A device for measuring the charge distribution of oil flow using a local transformer model

Abstract

This invention relates to a device for measuring the charge distribution of oil flow using a local transformer model. The device includes a temperature-controlled oil tank, a circulating pump, a speed regulating device, a buffer tank, a test chamber, and a measuring chamber. The temperature-controlled oil tank, circulating pump, buffer tank, test chamber, and measuring chamber are sequentially connected by insulated pipes. The measuring chamber is connected to the temperature-controlled oil tank via an insulated pipe. The speed regulating device is connected to two insulated pipes connecting the circulating pump. A flow meter is installed on the insulated pipe connecting the buffer tank and the test chamber. A first electrometer and a second electrometer are connected to the test chamber. A third electrometer is connected to the measuring chamber. A vacuum pump is connected to the insulated pipe connecting the measuring chamber and the temperature-controlled oil tank. This invention can accurately determine the degree of charge in oil flow and study the spatial distribution characteristics of the charge in oil flow, belonging to the technical field of oil flow charge measurement equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil flow electrification measuring device, and particularly relates to a device for measuring oil flow electrification distribution based on a local transformer model. BACKGROUND

[0002] In the existing forced oil circulation transformer, due to the large flow rate of transformer oil, when flowing through the oil channel formed by the winding gap and the insulating paper board, positive and negative charges are prone to separate, the positive charges generally circulate in the oil and then are released by leakage at various parts of the transformer, and the negative charges are prone to accumulate on the surface of the solid insulation such as the insulating paper board and gradually migrate to the inside, which is called oil flow electrification. In high-grade transformers such as 500kV transformers, due to the increase of the resistivity of the insulating material, it is difficult for the charges to diffuse and leak, and the charges are forced to accumulate on the surface of the solid insulation, which is prone to cause electrostatic discharge in the transformer and further cause transformer failure. At present, the main methods for studying the oil flow electrification of transformer insulating oil include micro-electrostatic measurement method, rotating disc method and pipeline type measurement method.

[0003] The micro-electrostatic measurement method and the rotating disc method both belong to electrostatic characteristic analysis devices, which generate oil flow electrification by different ways of rubbing the transformer insulating oil and the insulating paper board, and then record the leakage current generated by the oil flow electrification to represent the degree of oil flow electrification, but the simulated oil flow electrification process of the two methods is quite different from the actual oil flow electrification process in the transformer. The micro-electrostatic measurement method forces the insulating oil to penetrate the insulating paper to generate oil flow electrification, which is completely different from the fact that the insulating oil only flows through the surface of the insulating paper and paper board in the transformer. In order to make the insulating oil have better permeability, the insulating paper is replaced by filter paper, although the main components of the filter paper and the insulating paper are the same, but according to the comparison of the results of the two, there is still a gap in the numerical value; the rotating disc method applies the principle that the insulating oil in the transformer only flows through the surface of the insulating paper board, but the process of repeated rubbing is not consistent with the actual situation, so the two methods can only be used to preliminarily determine the degree of oil flow electrification of the insulating oil.

[0004] The pipeline type measurement method is most consistent with the actual oil flow electrification process in the transformer, which simulates the oil flow electrification of the transformer insulating oil and the solid insulation by making a simple single-layer rectangular oil channel, and measures and records the leakage current generated in the test to represent the degree of oil flow electrification of the transformer insulating oil. However, the above pipeline type measurement device is too simple for the actual structure of the complex transformer, and cannot study the spatial distribution characteristics of the oil flow electrification. At the same time, the original measurement method represents the degree of oil flow electrification of the insulating oil by the current size, ignoring the measurement of the charge density, but the actual harm of the oil flow electrification to the transformer is the partial discharge or even flashover caused by the accumulation of charges on the insulating paper board. SUMMARY

[0005] In view of the technical problems existing in the prior art, the present application aims to provide a device for measuring oil flow electrification distribution by local transformer model, which can accurately determine the electrification degree of oil flow and study the distribution characteristics of oil flow electrification in space.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The device for measuring oil flow electrification distribution by local transformer model comprises a temperature-controlled oil storage tank, a circulating pump, a speed regulating device, a buffer tank, a test tank and a measuring tank, the temperature-controlled oil storage tank, the circulating pump, the buffer tank, the test tank and the measuring tank are sequentially connected through insulation pipelines, the measuring tank is connected with the temperature-controlled oil storage tank through an insulation pipeline; the speed regulating device is connected with two insulation pipelines connected with the circulating pump, the insulation pipeline connecting the buffer tank and the test tank is provided with a flow meter, the test tank is connected with a first electrometer and a second electrometer; the measuring tank is connected with a third electrometer; the insulation pipeline connecting the measuring tank and the temperature-controlled oil storage tank is connected with a vacuum pump.

