Sleeve core surface potential measuring device and method based on electrostatic probe method

Abstract

The invention provides a sleeve core surface potential measuring device and method based on an electrostatic probe method. The device comprises a test cavity, a guide rod, a high-voltage wiring assembly, a glass fiber reinforced plastic cylinder, a driving device and a self-movable measuring structure, the side wall of the test cavity is provided with an extraction opening, an inflation opening and a cabin door capable of being opened and closed; the first end of the high-voltage wiring assembly is arranged in the test cavity; the glass fiber reinforced plastic cylinder is arranged in the test cavity; the first end of the guide rod is movably arranged in the glass fiber reinforced plastic cylinder in a penetrating manner and is in sliding connection with the first end of the high-voltage wiring assembly, and the guide rod bears a tested core body; the driving device drives the guide rod to move so as to enable the measured core body to move from the pressurizing position to the measuring position, and drives the guide rod to rotate so as to drive the measured core body to rotate; the measuring structure measures the surface potential of the measured core body at the measuring position. According to the invention, the surface potential of the measured core can be comprehensively scanned, the accuracy of surface potential measurement is improved, and automatic measurement of the measured core can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of potential measurement, in particular to a bushing core surface potential measurement device and method based on electrostatic probe method. BACKGROUND

[0002] UHV DC bushing is one of the key devices of UHV power transmission system, and the epoxy impregnated paper dry bushing is widely used due to its excellent characteristics. The dry bushing usually uses silicone rubber as external insulation, and is lined with epoxy glass steel cylinder inside. The glass steel cylinder is filled with SF6 gas as auxiliary insulation, and the main insulation is the capacitor core of the epoxy resin impregnated insulation paper. Due to the particularity of the structure of the bushing, the electric field distribution on the surface of the epoxy core is complex, which has both radial and tangential electric field components. Under the action of long-term DC voltage, the charge accumulation on the surface of the core-SF6 is easy to cause electric field distortion, partial discharge, and even surface flashover, which eventually leads to insulation failure. Therefore, it is of great significance to study the charge accumulation behavior on the surface of the core and accurately master the potential distribution characteristics of the core surface for the optimization design and operation state evaluation of the bushing structure.

[0003] The commonly used surface potential measurement methods mainly include non-contact electrostatic probe method, Kelvin probe method, contact potential difference method, etc. Among them, the active electrostatic probe method has been widely used in the surface electrostatic potential measurement of insulating materials due to its high sensitivity, good spatial resolution and fast response speed, and has become the most classic and reliable non-contact potential measurement method in modern electrostatic measurement. However, the active electrostatic probe method is a "single-point measurement" method, and the measurement target is only a local and discrete position directly below the probe. In order to realize the global view, the probe needs to be scanned point by point on the surface of the sample to obtain the potential distribution, which is complex to operate. SUMMARY

[0004] In view of this, the present application provides a bushing core surface potential measurement device based on electrostatic probe method, which aims to solve the problem of point-by-point scanning when the active electrostatic probe method is used to comprehensively measure the surface potential of the bushing core in the prior art. The present application also provides a surface potential measurement method using the above-mentioned bushing core surface potential measurement device based on electrostatic probe method.

[0005] In one aspect, the present application provides a bushing core surface potential measuring device based on electrostatic probe method, which comprises a test cavity, a guide rod, a high-voltage wiring assembly, a glass steel cylinder, a driving device and a self-movable measuring structure; wherein the sidewall of the test cavity is provided with an air outlet, an air inlet and a hatch; the high-voltage wiring assembly is arranged in the sidewall of the first side of the test cavity and the first end is arranged in the test cavity; the glass steel cylinder is arranged in the test cavity; the guide rod is movably suspended in the test cavity, the first end of the guide rod is movably arranged in the interior of the glass steel cylinder and is slidably connected with the first end of the high-voltage wiring assembly, and the guide rod is used for carrying the measured core; the driving device is arranged in the test cavity and is connected with the guide rod, which is used for driving the guide rod to move so as to move the measured core from the pressurized position in the glass steel cylinder to the measuring position outside the glass steel cylinder, and is used for driving the guide rod to rotate so as to drive the measured core to rotate; the measuring structure is suspended on one side of the guide rod and is used for measuring the surface potential of the measured core in the measuring position.

[0006] Further, in the above-mentioned bushing core surface potential measuring device based on electrostatic probe method, the driving device comprises a moving driving mechanism and a rotating driving mechanism; wherein the moving driving mechanism is arranged in the test cavity and is connected with the guide rod, which is used for driving the guide rod to move so as to move the measured core to the measuring position; the rotating driving mechanism is arranged in the moving driving mechanism and is connected with the guide rod, which is used for driving the guide rod to rotate.

[0007] Further, in the above-mentioned bushing core surface potential measuring device based on electrostatic probe method, the measuring structure comprises a measuring mechanism, a first driving mechanism and a second driving mechanism; wherein the first driving mechanism is arranged in the test cavity and is connected with the second driving mechanism, the measuring mechanism is arranged in the second driving mechanism and is arranged on one side of the measured core in the measuring position, the second driving mechanism is used for driving the measuring mechanism to move from the starting position to the detection starting position at the guide rod, and the first driving mechanism is used for driving the measuring mechanism to move from the detection starting position to the detection ending position along the axial direction of the guide rod.

[0008] Further, in the above-mentioned bushing core surface potential measuring device based on electrostatic probe method, the measuring mechanism comprises an active electrostatic probe and an electrostatic potentiometer; wherein the electrostatic potentiometer is arranged outside the test cavity, the active electrostatic probe is insulated and arranged at the end of the second driving mechanism and is arranged above the measured core in the measuring position, and the active electrostatic probe is connected with the electrostatic potentiometer.

[0009] Further, in the above-mentioned bushing core surface potential measuring device based on electrostatic probe method, the high-voltage wiring assembly comprises a sleeve and a wiring part; wherein the sleeve is arranged in the sidewall of the first side of the test cavity, the first end of the sleeve is arranged in the test cavity and is slidably connected with the first end of the guide rod, the second end of the sleeve is arranged outside the test cavity and is connected with the wiring part, and the wiring part is used for being connected with the high-voltage power supply.

