JP3759219B2 - insulator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an insulator used to insulate and support an electric wire on a support such as a power pole or a steel tower in a low-voltage, high-voltage, extra-high-voltage aerial transmission and distribution system, and more specifically, a leakage current can be measured. It is about Choshi.
[0002]
[Prior art]
As a conventional insulator, for example, the one shown in FIG. 3 is known. This insulator 21 shows a pin insulator, and has a porcelain 22 and a pin 23 made of iron for fixing the porcelain 22 to a support (not shown). The porcelain 22 is formed with a concave support portion 22a for supporting the overhead electric wire. In the case of high pressure, a red glaze is applied to the lower end portion 22b.
[0003]
Such insulators are widely used in an aerial transmission and distribution system to insulate and support electric wires with support such as utility poles and steel towers, especially when installed near the coast, Leakage current due to salt pollution such as salt damage is a major problem. That is, as the surface contamination of the insulator progresses, the leakage current increases and power is lost, and the dielectric strength is reduced, which may cause a large-scale ground fault. There are two types of salt fouling of eggplant: rapid fouling due to typhoons and constant cumulative fouling, including during seasonal winds. However, since both differ greatly depending on the region and season, the time and degree of fouling cannot be determined. .
[0004]
In view of this, conventionally, for example, the degree of progress of the fouling of the insulator is predicted based on the data for the past several years for each region, and the insulator is regularly washed by water discharge or the like based on the prediction result.
[0005]
[Problems to be solved by the invention]
However, it is extremely troublesome and difficult to predict the degree of progress of eggplant contamination from a large amount of past data. In addition, even if the degree of pollution is predicted, the installation location of towers, utility poles, etc. is naturally different from the natural environment, so the pollution progresses faster than expected and the specified value is earlier than the period in which leakage current is expected. Or the progress of fouling may be slower than expected, and the insulator could not be cleaned efficiently.
[0006]
The present invention has been made paying attention to such a conventional problem, and can easily and accurately know the degree of contamination of the insulator, so that the insulator can be efficiently cleaned, and the power loss due to leakage current is effective. It is an object of the present invention to provide an insulator that is appropriately configured so that the occurrence of a large-scale ground fault can be prevented.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a pin for fixing to a support, and insulates and supports an electric wire,
The pin is made of a non-magnetic metal, and a current transformer for measuring leakage current is provided around the pin.
[0008]
The current transformer is preferably covered with a shield case made of a high magnetic permeability magnetic material from the viewpoint of magnetically shielding the current transformer from an AC magnetic field generated by the electric wire.
[0009]
The shield case is fixed to the insulator pin on the side far from the support portion of the electric wire, and on the side close to the support portion, it is configured not to contact the pin electrically or spatially. Is preferable in that it is accurately measured.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. In FIG. 1, the overhead electric wires 1 a and 1 b are insulated and supported by an insulator 2, and these insulators 2 are fixed to a support 4 via an arm metal 3.
[0011]
As shown in detail in FIG. 2, the insulator 2 includes a porcelain 5 and a pin 6 for attaching the porcelain 5 to the armrest 3. The porcelain 5 is formed with a concave support portion 5a for supporting the overhead electric wire, and in the case of high pressure, a red glaze is applied to the lower end portion 5b. The pin 6 is formed of a nonmagnetic metal, for example, SUS304, and a current transformer 8 is provided around the pin 6 in a shield case 7 made of a high magnetic permeability magnetic material. The shield case 7 is fixed to the pin 6 on the side of the porcelain 5 far from the support portion 5a of the electric wire, and does not contact the pin 6 electrically or spatially on the side close to the support portion 5a.
[0012]
Here, for example, when the surface of the porcelain 5 of the insulator 2 supporting the overhead wire 1a is soiled due to salt damage or the like, when the arm 3 is grounded via a ground wire (not shown), from the overhead wire 1a, When a leakage current flows through the surface of the porcelain 5, the pin 6, the arm metal 3 and the ground wire, and the support 4 is a steel tower, the surface of the porcelain 5, the pin 6, the arm metal 3 and the support 4 from the overhead wire 1a. Leakage current will flow through. Further, when the support 4 is made of an insulating material such as concrete and the armrest 3 is not grounded, it depends on the degree of contamination of the insulator 2 on the overhead wire 1b side, but between the overhead wires 1a and 1b. Then, a leakage current flows through the surface of the porcelain 5 of each insulator 2, the pin 6 and the brace 3.
[0013]
In this embodiment, as described above, the leakage current flowing through the surface of the porcelain 5 and the pin 6 of the insulator 2 is measured by the current transformer 8 and stored in the data recording device 10 attached to the support 4 via the signal line 9. To do. For example, the data recording device 10 is provided with an A / D converter, a microprocessor, and a memory, and the voltage signal output from the current transformer 8 corresponding to the magnitude of the leakage current is converted into a digital signal by the A / D converter. Convert and store in memory.
[0014]