[0008] As a preferred, the temperature-controlled oil storage tank comprises an oil storage tank body and an oil storage tank cover, the oil storage tank body and the oil storage tank cover are sealingly connected; a heating silica gel plate is installed on the outside of the oil storage tank body; the oil storage tank body is provided with a first connecting port, a second connecting port, a third connecting port and a fourth connecting port, the first connecting port is connected with a first three-way pipe, the other two ports of the first three-way pipe are respectively provided with a first circulating valve and an oil outlet valve, the first circulating valve is connected with the circulating pump through an insulation pipeline; the second connecting port is connected with a K-type thermometer; the third connecting port is connected with a second three-way pipe, the other two ports of the second three-way pipe are respectively provided with a nitrogen control valve and a vacuum pump valve, the vacuum pump valve is connected with the vacuum pump through an insulation pipeline; the fourth connecting port is connected with a third three-way pipe, the other two ports of the third three-way pipe are respectively provided with a second circulating valve and an oil inlet valve, the second circulating valve is connected with the measuring tank through an insulation pipeline.

[0009] As a preferred, the buffer tank comprises a buffer tank body and a first metal mesh, the first metal mesh is arranged in the buffer tank body, the buffer tank body is provided with a buffer tank oil inlet and a buffer tank oil outlet, the buffer tank oil inlet is connected with the circulating pump through an insulation pipeline, the buffer tank oil outlet is connected with the test tank through an insulation pipeline; a first metal base is installed at the bottom of the buffer tank body as a measuring point, the first metal base is grounded, the first metal mesh is connected with the first metal base; the buffer tank body is provided with a buffer tank oil-free measurement area, the first metal base extends to the buffer tank oil-free measurement area.

[0010] As a preferred, the first metal mesh and the first metal base are made of red copper, and the buffer tank body is made of steel plate.

[0011] As a kind of preferred, the measuring tank includes measuring tank box and second metal net, second metal net is arranged in measuring tank box, measuring tank box is equipped with measuring tank oil inlet and measuring tank oil outlet, measuring tank oil inlet is connected with test tank through insulating pipeline, and measuring tank oil outlet is connected with temperature control oil tank through insulating pipeline;Second metal base is installed at the bottom of measuring tank box as measuring point, and second metal base lead connection third electrometer, and measuring tank box is equipped with measuring tank oil-free measurement area, and second metal base extends to measuring tank oil-free measurement area.

[0012] As a kind of preferred, second metal net and second metal base are made of red copper, and measuring tank box is made of steel plate.

[0013] As a kind of preferred, the test tank includes test tank box, first internal insulation layer, second internal insulation layer and copper pole, the first internal insulation layer covers the inner side wall of the test tank box, and the second internal insulation layer covers the inner side of the first internal insulation layer;The number of copper poles is several, and the several copper poles are arranged in linear array in the test tank box, each copper pole is fixed and supported by two copper rods, and the outer side of all copper poles is wrapped with insulating paper;Test tank box is equipped with test tank oil inlet and test tank oil outlet, test tank oil inlet is connected with buffer tank through insulating pipeline, test tank oil outlet is connected with measuring tank, and test tank box is equipped with baffle.

[0014] As a kind of preferred, the test tank box is equipped with test tank oil-free measurement area, the test tank oil-free measurement area is located at the outer side of the test tank box, and the copper pole extends to the test tank oil-free measurement area through the first internal insulation layer and the second internal insulation layer in sequence.

[0015] As a kind of preferred, the baffle is made of organic glass, the baffle is located at the test tank oil inlet, and the baffle and the inner wall of the test tank box have a gap.

[0016] As a kind of preferred, all the insulating pipelines are made of polytetrafluoroethylene.

[0017] The principle of the application is that the oil channel of each channel in the transformer is composed of multiple layers of cake oil channels in parallel, and multiple channels are connected in series to form a phase of the transformer, a single-phase transformer has only one phase, and a three-phase transformer has three parallel phases, so the transformer can be regarded as a collection of multiple channels, and therefore the basic unit of the transformer is simulated and prepared, that is, a single-channel oil channel.