[0010] Furthermore, the aforementioned device for measuring the surface potential of the sleeve core based on the electrostatic probe method also includes a temperature adjustment device; wherein the temperature adjustment device is disposed on the guide rod and is used to adjust the temperature of the core being measured.

[0011] Furthermore, in the aforementioned device for measuring the surface potential of the sleeve core based on the electrostatic probe method, the temperature control device includes: a heating tube; wherein, the guide rod is hollow inside, and the second end of the guide rod is movably inserted through the side wall of the second side of the test chamber and placed outside the test chamber; the heating tube is inserted through the end wall of the second end of the guide rod and partially placed inside the guide rod, the portion of the heating tube placed outside the guide rod is used to connect to a liquid tank to receive liquid with a preset temperature, and the portion of the heating tube placed inside the guide rod is used to transport liquid into the guide rod; the side wall of the guide rod outside the test chamber has a liquid outlet for outputting liquid from the guide rod.

[0012] In this invention, a guide rod is movably suspended within the test chamber and movably inserted through the interior of a fiberglass cylinder. The first end of the guide rod is slidably connected to the first end of a high-voltage wiring assembly, and the second end of the high-voltage wiring assembly is connected to a high-voltage power supply. Together, they constitute the core of the electric field generation. Combined with the fiberglass cylinder, this simulates the electric field environment on the surface of the core being tested during actual operation of the bushing. The core being tested is carried on the guide rod, and a driving device drives the core being tested from the pressurized position inside the fiberglass cylinder to the measurement position outside the fiberglass cylinder, and also drives the core being tested to rotate. The surface potential of the core being tested is measured by the rotation of the core being tested driven by the driving device and the movement of the measuring structure itself. This allows for a comprehensive scan of the surface potential of the core being tested, improving the accuracy of surface potential measurement. Furthermore, it enables automatic measurement of the surface potential of the core being tested, is simple to operate, and solves the problem of point-by-point scanning required when using the active electrostatic probe method to comprehensively measure the surface of the bushing core in existing technologies.

[0013] On the other hand, the present invention also proposes a method for measuring the surface potential of a sleeve core using any of the above-mentioned electrostatic probe-based surface potential measuring devices. This method includes the following steps: mounting the core to be tested on a guide rod; driving the guide rod to move so that the core to be tested is placed in a pressurized position inside a fiberglass cylinder; evacuating the test chamber and then filling it with insulating gas; applying pressure to the guide rod to a set rated voltage using a high-voltage wiring assembly, maintaining the pressure for a preset time, and then stopping the pressure application; driving the guide rod to move so that the core to be tested moves from the pressurized position inside the fiberglass cylinder to a measurement position outside the fiberglass cylinder, and the measuring structure itself moves to the detection start position; following a preset path, driving the guide rod to rotate, and the measuring structure itself moves along the axial direction of the guide rod, measuring the surface potential of the core to be tested; obtaining the relationship between the surface potential of the core to be tested and the path based on the surface potential measured by the measuring structure and the preset path.

[0014] Furthermore, in the above surface potential measurement method, in the step of driving the guide rod to rotate according to a preset path, moving the measuring structure itself along the axial direction of the guide rod, and measuring the surface potential of the core being measured, according to the preset path, the driving device drives the guide rod to rotate clockwise one revolution, and the measuring structure itself moves one step from the detection start position along the axial direction of the guide rod. The driving device drives the guide rod to rotate counterclockwise one revolution, and the measuring structure itself moves one step along the axial direction of the guide rod. The above process is repeated until the measuring structure itself moves to the detection end position.

[0015] Furthermore, in the above surface potential measurement method, in the step where the driving device drives the guide rod to rotate according to a preset path, the measuring structure itself moves along the axial direction of the guide rod, and the surface potential of the core being measured is measured, the scanning path of the measuring structure is S = 2L. x +2h y In the formula, S is the scanning path of the measurement structure, and L... x h is the scanning path of the measurement structure as the guide rod rotates one revolution. y To measure the step length of the structure moving along the axial direction of the guide rod, where L x =πD, where D is the diameter of the core being measured; in the step of obtaining the relationship between the surface potential of the core being measured and the path based on the surface potential measured by the measuring structure and the preset path, the moving speed of the measuring structure is set to v, the relationship between the surface potential V and the measurement time t is obtained based on the measurement of the measuring structure, V(t), and then the relationship between the surface potential V and the scanning path S is obtained based on the moving speed v of the measuring structure and the scanning path S, V(S / v).

[0016] In this invention, a driving device drives a guide rod to move, causing the core under test to move from the pressurized position to the measurement position. The measuring structure itself moves to the detection starting position. Following a preset path, the driving device drives the guide rod to rotate, and the measuring structure itself moves along the axial direction of the guide rod, measuring the surface potential of the core under test. The relationship between the surface potential of the core under test and the path is then obtained based on the surface potential measured by the measuring structure and the preset path. This method can simulate the electric field environment on the surface of the core under test during actual operation of the bushing and can perform a comprehensive scan of the surface potential of the core under test, improving the accuracy of surface potential measurement. It achieves automated and high-precision measurement of the potential distribution across the entire surface of the core under test. Furthermore, this method is simple to operate and easy to implement. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 A schematic diagram of the structure of the sleeve core surface potential measuring device based on the electrostatic probe method provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the scanning path of the active electrostatic probe in the sleeve core surface potential measuring device based on the electrostatic probe method provided in the embodiments of the present invention;

[0020] Figure 3 A flowchart of a method for measuring the surface potential of a sleeve core based on an electrostatic probe, provided for an embodiment of the present invention. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] Device Example:

[0023] See Figure 1 , Figure 1 This is a schematic diagram of the casing core surface potential measuring device based on the electrostatic probe method provided in an embodiment of the present invention. As shown in the figure, the casing core surface potential measuring device based on the electrostatic probe method includes: a test chamber 1, a guide rod 2, a high-voltage wiring assembly 3, a fiberglass cylinder 4, a driving device 5, and a measuring structure 6. The test chamber 1 has an extraction port 110, an inflation port, and an openable door 8 on its side wall. Specifically, the extraction port 110 and the inflation port are both located on the top side wall of the test chamber 1. The extraction port 110 is used to evacuate the test chamber 1, and the inflation port is used to fill the test chamber 1 with an insulating gas, such as SF6 gas. A through-hole is provided on one side wall of the test chamber 1, and the door 8 is openable at the through-hole to facilitate testing and measurement.

