CN114814387B - A high voltage electrode device and method for measuring spatial charge distribution of thick samples - Google Patents
A high voltage electrode device and method for measuring spatial charge distribution of thick samples Download PDFInfo
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- CN114814387B CN114814387B CN202210365780.4A CN202210365780A CN114814387B CN 114814387 B CN114814387 B CN 114814387B CN 202210365780 A CN202210365780 A CN 202210365780A CN 114814387 B CN114814387 B CN 114814387B
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- 238000000034 method Methods 0.000 title claims abstract description 24
- 229910052751 metal Inorganic materials 0.000 claims description 54
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- 239000003990 capacitor Substances 0.000 claims description 22
- 239000007787 solid Substances 0.000 claims description 15
- 239000003822 epoxy resin Substances 0.000 claims description 13
- 229920000647 polyepoxide Polymers 0.000 claims description 13
- 238000009413 insulation Methods 0.000 claims description 10
- 229920002545 silicone oil Polymers 0.000 claims description 8
- 238000002955 isolation Methods 0.000 claims description 7
- 230000015556 catabolic process Effects 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 238000001291 vacuum drying Methods 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims 2
- 238000005259 measurement Methods 0.000 abstract description 15
- 230000005684 electric field Effects 0.000 description 12
- 239000011810 insulating material Substances 0.000 description 4
- 239000003989 dielectric material Substances 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
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- 239000000463 material Substances 0.000 description 2
- -1 polytetrafluoroethylene Polymers 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/12—Measuring electrostatic fields or voltage-potential
- G01R29/14—Measuring field distribution
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
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Abstract
The invention relates to a high-voltage electrode device and a method for measuring thick sample space charge distribution, which belong to the technical field of space charge measurement, wherein an outer layer flat plate electrode, an insulating tube and an inner layer flat plate electrode form an upper flat plate electrode, which is equivalent to dividing a circular area on the upper flat plate electrode by using the insulating tube, the inner layer flat plate electrode applies a first direct-current high voltage and a pulse voltage, the outer layer flat plate electrode applies a second direct-current high voltage with the same amplitude as the first direct-current high voltage, the insulating tube separates the pulse application area from the whole area of the electrode, the increase of equivalent load capacitance caused by overlarge electrode area is prevented, and the measurement of the thick sample space charge distribution is realized.
Description
Technical Field
The invention relates to the technical field of space charge measurement, in particular to a high-voltage electrode device and a method for measuring space charge distribution of a thick sample.
Background
Space charge is an important parameter for characterizing the electrical performance of dielectric materials, and space charge measurement is of great significance for the study of dielectric properties of dielectrics. There are a large number of traps in the polymer which, under the action of an electric field, trap carriers to form space charges inside the medium. Space charges can cause severe distortion to the internal electric field of the insulating material. Wherein, the space charges with the same polarity reduce the electric field intensity of the accumulation area, and the space charges with different polarities increase the electric field intensity of the accumulation area, thereby affecting the charge injection of the electrode, the mobility of carriers, the breakdown intensity of the insulating material, and the like. Thus, by measuring the space charge distribution of the material, not only the build-up and decay process of the space charge in the insulating material can be understood, but also the electrical breakdown and electrical aging process of the dielectric material can be understood more deeply. This is of great importance for the analysis and optimization of the insulating material.
There are many methods for measuring space charge, and a relatively common method is the Electro-Acoustic-impulse (PEA) method. The conventional PEA device measures space charge distribution by applying pulse voltage to the electrode pair Bao Shiyang, the applied voltage is smaller, and the area of the used electrode is smaller. However, when the space charge distribution of a thick sample is measured, a higher voltage needs to be applied to ensure that the electric field meets the measurement requirement. The increased voltage increases the probability of flashover, and thus the area of the sample needs to be increased, and the electrode area is correspondingly increased in order to ensure that the electric field in the sample is uniform. However, if a pulse voltage is applied to a larger area electrode, the equivalent load capacitance of the electrode increases, and it is difficult to apply a narrow pulse signal to the sample. Therefore, it is difficult for conventional PEA devices to measure thick sample space charge distribution.