[0018] When the partial transformer model is prepared, the winding is regarded as a cuboid for more convenient theoretical calculation of charge density, because the width of the oil channel in the actual transformer is not uniform along the radial direction, the outer diameter is slightly higher than the inner diameter, but the difference is much smaller than the thickness of the winding. After the model is simplified from trapezoidal to cuboid, the calculation formula of charge density is more simple.

[0019] When transformer insulating oil flows from bottom to top through this partial transformer model, an oil flow becomes charged on each winding. The negative charge generated on the solid insulation by this oil flow, formed by copper leads connected inside the winding electrodes, can be collected to characterize the magnitude of the oil flow charge. Simultaneously, this invention introduces a surface potentiometer to measure the surface potential of the solid insulation. By simplifying calculations, the potential measurement can be converted into a charge distribution measurement, allowing for the study of the charge distribution generated by the oil flow charge.

[0020] In summary, the present invention has the following advantages:

[0021] By employing this invention, the electrification process of the oil flow in an actual transformer can be simulated, truly reflecting the electrification characteristics of the insulating oil flow. Furthermore, the charge density distribution of the charge generated by the electrified insulating oil flow in the transformer at different spatial orientations can be studied. It can be further applied to the simulation of the electric field distribution inside the transformer to study the influence of the electrified transformer oil flow on the electric field distribution. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a device for measuring the charge distribution of oil flow using a local transformer model.

[0023] Figure 2 This is a cross-sectional view of the temperature-controlled oil reservoir.

[0024] Figure 3 This is the front view of the buffer box.

[0025] Figure 4 This is a side view of the buffer box.

[0026] Figure 5 This is the front view of the measuring box.

[0027] Figure 6 This is a side view of the measuring box.

[0028] Figure 7 This is the front view of the test chamber.

[0029] Figure 8 This is a side view of the test chamber.

[0030] Among them, 1 is a temperature-controlled oil storage tank, 2 is a circulating pump, 3 is a speed regulating device, 4 is a buffer tank, 5 is a test chamber, 6 is a measuring box, 7 is an insulated pipe, 8 is a flow meter, 9 is a first electrometer, 10 is a second electrometer, 11 is a third electrometer, 12 is a vacuum pump, 13 is a vacuum pump valve, 14 is the oil storage tank body, 15 is the oil storage tank cover, 16 is a heating silicone plate, 17 is a first tee pipe, 18 is a second connection port, 19 is a second tee pipe, 20 is a third tee pipe, 21 is a first circulation valve, 22 is an oil outlet valve, 23 is a K-type thermometer, 24 is a nitrogen control valve, 25 is a vacuum pump valve, and 26 is a second circulation valve. 27 is the oil inlet valve, 28 is the buffer tank body, 29 is the first metal mesh, 30 is the oil inlet of the buffer tank, 31 is the oil outlet of the buffer tank, 32 is the first metal base, 33 is the oil-free measurement area of ​​the buffer tank, 34 is the measurement tank body, 35 is the second metal mesh, 36 is the oil inlet of the measurement tank, 37 is the oil outlet of the measurement tank, 38 is the second metal base, 39 is the test chamber body, 40 is the first internal insulation layer, 41 is the second internal insulation layer, 42 is the copper electrode, 43 is the copper rod, 44 is the insulating paper, 45 is the oil inlet of the test chamber, 46 is the oil outlet of the test chamber, 47 is the baffle, 48 is the oil-free measurement area of ​​the test chamber, and 49 is the oil-free measurement area of ​​the measurement tank. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments.

[0032] A device for measuring the charge distribution of oil flow using a local transformer model includes a temperature-controlled oil tank, a circulating pump, a speed regulating device, a buffer tank, a test chamber, and a measuring chamber. The temperature-controlled oil tank, circulating pump, buffer tank, test chamber, and measuring chamber are sequentially connected by insulated pipes. The measuring chamber is connected to the temperature-controlled oil tank via an insulated pipe. The speed regulating device is connected to two insulated pipes connecting the circulating pump. A flow meter is installed on the insulated pipe connecting the buffer tank and the test chamber. A first electrometer and a second electrometer are connected to the test chamber. A third electrometer is connected to the measuring chamber. A vacuum pump is connected to the insulated pipe connecting the measuring chamber and the temperature-controlled oil tank. In this embodiment, the first, second, and third electrometers are all connected to a computer. During operation, transformer insulating oil heated to a set temperature in the temperature-controlled oil tank flows sequentially through the buffer tank, test chamber, and measuring chamber at a fixed flow rate under the action of the circulating pump and speed regulating device. The test results are recorded by the three electrometers (first, second, and third electrometers). All insulated pipes are made of polytetrafluoroethylene (PTFE). Insulated pipelines also serve as insulation to isolate electrical connections between different parts when transporting insulating oil. The first electrometer is a current electrometer, the second is a voltage electrometer, and the third is a current electrometer. The speed control device uses a speed-regulating valve. The flow rate is controlled by adjusting the valve opening and closing degree using a speed-regulating knob.

