Experimental system for wide-area measurement of electrostatic potential and triggering of dc flashover

Abstract

The application provides an experimental system for wide-range measurement of electrostatic potential and triggering of direct-current flashover, which comprises a cavity, a position adjusting device, a measurement probe and a bearing device; the position adjusting device is arranged in the cavity; the measurement probe is arranged on the position adjusting device and used for adjusting the position of the measurement probe; the bearing device is arranged in the cavity and used for bearing a test sample arranged in the cavity; or the bearing device is arranged at the end of the cavity and used for bearing a capacitor core partially arranged in the cavity; the measurement probe is used for measuring the test sample or the capacitor core arranged in the cavity. In the application, the position adjusting device adjusts the position of the measurement probe, so that the measurement probe can accurately measure the potential at different positions of the test sample or the capacitor core according to actual requirements, the measurement accuracy is improved, the wide-range measurement of the test sample or the capacitor core is realized, and the charge distribution characteristics of the test sample or the capacitor core can be accurately obtained.

Description

Technical Field

[0001] This invention relates to the field of high voltage testing technology, and more specifically, to an experimental system for wide-area measurement of electrostatic potential and triggering DC flashover. Background Technology

[0002] Gas-insulated transmission and transformation equipment is widely used in DC transmission systems, such as gas-insulated DC circuit breakers (GIS), gas-insulated transmission lines (GIL), and DC bushings using SF6 or mixed gas insulation. Under long-term DC voltage, surface charges easily accumulate at the interface between solid and gas insulation. These charges cause electric field distortion and alter the insulation performance of the gas-solid interface, potentially leading to serious insulation faults. Therefore, research on gas-solid interface charges and their impact on surface insulation performance is a crucial means to support the design optimization, process improvement, fault analysis, and technological innovation of gas-insulated transmission and transformation equipment.

[0003] In charge measurement, studying surface charge and surface charge-induced flashover on small-sized material samples in the laboratory is a widely adopted research method in universities and research institutions both domestically and internationally. Its advantages include small sample size, convenient replacement, and suitability for experimental research requiring numerous repetitive tests. However, the commonly used charge measurement device is the Trek commercial electrostatic probe, which measures the electrostatic potential distribution on the surface of a solid insulating sample using non-contact measurement technology, thus obtaining the charge distribution across the entire surface measurement range. This type of probe is relatively large (head cross-section approximately 11×11mm), and the probe head cannot touch other objects during measurement. Generally, the sample and metal electrodes (usually high-voltage and ground electrodes) are kept in a charged arrangement during the measurement process. This directly restricts the probe's movement space. For experimental systems with small electrode spacing (millimeters or centimeters), the effective measurement area of ​​the electrostatic probe will be very small, and the charge density in the contact area between the metal electrode and the material sample cannot be accurately measured. Electrostatic potential measurement tests require simulating a high-pressure insulating gas environment in a sealed metal cavity. However, when it is not possible to directly and manually contact the material sample and metal electrodes, there is a lack of effective means to increase the area of ​​the electrostatic potential measurement region on the surface of the material sample between the metal electrodes. Summary of the Invention

[0004] In view of this, the present invention proposes an experimental system for wide-area measurement of electrostatic potential and triggering DC flashover, aiming to solve the problem of limited measurement area of ​​electrostatic potential of insulating material samples in the prior art.

[0005] This invention proposes an experimental system for wide-area measurement of electrostatic potential and triggering DC flashover. The system includes: a cavity, a position adjustment device, a measuring probe, and a support device; wherein, the position adjustment device is disposed within the cavity; the measuring probe is disposed within the position adjustment device for adjusting the position of the measuring probe; the support device is disposed within the cavity to support the test sample placed within the cavity; or, the support device is disposed at the end of the cavity to support a portion of the capacitor core placed within the cavity; the measuring probe is used to measure the test sample or the capacitor core placed within the cavity.

[0006] Furthermore, in the above-mentioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, when the carrier device is located at the end of the cavity, the capacitor core is located on the carrier device, and the capacitor core passes through the cavity and is partially placed inside the cavity.

[0007] Furthermore, in the aforementioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, when the carrier device is located within the cavity, it further includes: a charge application device and a DC discharge triggering device; wherein, the charge application device is located within the position adjustment device and is used to apply charge to the test sample; the DC discharge triggering device is located within the cavity and is used to trigger DC discharge on the test sample; the carrier device itself is movable and is used to move the test sample to the DC discharge triggering area of ​​the DC discharge triggering device, or to move the test sample away from the DC discharge triggering area.

[0008] Furthermore, in the aforementioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, when the support device is placed inside the cavity, the support device includes: a translation mechanism, a first insulating platform, a height adjustment mechanism, and a second insulating platform; wherein, the translation mechanism is placed inside the cavity, the first insulating platform is placed on the translation mechanism, and the translation mechanism is used to drive the first insulating platform to move along the length direction of the cavity to be placed in or away from the DC discharge triggering area; the height adjustment mechanism is placed on the first insulating platform, the second insulating platform is placed on the height adjustment mechanism, the test sample is placed on the second insulating platform, and the height adjustment mechanism is used to adjust the position of the test sample in the height direction of the cavity.

[0009] Furthermore, in the aforementioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, the height adjustment mechanism includes: an insulating adjustment plate, a driving mechanism, and at least two connecting bodies; wherein, each connecting body is respectively placed on both sides of the first insulating platform, the insulating adjustment plate is placed side by side above the first insulating platform, the first end of each connecting body is rotatably connected to the side wall of the first insulating platform, and the second end of each connecting body is rotatably connected to the side wall of the insulating adjustment plate; the driving mechanism is connected to one of the connecting bodies and is used to drive the connected connecting body to rotate; the second insulating platform is disposed on the side of the insulating adjustment plate opposite to the first insulating platform.

