0035] (1) The testing device provided by the present invention can perform tests on the conductivity current, time-domain current, surface potential, dielectric constant and dielectric loss tangent of inorganic powders under different temperatures, pressures and humidity.

[0036] (2) The present invention can apply pressure by lifting bolts to ensure that the pressure direction is perpendicular to the electrode and that the pressure on the powder between the electrodes is the same as the pressure measured by the sensor, thereby realizing the measurement of the pressure on the powder between the electrodes and realizing the macroscopic characterization of the stacking state of inorganic powder.

[0037] (3) The wiring used for testing in this invention uses shielded wires and radio frequency connectors to prevent external electromagnetic interference and achieve accurate testing of small currents. Attached Figure Description

[0038] Figure 1 A cross-sectional schematic diagram of a three-electrode apparatus for testing the dielectric properties of inorganic powders;

[0039] Figure 2 Top view of the protective electrode;

[0040] Figure 3 This is a schematic diagram of the three-dimensional structure of the high-voltage electrode;

[0041] Figure 4 This is a cross-sectional schematic diagram of the three-electrode device after powder injection;

[0042] In the diagram, 1-top cover, 2-bottom cover, 3-outer insulating barrel, 4-high voltage electrode, 5-inner insulating ring, 6-protective electrode, 7-standard plate, 8-pad, 9-pressure sensor, 10-first insulating column, 11-second insulating column, 12-insulating ring, 13-measuring electrode, 14-lifting bolt, 15-connector mounting hole, 16-measuring electrode lead through hole, 17-positioning through hole, 18-sample to be tested. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0045] Example 1:

[0046] This embodiment is implemented based on a novel three-electrode device, the specific device being as follows: Figure 1As shown, the test chamber includes an upper cover 1, a lower cover 2, an outer insulating barrel 3, a high-voltage electrode 4, a protective electrode 6, and a measuring electrode 13. The upper cover 1 is detachably fixed above the lower cover 2 by multiple lifting bolts 14 to form a height-adjustable test chamber. The outer insulating barrel 3, the high-voltage electrode 4, the protective electrode 6, and the measuring electrode 13 are placed inside the test chamber. The high-voltage electrode 4 is barrel-shaped and located inside the outer insulating barrel 3, and an inner insulating ring 5 is fixedly fitted inside the high-voltage electrode 4. The protective electrode 6 is barrel-shaped and installed upside down inside the inner insulating ring 5, and is tightly fitted to the inner insulating ring 5. The measuring electrode 13 is placed inside the protective electrode 6, and the two are electrically insulated from each other by an insulating structure. A standard plate 7 and a pad 8 are placed on top of the protective electrode 6, and a pressure sensor 9 is installed on the pad 8.

[0047] Among them, such as Figure 3 As shown, a terminal mounting hole 15 is opened on the side wall of the high voltage electrode 4. One end of the electrode terminal is fixedly connected to the high voltage electrode 4 through the terminal mounting hole 15, and the other end is connected to the high voltage electrode lead. The free end of the high voltage electrode lead extends to the outside of the test chamber.

[0048] Among them, such as Figure 2 As shown, the bottom of the protective electrode 6 is provided with a measuring electrode lead through hole 16, a terminal mounting hole 15 and multiple positioning through holes 17. The measuring electrode lead through hole 16 is located at the center of the bottom, and the terminal mounting hole 15 is located at the bottom edge. One end of the electrode terminal is fixedly connected to the protective electrode 6 through the terminal mounting hole 15, and the other end is connected to the shielding wire. The free end of the shielding wire extends to the outside of the test chamber.

[0049] The measuring electrode 13 is a cylinder with an insulating ring 12 fitted on its outer side. Its bottom surface is connected to the second insulating post 11 and placed inside the protective electrode 6. The second insulating post 11 is in close contact with the first insulating post 10, and the outer walls of the second insulating post 11 and the insulating ring 12 are in close contact with the inner wall of the protective electrode 6. The center of the first insulating post 10 and the second insulating post 11 is provided with a through hole corresponding to the through hole 16 of the measuring electrode lead for the measuring electrode lead to pass through. The bottom of the measuring electrode 13 is provided with a terminal mounting hole 15. One end of the electrode terminal is fixedly connected to the measuring electrode 13 through the terminal mounting hole 15, and the other end is connected to the measuring electrode lead. The free end of the measuring electrode lead extends to the outside of the test chamber.