[0033] The temperature-controlled oil storage tank includes a tank body and a tank cover, which are sealed together. A heating silicone plate is installed on the outside of the tank body. The tank body has a first connection port, a second connection port, a third connection port, and a fourth connection port. The first connection port is connected to a first tee pipe, and the other two ports of the first tee pipe are respectively equipped with a first circulation valve and an oil outlet valve. The first circulation valve is connected to a circulation pump through an insulated pipe. A K-type thermometer is connected to the second connection port. The third connection port is connected to a second tee pipe, and the other two ports of the second tee pipe are respectively equipped with a nitrogen control valve and a vacuum pump valve. The vacuum pump valve is connected to a vacuum pump through an insulated pipe. The fourth connection port is connected to a third tee pipe, and the other two ports of the third tee pipe are respectively equipped with a second circulation valve and an oil inlet valve. The second circulation valve is connected to a measuring box through an insulated pipe. The heating silicone plate covers the outer surface of the tank body for heating, which provides more uniform heating compared to heating with a heating resistance wire. Temperature feedback from a type K thermocouple thermometer allows for control of the heating power of the silicone plate and timely temperature adjustment.

[0034] The buffer chamber includes a chamber body and a first metal mesh, which is housed within the chamber. The chamber body has an oil inlet and an oil outlet. The oil inlet is connected to a circulating pump via an insulated pipe, and the oil outlet is connected to a test chamber via an insulated pipe. A first metal base is installed at the bottom of the chamber body as a measuring point. The lead of the first metal base is grounded to remove all initial charge from the insulating oil, ensuring that the insulating oil entering the test chamber is electrically neutral. The first metal mesh and the first metal base are connected. The chamber body has an oil-free measuring area, and the first metal base extends into this area.

[0035] Both the first metal mesh and the first metal base are made of copper, which has good conductivity. The buffer box body is made of steel plate. Compared to copper, which has lower conductivity, this ensures that most of the charge is grounded through the copper measuring point or flows into the electrometer.

[0036] The measuring chamber includes a measuring chamber body and a second metal mesh, which is installed inside the measuring chamber body. The measuring chamber body has an oil inlet and an oil outlet. The oil inlet is connected to the test chamber via an insulated pipe, and the oil outlet is connected to a temperature-controlled oil storage tank via an insulated pipe. A second metal base is installed at the bottom of the measuring chamber body as a measuring point. The lead wire of the second metal base is connected to a third electrometer to measure the current generated by the positive charge in the insulating oil after the oil flow becomes energized. The measuring chamber body has an oil-free measuring area, and the second metal base extends into the oil-free measuring area. The oil outlet is connected to a second circulation valve.

[0037] In this embodiment, the buffer box and the measuring box contain multiple metal meshes to capture charges, and the measuring point leads are led out from the metal base to connect to ground or an electrometer.

[0038] Both the second metal mesh and the second metal base are made of copper, which has good conductivity. The measuring box body is made of steel plate. Compared to copper, which has lower conductivity, this ensures that most of the charge passes through the copper measuring point to ground or flows into the electrometer.

[0039] The test chamber includes a test chamber body, a first internal insulation layer, a second internal insulation layer, and copper electrodes. The first internal insulation layer covers the inner wall of the test chamber body, and the second internal insulation layer covers the inner side of the first internal insulation layer. There are several copper electrodes arranged in a linear array inside the test chamber body. Each copper electrode is fixed and supported by two copper rods, and the outer side of all copper electrodes is wrapped with insulating paper. The test chamber body has an oil inlet and an oil outlet. The oil inlet is connected to a buffer box through an insulating pipe, and the oil outlet is connected to a measuring box. A baffle is provided inside the test chamber body.

[0040] The test chamber is equipped with an oil-free measurement area, which is located on the outside of the test chamber. The copper electrodes pass through the first and second internal insulation layers and extend to the oil-free measurement area.

[0041] The baffle is made of plexiglass and is located at the oil inlet of the test chamber. There is a gap between the baffle and the inner wall of the test chamber.