[0024] The high-voltage wiring assembly 3 is installed through the side wall of the first side of the test chamber 1. Part of the high-voltage wiring assembly 3 and its first end are placed inside the test chamber 1. The other part and the second end of the high-voltage wiring assembly 3 are placed outside the test chamber 1. The second end of the high-voltage wiring assembly 3 is used to connect to a high-voltage power supply so as to introduce the voltage of the external high-voltage power supply into the test chamber 1.

[0025] The fiberglass cylinder 4 is disposed inside the test chamber 1. Specifically, the fiberglass cylinder 4 is suspended inside the test chamber 1, and is disposed near the first end of the sleeve 31 of the high-voltage wiring assembly 3. In a specific implementation, the fiberglass cylinder 4 can be connected to the inner wall of the test chamber 1 through a connector.

[0026] The guide rod 2 is movably suspended inside the test chamber 1. The first end of the guide rod 2 is movably inserted through the interior of the fiberglass cylinder 4, and the first end of the guide rod 2 is slidably connected to the first end of the high-voltage wiring assembly 3. Specifically, the guide rod 2 is located at the center of the test chamber 1 and is movable within the test chamber 1. Since the guide rod 2 is movably inserted through the interior of the fiberglass cylinder 4, and the first end of the guide rod 2 is slidably positioned inside the sleeve 31 after being inserted through the fiberglass cylinder 4, the portion of the guide rod 2 near the first end can slide into the sleeve 31 or slide out of the sleeve 31.

[0027] Preferably, the high-voltage wiring assembly 3 includes a sleeve 31 and a connector 32. The sleeve 31 has a first open end and a second closed end, and its interior is hollow. The sleeve 31 passes through the sidewall of the first side of the test chamber 1 and is connected to the sidewall of the first side of the test chamber 1. The first end of the sleeve 31 ( Figure 1 The left end shown is placed inside the test chamber 1, and the first end of the sleeve 31 is connected to the first end of the guide rod 2. Figure 1 The right end shown is slidably connected. Specifically, the first end of the guide rod 2 is slidably inserted through the opening at the first end of the sleeve 31 and placed inside the sleeve 31. Furthermore, the first end of the guide rod 2 is slidably connected to the portion of the sleeve 31 placed inside the test chamber 1. The second end of the sleeve 31 ( Figure 1 The right end (shown) is placed outside the test chamber 1, and the second end of the sleeve 31 is connected to the connector 32, which is used to connect to a high-voltage power supply. The outer surface of the connector 32 is made of a highly insulating material, and the inner core is made of a highly conductive material. Both ends of the inner core are equipped with reconfigurable interfaces for wiring.

[0028] The guide rod 2 is used to support the core 7 under test. Specifically, the core 7 under test is assembled on the guide rod 2, and the core 7 under test is only a part of the rod segment assembled on the guide rod 2. In a specific implementation, both ends of the core 7 under test are fixed to the guide rod 2 using adjustable clamps.

[0029] A driving device 5 is installed inside the test chamber 1 and is connected to the guide rod 2. The driving device 5 drives the guide rod 2 to move, thereby moving the core sample 7 on the guide rod 2 from the pressurized position inside the fiberglass cylinder 4 to the measurement position outside the fiberglass cylinder 4. Furthermore, the driving device 5 drives the guide rod 2 to rotate, thereby rotating the core sample 7. Specifically, since the guide rod 2 is movably inserted inside the fiberglass cylinder 4, the movement of the guide rod 2 drives the movement of the core sample 7 on it. When the core sample 7 is inside the fiberglass cylinder 4, it is in the pressurized position; when the core sample 7 is moved outside the fiberglass cylinder 4 by the guide rod 2, it is in the measurement position. When the core under test 7 is inside the fiberglass cylinder 4, a vacuum is drawn into the test chamber 1, and then SF6 gas is introduced into the test chamber 1. The high-voltage power supply applies high voltage to the guide rod 2 through the high-voltage wiring assembly 3, thereby pressurizing the core under test 7. After pressurization is completed, the guide rod 2 moves the core under test 7 out of the fiberglass cylinder 4 and places it in the measurement position outside the fiberglass cylinder 4.

[0030] In practice, the specific location of the measurement can be determined according to the actual situation, and this embodiment does not impose any restrictions on this.

[0031] The measuring structure 6 is suspended on one side of the guide rod 2. Specifically, the measuring structure 6 is positioned above the guide rod 2, and the driving device 5 is positioned below the guide rod 2. The measuring structure 6 is used to measure the surface potential of the core 7 under test, which is in the measuring position. More specifically, the measuring structure 6 is movable, and it measures the surface potential of the core 7 under test, which is in the measuring position, by moving itself.

[0032] Preferably, the test chamber 1 is provided with observation windows 10 at both the pressurization position and the measurement position. Specifically, there are two observation windows 10, one at the pressurization position and the other at the measurement position. Observation of the experiment is facilitated through the observation windows 10, allowing for monitoring and observation during the experiment and ensuring the safety and controllability of the test process. Each observation window 10 can be made of thickened tempered glass with a pressure resistance rating of 0.5 MPa.

[0033] Preferably, the casing core surface potential measuring device based on the electrostatic probe method further includes a pressure measuring device 11. The pressure measuring device 11 is disposed in the test chamber 1 and is used to measure the pressure inside the test chamber 1. Specifically, the pressure measuring device 11 can be a pressure gauge.

[0034] In practice, the test chamber 1 is a horizontally placed container, and the test chamber 1 is a stainless steel cylinder with a diameter of Φ600mm and a length of 1000mm.

[0035] In practice, the bottom of the test chamber 1 is mounted on the roller stand 12. The roller stand 12 has sufficient strength to support the test chamber 1, and the interior of the roller stand 12 has sufficient space for the installation of instrumentation and electrical components.

[0036] Test chamber 1 is used to create a closed, isolated testing environment. It can withstand a maximum gas pressure ≥0.4MPa during operation, with a gas leakage rate ≤0.5% per month. Test chamber 1 is equipped with a pressure gauge with a measurement range of -0.1 to 0.5MPa.

