JPH11133098A - Insulation abnormality diagnosing device for gas insulated electric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation abnormality diagnosing device using an antenna sensor capable of fixing without affecting the insulation performance of electric apparatus and without stopping the operation of the main electric apparatus. SOLUTION: Electromagnetic wave due to partial discharge generated inside an electric apparatus box 1 is emitted outside the box from a conductor 7 conduction part. For the electromagnetic wave progressing along the surface of the cover 8 of a current sensor 6, maximum potential difference is caused in gaps 11 and 12. An antenna sensor 21 is arranged close to at least one of the gaps 11 and 12. Based on the electromagnetic wave signal detected by the antenna sensor 21, a judgment part diagnoses the existence of insulation abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation abnormality diagnosis apparatus for monitoring a partial discharge generated inside a container of a gas insulated electric device such as a gas circuit breaker and a gas insulated switchgear.

[0002]

2. Description of the Related Art When metal foreign matter such as metal chips or burrs is present in a container of a gas-insulated electric device, partial discharge may occur from the tip of the metal foreign matter. In addition, partial discharge may also occur when there is a contact failure at the contact portion of the conductor. If the partial discharge generated inside the gas-insulated electric device is left in this way, there is a possibility that a dielectric breakdown will eventually occur and a serious accident may develop.

[0003] Therefore, in order to prevent the accident of the gas-insulated electrical equipment, it is necessary to monitor whether there is a metallic foreign substance inside the container of the gas-insulated electrical equipment or whether or not a partial discharge has occurred. is there. In view of the above, conventionally, various insulation abnormality diagnostic apparatuses have been proposed which monitor the presence or absence of abnormal electromagnetic waves generated by partial discharge generated inside a container of a gas insulated electric device.

[0004] Since the gas-insulated electric equipment is shielded by a metal container, the detection of the partial discharge inside the container due to the electromagnetic wave must detect the electromagnetic wave leaking from the container. It is considered that the insulator part is best as a place where the electromagnetic wave leaks. However, it is necessary for this insulator part to maintain high insulation performance, and it is necessary to prevent the electric field from being disturbed by attaching an antenna sensor.

Therefore, it is necessary to attach an antenna sensor to the insulator attachment portion from the viewpoint of easy detection of electromagnetic waves and the viewpoint of coordination of insulation. For this reason, as an antenna sensor in the conventional insulation abnormality diagnostic device, a ring-shaped antenna sensor arranged so as to surround the insulator is used at the insulator mounting portion of the gas-insulated electric device. The electromagnetic wave signal detected by the antenna sensor is analyzed in the insulation abnormality diagnosis device main body, and the presence or absence of partial discharge is determined.

[0006]

When the above-mentioned antenna sensor is to be mounted on electric equipment, it is necessary to divert the fixing bolt of the insulator flange because the antenna is large. However, since gas-insulated electrical equipment is usually filled with a high-pressure gas of 5 kgf / cm ² , removing or loosening the bolts of the container may result in damage to insulators, impair the reliability of electrical equipment, etc. May occur. In addition, it was necessary to stop the operation of the electric device to fix the antenna.

An object of the present invention is to provide an insulation abnormality diagnosis apparatus using an antenna sensor which can be attached without affecting the insulation performance of the main electric equipment and without stopping the operation of the main electric equipment. It is the purpose.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object. When a partial discharge occurs in a container of a gas-insulated electric device, an electromagnetic wave is generated. Since the gas-insulated electric device is sealed by the metal container, the electromagnetic wave leaks to the outside from the portion of the container leading out the conductor.

When the gas-insulated electrical device is provided with a current sensor and a cover for the current sensor in the lead-out portion, the electromagnetic wave is radiated from the lead-out portion to the external space, and at the same time, the surface of the current sensor cover is exposed. And proceed along the container. Therefore, the current sensor cover itself has a function as an antenna. A gap is provided in the current sensor cover for the purpose of preventing a circulating current from being induced by a current flowing through the conductor.
In addition, a gap is formed between the current sensor cover and the container so that a circulation path is not formed between the current sensor cover and the electric device container. For an electromagnetic wave traveling along the current sensor cover, a maximum potential difference occurs in these gaps.

In the present invention, an antenna sensor is arranged near at least one of the two gaps to detect an electromagnetic wave due to partial discharge, and a determination means determines whether or not a partial discharge has occurred based on the electromagnetic wave signal. I do. By arranging the antenna sensor at the position where the intensity of the electromagnetic wave is highest, a small and lightweight antenna sensor can be used. For this reason, the antenna sensor can be attached by a simple method, and there is no need to use the bolt of the container, so that the reliability of the electric device is not reduced. Further, since the antenna sensor is arranged with respect to the current sensor cover, it does not affect the insulation performance at the lead-out portion of the conductor, and furthermore, the antenna sensor can be mounted at a position away from the charged portion, so that the electric device can be mounted. The antenna sensor can be mounted while the operation is continued.