[0010] Furthermore, in the above-mentioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, a plurality of guide posts are provided on the side of the insulating adjustment plate facing away from the first insulating platform. Each guide post is fitted with a buffer spring. The first end of each buffer spring is connected to the insulating adjustment plate, and the second end of each buffer spring is connected to the second insulating platform.

[0011] Furthermore, in the aforementioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, the DC discharge triggering device includes: two support columns, two trigger electrodes, and two pressure blocks; wherein, the two support columns are respectively placed on both sides of the bearing device, and the bottom ends of the two support columns are both located in the cavity; the first ends of the two trigger electrodes are respectively locked to the top ends of the two support columns by the two pressure blocks, and the second ends of the two trigger electrodes extend relative to each other and have a preset distance; the test sample is positioned below the second ends of the two trigger electrodes under the drive of the translation mechanism, and the height adjustment mechanism is used to adjust the position of the test sample in the height direction of the cavity so that the second insulating platform clamps the test sample with the second ends of the two trigger electrodes.

[0012] Furthermore, in the above-mentioned experimental system for wide-area measurement of electrostatic potential and triggering DC flashover, each triggering electrode includes: a finger electrode, an insulating sleeve, and a conductive rod; wherein, the finger electrode has a through hole inside, the insulating sleeve is disposed in the through hole and its first end extends to the outside of the finger electrode; the conductive rod is disposed inside the insulating sleeve, and the first end of the conductive rod corresponds to the first end of the insulating sleeve, and the first end of the conductive rod is placed outside the insulating sleeve.

[0013] Furthermore, in the above-mentioned experimental system for measuring electrostatic potential and triggering DC flashover over a wide area, the charge application device includes: a grid plate, a corona needle, and at least one connecting post; wherein, the grid plate is connected to the position adjustment device through each connecting post; one end of the corona needle is connected to the position adjustment device, and the other end of the corona needle extends toward the grid plate.

[0014] Furthermore, in the aforementioned experimental system for wide-area measurement of electrostatic potential and triggering DC flashover, the position adjustment device includes: a first adjustment mechanism, a second adjustment mechanism, a third adjustment mechanism, and a rotation mechanism; wherein, the first adjustment mechanism is disposed within the cavity, the second adjustment mechanism is disposed within the first adjustment mechanism, the third adjustment mechanism is disposed within the second adjustment mechanism, the rotation mechanism is disposed within the third adjustment mechanism, and the measuring probe is disposed within the rotation mechanism; the first adjustment mechanism is used to adjust the position of the measuring probe in the length direction of the cavity; the second adjustment mechanism is used to adjust the position of the measuring probe in the width direction of the cavity; the third adjustment mechanism is used to adjust the position of the measuring probe in the height direction of the cavity; and the rotation mechanism is used to drive the measuring probe to rotate, thereby adjusting the angle of the measuring probe.

[0015] In this invention, a position adjustment device is disposed within a cavity and equipped with a measuring probe. A carrying device carries the test sample or a partially disposed capacitor core within the cavity. The position adjustment device adjusts the position of the measuring probe, enabling the measuring probe to accurately measure the potential of the test sample or capacitor core, thereby improving measurement accuracy. Furthermore, it allows for the measurement of the potential at different locations on the test sample or capacitor core according to actual needs, achieving wide-area measurement of the test sample or capacitor core. This enables accurate determination of the charge distribution characteristics of the test sample or capacitor core, solving the problem of limited measurement area for electrostatic potential of insulating material samples in the prior art. Attached Figure Description

[0016] 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: Figure 1 A schematic diagram of the structure of an experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the capacitor core in the experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention. Figure 3 A schematic diagram of the structure of the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover provided in an embodiment of the present invention, wherein the test sample is located in the DC discharge triggering region; Figure 4 A top view of the test sample in the DC discharge triggering region of the experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention; Figure 5 A schematic diagram of the structure of the test sample far from the DC discharge triggering region in the experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention. Figure 6 A schematic diagram of the structure of the test sample far from the DC discharge triggering region in the experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention. Figure 7 A schematic diagram of the supporting device in the experimental system for wide-area measurement of electrostatic potential and triggering DC flashover provided in an embodiment of the present invention; Figure 8 A schematic diagram of the main structure of the support device in the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover provided in an embodiment of the present invention; Figure 9A schematic diagram of the trigger electrode in the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover provided in an embodiment of the present invention; Figure 10 A partial cross-sectional view of the trigger electrode is shown in the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover provided in an embodiment of the present invention. Detailed Implementation

[0017] 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.

[0018] See Figures 1 to 10 The figure shows a preferred structure of the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover in this embodiment. As shown, the experimental system for wide-area measurement of electrostatic potential and triggering of DC flashover includes: a cavity 1, a position adjustment device 2, a measuring probe 3, and a support device 4. The cavity 1 is hollow inside, providing an adjustable air pressure environment. The cavity 1 has an exhaust port 11 for evacuating or filling the cavity 1 with air. A pressure gauge 9 is installed on the cavity 1 to monitor the pressure inside the cavity 1. The cavity 1 also has a viewing window 12 for observing the experimental status. A support 15 is provided at the bottom of the cavity 1 to support it.

[0019] Position adjustment device 2 is disposed inside cavity 1, and measuring probe 3 is disposed on position adjustment device 2. Position adjustment device 2 is used to adjust the position of measuring probe 3. Specifically, position adjustment device 2 adjusts the measuring probe 3 in the length direction of cavity 1. Figure 1 (shown in the left-to-right direction) and width direction ( Figure 1 (as shown in the direction perpendicular to the paper) and the height direction ( Figure 1 The position of the measuring probe 3 (as shown in the top-to-bottom direction) and the angle of the measuring probe 3 are adjusted.

[0020] See Figure 1 The support device 4 is disposed within the cavity 1, and the test specimen 5 is also placed within the cavity 1. The support device 4 is used to support the test specimen 5 placed within the cavity 1. Alternatively, see [link to other documentation]. Figure 2 The supporting device 4 is located at the end of the cavity 1. The capacitor core 6 is partially placed inside the cavity 1 and partially placed outside the cavity 1. The supporting device 4 supports the capacitor core 6.