Disclosure of Invention
The invention aims to provide a high-voltage electrode device and a method for measuring the space charge distribution of a thick sample, so as to realize measurement of the space charge distribution of the thick sample.
In order to achieve the above object, the present invention provides the following solutions:
A high-voltage electrode device for measuring the space charge distribution of a thick sample comprises a pressurizing device, an insulating tube, an inner layer flat plate electrode and an outer layer flat plate electrode;
the insulating tube is of a hollow cylinder structure, the inner layer flat plate electrode is nested in the hollow part of the insulating tube, a cylindrical through hole matched with the insulating tube is formed in the outer layer flat plate electrode, and the insulating tube and the inner layer flat plate electrode are both arranged in the cylindrical through hole;
The upper surface of the inner layer plate electrode in the upper plate electrode is connected with the pressurizing device;
The pressurizing device is used for introducing a first direct-current high voltage and pulse voltage to the inner layer flat plate electrode and applying the first direct-current high voltage and pulse voltage to the thick sample to be tested, the outer layer flat plate electrode is used for introducing a second direct-current high voltage and applying the second direct-current high voltage to the thick sample to be tested, and the amplitude of the first direct-current high voltage is equal to that of the second direct-current high voltage.
Optionally, the heights of the inner layer flat plate electrode and the outer layer flat plate electrode in the upper surface of the upper flat plate electrode are the same, the insulating tube on the upper surface of the upper flat plate electrode is higher than the inner layer flat plate electrode and the outer layer flat plate electrode to form an annular bulge structure, and the annular bulge structure is used for increasing the insulating distance and preventing the influence of creeping discharge generated by applying high voltage when measuring a thick sample to be measured.
Optionally, the pressurizing device comprises a pressure equalizing ball, a high-pressure guide rod and a blocking circuit;
One end of the high-voltage guide rod is in threaded connection with the voltage-equalizing ball, and the other end of the high-voltage guide rod is connected with the inner-layer flat plate electrode;
The direct-isolation loop is connected with the high-voltage guide rod and is used for accessing pulse voltage and is accessed into the inner-layer flat plate electrode through the high-voltage guide rod.
Optionally, the blocking circuit comprises a blocking capacitor and a BNC connector;
one pin of the blocking capacitor is connected with the high-voltage guide rod, the other pin of the blocking capacitor is connected with the BNC connector, the blocking capacitor is used for isolating direct-current high voltage from pulse voltage, and the BNC connector is used for being connected with the pulse voltage and introducing the pulse voltage into the high-voltage guide rod after passing through the blocking capacitor.
Optionally, the pressurizing device further comprises a metal shielding shell and an epoxy resin insulating layer;
The metal shielding shell is of a sleeve structure, and is sleeved on a high-voltage guide rod, the high-voltage guide rod is positioned at the axis of the metal shielding shell and is not contacted with the metal shielding shell, and an epoxy resin insulating layer is filled between the metal shielding shell and the high-voltage guide rod;
The blocking capacitor is arranged in the epoxy resin insulating layer, and the BNC connector is arranged on the metal shielding shell;
The metal shielding shell is grounded, the metal shielding shell is used for shielding external interference signals, and the epoxy resin insulating layer is used for preventing insulation breakdown between the high-voltage guide rod and the metal shielding shell.
Optionally, when the thick sample to be measured is a solid sample, the hollow part of the insulating tube is provided with a semiconductive layer, the inner layer flat electrode is contacted with the solid sample through the semiconductive layer, and the semiconductive layer, the insulating tube and the outer layer flat electrode are in close contact with the solid sample without air gaps;
when the thick sample to be measured is a liquid sample, the hollow part of the insulating tube is provided with a chamfer structure, the inner layer flat plate electrode is in direct contact with the liquid sample, and the insulating tube and the outer layer flat plate electrode are in close contact with the liquid sample without an air gap.
Optionally, the area of the upper plate electrode is smaller than that of the lower plate electrode.
Optionally, the inner layer flat plate electrode, the outer layer flat plate electrode and the lower flat plate electrode are all metal electrodes;
The high-voltage guide rod and the metal shielding shell are made of metal aluminum.