As described above, by recording the leakage current in the data recording device 10, for example, when a storage medium such as an IC memory card or a floppy disk is used as the memory, after storing for a certain period, only the recording medium is recovered. Then, it becomes possible to analyze with an analysis device such as an office. When a memory with a backup battery is used, the data recording device 10 can be collected and analyzed together with the main body. Alternatively, when the data recording device 10 is provided with a communication function, it is possible to observe information at a remote location one by one at a management office or the like.
[0015]
As described above, in this embodiment, since the pin 6 of the insulator 2 is formed of SUS304, which is a nonmagnetic metal, the overhead electric wire supported by the insulator 2 is compared with the case where it is formed of magnetic metal. The leakage current can be accurately measured without being affected by the magnetic field generated by the flowing current.
[0016]
Here, in the embodiment shown in FIG. 1, the present inventor conducted an experiment in which a current of 2000 [A] was passed through the overhead wires 1a and 1b to measure the leakage current, and as a lever, the pin was formed of iron. Using the conventional insulator shown in FIG. 3 incorporating a current transformer, an experiment for measuring the leakage current was performed in the same manner. In each experiment, an insulator that was not soiled was used.
[0017]
As a result, in the former experiment shown in FIG. 1, no leakage current was observed below the noise of the measurement system. On the other hand, in the latter experiment in which a current transformer was incorporated in the conventional insulator, an apparent leakage current of about 200 [mA] was observed. In other words, if the insulator pin is made of magnetic metal, the magnetic field generated by the current flowing through the overhead wire is amplified, and the output of the current transformer becomes larger than the leakage current, making accurate measurement impossible.
[0018]
In the above-described embodiment, the current transformer 8 is covered with the shield case 7 made of a high permeability magnetic material. Thus, if the current transformer 8 is magnetically shielded, the noise of the magnetic field generated by the current flowing through the overhead wire supported by the insulator 2 can be greatly reduced. According to an experiment by the present inventor, it was confirmed that when the shield case 7 is provided, the noise level can be lowered by about 10 times compared to the case where the shield case 7 is not provided.
[0019]
Moreover, as described above, the shield case 7 is fixed to the pin 6 on the side far from the support portion 5a of the electric wire of the porcelain 5, and is electrically and spatially connected to the pin 6 on the side close to the support portion 5a. Therefore, the leakage current can be effectively passed through the pin 6 at the center of the current transformer 8, and the pin 6 and the shield case 7 can be electrically connected to a common ground. Accordingly, since the noise level can be greatly reduced, it is resistant to noise and accurate measurement is possible. That is, when the shield case 7 is fixed to the pins 6 on both sides near the porcelain 5 and on the far side, leakage current easily flows on the surface of the shield case 7, and the pin 6 at the center of the current transformer 8 Since it becomes difficult to flow, accurate measurement cannot be performed. Further, if both sides are electrically floated and supported from the pin 6, since the ground is not common, the potential of the shield case 7 rises and noise due to the electric field increases.
[0020]
In addition, this invention is not limited only to embodiment mentioned above, Many deformation | transformation or a change is possible. For example, in the above-described embodiment, the pin insulator is shown. However, the present invention is effectively applied to other insulators having pins for fixing to a support, for example, a line post insulator or a solid insulator. Can do. In the above-described embodiment, the pin 6 is formed of a stainless steel-based nonmagnetic metal. However, the pin 6 can be formed of a nonmagnetic metal other than the stainless steel, and the same effect can be obtained. Furthermore, the shield case 7 can be omitted when the influence of the magnetic field from the supporting electric wire is small.
[0021]
【The invention's effect】
According to the present invention, since the leakage current in the power overhead transmission / distribution line can be monitored, it is possible to easily and accurately know the degree of contamination of the insulator, and thereby the insulator can be efficiently cleaned. Therefore, it is possible to effectively reduce the power loss due to the leakage current and to prevent the occurrence of a large-scale ground fault.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is an external view showing the insulator shown in FIG. 1 in a partial cross section.
FIG. 3 is an external view showing a conventional insulator in partial cross section.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a Overhead electric wire 1b Overhead electric wire 2 Insulator 3 Arm metal 4 Support object 5 Porcelain 5a Support part 6 Pin 7 Shield case 8 Current transformer 9 Signal line 10 Data recording device

Claims (3)

In an insulator that has a pin for fixing to a support and insulates and supports an electric wire,
An insulator comprising a non-magnetic metal for the pin and a current transformer for measuring leakage current around the pin. In the insulator according to claim 1,
An insulator provided with a shield case made of a high permeability magnetic material so as to cover the current transformer. In the insulator according to claim 2,
The shield case is fixed to the pin on the side far from the support portion of the electric wire, and is configured not to contact the pin electrically or spatially on the side close to the support portion. Reiko to do.

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