[0021] The measuring probe 3 is used to measure the potential on the surface of the test sample 5 or the potential on the surface of the capacitor core 6 placed in the cavity 1.

[0022] As can be seen, in this embodiment, the position adjustment device 2 is disposed inside the cavity 1 and is equipped with a measuring probe 3. The bearing device 4 carries the test sample 5 placed inside the cavity 1 or the capacitor core 6 partially placed inside the cavity 1. The position adjustment device 2 adjusts the position of the measuring probe 3 so that the measuring probe 3 can accurately measure the potential of the test sample 5 or the capacitor core 6, thereby improving the measurement accuracy. It can also measure the potential at different positions of the test sample 5 or the capacitor core 6 according to actual needs, realizing wide-area measurement of the test sample 5 or the capacitor core 6. In this way, the charge distribution characteristics of the test sample 5 or the capacitor core 6 can be accurately obtained, solving the problem of limited measurement area of ​​electrostatic potential of insulating material samples in the prior art.

[0023] See Figures 1 to 6 In the above embodiments, the position adjustment device 2 includes: a first adjustment mechanism 21, a second adjustment mechanism 22, a third adjustment mechanism 23, and a rotation mechanism 24. The first adjustment mechanism 21 is disposed within the cavity 1, the second adjustment mechanism 22 is disposed within the first adjustment mechanism 21, the third adjustment mechanism 23 is disposed within the second adjustment mechanism 22, the rotation mechanism 24 is disposed within the third adjustment mechanism 23, and the measuring probe 3 is disposed within the rotation mechanism 24.

[0024] The first adjustment mechanism 21 is used to adjust the position of the measuring probe 3 along the length of the cavity 1, the second adjustment mechanism 22 is used to adjust the position of the measuring probe 3 along the width of the cavity 1, and the third adjustment mechanism 23 is used to adjust the position of the measuring probe 3 along the height of the cavity 1. The rotation mechanism 24 is used to drive the measuring probe 3 to rotate, so as to adjust the angle of the measuring probe 3.

[0025] In specific implementation, the first adjusting mechanism 21, the second adjusting mechanism 22, and the third adjusting mechanism 23 can all be a slide rail and slider structure, a lead screw and slider structure, or other structures. This embodiment does not impose any restrictions on this. The slide rail or lead screw of the first adjusting mechanism 21 extends along the length direction of the cavity 1. The slide rail or lead screw of the second adjusting mechanism 22 is disposed on the slider of the first adjusting mechanism 21, and extends along the width direction of the cavity 1. The slide rail or lead screw of the third adjusting mechanism 23 is disposed on the slider of the second adjusting mechanism 22, and extends along the height direction of the cavity 1. The rotating mechanism 24 is disposed on the slider of the third adjusting mechanism 23.

[0026] In a specific implementation, the rotating mechanism 24 can be a structure of a drive motor and a mounting plate. The drive motor drives the mounting plate to rotate 360°. The measuring probe 3 is set on the mounting plate, so the rotation of the mounting plate drives the rotation of the measuring probe 3.

[0027] As can be seen, in this embodiment, the position adjustment device 2 adjusts the position of the measuring probe 3 in the length, width and height directions of the cavity 1, and can drive the measuring probe 3 to rotate, thereby adjusting the angle of the measuring probe 3. This realizes the adjustment of multiple positions of the measuring probe 3, thereby enabling the measurement of different positions of the capacitor core 6 or the test sample 5, expanding the measurement range. Furthermore, the position adjustment device 2 constitutes a multi-degree-of-freedom motion platform, which can realize the adjustment of the relative position between the test sample 5 and the measuring probe 3.

[0028] See Figure 2 In the above embodiment, when the supporting device 4 is disposed at one end of the cavity 1, the capacitor core 6 is disposed on the supporting device 4, and the capacitor core 6 passes through the cavity 1 and is partially placed inside the cavity 1. Specifically, the supporting device 4 may pass through one end of the cavity 1 and be partially placed inside the cavity 1, while the other part is placed outside the cavity 1. The capacitor core 6 passes through the supporting device 4 and is connected to the supporting device 4, with a portion of the capacitor core 6 placed inside the cavity 1 and the other part placed outside the cavity 1. The measuring probe 3 measures the portion of the capacitor core 6 placed inside the cavity 1.

[0029] In specific implementation, the supporting device 4 can be a sleeve or other device, as long as it can fix the capacitor core 6. This embodiment does not impose any restrictions on the structure of the supporting device 4.

[0030] See Figure 1 , Figures 3 to 10 In the above embodiments, when the supporting device 4 is disposed in the cavity 1 to support the test sample 5, the experimental system for wide-area electrostatic potential measurement and triggering DC flashover further includes: a charge application device 7 and a DC discharge triggering device 8. The charge application device 7 is disposed in the position adjustment device 2 and is used to apply charge to the test sample 5.

[0031] Specifically, the charge application device 7 includes: a grid electrode 71, a corona needle 72, and at least one connecting post 73. The grid electrode 71 is connected to the position adjustment device 2 through each connecting post 73, such that there is a certain distance between the grid electrode 71 and the position adjustment device 2.

[0032] One end of the corona needle 72 is connected to the position adjustment device 2, and the other end of the corona needle 72 extends towards the grid plate pole 71. Specifically, the position adjustment device 2 is provided with a terminal block, one end of the corona needle 72 is connected to the terminal block, and there is a certain gap between the other end of the corona needle 72 and the grid plate pole 71. This gap can be determined according to the actual situation, and this embodiment does not impose any restrictions on it. The terminal block on the position adjustment device 2 is used to connect to a high-voltage DC power supply outside the cavity 1. A DC voltage is applied to the corona needle 72 through the high-voltage DC power supply, and the corona needle 72 performs corona discharge to apply charge to the surface of the test sample 5, so that the charge accumulates on the surface of the test sample 5, thereby forming the expected charge distribution on the surface of the test sample 5.