A method of measuring thick sample space charge distribution based on the aforementioned high voltage electrode device, the method comprising:
Arranging a thick sample to be measured between a lower plate electrode and an upper plate electrode;
connecting the pressurizing device with an inner layer plate electrode in the upper plate electrode;
introducing a first direct-current high voltage on the pressurizing device, and introducing a second direct-current high voltage on an outer layer plate electrode in the upper plate electrode, wherein the amplitude of the first direct-current high voltage is equal to that of the second direct-current high voltage;
The pressurizing device is connected with pulse voltage;
and measuring the space charge distribution of the thick sample to be measured at the lower plate electrode.
Optionally, the thick sample to be measured is disposed between the lower plate electrode and the upper plate electrode, and specifically includes:
When the thick sample to be measured is a solid sample, placing the thick sample to be measured on a lower flat plate electrode;
Dropping silicone oil on the upper surface of the thick sample to be measured, then placing a semiconductive layer, and smearing silicone oil on the surface of the semiconductive layer;
Aligning and clamping the semiconductive layer on the hollow part of the insulating tube of the upper plate electrode, so that the insulating tube, the outer plate electrode and the semiconductive layer are in close contact with a thick sample to be tested without an air gap;
when the thick sample to be measured is a liquid sample, immersing the lower plate electrode in the liquid sample;
Immersing the upper plate electrode in the liquid sample, and carrying out vacuum air suction through a vacuum drying oven so that no bubbles exist between the thick liquid sample to be detected and the upper plate electrode.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
The invention discloses a high-voltage electrode device and a method for measuring the space charge distribution of a thick sample, wherein an upper flat electrode is formed by an outer flat electrode, an insulating tube and an inner flat electrode, which are equivalent to dividing a circular area on the upper flat electrode by using the insulating tube, the inner flat electrode applies a first direct-current high voltage and a pulse voltage, the outer flat electrode applies a second direct-current high voltage with the same amplitude as the first direct-current high voltage, the insulating tube separates the pulse application area from the whole area of the electrode, the increase of equivalent load capacitance caused by the overlarge area of the electrode is prevented, and the measurement of the space charge distribution of the thick sample is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a high voltage electrode device for measuring space charge distribution of a thick sample according to the present invention;
fig. 2 is a diagram of an upper plate electrode structure according to the present invention.
The symbol is that 1-voltage equalizing ball, 2-high voltage guide rod, 3-metal shielding shell, 4-direct circuit, 41-direct capacitor, 42-BNC connector, 5-epoxy resin insulating layer, 6-insulating tube, 7-inner layer plate electrode, 8-outer layer plate electrode, 9-semiconductive layer, 10-thick sample to be tested, 11-lower plate electrode.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a high-voltage electrode device and a method for measuring the space charge distribution of a thick sample, so as to realize measurement of the space charge distribution of the thick sample.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
In order to solve the problem that the PEA measuring device is difficult to measure the space charge distribution of a thick sample in the prior art, the invention provides a high-voltage electrode device for measuring the space charge distribution of the thick sample, which is shown in figure 1 and comprises a pressurizing device, an insulating tube 6, an inner-layer flat plate electrode 7 and an outer-layer flat plate electrode 8.
The insulating tube 6 is of a hollow cylinder structure, the inner layer flat plate electrode 7 is nested in the hollow part of the insulating tube 6, a cylindrical through hole matched with the insulating tube 6 is formed in the outer layer flat plate electrode 8, the insulating tube 6 and the inner layer flat plate electrode 7 are arranged in the cylindrical through hole, and the outer layer flat plate electrode 8, the insulating tube 6 and the inner layer flat plate electrode 7 form an upper flat plate electrode. The upper surface of the inner plate electrode 7 in the upper plate electrode is connected with a pressurizing device, and a thick sample 10 to be measured is arranged between the lower plate electrode 11 and the lower surface of the upper plate electrode. The pressurizing device is used for introducing a first direct-current high voltage and pulse voltage to the inner-layer flat plate electrode 7 and applying the first direct-current high voltage and pulse voltage to the thick sample 10 to be tested, the outer-layer flat plate electrode 8 is used for introducing a second direct-current high voltage and applying the second direct-current high voltage to the thick sample 10 to be tested, and the amplitude of the first direct-current high voltage is equal to that of the second direct-current high voltage. After the first direct-current high voltage, the second direct-current high voltage and the pulse voltage are applied to the thick sample 10 to be measured, the space charge distribution of the thick sample 10 to be measured is measured at the lower plate electrode 11.
