Deterioration diagnosis method and deterioration diagnosis system

Abstract

To provide a simple and safe method and system for diagnosing deterioration of an insulator.SOLUTION: The deterioration diagnosis method is a deterioration diagnosis method for an insulator having a silicone rubber surface, the method including preparing a plasma generator including a dielectric having a first surface and a second surface opposite to the first surface, a first electrode disposed on the first surface, and a second electrode disposed on the second surface, disposing the plasma generator so that the first electrode is in contact with the silicone rubber surface in an air atmosphere, and applying a measurement voltage, which is an AC voltage or a pulse voltage, between the first electrode and the second electrode to generate plasma; The water repellency of the silicone rubber surface is lowered by exposing the silicone rubber surface to the plasma, and then the application of the measuring voltage is stopped, and the time from the stop of the application of the measuring voltage to the recovery of the water repellency to a steady state is measured, and the deterioration state of the silicone rubber surface is diagnosed from the measured time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a degradation diagnosis method and a degradation diagnosis system. [Background technology]

[0002] The use of insulators made of silicone rubber (SiR) (also known as polymer insulators) is expanding worldwide, but their use in Japan is limited. Outdoor polymer insulators are lightweight and have a highly water-repellent surface, but because they are exposed to environments containing elements such as ultraviolet (UV) rays, heat, humidity, and dirt, there are concerns about surface deterioration and a decrease in insulating strength over long-term use.

[0003] The water repellency of a polymer insulator surface (SiR surface) temporarily decreases due to factors such as wind and rain caused by a typhoon or contaminants. However, this decreases and recovers as low-molecular-weight compounds (LMW) seep out from the interior of the polymer insulator. This means that the decrease and recovery of water repellency occurs repeatedly over a long period of time. During this time, contaminants deposited on the SiR surface are absorbed by the LMW, causing a contaminant layer to form on the SiR surface. If the water repellency of this contaminant layer is low, a water film may form on the SiR surface during rain, for example. This water film may lead to dry-band arc discharges and even flashovers. In other words, a decrease in water repellency on the SiR surface is a sign of SiR surface degradation and may result in a decrease in insulation strength. Therefore, a method for diagnosing the deterioration state of SiR surfaces would contribute to the long-term maintenance of polymer insulators. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5930891 [Patent Document 2] Japanese Patent Publication No. 2021-193347 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-139514 [Patent Document 4] Patent Publication No. 2021-81412 Summary of the Invention [Problem to be solved by the invention]

[0005] The methyl groups (-CH3) responsible for the water repellency of the SiR surface may decrease over time, resulting in a decrease in water repellency. Therefore, it is conceivable that the water repellency can be quantitatively determined by measuring the contact angle of a water droplet on the SiR surface, thereby determining the state of deterioration of the SiR surface.

[0006] However, the contact angle of water droplets on the SiR surface of a polymer insulator that has been used outdoors for 20 years may be higher than that of an unused polymer insulator. Over a long period of time, the SiR surface becomes contaminated, and the minute irregularities caused by the contaminants on the SiR surface increase the contact angle of water droplets. Therefore, it is difficult to determine the deterioration state of a polymer insulator by measuring the contact angle of water droplets on the SiR surface.

[0007] Another option is to remove the polymer insulators from the site, apply a high voltage while spraying salt mist or water on them, and then detect the leakage current to determine the state of degradation of the polymer insulators.However, it is difficult to assess degradation at the site where the polymer insulators are installed.

[0008] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a simple and safe method and system for diagnosing deterioration of an insulator. [Means for solving the problem]

[0009] A degradation diagnosis method according to an embodiment is a degradation diagnosis method for an insulator having a silicone rubber surface, and includes the steps of: preparing a plasma generating device having a dielectric having a first surface and a second surface opposite the first surface, a first electrode arranged on the first surface, and a second electrode arranged on the second surface; positioning the plasma generating device in an atmospheric environment so that the first electrode is in contact with the silicone rubber surface; applying a measurement voltage that is an AC voltage or a pulse voltage between the first electrode and the second electrode to generate plasma; exposing the silicone rubber surface to the plasma to reduce the water repellency of the silicone rubber surface; then stopping the application of the measurement voltage; measuring the time from when the application of the measurement voltage was stopped until the water repellency returns to a steady state; and diagnosing the degradation state of the silicone rubber surface from the measured time. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a degradation diagnosis system. [Figure 2] FIG. 1 is a schematic diagram showing an example of an insulator that can be diagnosed by the deterioration diagnosis system. [Figure 3] FIG. 1 is a schematic diagram showing an example of the structure of a plasma generating device. [Figure 4] FIG. 1 is a schematic diagram showing an example of the structure of a plasma generating device. [Figure 5] FIG. 10 is a diagram showing experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings. In each embodiment shown below, substantially identical components are denoted by the same reference numerals, and some of their descriptions may be omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones.