[0033] In practice, there may be one corona needle 72 or at least two, with each corona needle 72 corresponding to the center position of the grid electrode 71. The grid electrode 71 may be a metal plate.

[0034] The charge application device 7 is a grid plate electrode 71 and a corona needle 72 arranged above the surface of the test sample 5, and in conjunction with an adjustable high voltage DC power supply, to form a corona discharge area with adjustable intensity and range on the surface of the test sample 5, thereby forming an accumulated charge with certain distribution characteristics on the surface of the test sample 5.

[0035] The DC discharge triggering device 8 is installed inside the cavity 1. The DC discharge triggering device 8 is used to trigger the DC discharge of the test sample 5. The area where the DC discharge triggering device 8 triggers the DC discharge is the DC discharge triggering area.

[0036] The support device 4 is disposed inside the cavity 1, and the support device 4 itself is movable. Specifically, the support device 4 is placed on one side of the position adjustment device 2. The support device 4 moves along the length direction of the cavity 1. The support device 4 is used to move the test sample 5 by moving itself along the length direction of the cavity 1, so that the test sample 5 is placed in the DC discharge trigger area, or so that the test sample 5 is moved away from the DC discharge trigger area.

[0037] In practice, the position adjustment device 2 is placed at the first end of the bearing device 4. Figure 1 One side of the left end (as shown), relative to Figure 1 Specifically, the position adjustment device 2 is located on the left side of the first end of the bearing device 4, and the DC discharge triggering device 8 is located on the second end of the bearing device 4. Figure 1 At the right end shown, the DC discharge triggering area corresponds to the second end of the carrier device 4. The first end of the carrier device 4 is far from the DC discharge triggering area, and this area can be recorded as the measurement area of ​​the measuring probe 3. The measuring probe 3 is used to measure the potential of the test sample 5.

[0038] See Figure 1 , Figures 3 to 8 When the support device 4 is installed inside the cavity 1 to support the test sample 5, the support device 4 includes: a translation mechanism 41, a first insulating platform 42, a height adjustment mechanism 43, and a second insulating platform 44. The translation mechanism 41 is installed inside the cavity 1, and the first insulating platform 42 is installed within the translation mechanism 41. The translation mechanism 41 drives the first insulating platform 42 to move along the length of the cavity 1, so that the first insulating platform 42 is positioned in the DC discharge triggering area, or the first insulating platform 42 is moved away from the DC discharge triggering area.

[0039] In specific implementation, the translation mechanism 41 can be a slide rail and slider structure, a lead screw and slider structure, or other structures; this embodiment does not impose any restrictions on this. The first insulating platform 42 is disposed on the slider of the translation mechanism 41, and the sliding of the slider of the translation mechanism 41 drives the first insulating platform 42 to move along the length direction of the cavity 1.

[0040] A height adjustment mechanism 43 is disposed on the first insulating platform 42, and a second insulating platform 44 is disposed on the height adjustment mechanism 43. The test sample 5 is placed on the second insulating platform 44. The height adjustment mechanism 43 is used to adjust the position of the test sample 5 in the height direction of the cavity 1. Specifically, the second insulating platform 44 is disposed side by side with the first insulating platform 42, and the second insulating platform 44 is positioned above the first insulating platform 42. The height adjustment mechanism 43 adjusts the position of the second insulating platform 44 in the height direction of the cavity 1, thereby adjusting the position of the test sample 5 in the height direction of the cavity 1.

[0041] Since the test sample 5 is placed on the second insulating platform 44, the translation mechanism 41 drives the first insulating platform 42 to move along the length direction of the cavity 1, and then the height adjustment mechanism 43 and the second insulating platform 44 drive the test sample 5 to move along the length direction of the cavity 1, so that the test sample 5 is placed in the DC discharge triggering area or away from the DC discharge triggering area.

[0042] See Figure 1 , Figures 3 to 8 The height adjustment mechanism 43 includes: an insulating adjustment plate 431, a drive mechanism, and at least two connecting bodies 432. The connecting bodies 432 are arranged in pairs, with each connecting body 432 positioned on opposite sides of the first insulating platform 42. Figure 4(The first insulating platform 42 shown is located on both its upper and lower sides). Insulating adjusting plates 431 are arranged side by side above the first insulating platform 42. Specifically, the insulating adjusting plates 431 are parallel to the first insulating platform 42, and are positioned above the first insulating platform 42 and below the second insulating platform 44. The first end of each connector 432 is rotatably connected to the side wall of the corresponding side of the first insulating platform 42, and the second end of each connector 432 is rotatably connected to the side wall of the corresponding side of the insulating adjusting plate 431.

[0043] The drive mechanism is connected to one of the connectors 432. The drive mechanism is used to drive the connector 432 to rotate. The rotation of the connector 432 causes the position of the insulating adjustment plate 431 in the height direction of the cavity 1 to be adjusted.

[0044] The second insulating platform 44 is located on the side of the insulating adjusting plate 431 that is away from the first insulating platform 42. The position adjustment of the insulating adjusting plate 431 in the height direction of the cavity 1 drives the second insulating platform 44 and the test sample 5 on it to adjust their positions in the height direction of the cavity 1, thereby realizing the adjustment of the position of the test sample 5 in the height direction of the cavity 1.

[0045] Multiple guide posts are provided on the side of the insulating adjustment plate 431 facing away from the first insulating platform 42, and the guide posts are spaced apart on the insulating adjustment plate 431. Each guide post is fitted with a buffer spring 45, the first end of each buffer spring 45 is connected to the insulating adjustment plate 431, and the second end of each buffer spring 45 is connected to the second insulating platform 44.

[0046] In practice, the first insulating platform 42, the second insulating platform 44, the insulating adjusting plate 431, and each guide column are all made of high-insulation materials to ensure sufficient dielectric strength and mechanical strength under high-voltage test conditions.