[0050] Furthermore, the height of the outer wall of the protective electrode 6 is not less than the height of the inner insulating ring 5. The height of the inner insulating ring 5 is greater than the height of the inner wall of the high-voltage electrode 4. The height of the insulating ring 12 is the same as the height of the measuring electrode 13. The inner insulating ring 5, the first insulating post 10, the second insulating post 11, and the insulating ring 12 are made of polytetrafluoroethylene. The high-voltage electrode 4, the protective electrode 6, and the measuring electrode 13 are made of brass.

[0051] The method for testing and studying the dielectric properties of inorganic powders based on the above-mentioned three-electrode device specifically includes the following steps:

[0052] Step 1: First, fit the insulating ring 12 onto the outside of the measuring electrode 13. Then, fix one end of the electrode terminal to the measuring electrode 13 through the terminal mounting hole 15, and connect the other end to the measuring electrode lead. The free end of the measuring electrode lead passes through the central through hole of the second insulating post 11, and fix the second insulating post 11 to the measuring electrode 13. Then, install the first insulating post 10 at the bottom of the protective electrode 6, and fix the two with bolts through the positioning through hole 17. Then, the free end of the measuring electrode lead passes through the central through hole of the first insulating post 10 and the measuring electrode lead through hole 16 at the center of the protective electrode 6 in sequence and extends out. The measuring electrode 13, the insulating ring 12, the first insulating post 10, the second insulating post 11, and the inner wall of the protective electrode 6 are tightly fitted together. The top surface of the measuring electrode 13 and the upper edge of the protective electrode 6 are in the same plane. Finally, fix one end of the electrode terminal to the protective electrode 6 through the terminal mounting hole 15, and connect the other end to the shielding wire. The free end of the shielding wire extends out, thus obtaining the protective electrode system.

[0053] Step 2: First, install the inner insulating ring 5 inside the high-voltage electrode 4, ensuring that the outer wall of the inner insulating ring 5 is tightly fitted to the inner wall of the high-voltage electrode 4. Then, fix one end of the electrode terminal to the high-voltage electrode 4 through the terminal mounting hole 15, and connect the other end to the high-voltage electrode lead. The free end of the high-voltage electrode lead extends out, thus obtaining the high-voltage electrode system.

[0054] Step 3: First, place the outer insulating bucket 3 on the lower cover 2. Then, place the protective electrode system obtained in step 1 upside down inside the high-voltage electrode system obtained in step 2, ensuring that the outer wall of the protective electrode 6 is tightly fitted to the inner wall of the inner insulating ring 5. Place the entire assembly inside the outer insulating bucket 3. Then, place the standard plate 7 above the protective electrode 6, ensuring that the measuring electrode lead extends out. Place the pad 8 on top of the standard plate 7, on which the pressure sensor 9 is installed. Fix the upper cover 1 with the lifting bolt 14, so that the upper cover 1 contacts the pressure sensor 9, and ensure that the standard plate 7 is fitted to the edge of the inner insulating ring 5. Correct the distance between the two to obtain a specific pressure value.

[0055] Step 4: First, separate the protective electrode system and the high-voltage electrode system. Inject the inorganic powder to be tested into the inner insulating ring 5 and spread it evenly. Then, place the protective electrode system inside the high-voltage electrode system. Next, place the standard plate 7 above the protective electrode 6, ensuring the measuring electrode lead extends out. Place the pad 8 with the pressure sensor 9 installed above the standard plate 7. Fix the upper cover 1 with the lifting bolt 14 so that the upper cover 1 contacts the pressure sensor 9. Adjust the lifting bolt 14 so that the pressure value is the same as the pressure value in step 3. Use a feeler gauge to measure the distance between the standard plate 7 and the inner insulating ring 5. This distance value is the thickness value of the inorganic powder (sample 18 to be tested), and it is also the distance value between the measuring electrode 13 and the high-voltage electrode 4. Figure 4 As shown.

[0056] Step 5: First, connect the high-voltage test lead of the testing instrument to the free end of the high-voltage electrode lead, connect the measuring lead of the testing instrument to the free end of the measuring electrode lead, and connect the ground wire of the testing instrument to the free end of the shield wire. To avoid external electromagnetic interference during testing, shielded wires and RF connectors are used for the measurement wiring to achieve accurate testing of small currents.

[0057] Step 6: Calculate the voltage applied to the powder according to the requirements of the test electric field strength, and complete the test of conduction current, time-domain current, surface potential, dielectric constant and dielectric loss tangent under different electric field conditions.