[0037] In practice, the diameter of guide rod 2 can be Φ45mm.

[0038] As can be seen, in this embodiment, the guide rod 2 is movably suspended inside the test chamber 1, and the guide rod 2 is movably inserted inside the fiberglass cylinder 4, with its first end slidably connected to the first end of the high-voltage wiring assembly 3. The second end of the high-voltage wiring assembly 3 is connected to the high-voltage power supply, together forming the core part of electric field generation. Combined with the fiberglass cylinder 4, it can simulate the electric field environment on the surface of the core 7 under test during actual operation of the bushing. The core 7 under test is carried on the guide rod 2, and the driving device 5 drives the core 7 under test to move from the pressurized position inside the fiberglass cylinder 4 to the measurement position outside the fiberglass cylinder 4, and drives the core 7 under test to rotate. The surface potential of the core 7 under test is measured by the rotation of the core 7 under test driven by the driving device 5 and the movement of the measuring structure 6 itself. It can perform a comprehensive scan of the surface potential of the core 7 under test, improve the accuracy of surface potential measurement, and realize automatic measurement of the surface potential of the core 7 under test. The operation is simple and solves the problem that the active electrostatic probe method in the prior art needs to scan point by point when performing a comprehensive measurement of the surface of the bushing core.

[0039] See Figure 1 In the above embodiment, the driving device 5 includes a moving driving mechanism 51 and a rotating driving mechanism 52. The moving driving mechanism 51 is disposed within the test chamber 1 and is connected to the guide rod 2. The moving driving mechanism 51 drives the guide rod 2 to move, thereby moving the core 7 to the measurement position. Specifically, a support frame is disposed within the test chamber 1 and below the guide rod 2. The moving driving mechanism 51 is disposed on the support frame and positioned below the guide rod 2. The moving driving mechanism 51 drives the guide rod 2 horizontally (relative to) the guide rod 2. Figure 1 The movement allows the tested core 7 to move from the pressurized position inside the fiberglass cylinder 4 to the measuring position outside the fiberglass cylinder 4, or the tested core 7 to move from the measuring position to the pressurized position.

[0040] In specific implementation, the moving drive mechanism 51 can be a combination of a drive motor and a synchronous belt, or a combination of a drive motor and a lead screw. Of course, its specific structure can also be determined according to the actual situation, as long as it can drive the guide rod 2 to move. This embodiment does not impose any restrictions on the structure of the moving drive mechanism 51.

[0041] A rotary drive mechanism 52 is disposed on the movable drive mechanism 51 and is connected to the guide rod 2. The rotary drive mechanism 52 is used to drive the guide rod 2 to rotate. Specifically, the rotary drive mechanism 52 can be a drive motor connected to the guide rod 2 through a transmission mechanism. The drive motor drives the guide rod 2 to rotate through the transmission mechanism. This transmission mechanism can include two rotating wheels and a transmission belt. The two rotating wheels are respectively connected to the drive shaft of the drive motor and the guide rod 2, and the transmission belt can rotatably wrap around the two rotating wheels. Of course, the structure of the rotary drive mechanism 52 can also be determined according to the actual situation, as long as it can drive the guide rod 2 to rotate. This embodiment does not impose any restrictions on the structure of the rotary drive mechanism 52. The clockwise and counterclockwise rotation of the guide rod 2 is achieved by the forward and reverse rotation of the drive motor.

[0042] See Figure 1 In the above embodiment, the measuring structure 6 includes a measuring mechanism, a first driving mechanism 61, and a second driving mechanism 62. The first driving mechanism 61 is disposed within the test chamber 1, and its driving end is connected to the second driving mechanism 62. The measuring mechanism is disposed at the driving end of the second driving mechanism 62 and is positioned on one side of the core 7 being measured. The second driving mechanism 62 drives the measuring mechanism to move from the starting position to the guide rod 2 to the detection starting position, and the first driving mechanism 61 drives the measuring mechanism to move from the detection starting position along the axial direction of the guide rod 2 to the detection ending position.

[0043] Specifically, the measuring structure 6 is positioned above the guide rod 2. When the core being measured 7 is in the pressurized position inside the fiberglass cylinder 4, the measuring mechanism is in the initial position above the guide rod 2. When the core being measured 7 moves to the measuring position outside the fiberglass cylinder 4, the measuring mechanism, under the action of the second drive mechanism 62, moves from the initial position to the probe rod 2 to the detection starting position. Figure 1 The second drive mechanism 62 drives the measuring mechanism to move from top to bottom. Then, driven by the first drive mechanism 61, the measuring mechanism moves from the detection start position to the detection end position along the axis of the guide rod 2.

[0044] Both the first driving mechanism 61 and the second driving mechanism 62 are suspended inside the test chamber 1 and positioned above the guide rod 2. The second driving mechanism 62 can be an electrically operated telescopic rod, which extends or retracts to drive the movement of the measuring mechanism, causing the measuring mechanism to move from the starting position to the detection starting position, or vice versa. Of course, the structure of the second driving mechanism 62 can also be determined according to the actual situation, as long as it can drive the measuring mechanism to move. This embodiment does not impose any restrictions on the structure of the second driving mechanism 62.

[0045] The first drive mechanism 61 can be a combination of a drive motor, a lead screw and a nut, or a combination of a drive motor and a timing belt. Of course, the structure of the first drive mechanism 61 can also be determined according to the actual situation, as long as it can drive the measuring mechanism to move laterally along the guide rod 2. This embodiment does not impose any restrictions on the structure of the second drive mechanism 62.

[0046] The measuring mechanism includes an active electrostatic probe 63 and an electrostatic potentiometer. The electrostatic potentiometer is located outside the test chamber 1, while the active electrostatic probe 63 is located inside the test chamber 1. The active electrostatic probe 63 is insulated at the end of the second drive mechanism 62 and positioned above the core 7 under test, which is in the measurement position. The active electrostatic probe 63 is connected to the electrostatic potentiometer. The active electrostatic probe 63 measures the surface potential of the core 7 under test.