[0012] In this specification, unless otherwise specified, the term "connect" may include not only direct connection but also indirect connection.

[0013] (Example of a deterioration diagnosis system configuration) FIG. 1 is a schematic diagram showing an example of the configuration of a degradation diagnosis system. FIG. 1 shows the degradation diagnosis system 1. The degradation diagnosis system 1 has a plasma generation unit 100, a measurement unit 200, a droplet supply unit 300, and a control unit 400. The operations of the plasma generation unit 100, the measurement unit 200, and the droplet supply unit 300 can be controlled by the control unit 400. At least two of the plasma generation unit 100, the measurement unit 200, the droplet supply unit 300, and the control unit 400 may be configured as a single device. At least two of the plasma generation unit 100, the measurement unit 200, the droplet supply unit 300, and the control unit 400 may be configured as different devices.

[0014] The deterioration diagnosis system 1 can diagnose the deterioration state of, for example, an insulator. The deterioration state includes, for example, the deterioration state of the surface of the insulator.

[0015] 2 is a schematic diagram showing an example of an insulator that can be diagnosed by the deterioration diagnosis system 1. FIG. 2 is a schematic cross-sectional view showing a part of an example of the structure of an insulator 10.

[0016] The insulator 10 has a core 11 and an outer sheath 12. The insulator 10 may further have connecting metal fittings at both ends in the length direction.

[0017] The core 11 can be made of a composite material such as fiber reinforced plastic (FRP), etc. The core 11 has, for example, a cylindrical or columnar shape.

[0018] The body portion 12a is provided by adhering to the outer peripheral surface of the core 11. The jacket 12 includes the body portion 12a and a shed portion (pleated portion) 12b. The body portion 12a covers the outer peripheral surface (outside surface) of the core 11. The shed portion 12b protrudes from the body portion 12a in a direction intersecting with the longitudinal direction of the insulator 10. FIG. 2 shows a plurality of shed portions 12b. The number of the shed portions 12b is not limited to the number shown in FIG. 2.

[0019] The surfaces of the outer cover 12 (the surface of the body portion 12a and the surface of the cap portion 12b) are silicone rubber surfaces made of silicone rubber. The surface of the outer cover 12 may contain unavoidable impurities. Silicone rubber has, for example, a siloxane bond (Si—O) as its skeleton.

[0020] Next, an example of a degradation diagnosis method for the insulator 10 using the degradation diagnosis system 1 will be described.

[0021] First, discharge plasma is generated by plasma generating unit 100. Examples of discharge plasma include oxygen plasma. Discharge plasma is generated, for example, by preparing plasma generating device 101 and disposing plasma generating device 101 on a part of surface 120 in an atmospheric environment, as shown in FIG.

[0022] 3 and 4 are schematic diagrams showing an example of the structure of the plasma generator 101. Fig. 3 is a schematic top view of the plasma generator 101. Fig. 4 is a schematic cross-sectional view of the plasma generator 101.

[0023] The plasma generator 101 has a first electrode 102, a solid dielectric 103, a second electrode 104, and a power supply 105. 3 and 4 show a case where the first electrode 102, the solid dielectric 103, and the second electrode 104 are stacked in this order on the surface 120. However, the present invention is not limited to this, and the first electrode 102, the solid dielectric 103, and the second electrode 104 may be stacked in this order below the surface 120.

[0024] The first electrode 102 is disposed on a first surface of the solid dielectric 103. The second electrode 104 is disposed on a second surface opposite the first surface of the solid dielectric 103. The first electrode 102 and the second electrode 104 may be mesh or perforated conductive plates, and can be formed, for example, from a conductive metal mesh plate or a metal perforated plate (porous plate). The first electrode 102 and the second electrode 104 contain a metal element such as aluminum or iron.

[0025] When the first electrode 102 is formed using a conductive metal mesh plate, the first electrode 102 can be formed using a metal mesh plate having an average pore size of, for example, 0.1 mm.

[0026] The solid dielectric 103 is provided between the first electrode 102 and the second electrode 104, and is in contact with each of the first electrode 102 and the second electrode 104. The solid dielectric 103 has a thickness of, for example, a few millimeters or less (for example, 0.5 mm). The solid dielectric 103 can be formed using a material such as glass.