Preferably, the insulating tube 6 and the outer flat electrode 8 are connected together in a nested manner, and the connection is fastened by pressure. The insulating tube 6, the inner layer flat plate electrode 7 and the outer layer flat plate electrode 8 are in close contact without gaps, and the radius of the insulating tube 6 is far smaller than the width of the upper flat plate electrode.
A circular region is divided by an insulating tube 6 made of polytetrafluoroethylene material in the central region of the plate electrode. The dc voltage is applied to the entire rectangular electrode, and the pulse voltage is applied in addition to the dc voltage in the circular region of the rectangular electrode divided by the insulating tube 6 at the center thereof, thereby realizing measurement of space charge and space electric field. The pulse application area is separated from the whole area of the electrode by the insulating tube 6 in the central area, so that the increase of equivalent load capacitance caused by the overlarge electrode area is prevented, and the measuring effect is prevented from being influenced.
Illustratively, referring to fig. 2, the heights of the inner and outer flat electrodes 7 and 8 in the upper surface of the upper flat electrode are the same, the insulating tube 6 in the upper surface of the upper flat electrode is higher than the inner and outer flat electrodes 7 and 8 to form an annular protrusion structure for increasing an insulation distance to prevent the influence of creeping discharge generated by applying high voltage when measuring the thick sample 10 to be measured. The insulation distance of the pulse voltage application area on the upper surface of the electrode is effectively increased through the bulge structure of the insulation tube 6 on the upper surface of the flat plate electrode, so that the influence caused by the pulse voltage creeping discharge is reduced.
The pressurizing device comprises a pressure equalizing ball 1, a high-pressure guide rod 2 and a blocking circuit 4. One end of the high-voltage guide rod 2 is in threaded connection with the voltage equalizing ball 1, the other end of the high-voltage guide rod 2 is connected with the inner-layer flat plate electrode 7, and the voltage equalizing ball 1 is used for being connected with high-voltage direct current and is connected with the inner-layer flat plate electrode 7 through the high-voltage guide rod 2. The blocking circuit 4 is connected with the high-voltage guide rod 2, and the blocking circuit 4 is used for accessing pulse voltage and is accessed into the inner layer flat plate electrode 7 through the high-voltage guide rod 2. The diameter of the high-voltage guide rod 2 is smaller than that of the inner-layer flat electrode 7.
The top end of the high-voltage guide rod 2 is connected with the pressure equalizing ball 1 through a thread structure, and the bottom end is tightly connected with the inner layer flat plate electrode 7 of the upper flat plate electrode. The pressure equalizing ball 1 has a polished smooth spherical structure. The high-voltage direct current is connected to the equalizing ball 1, so that compared with the direct connection, the equalizing ball has fewer metal burrs, and when the applied direct current voltage is higher, the influence of partial discharge can be effectively reduced. The pressurizing device is inserted into the center of the annular bulge structure of the insulating tube 6 through the high-voltage guide rod 2, is tightly attached to the inner layer plate electrode 7 of the upper plate electrode under the action of pressure, and the position of the high-voltage guide rod 2 is fixed by the insulating tube 6 and does not move, so that the electrode is formed into a whole.
