JPH10160783A - Antenna for detecting salt damage of insulator and device for detecting salt damage of insulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna for detecting only electromagnetic waves due to a partial discharge generated at an insulator and a device for detecting salt damage of the insulator using the antenna. SOLUTION: A fine antenna is formed at the tip of a high-frequency transmission cable. As a first form, an inner conductor 23 of a cable 22 is allowed to project from an external conductor 24, thus forming a rod antenna. As another form, a loop antenna and a half-wave dipole antenna are available. Each antenna is formed to a size so that it detects only electromagnetic waves due to a partial discharge generated at an insulator when it is arranged near the insulator and does not detect a noise from a remote location, thus preventing electromagnetic waves from a generation source away from the insulator from interfering with a diagnosis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna for detecting salt damage of insulators caused by salting, and a salt damage detecting device using the antenna.

[0002]

2. Description of the Related Art Insulators used for substations, electric equipments, etc. installed along the sea (sea salt contaminated areas) may cause partial discharge due to salting on the insulators. If the partial discharge is left unattended, dielectric breakdown may occur due to the progress of contamination, which may lead to a serious accident. Therefore,
In order to prevent accidents due to salt damage, it is necessary to monitor the contamination status of the insulator and wash the insulator when the contamination has progressed.

[0003] In the usual measurement of the pollution degree of an insulator, the insulator is immersed in fresh water and its salt content is measured. This pollution degree measurement method
The equipment and labor are both large, and expensive measuring instruments are required. In addition, there is a problem that it is difficult to measure the degree of pollution at an appropriate time because the typhoon rapidly advances the pollution and the cleaning effect by rainfall recovers the pollution.

[0004]

Accordingly, there has been proposed a salt damage detecting apparatus using an electromagnetic wave for monitoring the presence or absence of an abnormal electromagnetic wave generated in an insulator. This salt damage detection device,
When an antenna (sensor) is disposed near the insulator and abnormal electromagnetic waves generated by the insulator are detected by the antenna, it is determined that salt damage has occurred in the insulator. However, the normal antenna used here is the same type of electromagnetic waves from other sources, for example, electromagnetic waves generated by power lines or other electrical devices, public broadcast waves, radio stations, and electromagnetic waves generated by a two-cycle engine as noise. To detect. These noises are indistinguishable from abnormal electromagnetic waves generated by the insulator, and cause erroneous determination.

[0005] Therefore, it is desired that an antenna for detecting salt damage of an insulator can detect only an electromagnetic wave generated from a partial discharge due to contamination of the insulator separately from external noise. An object of the present invention is to provide an antenna capable of detecting only an electromagnetic wave due to a partial discharge generated in an insulator. Another object of the present invention is to provide a device for detecting salt damage of an insulator using the antenna.

[0006]

According to the present invention, a small antenna such as a rod antenna, a loop antenna, and a half-wave dipole antenna is formed at the end of a high-frequency transmission cable to achieve the above object. Each antenna having such a configuration is formed to have a size that, when placed near the insulator, detects only electromagnetic waves due to partial discharge generated in the insulator and does not detect noise from a distance. As a result, the state of salt damage on the insulator can be always accurately detected, and the necessity of insulator cleaning can be more accurately determined.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a salt damage detection device. In the figure, reference numeral 1 denotes a number of insulators provided in a substation or attached to electric equipment. The detection of the salt damage of the insulator is performed for one of the many insulators 1. 2 is 1
An electromagnetic wave antenna attached to two insulators.

Reference numeral 4 denotes a salt damage detecting device for monitoring the detection signal of the electromagnetic wave antenna 2 and monitoring the presence or absence of salt damage in the insulator 1. Reference numeral 5 denotes a noise antenna for detecting an electromagnetic wave situation near the insulator 1. Electromagnetic wave antenna 2
Is attached to the mounting flange 6 of the insulator 1 and connected to the salt damage detecting device 4 by a high-frequency transmission cable 7 such as a coaxial cable or a parallel feeder line. The structure of the electromagnetic wave antenna 2 is shown in FIGS.