[0047] See Figure 2 The rotary drive mechanism 52 drives the guide rod 2 to rotate clockwise one revolution when the core 7 under test is placed in the measurement position. Then, the first drive mechanism 61 drives the measuring mechanism to move one step along the axis of the guide rod 2 from the detection start position. Then, after the measuring mechanism moves one step, the rotary drive mechanism 52 drives the guide rod 2 to rotate counterclockwise one revolution. Then, after the guide rod 2 rotates counterclockwise, the first drive mechanism 61 drives the measuring mechanism to move one step along the axis of the guide rod 2 in the same direction. The above operation is repeated. By alternating the actions of the rotary drive mechanism 52 and the first drive mechanism 61, the measuring mechanism moves to the detection end position. According to the above cycle, the full surface scanning of the core 7 under test is achieved. Specifically, the action paths of the rotary drive mechanism 52 and the first drive mechanism 61 form an "S-shaped path", which enables the active electrostatic probe 63 in the measuring mechanism to scan and measure the surface of the core 7 under test using the "S-shaped path".

[0048] In practical implementation, the active electrostatic probe 63 can be selected as Trek3455ET, and the matching electrostatic potentiometer Trek341B has a measurement range of 0-±20kV and an accuracy of full scale ≤±0.5%.

[0049] As can be seen, in this embodiment, the drive device 5 and the measuring structure 6 have simple structures and are easy to implement.

[0050] See Figure 1 In the above embodiments, the sleeve core surface potential measuring device based on the electrostatic probe method further includes a temperature regulating device. The temperature regulating device is disposed on the guide rod 2 and is used to regulate the temperature of the core 7 being measured.

[0051] The interior of guide rod 2 is hollow, and the second end of guide rod 2 ( Figure 1 The left end (shown) is movably inserted through the side wall of the second side of the test chamber 1, wherein the second side of the test chamber 1 and the first side are opposite to each other. The second end of the guide rod 2 is placed outside the test chamber 1.

[0052] The temperature regulating device includes a heating tube 9. The heating tube 9 passes through the end wall of the second end of the guide rod 2, with a portion of the heating tube 9 inside the guide rod 2 and another portion outside. The portion of the heating tube 9 outside the guide rod 2 is connected to a liquid tank 14. The heating tube 9 receives liquid with a preset temperature from the liquid tank 14, and the portion inside the guide rod 2 transports the liquid into the guide rod 2. Specifically, the liquid tank 14 stores liquid, and a heating device can be installed inside the liquid tank 14 to heat the liquid to a preset temperature. The liquid tank 14 then transports the liquid to the heating tube 9. The end of the heating tube 9 inside the guide rod 2 is an open end, allowing the heating tube 9 to transport the liquid with the preset temperature into the guide rod 2. Since the core being tested 7 is located on the outer wall of the guide rod 2, the liquid with the preset temperature is placed inside the guide rod 2 to heat the core being tested 7. In practice, the preset temperature of the liquid can be determined according to the actual situation, and this embodiment does not impose any restrictions on it.

[0053] The guide rod 2 has a liquid outlet 21 on its side wall outside the test chamber 1, which is used to output the liquid after heat exchange inside the guide rod 2. Furthermore, the liquid outlet 21 is connected to the liquid tank 14, and the liquid outlet 21 is used to transport the liquid after heat exchange into the liquid tank 14.

[0054] In specific implementation, the liquid tank 14 can be an oil bath system, which uses liquid at a preset temperature to heat and control the temperature of the core 7 under test on the guide rod 2, so that the temperature of the core 7 under test can be adjusted within the range of 20 to 100°C.

[0055] As can be seen, in this embodiment, by supplying liquid with a preset temperature into the heating tube 9, the heat of the liquid is transferred to the core under test 7, thereby adjusting the temperature of the core under test 7. The temperature of the core under test 7 can be adjusted according to the actual working conditions and controlled. This not only simulates the actual operating temperature gradient of the sleeve core, forming a stable temperature gradient from the inside to the outside from the guide rod 2, simulating the inherent characteristics of the actual operation of the sleeve, but also greatly improves the accuracy and depth of the surface potential measurement of the core under test 7 in the laboratory environment. Furthermore, it can simulate various working temperature conditions, no longer limited to room temperature conditions, thus expanding the measurement range.

[0056] In practice, the bottom of the test chamber 1 is provided with a lead wire interface 13, which is used for wiring the motor leads in the drive device 5 and the measuring structure 6.

[0057] In practice, the device can be controlled by a preset program to achieve accurate and automatic measurement, avoiding errors caused by manual operation and damage to the active electrostatic probe.

[0058] Combination Figure 1The operation of the casing core surface potential measuring device based on the electrostatic probe method is described as follows: The core 7 to be tested is installed on the guide rod 2. The moving drive mechanism 51 drives the guide rod 2 to move, so that the core 7 to be tested is placed in the pressurized position inside the fiberglass cylinder 4. At this time, the active electrostatic probe 63 in the measuring mechanism is in the initial position. The air in the test chamber 1 is extracted through the air extraction port 110 until the inside of the test chamber 1 is in a vacuum state. The air extraction port 110 is closed, and then SF6 gas is injected through the gas filling port. When the gas pressure in the chamber reaches 0.3MPa, the gas filling is stopped. The pressure in the test chamber 1 is monitored by the pressure measuring device 11. When the pressure monitored by the pressure measuring device 11 is stable, the gas filling port is closed. Liquid with a preset temperature is supplied to the heating tube 9 through the liquid tank 14. The liquid is supplied to the guide rod 2 through the end of the heating tube 9 placed inside the guide rod 2. The temperature of the liquid is used to heat the core 7 to be tested. The liquid after heat exchange in the guide rod 2 is output through the liquid outlet 21. Then, the high-voltage power supply applies high voltage to the guide rod 2 through the high-voltage wiring assembly 3 until the set rated voltage is reached, and maintains it for a certain period of time to stabilize the surface potential. After pressurization, the moving drive mechanism 51 drives the guide rod 2 to move the core 7 under test from the fiberglass cylinder 4 to the measurement position. Then, the second drive mechanism 62 drives the active electrostatic probe 63 to move from the starting position to the probe rod 2 to the detection starting position. Then, the active electrostatic probe 63 scans and measures the surface of the core 7 under test using an "S-shaped path": the rotation drive mechanism 52 drives the guide rod 2 to rotate clockwise one revolution, the first drive mechanism 61 drives the active electrostatic probe 63 to move one step from the detection starting position along the axis of the guide rod 2, then the rotation drive mechanism 52 drives the guide rod 2 to rotate counterclockwise one revolution, the first drive mechanism 61 drives the active electrostatic probe 63 to continue moving one step along the axis of the guide rod 2, and then repeats the above operation until the active electrostatic probe 63 moves to the detection end position.