[0047] See Figure 1 , Figures 3 to 8 The DC discharge triggering device 8 includes two support columns 81, two trigger electrodes 82, and two pressure blocks 83. The two support columns 81 are respectively positioned on both sides of the supporting device 4. Specifically, the two support columns 81 are positioned at the second end of the supporting device 4, and are respectively positioned on both sides of the second end of the supporting device 4. The bottom ends of both support columns 81 are disposed on the bottom wall of the cavity 1, and each support column 81 is perpendicular to the bottom wall of the cavity 1.

[0048] The first ends of the two trigger electrodes 82 are locked to the tops of the two support columns 81 by two pressure blocks 83, respectively. Specifically, the two trigger electrodes 82 correspond one-to-one with the two support columns 81, and the two pressure blocks 83 correspond one-to-one with the two trigger electrodes 82. The first end of each trigger electrode 82 is placed at the top of the corresponding support column 81, and the first end of the trigger electrode 82 is locked to the top of the support column 81 by the corresponding pressure block 83. The second ends of the two trigger electrodes 82 extend relative to each other, and there is a preset distance between the second ends of the two trigger electrodes 82. This preset distance can be determined according to the actual situation, and this embodiment does not impose any restrictions on it.

[0049] In practice, the pressure block 83 can be an insulating pressure block, specifically made of high-strength insulating material. The position of the trigger electrode 82 and the distance between the second ends of the two trigger electrodes 82 can be adjusted according to actual needs. After adjustment, the trigger electrode 82 and the support column 81 can be locked by the pressure block 83.

[0050] In practice, each pressure block 83 can be locked to the top of its corresponding support column 81 via bolts, and each pressure block 83 presses against its corresponding trigger electrode 82. Of course, the locking structure between the pressure block 83 and the top of its corresponding support column 61 can be other methods, and this embodiment does not impose any restrictions on this.

[0051] When the test sample 5 is placed in the DC discharge trigger region under the drive of the translation mechanism 41, it is located below the second ends of the two trigger electrodes 82. That is, when the translation mechanism 41 drives the test sample 5 to be placed in the DC discharge trigger region, the test sample 5 is located below the second ends of the two trigger electrodes 82. Furthermore, the preset distance between the second ends of the two trigger electrodes 82 is less than the radial distance of the test sample 5. However, the second ends of the two trigger electrodes 82 do not completely cover the test sample 5, but only block and limit the two ends of the test sample 5 in the radial direction.

[0052] The height adjustment mechanism 43 is used to adjust the position of the test sample 5 in the height direction of the cavity 1 so that the second insulating platform 44 clamps the test sample 5 with the second ends of the two trigger electrodes 82. Specifically, the height adjustment mechanism 43 adjusts the position of the test sample 5 in the height direction of the cavity 1 so that the second insulating platform 44 lifts the test sample 5 upward. Since the test sample 5 is located below the second ends of the two trigger electrodes 82, the lifting of the test sample 5 clamps the test sample 5 with the second insulating platform 44 and the second ends of the two trigger electrodes 82. This ensures stable clamping between the trigger electrodes 82 and the test sample 5, ensuring stable contact and moderate pressure between the trigger electrodes 82 and the test sample 5, and can adapt to test samples 5 of different specifications. This not only improves the operability and repeatability of the test sample 5 clamping process, but also, under the premise of ensuring electrical safety, facilitates rapid switching between multiple batches and specifications of test samples 5, thereby improving testing efficiency.

[0053] In practice, the positions of the trigger electrode 82 and the test sample 5, as well as the distance between the two trigger electrodes 82, are determined according to the thickness, shape, and size of the test sample 5. The positions of the two trigger electrodes 82 are adjusted so that the trigger electrodes 82 and the surface of the test sample 5 maintain uniform contact.

[0054] Preferably, the supporting device 4 further includes a limiting block 46. The limiting block 46 is disposed on the translation mechanism 41 and is located outside the DC discharge triggering device 8. The limiting block 46 is used to limit the position of the test sample 5, ensuring that the test sample 5 is positioned at the DC discharge triggering device 8. Specifically, the limiting block 46 is located at the second end of the supporting device 4, that is, at the position of the translation mechanism 41 corresponding to the second end of the supporting device 4. The DC discharge triggering device 8 is located close to the second end of the supporting device, but closer to the middle of the supporting device 4 than the position of the limiting block 46. The limiting block 46 limits the position of the overall structure of the first insulating platform 42, the height adjustment mechanism 43, and the second insulating platform 44, ensuring that the test sample 5 is placed in the DC discharge triggering area. This ensures the positioning accuracy and mechanical safety of the test sample 5 during clamping and release, preventing damage to the test sample 5 and the trigger electrode 82 due to impact or overtravel.

[0055] In practice, the positions of the limiting block 46 and the DC discharge triggering device 8 can be determined according to actual needs. As long as the test sample 5 is blocked by the limiting block 46 and cannot move, it is placed at the DC discharge triggering device 8, so that the test sample 5 is pressed by the two triggering electrodes 82. This embodiment does not impose any restrictions on the positions of the limiting block 46 and the DC discharge triggering device 8.

[0056] See Figures 9 to 10 Each trigger electrode 82 includes: a finger electrode 821, an insulating sleeve 822, and a conductive rod 823. The finger electrode 821 has a through hole inside, and the insulating sleeve 822 is disposed within the through hole. The first end of the insulating sleeve 822 ( Figure 10 The right end (as shown) extends to the outside of the finger electrode 821.

[0057] The conductive rod 823 is disposed inside the insulating sleeve 822, and the first end of the conductive rod 823 ( Figure 10 The right end shown corresponds to the first end of the insulating sleeve 822, and the first end of the conductive rod 823 is placed outside the insulating sleeve 822.