The dc blocking circuit 4 comprises, by way of example, a dc blocking capacitor 41 and a BNC connector 42. One pin of the blocking capacitor 41 is connected with the high-voltage guide rod 2, the other pin of the blocking capacitor 41 is connected with the BNC connector 42, the blocking capacitor 41 is used for isolating direct-current high voltage and pulse voltage, and the BNC connector 42 is used for connecting the pulse voltage and introducing the pulse voltage into the high-voltage guide rod 2 after passing through the blocking capacitor 41. The structure and working principle of the blocking circuit 4 are as follows, the blocking capacitor 41 has two pins, in order to prevent partial discharge at the connection position of the pins, the original pins of the capacitor are thickened by a metal sleeve, one end of the thickened pins is welded on the middle high-voltage guide rod 2, and the other end is welded on the metal core of the BNC connector 42 on the metal shielding shell 3. The dc blocking capacitor 41 plays a role in isolating dc high voltage from a pulse power supply, and the BNC connector 42 is connected to the pulse power supply at the outer side of the metal shielding shell 3 to form a complete dc blocking circuit 4.
The pressurizing means also comprises, for example, a metallic shielding shell 3 and an epoxy insulating layer 5. The metal shielding shell 3 is of a sleeve structure, the metal shielding shell 3 is sleeved on the high-voltage guide rod 2, the high-voltage guide rod 2 is located at the axis position of the metal shielding shell 3, the high-voltage guide rod 2 is not contacted with the metal shielding shell 3, and an epoxy resin insulating layer 5 is filled between the metal shielding shell 3 and the high-voltage guide rod 2. The blocking capacitor 41 is disposed in an epoxy insulating layer and the BNC connector 42 is disposed on the metallic shield case 3. The metal shielding shell 3 is grounded, the metal shielding shell 3 is used for shielding external interference signals, and the epoxy resin insulating layer 5 is used for preventing insulation breakdown between the high-voltage guide rod 2 and the metal shielding shell 3. The epoxy resin insulating layer 5 plays a role of improving insulating strength. The pressurizing device can apply a voltage of 30kV at most.
Illustratively, the bottom end of the inner flat electrode 7 is slightly higher than the plane of the insulating tube 6 and the bottom end of the outer flat electrode 8 on the side of the electrode contacting the sample. When the thick sample 10 to be measured is a solid sample, the semi-conductive layer 9 is arranged at the hollow part of the insulating tube 6, the inner layer flat plate electrode 7 is contacted with the solid sample through the semi-conductive layer 9, and the semi-conductive layer 9, the insulating tube 6 and the outer layer flat plate electrode 8 are in close contact with the solid sample without air gaps. When the thick sample 10 to be measured is a liquid sample, the hollow part of the insulating tube 6 is provided with a chamfer structure, the inner layer flat plate electrode 7 is directly contacted with the liquid sample, and the insulating tube 6 and the outer layer flat plate electrode 8 are closely contacted with the liquid sample without air gaps.
Namely, when the solid sample is measured, the inner layer flat plate electrode 7 is not required to be added on one side of the contact surface of the inner layer flat plate electrode 7, which is close to the sample, of the insulating tube 6, but the inner layer flat plate electrode 7 is adjusted to be high, so that an air gap is prevented from being generated, the semiconductive layer 9 is conveniently placed, and the semiconductive layer 9 is used as a transition layer, so that acoustic impedance matching can be ensured. When a liquid sample is measured, the inner layer flat plate electrode 7 does not need to be heightened, the structure is changed into that a chamfer structure is needed to be added on one side, close to the sample, of the contact surface of the inner layer flat plate electrode 7 and the insulating tube 6, so that the discharge generated on the insulating tube 6 by the inner layer flat plate electrode 7 and the outer layer flat plate electrode 8 is improved, and the electric field size is reduced.
Illustratively, the upper plate electrode has a smaller area than the lower plate electrode 11. With this structure, the creepage distance from the upper plate electrode to the lower plate electrode 11 is increased.
Illustratively, the inner plate electrode 7, the outer plate electrode 8, and the lower plate electrode 11 are all metal electrodes. The high-voltage guide rod 2 and the metal shielding shell 3 are made of metal aluminum.