[0059] It should be noted that the active electrostatic probe 63 is always in measurement mode during the rotation of the guide rod 2.

[0060] In summary, this embodiment can simulate the surface electric field environment of the core 7 under test during actual operation of the bushing. The core 7 under test is supported on the guide rod 2. The rotation of the core 7 under test and the movement of the measuring structure 6 are driven by the driving device 5 to measure the surface potential of the core 7 under test. It can perform a comprehensive scan of the surface potential of the core 7 under test, improve the accuracy of surface potential measurement, and realize the automatic measurement of the surface potential of the core 7 under test. The operation is simple.

[0061] In this embodiment, by rotating the guide rod 2 and moving the measuring mechanism laterally, the measurement of the entire surface of a large-sized, long cylindrical dry bushing core can be expanded from "single-point measurement" to "comprehensive measurement". Furthermore, the test chamber 1 is a sealed structure, and pressure regulation is achieved by filling it with insulating gas, simulating the actual operating environment of the bushing. The guide rod 2 is heated by a temperature regulating device, and the guide rod 2 transfers heat to the core 7 under test, achieving controllable heating of the core 7. Moreover, the fiberglass cylinder 4 and the high-voltage guide rod 2 together simulate the electric field distribution on the core surface during actual bushing operation, improving the accuracy of potential measurement. To simulate the actual operating conditions of the UHVDC bushing, a DC voltage and a high-frequency harmonic voltage from 150Hz to 20kHz can be applied simultaneously with the standard power frequency voltage. Specific voltage parameters can be configured according to actual on-site needs, thus enabling the device to integrate multi-physics field coupling simulation. Meanwhile, the guide rod 2 is moved and rotated by the drive device 5, and the active electrostatic probe 63 is moved by the first drive mechanism 61 and the second drive mechanism 62. Combined with the scanning path preset by the control system, the accurate capture and automatic measurement of the potential distribution are realized.

[0062] This device enables automated and high-precision measurement of the potential distribution across the entire surface of large-size cores, making it suitable for measuring the surface potential of bushing cores. Furthermore, it can simulate the actual operating voltage environment of bushings, applying power frequency AC voltage, DC voltage, high-frequency harmonic voltage, and composite voltages, thus improving the engineering comparability of test results.

[0063] Method Implementation Examples:

[0064] This embodiment also proposes a surface potential measurement method using any of the above-mentioned electrostatic probe-based sleeve core surface potential measurement devices. For the specific implementation process of the electrostatic probe-based sleeve core surface potential measurement device, please refer to the above description, and this embodiment will not repeat it here.

[0065] See Figure 3 The surface potential measurement method includes the following steps:

[0066] Step S1: The core to be tested is installed on the guide rod, and the driving device drives the guide rod to move so that the core to be tested is placed in the pressurized position inside the fiberglass cylinder.

[0067] Specifically, see Figure 1 Prepare a high-voltage power supply and set up the test circuit. Remove residual charge from the surface of the prepared epoxy core sample 7 using an ion blower. Open the chamber door 8 and assemble the core 7 onto the guide rod 2. Secure both ends of the core 7 with adjustable clamps to ensure that the core 7 does not wobble when the guide rod 2 moves or rotates. Then, close the chamber door 8.

[0068] See Figure 1 The driving device 5 includes a moving driving mechanism 51 and a rotating driving mechanism 52. The moving driving mechanism 51 is disposed within the test chamber 1 and is connected to the guide rod 2. The moving driving mechanism 51 drives the guide rod 2 to move, thereby moving the core 7 to the measurement position. The rotating driving mechanism 52 is disposed within the moving driving mechanism 51 and is connected to the guide rod 2. The rotating driving mechanism 52 drives the guide rod 2 to rotate.

[0069] The measuring structure 6 includes a measuring mechanism, a first driving mechanism 61, and a second driving mechanism 62. The first driving mechanism 61 is disposed within the test chamber 1, and its driving end is connected to the second driving mechanism 62. The measuring mechanism is disposed at the driving end of the second driving mechanism 62 and is positioned on one side of the core 7 being measured. The second driving mechanism 62 drives the measuring mechanism to move from the starting position to the guide rod 2 to the detection starting position, and the first driving mechanism 61 drives the measuring mechanism to move from the detection starting position along the axial direction of the guide rod 2 to the detection ending position.

[0070] The measuring mechanism includes an active electrostatic probe 63 and an electrostatic potentiometer. The electrostatic potentiometer is located outside the test chamber 1, while the active electrostatic probe 63 is located inside the test chamber 1. The active electrostatic probe 63 is insulated at the end of the second drive mechanism 62 and positioned above the core 7 under test, which is in the measurement position. The active electrostatic probe 63 is connected to the electrostatic potentiometer. The active electrostatic probe 63 measures the surface potential of the core 7 under test.

[0071] The moving drive mechanism 51 drives the guide rod 2 to move the core 7 under test to the pressurization position of the fiberglass cylinder 4, and the second drive mechanism 62 drives the active electrostatic probe 63 in the measuring mechanism to move to the starting position.

[0072] Step S2: After evacuating the test chamber, fill the test chamber with insulating gas.

[0073] Specifically, the air extraction port 110 is opened to extract the air from the test chamber 1 until the test chamber 1 is in a vacuum state, and then the air extraction port 110 is closed. Then, SF6 gas is introduced through the gas filling port. When the gas pressure in the test chamber 1 reaches 0.3 MPa, the gas filling is stopped, the pressure measuring device 11 monitors the pressure indication and stabilizes, and then the gas filling port is closed.

[0074] Preferably, the liquid tank 14 uses a heating device to heat the liquid to a preset temperature. The liquid tank 14 then delivers the liquid to the heating tube 9, which in turn delivers the liquid to the guide rod 2. The liquid in the guide rod 2 is used to transfer heat to the core 7 under test, so that the temperature of the core 7 under test reaches the target set temperature value and remains stable.

