JP2945315B2 - Method and apparatus for detecting insulator fouling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting contamination of an insulator for accurately determining the amount of contamination on the surface of the insulator.

[0002]

2. Description of the Related Art A method of measuring the amount of contamination on an insulator surface from a value of a leakage current by applying a voltage between electrodes provided on the surface of the insulator is conventionally known. However, since the value of the leakage current varies greatly depending on the wet state (humidity) in addition to the amount of contamination on the insulator surface, the measurement is performed with the insulator surface sufficiently wetted to cancel the influence of the wet state. Needed. However, for this purpose, a wetting device such as a steam chamber for wetting the surface is indispensable, and there is a problem that the actual amount of contamination of the insulator before wetting cannot be accurately obtained.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and does not require a wetting device, and a method for detecting contamination of an insulator which can accurately determine the amount of contamination of an actual insulator which is not wetted. It was made to provide a device.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for detecting contamination of an insulator according to the present invention comprises: a first measuring section having a small surface resistance on a surface of the insulator; A large second measuring section is provided, and leakage currents I ₁ and I ₂ when a voltage is applied to these measuring sections are compared to calculate the amount of contamination of the insulator. Note that this comparison operation is performed by a method in which the comparison operation is repeated by using the fact that the humidity and the contamination amount of both measurement units corresponding to the leakage currents I ₁ and I ₂ are the same, and a convergence value of the contamination amount is obtained. Is preferred. Further, an insulator fouling detection device of the present invention made in order to solve the above problems,
A first measuring section having a small surface resistance provided on the surface of the insulator, a second measuring section having a large surface resistance provided on the surface of the insulator at or near the insulator, and applying a voltage to these measuring sections. voltage applying means for applying a detecting means of the leakage current I _1, I ₂ flowing through each measurement section, these leakage currents I _1,
It is characterized in that a calculation means for calculating a fouling of the insulator by comparing calculating the I _2.

The first and second measuring units having different surface resistances may be constituted by glazing the insulator surface with two kinds of semiconductor glazes having different electric conductivity, or the first and second measuring units having different surface resistances. The measurement unit may be formed of a semiconductor glaze, and the second measurement unit having a larger surface resistance may be formed of a normal glaze.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of an apparatus of the present invention, wherein 1 is an insulator glazed with a semiconductor glaze, 2 is an insulator to be measured which is glazed with a normal glaze, and 3 and 3 are dummy insulators arranged above and below the insulator. It is. The semiconductor glaze itself used here is a known one. For example, a semiconductive metal oxide powder such as tin oxide or iron oxide is mixed in the glaze, and the conductive amount is changed by changing the mixing amount. The rates can be different. The insulator 1 and the insulator 2 are arranged close to each other so that the wet state (humidity) and the soiled state are the same, but the same insulator may be used.

A first measuring unit 4 and a second measuring unit 5 are provided on the surfaces of the insulator 1 glazed with the semiconductor glaze and the insulator 2 glazed with the usual glaze by appropriate electrodes. In this example, the surface resistance value of the first measuring unit 4 is at a level of approximately 10 MΩ in the dry state, and the second measuring unit 5
Has a level of 1000 MΩ in a dry state. Reference numeral 6 denotes voltage applying means for applying a voltage to the first measuring unit 4 and the second measuring unit 5. Further, the measuring units 4 and 5 are connected to detecting means 7 and 8 for detecting a leakage current flowing when a voltage is applied.

FIG. 2 shows an equivalent circuit of this measuring device, where R ₁ is the resistance of the semiconductor glaze, and R ₂ is the resistance of the insulator surface corresponding to the amount of contamination. When the voltage V is applied by the voltage applying means 6, the first measuring unit 4 applies I ₁ = V /
Since a leakage current of (1 / R ₁ + 1 / R ₂ ) flows and a leakage current of I ₂ = V / R ₂ flows in the second measuring section 5,
I ₁ > I ₂ . Then, these leakage currents I ₁ and I ₂ are measured by the detecting means 7 and 8 and are compared and calculated by the calculating means 9 as follows.

FIGS. 3 and 4 are graphs for explaining a comparison operation method according to the present invention. First, FIG. 3 shows the relationship between the wet state of the insulator surface and the surface leakage current. As described above, the humidity (wet state) and the amount of contamination of the measuring unit 4 of the insulator 1 and the measuring unit 5 of the insulator 2 are the same, but as is clear from the above expression, the leakage currents I ₁ and I ₂ are I ₁ > the I _2. FIG.
, Two curves each extending to the right are shown by solid lines. The lower side shows the case where the amount of contamination is zero, and the upper side shows the case where the amount of contamination is maximum. The lower curve is determined accurately by experiment, while the upper curve is not accurately determined and is shown for convenience. The curve with zero contamination amount shown in FIG. 3 is stored in advance in the arithmetic means 9 as data.

In the present invention, no data is taken in when the values of the leakage currents I ₁ and I ₂ measured as described above are I ₀₁ and I ₀₂ in FIG. This is because the insulator surface is not wet at all and effective measurement is impossible. Further, the humidity A ₁ , A _{2 at the} points P ₁ , P ₂ where the measured values of the leakage currents I ₁ , I ₂ intersect the curves X ₁ , X ₂ with zero contamination amount, respectively.
Is determined, and when A ₁ = A ₂ , the amount of contamination is determined to be zero. However, in many cases, A ₁ <A ₂ , so the comparison operation is performed as follows.