The high-voltage guide rod 2 is inserted into an annular area defined by the insulating tube 6 and is tightly connected with the inner-layer flat plate electrode 7, and pulse voltage and direct-current high voltage are applied to a circular area in the center of the insulating tube 6. The outer layer flat plate electrode 8 applies direct current high voltage to the sample to be tested in a mode of being directly connected with a direct current power supply, and the amplitude is consistent with the direct current high voltage applied by the high voltage guide rod 2. The insulating tube 6 is used for isolating the area where the pulse voltage is applied, and reducing the load capacitance of the upper plate electrode in the measuring process. The upper plate electrode does not contact one side of the test specimen, and the convex portion of the insulating tube 6 serves to increase the insulating distance, preventing the influence of creeping discharge generated by applying a large direct current voltage when measuring a thick test specimen. When the thick sample to be measured is a solid sample, the end area of the upper flat electrode is slightly higher than the contact plane of the electrode and the sample on the side where the upper flat electrode contacts the sample, the semiconductive layer 9 with the height slightly larger than the height difference between the lower plane of the upper flat electrode and the inner flat electrode is placed in the area and compacted when the area is actually measured, the lower surface of the semiconductive layer 9 is ensured, and the insulating tube 6 and the outer flat electrode 8 are in close contact with the sample to be measured without air gaps. When the thick sample to be measured is a liquid sample, the shape of the bottom end of the insulating tube is a chamfer structure, and the upper plate electrode is immersed in the liquid sample, so that no air bubble exists between the liquid sample and the upper plate electrode. The width of the upper plate electrode is slightly lower than that of the lower plate electrode 11, and the creepage distance from the upper plate electrode to the lower plate electrode 11 can be increased by this structure in practical application.
During measurement, direct-current high voltage is introduced to the voltage equalizing ball 1, and pulse voltage is applied through the direct-current blocking circuit 4, so that the requirement of applying a uniform direct-current electric field and pulse voltage to a sample to be measured during space charge measurement is met. Direct-current high voltage is directly applied to the outer-layer flat plate electrode 8, and the amplitude is consistent with the direct-current voltage on the voltage equalizing ball 1, so that the requirement of applying high voltage to measure the space charge of a thick sample is met.
The high-voltage electrode device of the invention has the following advantages:
(1) The flat plate electrode is divided into two areas through the insulating tube, pulse voltage and direct-current high voltage are applied to the inner metal electrode, and direct-current high voltage with the same amplitude as that of the central circular area is applied to the outer metal electrode. The division of the insulating tube reduces the electrode area of the pulse voltage application area, thereby reducing the equivalent load capacitance of the pulse power supply in the space charge measurement process. The area of the electrode for applying direct voltage is larger, and the uniformity of the electric field is ensured when high voltage is applied to measure thick samples.
(2) By the protruding structure of the insulating tube, the insulation distance of the creeping discharge is effectively increased, and the creeping discharge is prevented from being generated. When the thick sample to be measured is a solid sample, the bottom end of the inner layer metal electrode is slightly higher than the lower surface of the upper plate electrode, and the semiconductive layer is conveniently placed during measurement. The height of the semi-conductive layer is larger than the height difference that the bottom end of the inner metal electrode is slightly higher than the lower surface of the upper flat plate electrode, so that tight contact between the semi-conductive layer and a sample during measurement is ensured. When the thick sample to be measured is a liquid sample, the shape of the bottom end of the insulating tube is set to be a chamfer structure, and a semiconductive layer does not need to be put in.
(3) Through the pressure equalizing ball structure, the influence of partial discharge signals possibly generated when direct current high voltage is introduced on the test is effectively prevented.
(4) External signal interference is effectively reduced by grounding the metal shielding shell, and the insulating strength of the signal shielding area is improved by utilizing the epoxy resin insulating layer.
Based on the high-voltage electrode device, the invention also provides a method for measuring the space charge distribution of a thick sample, which comprises the following steps:
and step 1, arranging a thick sample to be measured between a lower plate electrode and an upper plate electrode.
Exemplary, the specific implementation process of step 1 is as follows:
when the thick sample to be measured is a solid sample, the thick sample to be measured is placed on a lower flat plate electrode, a semi-conductive layer is placed on the upper surface of the thick sample to be measured after silicone oil is dripped, and silicone oil is smeared on the surface of the semi-conductive layer;
When the thick sample to be measured is a liquid sample, the lower flat electrode is immersed in the liquid sample, the upper flat electrode is immersed in the liquid sample, and vacuum air suction is carried out through a vacuum drying oven, so that no air bubble exists between the thick sample to be measured and the upper flat electrode.