[0058] The first end of the finger electrode 821 ( Figure 10 The right end shown corresponds to the first end of the insulating sleeve 822 and the first end of the conductive rod 823, and the second end of the finger electrode 821 ( Figure 10 The left end shown) and the second end of the insulating sleeve 822 ( Figure 10 The left end shown) and the second end of the conductive rod 823 (shown on the left ... Figure 10 Corresponding to the left end shown. The first end of the insulating sleeve 822 is placed outside the first end of the finger electrode 821, and the first end of the conductive rod 823 is placed outside the first end of the insulating sleeve 822. The first end of the conductive rod 823 is used to connect to the pulse power supply so as to connect the pulse voltage and thus achieve flashover. In this way, the tiny air gap between the finger electrode 821 and the conductive rod 823 can be instantaneously discharged and broken down. When the charge application device 7 applies charge to the surface of the test sample 5, for the test sample 5 surface that has accumulated a large amount of charge, the high-energy charged particles generated by the discharge caused by the tiny air gap can then instantaneously induce surface flashover discharge between the high voltage end and the ground end on the surface of the test sample 5.

[0059] In specific implementation, the first end of cavity 1 ( Figure 1 The left end shown is provided with a high-voltage lead 10, which passes through the first end of the cavity 1. The first end of the high-voltage lead 10 is located outside the cavity 1 and is provided with a discharge post 16 and a discharge ball 14. The second end of the high-voltage lead 10 is located inside the cavity 1. The second end of the cavity 1 (shown on the left) Figure 1 The right end shown is provided with a grounding lead 14, which passes through the second end of the cavity 1. The first end of the grounding lead 14 is located outside the cavity 1 and is also provided with a grounding post 16 and a discharge ball 14. The second end of the grounding lead 14 is located inside the cavity 1.

[0060] One of the trigger electrodes 82 has its finger electrode 821 connected to the high voltage lead 10, and the other trigger electrode 82 has its finger electrode 821 connected to the ground lead 14.

[0061] In practical implementation, the insulating sleeve 822 can be a hollow polytetrafluoroethylene (PTFE) insulating sleeve, and the conductive rod 823 can be a brass conductive rod. The brass conductive rod is embedded inside the insulating sleeve 822, forming a through-hole electrode structure with "high external insulation and high internal conductivity." On the one hand, the PTFE hollow insulating sleeve has excellent insulation performance and high mechanical strength, which can effectively suppress the generation of surface discharge and creepage channels under high voltage, and effectively suppress parasitic discharge and charge leakage outside the measurement area, reducing the disturbance to the main electric field distribution inside the cavity 1. On the other hand, the internal brass conductive rod has good conductivity, which can reliably and stably transmit high voltage while maintaining the compact structure of the trigger electrode 82, so that the trigger electrode 82 can achieve DC discharge triggering on the surface of the test specimen 5 at any time during the test. In this way, the trigger electrode 82 can not only ensure the safe and reliable operation of the system under high voltage conditions, but also improve the controllability of the discharge trigger position and time, and is suitable for test specimens 5 with different structures and sizes.

[0062] See Figure 1 , Figures 3 to 10 The experimental process of a wide-area electrostatic potential measurement and DC flashover triggering experimental system is introduced, taking the test sample supported by the bearing device as an example: (1) Determine the distance between the second ends of the two trigger electrodes 82 according to the shape and size of the test sample 5, adjust the position of the two trigger electrodes 82, and lock the two trigger electrodes 82 to the top of the two support columns 81 by the two pressure blocks 83, thereby fixing the two trigger electrodes 82. Then, place the test sample 5 on the second insulating platform 44, and drive the first insulating platform 42, the height adjustment mechanism 43, the second insulating platform 44 and the test sample 5 to the DC discharge triggering area of ​​the DC discharge triggering device 8 by the translation mechanism 41, and ensure that the test sample 5 is placed below the second ends of the two trigger electrodes 82. Then, drive each connecting body 432 to rotate by the drive mechanism, so that the insulating adjustment plate 431 and the second insulating platform 44 move upward along the height direction of the cavity 1, so that the test sample 5 moves upward along the height direction of the cavity 1, and when it moves to the top, the drive mechanism stops driving the connecting body 432 to rotate. The top surface of the test sample 5 is pressed by the second ends of the two trigger electrodes 82, while the bottom surface of the test sample 5 is pressed against the second insulating platform 44. Under the action of the elastic force of each buffer spring 45, the test sample 5 is pushed upward, so that the test sample 5 is clamped and fixed by the second insulating platform 44 and the second ends of the two trigger electrodes 82.

[0063] The position adjustment device 2 drives the measuring probe 3 and the charge application device 7 to move to the DC discharge triggering area via the first adjustment mechanism 21, and the measuring probe 3 and the charge application device 7 are positioned above the test sample 5. The position adjustment device 2 adjusts the distance between the grid electrode 71 and the test sample 5, and adjusts the amplitude and characteristics of the DC voltage. By applying a DC voltage to the corona needle 72 and the grid electrode 71, a stable corona discharge area is formed on the surface of the test sample 5, resulting in a charge distribution of a certain intensity and spatial distribution characteristics on the surface of the test sample 5. The planar dimensions and position of the grid electrode 71 can be adjusted according to the size of the test sample 5 to obtain different surface charge distribution conditions.

[0064] (2) After applying a charge, the measuring probe 3 is placed above the test sample 5, and the measuring probe 3 measures the potential on the surface of the test sample 5. Furthermore, the position of the measuring probe 3 is adjusted by the position adjustment device 2 to realize the potential measurement on the surface of the test sample 5. The measuring probe 3 can transmit the collected potential data to the potential measuring device through the probe lead assembly on the side wall of the cavity 1, thereby obtaining electrostatic potential data at different positions on the surface of the test sample 5.

[0065] (3) After the measurement is completed, the measuring probe 3 is moved to the measurement area by the position adjustment device 2, away from the DC discharge trigger area. Then, pressure is applied by the two trigger electrodes 82 to carry out the withstand voltage test on the test sample 5.