[0011] First the value of the leakage current I ₁ and P ₁ point of intersection with the curve X ₁ fouling amount zero, comparing the point P ₂ value of the leakage current I ₂ intersects the curve X ₂ fouling zero amount. Here, since both humidity should be the same, the right side of the intersection P _{3 of} the perpendicular P ₁ A ₁ and the horizontal I ₂ P ₂ lowered from the point P ₁ , that is, the portion from P ₃ to P ₂ Can be ignored. In other words, there is no correct value of the amount of contamination within this range.

Therefore, when a curve X ₃ (indicated by a chain line in FIG. 3) passing through this point P ₃ is drawn, the corresponding amount of contamination of the insulator 2 to be measured is temporarily obtained. Since it should be equal to the fouling of fouling amount and insulator 1 of the insulator 2, and projecting this fouling amount insulator 1 side, pulling the curve X ₄ corresponding to the fouling amount. The intersection of the horizontal line I ₁ P ₁ and the curve X ₄ is defined as P ₄ . This series of comparison operation in the range between the point P ₁ and point P ₄ it can be seen that absent correct value of fouling amount.

Next, when the same comparison operation is repeated starting from the point P ₄ , the calculation results gradually converge on the graph of the amount of contamination-humidity as shown in the graph of FIG. Will be done. This calculation is the same as finding the intersection of two curves corresponding to the insulator 1 and the insulator 2 shown in the graph of FIG. Therefore, when such two curves are easily obtained, it is not always necessary to repeat the calculation for obtaining the convergence value as described above.

As described above, according to the present invention, it is not necessary to completely wet the measuring section by the steam chamber or the like as in the prior art, and there is an advantage that the amount of contamination of the actual insulator that is not wet can be accurately obtained. . However, if a cooling element is incorporated in the measuring units 4 and 5 and the insulator is too dry to be measured, it is not possible to perform measurement while dewing and moistening the measuring units 4 and 5 with the cooling element. It is possible.

In the measurement of the amount of fouling according to the present invention, it is preferable that the voltage is applied intermittently, for example, at a time interval of about once every 30 minutes. This is because, when a voltage is constantly applied, the measuring units 4 and 5 are dried by the Joule heat of the leakage current. Further, if the measurement is performed at predetermined time intervals, the tendency of the change in the amount of contamination over time can be grasped, so that the amount of contamination can be obtained while referring to the value of the amount of contamination obtained by the previous measurement. As a result, apparent abnormal values can be excluded from the data, and highly reliable measurement can be performed.

[0016]

As described above, according to the present invention, the first measuring section having a small surface resistance and the second measuring section having a larger surface resistance are provided, and the leakage obtained from these measuring sections is provided. Since the amount of contamination was calculated by comparing the current,
It is not necessary to perform the measurement by completely wetting the measuring unit as in the related art, and there is an advantage that the actual amount of contamination of the non-wetted insulator can be accurately obtained. This also eliminates the need for a wetting device such as a steam chamber, and has the advantage that the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a fouling detection device of the present invention.

FIG. 2 is an equivalent circuit diagram of FIG.

FIG. 3 is a graph showing a relationship between humidity and surface leakage current.

FIG. 4 is a graph showing the relationship between humidity and the amount of fouling.

[Explanation of symbols]

1 insulator glazed with a semiconductor glaze, 2 insulators to be measured, 3 dummy insulators, 1st measuring section, 5th measuring section, 6 voltage applying means, 7 leakage current detecting means,
8 Leakage current detection means, 9 Operation means

Claims (8)

(57) [Claims] 1. A first measuring section having a small surface resistance and a second measuring section having a higher surface resistance are provided on the surface of an insulator, and leakage occurs when a voltage is applied to these measuring sections. A method for detecting contamination of an insulator, comprising calculating an amount of contamination of the insulator by comparing the currents I ₁ and I ₂ . 2. A first measuring section having a small surface resistance and a second measuring section having a higher surface resistance are provided on the surface of the insulator, and leakage occurs when a voltage is applied to these measuring sections. A method for detecting fouling of an insulator, wherein a comparison operation is repeated by using the fact that the humidity and the fouling amount of both measurement units corresponding to the currents I ₁ and I ₂ are the same, and a convergence value of the fouling amount is obtained. 3. The method for detecting contamination of an insulator according to claim 1, wherein the voltage is applied intermittently and the measurement is performed at predetermined time intervals. 4. The method for detecting fouling of an insulator according to claim 2, wherein the fouling amount is obtained by referring to the value of the fouling amount obtained by the previous measurement. 5. The method for detecting contamination of an insulator according to claim 1, wherein a cooling element is incorporated in the measuring section, and the measurement is performed while the measuring section is moistened by dew condensation. 6. A first measuring section provided on the surface of the insulator and having a small surface resistance, a second measuring section provided on the surface of the insulator at or near the insulator and having a large surface resistance, and Voltage application means for applying a voltage to the measuring section, means for detecting leakage currents I ₁ and I ₂ flowing through each measuring section, and the amount of contamination of the insulator is determined by comparing and calculating these leakage currents I ₁ and I _2. A detector for detecting fouling of an insulator, comprising a calculating means. 7. The insulator fouling detecting device according to claim 6, wherein the first and second measuring units having different surface resistances are constituted by two kinds of semiconductor glazes. 8. The insulator according to claim 6, wherein the first measuring section having a different surface resistance is made of a semiconductor glaze, and the second measuring section having a large surface resistance is made of a normal glaze. Detection device.