[0075] In practice, the liquid tank 14 and the heating device can form an oil bath system, and the temperature of the oil bath system is set to 80°C to heat the guide rod 2.

[0076] Step S3: The high-voltage wiring assembly applies pressure to the conductor rod to the set rated voltage and holds it for a preset time before stopping the pressure application.

[0077] Specifically, the high-voltage power supply is connected to the connector 32 in the high-voltage wiring assembly 3. The high-voltage power supply applies high voltage to the conductor 2 through the high-voltage wiring assembly 3, gradually increasing the voltage to the set rated voltage and maintaining it for a preset time to stabilize the surface potential. In actual implementation, the set rated voltage and preset time can be determined according to the actual situation, and this embodiment does not impose any restrictions on them. After the pressurization is completed, the external voltage is removed.

[0078] In step S4, the driving device drives the guide rod to move, so that the core being measured moves from the pressurized position inside the fiberglass cylinder to the measurement position outside the fiberglass cylinder, and the measuring structure itself moves to the detection start position.

[0079] Specifically, the moving drive mechanism 51 drives the guide rod 2 to move, and the guide rod 2 moves the core 7 under test from the pressurized position inside the fiberglass cylinder 4 to the measurement position outside the fiberglass cylinder 4. Furthermore, the second drive mechanism 62 drives the active electrostatic probe 63 to move from the starting position to the probe rod 2 to the detection starting position.

[0080] In step S5, following a preset path, the driving device drives the guide rod to rotate, the measuring structure itself moves along the axial direction of the guide rod, and the surface potential of the core being measured is measured.

[0081] Specifically, see Figure 2 The preset path is an S-shaped path. According to the preset path, the driving device 5 drives the guide rod 2 to rotate clockwise one revolution, and the measuring structure 6 moves one step from the detection start position along the axis of the guide rod 2. The driving device 5 drives the guide rod 2 to rotate counterclockwise one revolution, and the measuring structure 6 moves one step along the axis of the guide rod 2. The above process is repeated until the measuring structure 6 moves to the detection end position.

[0082] More specifically, see Figure 2When the core under test 7 is placed in the measurement position, the rotation drive mechanism 52 drives the guide rod 2 to rotate the core under test 7 clockwise by one revolution. Then, the first drive mechanism 61 drives the active electrostatic probe 63 to move one step h from the detection starting position along the axial direction of the guide rod 2. y Then, the rotary drive mechanism 52 drives the guide rod 2 to rotate the core 7 under test counterclockwise by one revolution, and the first drive mechanism 61 drives the active electrostatic probe 63 to move another step h along the axis of the guide rod 2. y The measurement cycle is completed. The rotary drive mechanism 52 and the first drive mechanism 61 operate alternately until the active electrostatic probe 63 moves to the end of the detection position. In this way, the active electrostatic probe 63 scans and measures the surface of the core 7 under test using an "S-shaped path".

[0083] The scanning path of measurement structure 6 is S = 2L x +2h y In the formula, S is the scanning path of the measurement structure 6, and L... x The scanning path of the measuring structure 6 is the one-turn rotation of the core 7 driven by the guide rod 2. y To measure the step length of structure 6 moving along the axial direction of guide rod 2, where L x =πD, where D is the diameter of the core 7 being measured.

[0084] Step S6: Obtain the relationship between the surface potential of the core under test and the path based on the surface potential measured by the measurement structure and the preset path.

[0085] Specifically, when the measuring structure 6 moves, its moving speed is set to v. The relationship between the surface potential V and the measurement time t is obtained from the measurement of the measuring structure 6, V(t). Then, based on the moving speed v and the scanning path S of the measuring structure 6, the relationship between the surface potential V and the scanning path S, V(S / v), is obtained. More specifically, based on the formula t = S / v and the relationship between the surface potential V and the measurement time t, V(t), the formula t = S / v is substituted to obtain the relationship between the surface potential V and the scanning path S, V(S / v).

[0086] It should be noted that when measuring the surface potential V, the measuring structure 6 records the time while measuring the surface potential V, so that the relationship V(t) between the surface potential V and the measurement time t can be obtained.

[0087] After the active electrostatic probe 63 has completed scanning the entire surface of the core 7 under test, the measurement ends. At this time, the active electrostatic probe 63 has moved to the end of the detection position. Remove all voltage, wait for cooling and venting, open the chamber door 8 to take out the core 7 under test, check the position of the active electrostatic probe 63, the sealing status of the test chamber 1, etc., and after confirming that there are no abnormalities, end the test and check the recorded measurement data.

[0088] As can be seen, in this embodiment, the driving device drives the guide rod to move, so that the core under test moves from the pressurized position to the measurement position. The measuring structure itself moves to the detection starting position. According to the preset path, the driving device drives the guide rod to rotate, and the measuring structure itself moves along the axial direction of the guide rod, measuring the surface potential of the core under test. Then, based on the surface potential measured by the measuring structure and the preset path, the relationship between the surface potential of the core under test and the path is obtained. In this way, the method can simulate the electric field environment of the surface of the core under test during actual operation of the bushing, and can perform a comprehensive scan of the surface potential of the core under test, improving the accuracy of surface potential measurement. It realizes automated and high-precision measurement of the potential distribution of the entire surface of the core under test. Furthermore, the method is simple to operate and easy to implement.

[0089] It should be noted that the principle of the sleeve core surface potential measuring device and surface potential measuring method based on the electrostatic probe method in this invention is the same, and related parts can be referred to each other.

[0090] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0091] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0092] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A device for measuring the surface potential of a sleeve core based on the electrostatic probe method, characterized in that, include: The test chamber (1), guide rod (2), high-voltage wiring assembly (3), fiberglass cylinder (4), drive device (5), and self-movable measuring structure (6); among which, The side wall of the test chamber (1) is provided with an air extraction port (110), an air filling port and an openable hatch (8); The high-voltage wiring assembly (3) passes through the side wall of the first side of the test chamber (1) and its first end is placed inside the test chamber (1); The fiberglass cylinder (4) is disposed inside the test chamber (1); The guide rod (2) is movably suspended inside the test chamber (1). The first end of the guide rod (2) is movably inserted through the inside of the fiberglass cylinder (4) and slidably connected to the first end of the high voltage wiring assembly (3). The guide rod (2) is used to support the core to be tested (7). The driving device (5) is located inside the test chamber (1) and connected to the guide rod (2). It is used to drive the guide rod (2) to move so that the core to be tested (7) moves from the pressurized position inside the fiberglass cylinder (4) to the measurement position outside the fiberglass cylinder (4), and drives the guide rod (2) to rotate so as to drive the core to be tested (7) to rotate. The measuring structure (6) is suspended on one side of the guide rod (2) and is used to measure the surface potential of the core (7) being measured at the measuring position.