[0066] (4) After the test is completed, the translation mechanism 41 drives the first insulating platform 42, the height adjustment mechanism 43, the second insulating platform 44, and the test sample 5 to move towards the measurement area, away from the DC discharge trigger area, so that the test sample 5 is far away from the trigger electrode 82. During this process, the drive mechanism drives each connecting body 432 to rotate, so that the insulating adjustment plate 431, the second insulating platform 44, and the test sample 5 move downward along the height direction of the cavity 1, so that the test sample 5 is separated from the second end of the two trigger electrodes 82, and then the translation mechanism 41 drives the test sample 5 to move away from the trigger electrode 82 until the test sample 5 moves to the measurement area. Furthermore, the position adjustment device 2 moves the measuring probe 3 towards the test sample 5, so that the measuring probe 3 is placed above the test sample 5, and the measuring probe 3 measures the potential on the surface of the test sample 5. The measuring probe 3 can transmit the collected potential data to the potential measuring device through the probe lead assembly, thereby obtaining electrostatic potential data at different positions on the surface of the test sample 5. Users can spatially map and reconstruct the measurement data based on the movement trajectory of the test sample 5 and the scanning path of the measuring probe 3, thereby obtaining the spatial distribution characteristics of the surface potential of the test sample 5 and its variation with time or test conditions.

[0067] During the withstand voltage test, while maintaining the basic distribution of the main DC electric field unchanged, a pulse voltage can be applied to the conductive rods 823 of the two trigger electrodes 82 to trigger flashover along the surface of the test sample 5.

[0068] During the charge application phase, the test sample 5 moves to the DC discharge triggering region, achieving clamping and charge accumulation of the test sample 5. During the potential measurement phase, the position adjustment device 2 drives the test sample 5 out of the DC discharge triggering region, facilitating the potential measurement of the test sample 5 by the measurement probe 3.

[0069] In practice, by adjusting the relative position of the grid plate electrode 71 and the test sample 5, the gap between the corona needle 72 and the grid plate electrode 71, the voltage polarity and amplitude, etc., the density distribution and polarity of the surface charge can be changed within a certain range, providing a variety of repeatable initial charge states for subsequent flashover discharge research.

[0070] In this embodiment, the measuring probe 3 performs a wide-area scanning measurement of the electrostatic potential on the surface of the test sample 5. The measuring probe 3 works in conjunction with the position adjustment device 2 and the translation mechanism 41, enabling two-dimensional or multi-axis movement of the measuring probe 3 itself. This allows for precise scanning of local areas, and the translation mechanism 41 drives the test sample 5 to move, achieving rapid measurement of the electrostatic potential on the surface of the test sample 5. The surface potential data obtained by the measuring probe 3 can be used to invert and calculate the surface charge density distribution or to compare and analyze the charge accumulation patterns under different operating conditions, thus providing necessary quantitative information for the study of charge-induced flashover mechanisms.

[0071] In practice, a high-voltage trigger signal is applied via a conductive rod to trigger DC flashover discharge on the surface of the charged test sample 5 while maintaining the main DC electric field distribution essentially unchanged. Corresponding measuring equipment is used to record characteristic quantities such as discharge voltage, current, and optical signal. By changing the charge application conditions and triggering conditions, the influence of surface charge accumulation characteristics on flashover discharge initiation, voltage margin, and discharge path can be systematically studied.

[0072] This system can quickly and efficiently verify the surface discharge and surface charge accumulation effect of test sample 5 during the testing process. It realizes flexible control and rapid measurement of surface charge distribution of test sample 5, and achieves controllable flashover triggering of the surface of charged test sample 5 without significantly disturbing the main DC electric field distribution. It provides an experimental platform and technical path for the mechanism of charge accumulation and DC flashover at the gas-solid interface and insulation design.

[0073] This system improves the stability and reliability of the testing process. Through the coordinated control of the position adjustment device 2 and the translation mechanism 41, the test sample 5 maintains a stable and continuous operating state during clamping, release, and movement, effectively reducing the impact of mechanical vibration and shock, avoiding changes in contact state and fluctuations in test data caused by displacement instability, and improving the repeatability and reliability of test results. The system provides more uniform and controllable surface charge application. The grid electrode 71 and corona needle 72 can flexibly apply charge, allowing for precise control of the application area, intensity, and distribution pattern of the surface charge on the test sample 5 by adjusting parameters such as voltage amplitude and polarity. The system can also construct various typical charge distribution conditions according to research needs, facilitating subsequent flashover discharge law research. The system's measurement probe 3 can perform precise scanning and wide-area potential measurement on the surface of the test sample 5, thus improving the spatial resolution and accuracy of surface potential measurement, expanding the measurement coverage, and providing a more comprehensive and detailed evaluation of surface charge distribution and accumulation characteristics. This system, combined with integrated charge application, surface potential measurement, and discharge triggering, can complete comparative tests of multiple operating conditions and batches in a short time, greatly improving testing efficiency and enhancing versatility.

[0074] When testing the capacitor core 6, the capacitor core 6 is mounted on the support device 4. The rotation mechanism 24 in the position adjustment device 2 drives the measuring probe 3 to rotate. The measuring probe 3 measures the potential at various positions of the capacitor core 6, realizing the measurement of multi-point or circumferential electrostatic potential on the outer surface of the capacitor core 6.

[0075] This system is applied in a closed cavity 1 environment, which facilitates the application of charge and rapid measurement of potential under conditions such as high pressure, vacuum and different temperatures. At the same time, it can measure the flashover discharge characteristics under charge accumulation conditions. Combined with the position adjustment device 2, it can realize the experimental research of applying charge, measuring and inducing discharge on the surface of the test sample 5 and the capacitor core 6.

[0076] 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.

[0077] 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.