The antenna sensor according to the present invention comprises two skeleton slot antennas, one disposed near the gap between the current sensor covers, and the other one disposed between the current sensor covers and the container. And two skeleton slot antennas connected by a crossover can be used. Further, the antenna sensor of the present invention can be configured by attaching two foil electrodes at positions sandwiching one of the two gaps.

[0012]

Embodiments of the present invention will be described with reference to the drawings. In the following description, components having the same function in each drawing are denoted by the same reference numerals, and duplicate description is omitted. The configuration of the insulator mounting portion to which the antenna sensor is mounted will be described with reference to FIG. FIG. 1 is a partial cross-sectional view of an insulator mounting portion in a gas circuit breaker.

In FIG. 1, reference numeral 1 denotes a container, in which a shut-off portion 2 is housed and an insulating gas 3 is sealed. 4 is the container 1
Is an insulator mounting portion formed on the upper portion of the insulator 5 is an insulator. 7
Is a conductor drawn out of the interrupting section 2. Reference numeral 6 denotes a current transformer for measuring a current flowing through the conductor 7, which is arranged outside the insulator mounting portion 4. 8 is a current transformer cover. The current transformer cover 8 includes a cylindrical portion 9 covering the upper and side surfaces of the current transformer 6, and a disk portion 10 covering the lower portion. In the current transformer cover 8, a one-turn current path is not formed for the current induced by the current flowing through the conductor 7.
A gap 11 is formed between the cylindrical part 9 and the disk part 10. Further, a gap 12 is formed between the cylindrical portion 9 and the container 1 so that the current transformer cover 8 and the container 1 do not form a one-turn current path.

In the gas-insulated electric apparatus having the above-described structure, when the partial discharge 13 occurs in the container 1, an electromagnetic wave is generated by the partial discharge 13, and the electromagnetic wave travels in the container 1 as shown by the arrow, and the insulator mounting portion is formed. 4 is radiated to the outside from the opening. The electromagnetic wave radiated to the outside is divided into a component radiated to the open space and a component traveling along the surface of the current transformer cover 8 and the container 1.

The current transformer cover 8 forms an antenna sensor for electromagnetic waves traveling along its surface. In this antenna sensor, the potential difference is large in the gaps 11 and 12. Therefore, in this example, the electromagnetic wave due to the partial discharge is captured by the antenna sensor arranged near the gaps 11 and 12. FIG. 2 shows an arrangement configuration of the antenna sensor 21. Before describing FIG. 2, the antenna sensor 21 will be described with reference to FIG.

FIGS. 3A and 3B are views showing the configuration of the antenna sensor 21, wherein FIG. 3A is a perspective view and FIG. 3B is a side view. The antenna sensor 21 is composed of antenna elements 22 and 23 composed of two skeleton slot antennas. Each of the antenna elements 22 and 23 is formed of a stainless steel plate having a width of 20 to 40 mm and a thickness of 2 mm in a rectangular frame shape having a size of about 60 mm × 180 mm. Two antenna elements 22,
23, one antenna element 22 is arranged vertically and the other antenna element 23 is arranged adjacent to the horizontal position so that the antenna element 23 becomes L-shaped when viewed from the side, as shown in FIG. You.

Each of the antenna elements 22 and 23 is
They are interconnected by 4, 25. In addition, the antenna sensor 21 uses the coaxial cable 2
6 and connected to a diagnostic device main body to be described later via a coaxial cable 26. Returning to FIG. 2, the antenna sensor 2
1 is attached to an insulating plate 27 by an appropriate method, and the insulating plate 27 is
To be fixed. Therefore, it is not necessary to use the bolts used in the container 1 for mounting the antenna sensor 21.

Further, a vertically positioned antenna element 22 is disposed near the gap 11 between the cylindrical portion 9 and the disk portion 10,
The antenna element 23 in the horizontal position is arranged at the position of the gap 12 between the disk portion 9 and the container 2. Thus, the gap 11,
Since 12 is the position where the potential difference is large as described above, the antenna sensor 21 detects the electromagnetic wave efficiently. Also,
The antenna element 22 disposed in the vertical position mainly detects high-frequency electromagnetic waves, and the antenna element 23 disposed in the horizontal position.
Detects mainly low-frequency electromagnetic waves. Therefore, the antenna sensor 21 combining the two antenna elements 22 and 23 can detect electromagnetic waves in a wide frequency range. However, even if one of the antenna elements in the vertical position or the horizontal position is omitted, it is possible to detect an electromagnetic wave due to partial discharge.

Further, since the antenna sensor 21 is arranged at a position away from the insulator 5 and close to the container 1 and the current transformer cover 8 at the ground potential, the antenna sensor 21 may affect the insulation performance of the insulator mounting portion. Absent. Further, since the antenna sensor 21 is mounted at a position away from the charged portion, the antenna sensor 21 can be mounted while the operation of the electric device is continued.

FIG. 4 shows the configuration of the diagnostic apparatus main body 31.
The electromagnetic wave signal detected by the antenna sensor 21 is transmitted to the diagnostic device main body 31 via the coaxial cable 26, and the diagnostic device main body 31 analyzes the electromagnetic wave signal and determines whether or not partial discharge has occurred in the container 1. I do. The diagnostic device main body 31 is not limited to the illustrated one, but may be any one.