[0027] The power supply 105 can output a measurement voltage, for example, a pulse voltage or AC voltage of 7 kVpp or more, between the first electrode 102 and the second electrode 104. Vpp represents the difference between the maximum and minimum values ​​of the measurement voltage. The power supply 105 has output terminals 105a and 105b. The output terminal 105a is connected to the first electrode 102 via wiring 106a. The output terminal 105b is connected to ground 107. The second electrode 104 is connected to the output terminal 105b and ground 107 via wiring 106b. Examples of wiring 106a and wiring 106b include electric cables.

[0028] When diagnosing the deterioration state of the surface 120, a user such as an operator places the plasma generator 101 on the surface 120 so that the first electrode 102 is in contact with the surface 120. Then, the user precisely aligns the plasma generator 101 so that the diagnosis target region 108 overlaps the first electrode 102 and the second electrode 104.

[0029] The area or size of the first electrode 102 is preferably sufficiently smaller than the area of ​​the surface 120. For example, when the first electrode 102 is viewed from a first direction (vertical direction or stacking direction) intersecting the surface 120, the area of ​​the first electrode 102 is preferably smaller than the area of ​​the surface 120 and equal to or smaller than the area of ​​the region where the first electrode 102, the second electrode 104, and the surface 120 overlap (diagnosis target region 108). The shape of the first electrode 102 is not limited to a square, and may be other shapes such as a circle. The diagnosis target region 108 corresponds to the shed portion 12b of the insulator 10, for example.

[0030] When a small-area metal mesh plate is used as first electrode 102, it is placed in close proximity to surface 120. This causes discharge plasma to be generated near the surface of diagnosis target area 108 when the voltage output by power supply 105 is applied as a measurement voltage between first electrode 102 and second electrode 104. As a result, even when the voltage output by power supply 105 is relatively low, discharge plasma is likely to be irradiated onto the surface of diagnosis target area 108. This makes it possible to perform effective deterioration diagnosis even when power supply 105 is miniaturized.

[0031] Second electrode 104 is preferably small enough to be placed on surface 120. For example, when second electrode 104 is viewed in a direction intersecting surface 120 (e.g., the vertical direction or the stacking direction), the area of ​​second electrode 104 is preferably equal to or smaller than the area of ​​first electrode 102. Furthermore, connecting second electrode 104 to earth 107 makes it easier to prevent the user from getting an electric shock and also makes handling, such as positioning surface 120, easier. Furthermore, by using metal mesh plates with small areas as first electrode 102 and second electrode 104, discharge can be initiated even at a relatively low voltage, making it easier to miniaturize power source 105.

[0032] The second electrode 104 is assumed to be made of a conductive metal material such as a copper plate, but may be formed inside the solid dielectric 103. To prevent the user from getting an electric shock, the second electrode 104 is connected to the earth 107 before the power supply 105 outputs the measurement voltage.

[0033] After the user positions the first electrode 102 and the diagnostic region 108 on the surface 120, the user operates the power supply 105 to activate the power supply 105. This allows the power supply 105 to apply a measurement voltage between the first electrode 102 and the second electrode 104. The power supply 105 may be operated by the control unit 400.

[0034] When a measurement voltage is applied, a discharge occurs in the solid dielectric 103 under atmospheric pressure. Here, the first electrode 102 and the second electrode 104 are arranged on both sides of the solid dielectric 103, so that the flow of charges is prevented and no large current flows during discharge. As a result, a dielectric barrier discharge, which is a type of discharge plasma, occurs. It is preferable to form a small, uniform space between the first electrode 102 and the surface 120 arranged opposite to the first electrode 102 so that a dielectric barrier discharge can be formed.

[0035] As a result of the dielectric barrier discharge, discharge plasma is formed in the solid dielectric 103, and this plasma generates localized discharge energy. While ozone may be generated from atmospheric oxygen during this process, the amount of ozone generated is minimal and therefore poses little risk to the user's body. The energy from the discharge plasma is irradiated onto the diagnostic area 108 facing the first electrode 102. The discharge plasma slightly cuts and roughens the diagnostic area 108, creating irregularities that increase the surface roughness of the surface 120. Alternatively, the side chains responsible for the water repellency of the surface 120 are cleaved, temporarily reducing the water repellency of the surface 120. Examples of side chains responsible for the water repellency of the surface 120 include methyl groups. Because the plasma generator 101 does not irradiate areas other than the diagnostic area 108 with discharge energy, deterioration of the physical and chemical properties of those areas can be suppressed or completely prevented.