FIG. 2 shows a first example of the electromagnetic wave antenna 2,
An example in which the antenna is formed as a small rod antenna will be described. The micro rod antenna 21 processes the tip of the coaxial cable 22,
By cutting off the ends of the outer conductor 24 and the outer insulator 26, the inner conductor 23 and the inner insulator 25 are projected. The length A from which the internal conductor 23 protrudes is about 0.5 to 5 cm.

FIG. 3 shows a second example of the electromagnetic wave antenna 2,
The rod antenna 21 is obtained by adding a radial. The minute rod antenna 27 with a radial forms a rod antenna similarly to FIG. 2, and a conductive radial 28 electrically connected to the external conductor 24 is arranged. FIG.
Shows a third example of the electromagnetic wave antenna 2, which is formed as a minute loop antenna. Small loop antenna 29
Processes the tip of the coaxial cable 22 and forms the minute loop 30 with the inner conductor 23 and the outer conductor 24. The diameter B of the micro loop is about 0.5 to 5 cm.

FIG. 5 shows a fourth example of the electromagnetic wave antenna 2,
An example in which the antenna is formed as a minute half-wave dipole antenna will be described.
The minute half-wave dipole antenna 31 is connected to the coaxial cable 22.
Is processed to form a half-wave dipole 32 with the inner conductor 23 and the outer conductor 24. The length C of the half-wave dipole 32 is about 2 to 5 cm. The dimensions of these antennas 21, 27, 29, 31 are adjusted according to the distance between the insulator 1 and the antenna. Since the antennas 21, 27, 29, and 31 formed in this way have a minute shape, they detect only electromagnetic waves due to partial discharge of insulators generated in the vicinity, and detect external noise from transmission lines or other electric devices. do not do.

The antennas 21 and 2 described above are used.
7, 29 and 31 are formed using the coaxial cable 22, but also when a parallel feeder wire is used as the high-frequency transmission cable 7, it is similarly formed using a conductor of the parallel feeder wire at the end. Can be. In each of the above-described antennas, the tip of the high-frequency transmission cable is processed to be formed by the conductor of the cable, but the antenna is formed by using another conductor, and the antenna is connected to the tip of the high-frequency transmission cable. It can also be formed. further,
The high-frequency transmission cable forming the antenna and the high-frequency transmission cable connected to the salt damage detection device 4 can be integrated or formed separately.

Returning to FIG. 1, the configuration of the salt damage detecting device 4 will be described. In FIG. 1, reference numeral 41 denotes the electromagnetic wave antenna 2
And a selector for switching and selecting the detection signal of the noise antenna 5. Reference numeral 42 denotes a high-frequency amplifier (preamplifier) for amplifying the selected detection signal. Reference numeral 43 denotes a tuner that extracts signals at a plurality of predetermined frequency points from the amplified signal. This tuner 43 is provided with
With the control of 5, signals are extracted at a plurality of frequency points around 200 MHz.

An A / D converter 44 converts an output signal of the tuner 43 from an analog signal to a digital signal. Reference numeral 45 denotes a determiner that analyzes the output signal of the A / D converter 44 and determines whether or not a partial discharge has occurred in the insulator 1. This determiner is constituted by a CPU.
Further, the determiner 45 includes a selector 41 and a tuner 43.
Control.

Next, the operation of the salt damage detecting device 4 will be described. First, the external noise is measured. The electromagnetic wave antenna 2 is configured to detect only an electromagnetic wave generated in the vicinity, but also slightly detects an electromagnetic wave (noise) generated in a distant place. To prevent erroneous determination due to this noise,
The external noise is measured by switching the selector 41 to the noise antenna 5 side.

The noise signal detected by the noise antenna 5 is amplified by the amplifier 42 and input to the tuner 43. The tuner 43 extracts signals at a plurality of frequency points around 200 MHz under the control of the determiner 45. The detection signal at each frequency point is A / D
The signal is converted into a digital signal by the converter 44 and
5 is input. The determinator 45 compares the detection signal at each frequency point with a discrimination level for noise determination,
The frequency points beyond that level are stored.

Next, the selector is switched to the electromagnetic wave antenna 2 side to measure the electromagnetic wave due to the partial discharge. The electromagnetic wave signal detected by the electromagnetic wave antenna 2 is amplified by the amplifier 42 and input to the tuner 43. Tuner 43
Extracts signals at a plurality of frequency points around 200 MHz under the control of the decision unit 45. At this time,
The determiner 45 invalidates the data of the frequency points stored in the noise measurement and adopts only the electromagnetic wave signals of the remaining frequency points as valid signals.