An electromagnetic wave generated by partial discharge in an insulating gas has a wide range of frequency components. Diagnostic device body 31
Then, it is determined whether or not the antenna sensor 21 has detected an electromagnetic wave due to partial discharge based on signal strength at a plurality of predetermined frequency points and signal continuity (duration). Note that the antenna sensor 21 detects not only electromagnetic waves radiated from the inside of the container 1 but also noise from other electric devices, public broadcast waves, and external noise such as wireless stations.
Therefore, the diagnostic apparatus main body 31 performs signal detection at a plurality of frequency points other than the frequency point that matches the frequency of the external noise in order to eliminate the influence of the external noise.

In FIG. 4, the antenna sensor 21
It is provided for each phase of the phase gas circuit breaker. The electromagnetic wave signal detected by each antenna sensor 21 is input to the selector 32 via the coaxial cable 26. The selector 32 is
Under the control of the PU 36, one input signal is selected and output. The selected electromagnetic wave signal is amplified by the high frequency amplifier 33 and input to the detection tuner 34.

Under the control of the CPU 36, the tuner 34 detects a signal at a plurality of predetermined frequency points. As described above, when setting the frequency points, the frequency points that match the frequency of the external noise are excluded. The output signal is converted to a digital signal by the AD converter 35 and output to the CPU 36.
The CPU 36 determines the presence / absence of partial discharge by eliminating the influence of external noise from the comparison of signal strength and continuity at each frequency point and the signal strength of polyphase.

FIG. 5 shows another example of the antenna sensor.
In the antenna sensor 41 of this example, foil electrodes 42 and 43 are attached to the cylindrical portion 9 of the current transformer cover 8 and the container 2 at positions facing the gap 12 between the two via insulators 45 and 46, respectively. Can be Each of the foil electrodes 42 and 43 is connected to the aforementioned diagnostic apparatus main body 31 by a coaxial cable 44. In addition, as shown by the two-dot chain line in the figure, one foil electrode 43 can be attached to the disk portion 10 of the current transformer cover 8 instead of being attached to the container 1.

Also in the antenna sensor 41, since the foil electrodes 42 and 43 are arranged with the gap 11 or 12 having a large potential difference therebetween, the electromagnetic wave is efficiently detected. Further, the antenna sensor is easy to mount and does not affect the insulation of the insulator mounting portion, similarly to the antenna sensor shown in FIGS.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a configuration of an insulator mounting portion in a gas circuit breaker.

FIG. 2 is a diagram showing a configuration of a gas circuit breaker to which an antenna sensor according to the present invention is attached.

FIG. 3 is a diagram showing a detailed configuration of the antenna sensor of FIG. 2;

FIG. 4 is a diagram showing a configuration of a diagnostic device main body used in the present invention.

FIG. 5 is a diagram showing a configuration of a gas circuit breaker to which an antenna sensor according to a second example of the present invention is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container 4 ... Insulator mounting part 5 ... Insulator 6 ... Current transformer 7 ... Connection conductor 8 ... Current transformer cover 9 ... Cylindrical part 10 ... Disc part 11, 12 ... Gap 21 ... Antenna sensor 22, 23 ... Antenna element 24, 25 ... Crossover 26 ... Coaxial cable 27 ... Insulating plate 28, 29 ... Stainless steel band 31 ... Diagnostic device body 32 ... Selector 33 ... High-frequency amplifier 34 ... Detection tuner 35 ... A / D converter 36 ... CPU 41 ... Antenna sensor 42, 43 ... Electrode 45, 46 ... Insulator

Claims (3)

[Claims] 1. A part for leading a conductor from an electric equipment main body housed inside a container to the outside of the container, a current sensor provided on the lead part, a current sensor covering the current sensor, and induced by a current flowing through the conductor. A gas-insulated electric device having a gap for preventing a circulating current from flowing, and having the container and a current sensor cover arranged with a gap therebetween, wherein the gas-insulated electrical apparatus is arranged near at least one of the two gaps An antenna sensor that detects an electromagnetic wave leaking from the conductor lead-out portion, and an electromagnetic wave signal that is connected to the antenna sensor and detected by the antenna sensor is analyzed, and partial discharge occurs in the container of the gas-insulated electric device. An insulation abnormality diagnostic device for a gas-insulated electric device, comprising: a determination unit for determining whether or not the insulation abnormality is performed. 2. The antenna sensor according to claim 1, wherein the antenna sensor includes two skeleton slot antennas, one of which is disposed near a gap between the current sensor cover, and the other one which is provided between the current sensor cover and the container. The insulation abnormality diagnosis device for a gas-insulated electric device according to claim 1, wherein the two skeleton slot antennas are arranged between the two and are connected by a crossover. 3. The antenna sensor according to claim 1, wherein two foil electrodes are attached at positions sandwiching the gap.
Insulation abnormality diagnostic device for gas-insulated electrical equipment according to item 1.