And 2, connecting the pressurizing device with an inner layer plate electrode in the upper plate electrode.
And 3, introducing a first direct-current high voltage on the pressurizing device, and introducing a second direct-current high voltage on an outer layer plate electrode in the upper plate electrode, wherein the amplitude of the first direct-current high voltage is equal to that of the second direct-current high voltage.
And 4, introducing pulse voltage by the pressurizing device.
And 5, measuring the space charge distribution of the thick sample to be measured at the lower plate electrode.
The method for analyzing the charge transport process in the nano medium by using the high-voltage electrode device by taking the insulating paper sample as a thick sample to be measured comprises the following steps:
Step one, placing a sample. And placing the treated insulating paper sample to be tested on the upper surface of the lower electrode, coating silicone oil on the upper and lower surfaces of the insulating paper, and placing a cylindrical semiconductive layer above the insulating paper. The radius of the semi-conductive layer is slightly larger than that of the inner metal electrode, and the height of the semi-conductive layer is slightly larger than the height difference between the bottom end of the inner metal electrode and the lower surface of the upper flat plate electrode. After silicone oil is smeared on the upper surface of the semiconductive layer, the central area of the upper flat electrode is aligned with the semiconductive layer and placed on a sample to be tested, the upper flat electrode and the lower electrode are pressed tightly, and no bubbles are guaranteed to appear on the contact surface of the electrode, the sample to be tested and the semiconductive layer.
And secondly, inserting the high-voltage guide rod into the annular area of the insulating tube in alignment, and tightly connecting the high-voltage guide rod with the inner-layer metal electrode, so that the whole high-voltage electrode device is integrated.
And step three, applying direct-current voltage. After the second step is completed, a direct-current high-voltage power supply is directly connected with the voltage equalizing ball to apply direct-current voltage through the high-voltage guide rod and the inner-layer metal electrode, meanwhile, the direct-current high voltage is applied to the outer-layer metal electrode, and the amplitude of the applied direct-current high voltage is the same as that of the voltage equalizing ball, so that the direct-current voltage is applied to the whole upper plate electrode. The direct-current high-voltage power supply applies high-voltage direct current to the outer metal electrode through the structure of the voltage-equalizing ball and the guide rod, and the voltage-equalizing ball and the guide rod used in the method are not identical with the voltage-equalizing ball and the guide rod for pressurizing the inner metal electrode.
And step four, applying pulse voltage. BNC connectors on the side wall of the metal shielding shell are connected with a pulse power supply, and pulse voltage is applied to the central area of the insulating tube through a direct-isolation loop and a high-voltage guide rod.
And fifthly, after the first step to the fourth step are completed, measuring the space charge of the thick sample by using measuring equipment of the lower electrode.
The invention improves the electrode structure in the existing PEA measuring device, so that the electrode structure can simultaneously measure the space electric field and the space charge of a large-size sample. A circular area is divided in the central area of the plate electrode by using an insulating tube made of polytetrafluoroethylene. The direct current voltage is applied to the whole rectangular electrode, and the pulse voltage is applied in addition to the direct current voltage in the circular area of the rectangular electrode center divided by the insulating tube, thereby realizing the measurement of space charge and space electric field.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, which are intended to facilitate an understanding of the principles and concepts of the invention and are to be varied in scope and detail by persons of ordinary skill in the art based on the teachings herein. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210365780.4A CN114814387B (en) | 2022-04-08 | 2022-04-08 | A high voltage electrode device and method for measuring spatial charge distribution of thick samples |
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| CN202210365780.4A CN114814387B (en) | 2022-04-08 | 2022-04-08 | A high voltage electrode device and method for measuring spatial charge distribution of thick samples |
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| PEA–Kerr Combined Measurement Method for Space Charge and Electric Field Distribution of Oil–Paper Composite Insulation;Huang Meng 等;IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT;20230131;全文 * |
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