[0036] By forming the first electrode 102 relatively small and connecting the second electrode 104 to earth 107, it is possible to prevent the user from getting an electric shock due to the measurement voltage output from the power supply 105. The formation of a dielectric barrier discharge on the diagnostic target area 108 is carried out, for example, continuously or intermittently for a certain period of time, and the discharge is terminated by cutting off the output of the power supply 105 and stopping the application of the measurement voltage after the certain period of time has elapsed. The plasma generator 101 may be removed from the surface 120 after the discharge has ended.

[0037] After the application of the measurement voltage is stopped, the time from when the application of the measurement voltage is stopped until the water repellency returns to a steady state is measured. The water repellency is restored by the LMW seeping out from inside the outer cover 12 to the surface. An example of the LMW is silicone oil. The LMW has higher water repellency than the portion where the water repellency has decreased due to plasma exposure, so the water repellency of the surface 120 can be restored.

[0038] The recovered state of water repellency can be quantified, for example, by dropping a droplet containing water onto the diagnostic target area 108 and measuring the contact angle of the droplet with respect to the surface 120. The droplet can be dropped onto the diagnostic target area 108 from, for example, the droplet supply unit 300. An example of the droplet is a water droplet. The amount of the droplet dropped is, for example, 10 μL. The droplet supply unit 300 may have, for example, a nozzle connected to a tank that contains the liquid, or a dropper such as a dropper that dispenses the liquid.

[0039] The contact angle can be measured, for example, by the measurement unit 200. The measurement unit 200 has an imaging device such as a Charge Coupled Device (CCD).

[0040] The steady state is defined as the contact angle returning to the value before the dielectric barrier discharge irradiation or after a certain time has elapsed. The deterioration state of the insulator 10 is diagnosed (evaluated) by comparing this measurement result with the result obtained in advance from an unused insulator 10.

[0041] The control unit 400 may be configured by a control device using hardware that uses, for example, a processor, etc. Note that each operation may be stored as an operation program in a computer-readable recording medium such as a memory, and each operation may be executed by the hardware by appropriately reading out the operation program stored in the recording medium.

[0042] As described above, the degradation diagnosis system and degradation diagnosis method of the embodiment can safely and easily diagnose the degradation state of the insulator 10 by measuring the time from when the water repellency of the surface 120 is reduced by the dielectric barrier discharge until it is restored. [Example]

[0043] In order to confirm the effects of the embodiment, an experiment was conducted under the following conditions. The degradation states of the first, second, and third samples were assessed as measurement objects. The first sample was cut from an unused insulator that had not been used outdoors. The second sample was an aged deterioration sample cut from an insulator similar to the first sample after 10 years of use in a 22 kV power distribution system in a coastal area with an average annual temperature of 18°C ​​and an annual precipitation of 2300 mm. The third sample was an aged deterioration sample cut from an insulator similar to the first sample after 20 years of use in a 22 kV power distribution system in a coastal area with an average annual temperature of 18°C ​​and an annual precipitation of 2300 mm.

[0044] After reducing the water repellency of surface 120 by generating a dielectric barrier discharge under the conditions below, a water droplet was dropped onto surface 120 and the contact angle was measured at 10-minute intervals to observe the recovery state of surface 120. Measurement voltage: AC voltage with a frequency of 10 kHz Applied voltage: 8 kVpp Dielectric barrier discharge irradiation time: 5, 10, 15, 20, 25 [s]

[0045] FIG. 5 shows the experimental results. The horizontal axis of FIG. 5 represents the irradiation time of the dielectric barrier discharge (the time elapsed since the water repellency was reduced by the dielectric barrier discharge: treatment time) (seconds). The vertical axis of FIG. 5 represents the contact angle (water repellency) recovery time (minutes). FIG. 5 shows data D1, data D2, and data D3. Data D1 represents the change in the water repellency recovery time of the first sample. Data D2 represents the change in the water repellency recovery time of the second sample. Data D3 represents the change in the water repellency recovery time of the third sample.

[0046] As shown in Figure 5, the water repellency of the second and third samples, which are aged deterioration samples, decreased due to dielectric barrier discharge. The contact angle recovery time of the second and third samples was longer than that of the first sample. This shows that the deterioration diagnosis method of the embodiment can safely and easily diagnose the deterioration state of an insulator and grasp the degree of deterioration. By using the deterioration diagnosis method of the embodiment to diagnose the deterioration state of the insulator surface, the degree of deterioration of the insulator surface can be confirmed from the water repellency recovery time, as shown in Figure 5.