[0042] The test chamber in this embodiment is constructed based on a channel within one phase of a transformer. This channel contains ten windings, each with a cuboid structure. Although the width of the oil passages in an actual transformer is not uniform radially, with the outer diameter slightly larger than the inner diameter, this difference is much smaller than the thickness of the windings. Therefore, the simulation device ignores the difference between the outer and inner diameters. Each winding is a copper plate (the copper plate is the copper electrode mentioned above), and the surface of the copper plate is covered with insulating paper. Each copper plate is supported and fixed by two copper rods welded to the chamber body. These copper rods extend backward to the oil-free measurement area of ​​the test chamber as measurement leads. One copper rod connects to a voltage electrometer, and the other connects to a current electrometer. The measurement chamber body is a shielded box made of steel plate. Between the insulating oil and the outer shielding box, there are two layers: an inner layer of polytetrafluoroethylene (PTFE, the second internal insulation layer) to prevent excessive contact between the insulating oil and the outer shielding box, which could cause the metal conductor oil to become charged and affect the test results; and an outer layer of insulating paperboard (the first internal insulation layer) to simulate the actual transformer structure, where each phase is insulated from other phases using insulating paperboard. The bottom of the enclosure also has an acrylic baffle, which is designed to simulate the actual structure of a transformer where the insulating oil enters and exits in a narrow path.

[0043] After the electrically neutral insulating oil flows into the test chamber, it generates an oil flow that becomes charged on the insulating paper. The negative charge accumulated on the insulating paper is then transferred to the measuring end of the copper rod through the copper plate. The current electrometer measures and records the leakage current generated at this time. After the ammeter is turned off and grounded, the voltage electrometer measures and records the potential of the insulating paper in steady state. The accumulated charge density on the insulating paper is then calculated using the formula ρ = 2εU / d2, where ρ is the accumulated charge density on the insulating paper, ε is the dielectric constant of the insulating oil, d is the distance between the two windings, and U is the potential of the insulating paper measured by the voltage electrometer.

[0044] Based on the current measurement results and charge density calculation results of windings at different heights, the charge density distribution generated by the oil flow in different spatial dimensions can be obtained. The actual transformer is a superposition of this local transformer model, and the charge density distribution of the entire transformer can be extrapolated from the local transformer model. Furthermore, the influence of the charge distribution generated by the oil flow on the transformer electric field can be calculated in the transformer electric field simulation.

[0045] The operating procedure for this device is as follows:

[0046] (1) Assemble the pre-dried insulating paperboard and insulating paper in the test chamber, close the nitrogen control valve and vacuum pump valve of the temperature-controlled oil tank, open the vacuum pump valve, and evacuate the entire device for 30 minutes.

[0047] (2) Close the vacuum pump valve and the vacuum pump, open the oil inlet valve and the vacuum pump valve of the temperature-controlled oil storage tank, and inject the pre-treated insulating oil into the temperature-controlled oil storage tank through the oil inlet valve under vacuum conditions.

[0048] (3) After filling with sufficient insulating oil (not higher than the second circulation valve), close the oil inlet valve and continue to evacuate the insulating oil for 1 hour to remove air from the device.

[0049] (4) Turn on the three electrometers to preheat for 30 minutes and adjust the temperature control oil tank to the test temperature and maintain it for 30 minutes. Then, turn on the first circulation valve and the second circulation valve, turn on the circulation oil pump and gradually adjust the speed control valve so that the flow meter reaches the test flow rate. Observe the reading of the electrometer. After it stabilizes, turn off the circulation oil pump. The computer receives the electrometer reading record and performs charge density calculation.

[0050] (5) Open the nitrogen control valve to introduce nitrogen, and drain the insulating oil from the device through the oil outlet valve. After draining, close the nitrogen control valve. Clean and dry the device in preparation for the next test.

[0051] Please add any equipment, structures, functions, etc. that are not clearly explained.