[0058] Step 7: Calculate the conductivity, polarization intensity, dielectric constant and dielectric loss of the powder under different electric field strengths based on the results obtained in Step 6, thereby characterizing the dielectric properties of the powder.

[0059] Step 8: By changing the powder material, particle size, shape, pressure applied, temperature of the powder (by placing the entire device in a constant temperature drying oven), and blending different powders (different materials, different particle sizes), etc., repeat steps 1 to 7 to characterize the dielectric properties of the powder.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention, given for illustrative purposes, and are not exhaustive, nor intended to limit the invention to the precisely described content. Many modifications and variations are possible under the guidance of the above teachings. These embodiments were chosen and described only to best explain the principles of the invention and their practical application, thereby enabling those skilled in the art to better apply the invention in various embodiments and with various modifications suitable for the particular intended use. Therefore, it should be understood that the present invention is intended to cover all modifications and equivalents within the scope of the claims.

Claims

1. A three-electrode device for testing dielectric properties of inorganic powders, characterized in that, The utility model relates to a kind of high-voltage electrode test device, including upper cover, lower cover, outer insulation barrel, high-voltage electrode, protection electrode system, upper cover is detachably fixed above lower cover by multiple lifting bolts and constitutes height-adjustable test cavity, outer insulation barrel, high-voltage electrode, protection electrode system are placed in test cavity;High-voltage electrode is barrel-shaped and located in outer insulation barrel, and the inside of high-voltage electrode is fixedly sleeved with inner insulation ring;Protection electrode system includes protection pole, measuring pole and insulation structure;Protection electrode is barrel-shaped, measuring pole is placed in the inside of protection pole, and electrical insulation is realized between the two by insulation structure;Insulation structure includes first insulating column, second insulating column and insulation ring I;First insulating column is tightly fitted and installed at the bottom in protection pole, measuring pole is cylinder, and its outside is sleeved with insulation ring I;Measuring pole bottom is placed in protection pole after being connected with second insulating column, second insulating column is tightly fitted with first insulating column, and the outer wall of second insulating column and insulation ring I is tightly fitted with the inner wall of protection pole;Protection electrode system is installed in the inside of inner insulation ring in reverse, and is tightly fitted with inner insulation ring; Standard plate and cushion block are placed in the upper of protection pole in turn, and pressure sensor is installed on cushion block; The height sum of measuring pole, first insulating column and second insulating column is same with the inner wall height of protection pole;The outer wall height of protection pole is equal to the height of inner insulation ring;The height of inner insulation ring is greater than the inner wall height of high-voltage electrode; To-be-measured sample is located in inner insulation ring, and is below protection electrode system.

2. The three-electrode device of claim 1, wherein, High-voltage electrode is provided with terminal post mounting hole on side wall.

3. The three-electrode device of claim 2, wherein, One end of electrode terminal post is fixedly connected with high-voltage electrode through terminal post mounting hole, and the other end is connected with high-voltage lead, and the free end of high-voltage lead extends to outside of test cavity.

4. The three-electrode device of claim 1, wherein, Protection pole is provided with measuring pole lead through hole, terminal post mounting hole and multiple positioning through holes at bottom, wherein measuring pole lead through hole is located at center of bottom, and terminal post mounting hole is located at edge of bottom.

5. The three-electrode device of claim 4, wherein, One end of electrode terminal post is fixedly connected with protection pole through terminal post mounting hole, and the other end is connected with shielding wire, and the free end of shielding wire extends to outside of test cavity.

6. The three-electrode device of claim 4, wherein, First insulating column is provided with positioning hole corresponding to protection pole at bottom, and protection pole and first insulating column are fixed by bolt.

7. The three-electrode device of claim 6, wherein, Measuring pole is provided with terminal post mounting hole at bottom, one end of electrode terminal post is fixedly connected with measuring pole through terminal post mounting hole, and the other end is connected with measuring pole lead, and the free end of measuring pole lead extends to outside of test cavity.

8. Use of a three-electrode device according to claim 1, characterized in that It is used for completing the test of electric conductance current, time-domain current, surface potential, dielectric constant and dielectric loss tangent of inorganic powder under different temperature, different pressure and different humidity.

9. A method of using the three-electrode device of claim 1, wherein, Inorganic powder is injected into high-voltage electrode with inner insulation ring fixedly sleeved inside.

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