[0047] In the degradation diagnosis method of the embodiment, diagnosis is performed using dielectric barrier discharge, which generates little harmful ozone due to discharge, so no special configuration is required to protect users from ozone, and it is possible to suppress an increase in the size and cost of the degradation diagnosis system. Furthermore, even when the insulator 10 is installed on-site, by diagnosing only the diagnosis target area 108, it is possible to suppress or prevent quality degradation of the insulator due to degradation diagnosis. Therefore, the degradation state of the insulator 10 can be diagnosed safely and easily.

[0048] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0049] 1...deterioration diagnosis system, 10...frequency, 11...core, 12...outer sheath, 12a...body portion, 12b...cap portion, 100...plasma generation portion, 101...plasma generator, 103...solid dielectric, 105...power supply, 105a...output terminal, 105b...output terminal, 106a...wiring, 106b...wiring, 107...earth, 108...diagnosis target area, 120...surface, 200...measurement portion, 300...droplet supply portion, 400...control portion, D1...data, D2...data, D3...data.

Claims

1. A method for diagnosing deterioration of an insulator having a silicone rubber surface, comprising: providing a plasma generating device having a dielectric body having a first surface and a second surface opposite to the first surface, a first electrode disposed on the first surface, and a second electrode disposed on the second surface; The plasma generator is disposed in an atmospheric environment so that the first electrode is in contact with the surface of the silicone rubber; a measurement voltage which is an AC voltage or a pulse voltage is applied between the first electrode and the second electrode to generate plasma, and the water repellency of the silicone rubber surface is reduced by exposing the silicone rubber surface to the plasma, and then the application of the measurement voltage is stopped; measuring the time from when the application of the measurement voltage is stopped until the water repellency returns to a steady state, and diagnosing the deterioration state of the silicone rubber surface from the measured time; Deterioration diagnosis method.

2. when the first electrode is viewed from a first direction intersecting the silicone rubber surface, an area of ​​the first electrode is smaller than an area of ​​the silicone rubber surface and is equal to or smaller than an area of ​​a region where the first electrode, the second electrode, and the silicone rubber surface overlap; The deterioration diagnosis method according to claim 1 .

3. The first electrode is a mesh or perforated conductive plate. The deterioration diagnosis method according to claim 1 .

4. the second electrode is a conductive plate or is provided inside the dielectric; when the second electrode is viewed from a first direction intersecting the surface of the silicone rubber, the area of ​​the second electrode is equal to or smaller than the area of ​​the first electrode; The second electrode is connected to ground. The deterioration diagnosis method according to claim 1 .

5. the plasma comprises an oxygen plasma; The deterioration diagnosis method according to claim 1 .

6. the water repellency is reduced by the side chains of the silicone rubber contained in the surface of the silicone rubber being cleaved by the plasma; The deterioration diagnosis method according to claim 1 .

7. the side chain comprises a methyl group; The deterioration diagnosis method according to claim 6.

8. The water repellency is defined by dropping a liquid droplet on the surface of the silicone rubber and measuring the contact angle of the liquid droplet with respect to the surface of the silicone rubber. The deterioration diagnosis method according to claim 1 .

9. The water repellency is reduced by the plasma roughening the surface of the silicone rubber. The deterioration diagnosis method according to claim 1 .

10. The water repellency is restored by low molecular weight components seeping out from inside the insulator onto the silicone rubber surface. The deterioration diagnosis method according to claim 1 .

11. The low molecular weight component includes silicone oil. The deterioration diagnosis method according to claim 10.

12. A deterioration diagnosis system for an insulator having a silicone rubber surface, comprising: a plasma generating unit having a dielectric body having a first surface and a second surface opposite to the first surface, a first electrode disposed on the first surface, and a second electrode disposed on the second surface, wherein the plasma generating unit generates plasma by applying a measurement voltage which is an AC voltage or a pulse voltage between the first electrode and the second electrode, and exposes the silicone rubber surface to the plasma to reduce the water repellency of the silicone rubber surface; a droplet supply unit having a dropper that drops droplets containing water onto the silicone rubber surface; a measurement unit that measures the contact angle of the dropped droplet with respect to the silicone rubber surface, thereby measuring the time from when the application of the measurement voltage is stopped until the water repellency returns to a steady state; and A deterioration diagnosis system comprising:

Images