2. The device for measuring the surface potential of a sleeve core based on the electrostatic probe method according to claim 1, characterized in that, The driving device (5) includes: a moving driving mechanism (51) and a rotating driving mechanism (52); wherein, The moving drive mechanism (51) is disposed inside the test chamber (1) and connected to the guide rod (2), and is used to drive the guide rod (2) to move so that the core to be tested (7) moves to the measurement position; The rotary drive mechanism (52) is disposed on the mobile drive mechanism (51) and connected to the guide rod (2), and is used to drive the guide rod (2) to rotate.

3. The device for measuring the surface potential of a sleeve core based on the electrostatic probe method according to claim 1, characterized in that, The measuring structure (6) includes: a measuring mechanism, a first driving mechanism (61), and a second driving mechanism (62); wherein, The first driving mechanism (61) is disposed inside the test chamber (1) and connected to the second driving mechanism (62). The measuring mechanism is disposed in the second driving mechanism (62) and placed on one side of the core (7) being measured at the measuring position. The second driving mechanism (62) is used to drive the measuring mechanism to move from the starting position to the guide rod (2) to the detection starting position. The first driving mechanism (61) is used to drive the measuring mechanism to move from the detection starting position along the axial direction of the guide rod (2) to the detection ending position.

4. The sleeve core surface potential measuring device based on the electrostatic probe method according to claim 3, characterized in that, The measuring mechanism includes: an active electrostatic probe (63) and an electrostatic potentiometer; wherein, The electrostatic potentiometer is disposed outside the test chamber (1), and the active electrostatic probe (63) is insulated at the end of the second drive mechanism (62) and placed above the core (7) under test in the measurement position. The active electrostatic probe (63) is connected to the electrostatic potentiometer.

5. The device for measuring the surface potential of a sleeve core based on the electrostatic probe method according to claim 1, characterized in that, The high-voltage wiring assembly (3) includes: a bushing (31) and a connector (32); wherein, The sleeve (31) passes through the side wall of the first side of the test chamber (1). The first end of the sleeve (31) is placed inside the test chamber (1) and is slidably connected to the first end of the guide rod (2). The second end of the sleeve (31) is placed outside the test chamber (1) and is connected to the connector (32). The connector (32) is used to connect to a high-voltage power supply.

6. The device for measuring the surface potential of a sleeve core based on the electrostatic probe method according to claim 1, characterized in that, Also includes: Temperature control device; wherein, The temperature regulating device is located on the guide rod (2) and is used to regulate the temperature of the core being tested (7).

7. The sleeve core surface potential measuring device based on the electrostatic probe method according to claim 6, characterized in that, The temperature regulating device includes: a heating tube (9); wherein, The guide rod (2) is hollow inside, and the second end of the guide rod (2) is movably inserted through the side wall of the second side of the test chamber (1) and placed outside the test chamber (1); The heating tube (9) passes through the end wall of the second end of the guide rod (2) and is partially placed inside the guide rod (2). The part of the heating tube (9) placed outside the guide rod (2) is used to connect with the liquid tank (14) to receive liquid with a preset temperature. The part of the heating tube (9) placed inside the guide rod (2) is used to transport the liquid into the guide rod (2). The guide rod (2) is located on the side wall outside the test chamber (1) and has a liquid outlet (21) for outputting the liquid inside the guide rod (2).

8. A method for measuring surface potential using the casing core surface potential measuring device based on the electrostatic probe method as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The core to be tested is mounted on the guide rod, and the driving device drives the guide rod to move so that the core to be tested is placed in the pressurized position inside the fiberglass cylinder; After evacuating the test chamber, insulating gas is introduced into the test chamber. The high-voltage wiring assembly applies pressure to the conductor rod to a set rated voltage and holds it for a preset time before stopping the pressure application; The driving device drives the guide rod to move, so that the core being measured moves from the pressurized position inside the fiberglass cylinder to the measurement position outside the fiberglass cylinder, and the measuring structure itself moves to the detection start position; According to a preset path, the driving device drives the guide rod to rotate, the measuring structure itself moves along the axial direction of the guide rod, and measures the surface potential of the core being measured; The relationship between the surface potential of the core under test and the path is obtained based on the surface potential measured by the measurement structure and the preset path.

9. The surface potential measurement method according to claim 8, characterized in that, In the step of measuring the surface potential of the core under test by driving the guide rod to rotate according to a preset path, the measuring structure itself moving along the axial direction of the guide rod, and measuring the surface potential of the core under test, According to the preset path, the driving device drives the guide rod to rotate clockwise one full turn, and the measuring structure itself moves one step from the detection start position along the axial direction of the guide rod. The driving device then drives the guide rod to rotate counterclockwise one full turn, and the measuring structure itself moves one step along the axial direction of the guide rod. This process is repeated until the measuring structure itself moves to the detection end position.

10. The surface potential measurement method according to claim 9, characterized in that, In the step of measuring the surface potential of the core under test by rotating the guide rod according to a preset path, the measuring structure moves along the axial direction of the guide rod and the driving device drives the guide rod to rotate. The scanning path of the measuring structure is S = 2L. x +2h y In the formula, S is the scanning path of the measurement structure, and L... x h is the scanning path of the measurement structure as the guide rod rotates one revolution. y To measure the step length of the structure moving along the axial direction of the guide rod, where L x =πD, where D is the diameter of the core being measured; In the step of obtaining the relationship between the surface potential of the core under test and the path based on the surface potential measured by the measuring structure and the preset path, the moving speed of the measuring structure is set to v, the relationship between the surface potential V and the measurement time t is obtained according to the measurement of the measuring structure, V(t), and then the relationship between the surface potential V and the scanning path S is obtained according to the moving speed v of the measuring structure and the scanning path S of the measuring structure, V(S / v).

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