[0078] 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. An experimental system for wide-area measurement of electrostatic potential and triggering DC flashover, characterized in that, include: The cavity (1), the position adjustment device (2), the measuring probe (3), and the carrier device (4) are all included. The position adjustment device (2) is disposed inside the cavity (1); The measuring probe (3) is disposed on the position adjustment device (2) for adjusting the position of the measuring probe (3); The support device (4) is disposed inside the cavity (1) to support the test sample (5) placed inside the cavity (1); or, the support device (4) is disposed at the end of the cavity (1) to support a portion of the capacitor core (6) placed inside the cavity (1). The measuring probe (3) is used to measure the test sample (5) or to measure the capacitor core (6) placed in the cavity (1).

2. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 1, characterized in that, When the bearing device (4) is disposed at the end of the cavity (1), The capacitor core (6) is disposed on the bearing device (4), and the capacitor core (6) passes through the cavity (1) and is partially placed inside the cavity (1).

3. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 1, characterized in that, When the bearing device (4) is disposed within the cavity (1), it further includes: a charge application device (7) and a DC discharge triggering device (8); wherein, The charge application device (7) is disposed on the position adjustment device (2) and is used to apply charge to the test sample (5); The DC discharge triggering device (8) is disposed inside the cavity (1) and is used to trigger the DC discharge of the test sample (5); The carrier device (4) is movable, which is used to move the test sample (5) to the DC discharge triggering area of ​​the DC discharge triggering device (8), or to move the test sample (5) away from the DC discharge triggering area.

4. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 3, characterized in that, When the supporting device (4) is disposed within the cavity (1), the supporting device (4) includes: a translation mechanism (41), a first insulating platform (42), a height adjustment mechanism (43), and a second insulating platform (44); wherein, The translation mechanism (41) is disposed inside the cavity (1), and the first insulating platform (42) is disposed on the translation mechanism (41). The translation mechanism (41) is used to drive the first insulating platform (42) to move along the length direction of the cavity (1) to be placed or moved away from the DC discharge triggering area. The height adjustment mechanism (43) is disposed on the first insulating platform (42), the second insulating platform (42) is disposed on the height adjustment mechanism (43), the test sample (5) is placed on the second insulating platform (44), and the height adjustment mechanism (43) is used to adjust the position of the test sample (5) in the height direction of the cavity (1).

5. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 4, characterized in that, The height adjustment mechanism (43) includes: an insulating adjustment plate (431), a drive mechanism, and at least two connecting bodies (432); wherein, Each of the connectors (432) is placed on both sides of the first insulating platform (42), and the insulating adjustment plates (431) are placed side by side above the first insulating platform (42). The first end of each connector (432) is rotatably connected to the side wall of the first insulating platform (42), and the second end of each connector (432) is rotatably connected to the side wall of the insulating adjustment plate (431). The drive mechanism is connected to one of the connecting bodies (432) and is used to drive the connecting body (432) connected thereto to rotate; The second insulating platform (44) is disposed on the side of the insulating adjusting plate (431) opposite to the first insulating platform (42).

6. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 5, characterized in that, The insulating adjustment plate (431) has multiple guide posts on the side facing away from the first insulating platform (42). Each guide post is fitted with a buffer spring (45). The first end of each buffer spring (45) is connected to the insulating adjustment plate (431), and the second end of each buffer spring (45) is connected to the second insulating platform (44).

7. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 4, characterized in that, The DC discharge triggering device (8) includes: two support columns (81), two trigger electrodes (82), and two pressure blocks (83); wherein, The two support columns (81) are respectively placed on both sides of the bearing device (4), and the bottom ends of the two support columns (81) are both located in the cavity (1). The first ends of the two trigger electrodes (82) are locked to the top ends of the two support columns (81) by the two pressure blocks (83) respectively, and the second ends of the two trigger electrodes (82) extend relative to each other and have a preset distance; The test specimen (5) is positioned below the second ends of the two trigger electrodes (82) under the drive of the translation mechanism (41), and the height adjustment mechanism (43) is used to adjust the position of the test specimen (5) in the height direction of the cavity (1) so that the second insulating platform (44) clamps the test specimen (5) with the second ends of the two trigger electrodes (82).

8. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 7, characterized in that, Each of the aforementioned trigger electrodes (82) includes: a finger electrode (821), an insulating sleeve (822), and a conductive rod (823); wherein, The finger electrode (821) has a through hole inside, and the insulating sleeve (822) is disposed in the through hole with its first end extending to the outside of the finger electrode (821); The conductive rod (823) is disposed inside the insulating sleeve (822), and the first end of the conductive rod (823) corresponds to the first end of the insulating sleeve (822), and the first end of the conductive rod (823) is placed outside the insulating sleeve (822).

9. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to claim 3, characterized in that, The charge application device (7) includes: a grid plate electrode (71), a corona needle (72), and at least one connecting post (73); wherein, The grid plate pole (71) is connected to the position adjustment device (2) through each of the connecting posts (73); One end of the corona needle (72) is connected to the position adjustment device (2), and the other end of the corona needle (72) extends toward the grid plate pole (71).

10. The experimental system for wide-area measurement of electrostatic potential and triggering DC flashover according to any one of claims 1 to 9, characterized in that, The position adjustment device (2) includes: a first adjustment mechanism (21), a second adjustment mechanism (22), a third adjustment mechanism (23), and a rotation mechanism (24); wherein, The first adjustment mechanism (21) is disposed in the cavity (1), the second adjustment mechanism (22) is disposed in the first adjustment mechanism (21), the third adjustment mechanism (23) is disposed in the second adjustment mechanism (22), the rotation mechanism (24) is disposed in the third adjustment mechanism (23), and the measuring probe (3) is disposed in the rotation mechanism (24). The first adjustment mechanism (21) is used to adjust the position of the measuring probe (3) in the length direction of the cavity (1); The second adjustment mechanism (22) is used to adjust the position of the measuring probe (3) in the width direction of the cavity (1); The third adjustment mechanism (23) is used to adjust the position of the measuring probe (3) in the height direction of the cavity (1); The rotating mechanism (24) is used to drive the measuring probe (3) to rotate in order to adjust the angle of the measuring probe (3).

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