Here, the electromagnetic wave due to the partial discharge generated from the insulator exists in a frequency range of 200 MHz or less.
In contrast, public broadcasts, wireless stations, and the like are fixed at a much higher natural frequency. Therefore, tuner 43
By extracting only a signal at a frequency point near 200 MHz, erroneous determination due to noise from a distant place is prevented.

The signal output from the tuner 43 is A / D
The signal is converted into a digital signal by the converter 44 and
5 is input. The determiner 45 compares the electromagnetic wave signal with the identification level for detecting partial discharge, and determines that partial discharge has occurred when the intensity of the detection signal exceeds the identification level. Then, using a display device (not shown) or the like, the occurrence of salt damage to the insulator is notified to the outside.

As described above, when the electromagnetic wave due to the partial discharge is detected, the determiner 45 determines that the partial discharge has occurred in the insulator 1. Therefore, the state of contamination of the insulator due to salt damage can be monitored accurately and constantly.
This makes it possible to accurately determine the time for cleaning the insulator. As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said Embodiment, A various change is possible. For example, although only one insulator is measured, the presence or absence of partial discharge can be monitored for a plurality of insulators by attaching antennas to the plurality of insulators. In this case, by increasing the number of selections of the selector 41, only one salt damage detecting device 4 can be used.

Various methods have been proposed as methods of analyzing the detection signal in the decision unit 45, and these methods can be employed instead of the above method. Further, since the antenna of the present invention has a structure in which noise generated in a distant place is difficult to be picked up, it is possible to omit measurement of external noise using the noise antenna 5. When this is omitted, the selector 41 in the salt damage detecting device 4 can be omitted.

In order to reliably determine whether or not a partial discharge has occurred, if it is determined that a partial discharge has occurred, a similar detection operation is further repeated for a predetermined period (eg,
When it is determined that there is a partial discharge continuously (for 2 hours or 24 hours), it is possible to display an indication that the insulator has been stained outside for the first time.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a salt damage detection device of the present invention.

FIG. 2 is a diagram showing a first example of an electromagnetic wave antenna used in FIG.

FIG. 3 is a diagram showing a second example of the electromagnetic wave antenna used in FIG. 1;

FIG. 4 is a diagram showing a third example of the electromagnetic wave antenna used in FIG. 1;

FIG. 5 is a diagram showing a fourth example of the electromagnetic wave antenna used in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulator 2 ... Electromagnetic wave antenna 4 ... Salt damage detection device 5 ... Noise antenna 6 ... Flange 21, 27, 29, 31 ... Electromagnetic wave antenna 22 ... Coaxial cable 23 ... Inner conductor 24 ... Outer conductor 25 ... Inner insulator 26 ... Outer insulation Body 28 Radial 30 Micro loop 32 Half-wave dipole 41 Selector 42 Amplifier 43 Tuner 44 A / D converter 45 Judgment device (CPU)

Claims (4)

[Claims] 1. A rod antenna is formed at the end of a high-frequency transmission cable, and the size of the rod antenna is determined by detecting only an electromagnetic wave due to partial discharge generated in the insulator when the antenna is disposed near the insulator. An antenna for detecting salt damage of an insulator, wherein the antenna is formed in a size that does not detect noise from a distance. 2. A loop antenna is formed at the end of a high-frequency transmission cable, and the size of the loop antenna is determined by detecting only electromagnetic waves due to partial discharge generated in the insulator when the antenna is arranged near the insulator. An antenna for detecting salt damage of an insulator, wherein the antenna is formed in a size that does not detect noise from a distance. 3. A half-wave dipole antenna is formed at the end of a high-frequency transmission cable, and the size of the half-wave dipole antenna is adjusted when the antenna is arranged near an insulator.
An antenna for detecting salt damage of an insulator, wherein the antenna is formed to have a size that detects only electromagnetic waves due to partial discharge generated in the insulator and does not detect noise from a distance. 4. A determinator that uses the antenna according to claim 1 and analyzes a signal detected by the antenna to determine the presence or absence of a partial discharge in the insulator. Insulation salt damage detector.