[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An apparatus for measuring the distribution of charge on an oil stream in a partial transformer model, characterized by: The device comprises a temperature-controlled oil storage tank, a circulating pump, a speed regulating device, a buffer tank, a test tank and a measuring tank, the temperature-controlled oil storage tank, the circulating pump, the buffer tank, the test tank and the measuring tank are sequentially connected through insulating pipelines, the measuring tank is connected with the temperature-controlled oil storage tank through an insulating pipeline; the speed regulating device is connected with two insulating pipelines connected with the circulating pump, the insulating pipeline connecting the buffer tank with the test tank is provided with a flow meter, the test tank is connected with a first electrometer and a second electrometer; the measuring tank is connected with a third electrometer; the insulating pipeline connecting the measuring tank with the temperature-controlled oil storage tank is connected with a vacuum pump; The buffer tank comprises a buffer tank body and a first metal mesh, the first metal mesh is arranged in the buffer tank body, the buffer tank body is provided with a buffer tank oil inlet and a buffer tank oil outlet, the buffer tank oil inlet is connected with the circulating pump through an insulating pipeline, and the buffer tank oil outlet is connected with the test tank through an insulating pipeline; a first metal base is mounted at the bottom of the buffer tank body as a measuring point, the first metal base is grounded, and the first metal mesh is connected with the first metal base; the buffer tank body is provided with a buffer tank oil-free measuring area, and the first metal base extends to the buffer tank oil-free measuring area; The test tank comprises a test tank body, a first internal insulating layer, a second internal insulating layer and copper poles, the first internal insulating layer covers the inner side wall of the test tank body, and the second internal insulating layer covers the inner side of the first internal insulating layer; the number of the copper poles is several, the several copper poles are arranged in a linear array in the test tank body, each copper pole is fixedly supported by two copper rods, and the outer sides of all the copper poles are wrapped with insulating paper; the test tank body is provided with a test tank oil inlet and a test tank oil outlet, the test tank oil inlet is connected with the buffer tank through an insulating pipeline, and the test tank oil outlet is connected with the measuring tank; the test tank body is provided with a baffle; The test tank body is provided with a test tank oil-free measuring area, the test tank oil-free measuring area is located on the outer side of the test tank body, and the copper poles sequentially pass through the first internal insulating layer and the second internal insulating layer and extend to the test tank oil-free measuring area.

2. A device for measuring the distribution of charge on an oil stream in a partial transformer model according to claim 1, characterized in that: The temperature-controlled oil storage tank comprises a storage tank body and a storage tank cover, the storage tank body and the storage tank cover are sealingly connected; a heating silica gel plate is mounted on the outer side of the storage tank body; the storage tank body is provided with a first connecting port, a second connecting port, a third connecting port and a fourth connecting port, the first connecting port is connected with a first three-way pipe, the other two ports of the first three-way pipe are respectively provided with a first circulating valve and an oil outlet valve, and the first circulating valve is connected with the circulating pump through an insulating pipeline; the second connecting port is connected with a K-type thermometer; the third connecting port is connected with a second three-way pipe, the other two ports of the second three-way pipe are respectively provided with a nitrogen control valve and a vacuum pump valve, and the vacuum pump valve is connected with the vacuum pump through an insulating pipeline; the fourth connecting port is connected with a third three-way pipe, the other two ports of the third three-way pipe are respectively provided with a second circulating valve and an oil inlet valve, and the second circulating valve is connected with the measuring tank through an insulating pipeline.

3. A device for measuring the distribution of charge on an oil stream in a partial transformer model according to claim 1, characterized in that: The first metal mesh and the first metal base are made of red copper, and the buffer tank body is made of a steel plate.

4. A device for measuring the distribution of charge on an oil stream in a partial transformer model according to claim 1, characterized in that: The measuring tank comprises a measuring tank body and a second metal mesh, the second metal mesh is arranged in the measuring tank body, the measuring tank body is provided with a measuring tank oil inlet and a measuring tank oil outlet, the measuring tank oil inlet is connected with the test tank through an insulating pipeline, and the measuring tank oil outlet is connected with the temperature control oil storage tank through an insulating pipeline; a second metal base is arranged at the bottom of the measuring tank body as a measuring point, the second metal base is connected with a third electrometer through a lead wire, and the measuring tank body is provided with a measuring tank oil-free measuring area, and the second metal base extends to the measuring tank oil-free measuring area.

5. A device for measuring the distribution of charge on an oil stream in a partial transformer model according to claim 4, characterized in that: The second metal mesh and the second metal base are made of red copper, and the measuring tank body is made of a steel plate.

6. An apparatus for measuring the distribution of charge on an oil stream in a partial transformer model as defined in claim 1, wherein: The baffle is made of organic glass, the baffle is located at the oil inlet of the test tank, and a gap is formed between the baffle and the inner wall of the test tank body.

7. A device for measuring the distribution of charge on an oil stream in a partial transformer model according to claim 1, characterized in that: All the insulating pipelines are made of polytetrafluoroethylene.

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