JPH03250711A - Partial discharge detecting device for compressed gas insulation equipment - Google Patents

Abstract

PURPOSE:To detect partial discharge generated in a metallic container at high sensitivity by providing a slot, the length of which corresponds to the half of the wavelength of electromagnetic waves generated by the partial discharge in compressed gas insulation equipment, to the metallic container. CONSTITUTION:A slot 15, the length of which corresponds to the half of the wavelength of a partial discharge detecting frequency, is provided to a metallic container 1 and the slot 15 is used as an antenna for detecting electromagnetic wave generated by partial discharge. As a result, it becomes possible to efficiently and surely detect electromagnetic waves generated by partial discharge in the metallic container 1 by means of the slot 15 directly provided to the container 1 and to completely shield external noise. Therefore, an inexpensive highly reliable partial discharge detecting device for compressed gas insulation equipment which can detect partial discharge generated in the metallic container 1, has a simple constitution, and is free from gas leakage can be obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a partial discharge detection device for gas-insulated equipment in which a high-voltage conductor is insulated by an insulating medium such as SF6 gas. Regarding.

(Prior art) In recent years, in substations and the like, high voltage conductors are placed in metal containers at ground potential, and gas with excellent insulation performance, such as SF6 gas, is compressed and filled to insulate the high voltage conductors. A gas insulated switchgear is used. The SF6 gas used in this gas-insulated lid has excellent zero-N resistance under a uniform electric field! However, under an unequal electric field, the insulation property deteriorates dramatically.

Incidentally, various factors can be considered to disturb the electric field distribution within gas-insulated equipment, but the main ones include defects such as dents on the surface of the high-voltage conductor and foreign metal particles mixed into the equipment during assembly or transportation.

Of course, other possibilities include poor contact in the high voltage section due to assembly errors, and even defects in insulating spacers such as Dito.

If an unequal electric field is formed in the gas insulated equipment due to such a defect, partial discharge may occur during operating conditions, which may eventually lead to a serious situation of complete circuit failure. Therefore, it is possible to reliably detect partial discharge before it leads to total path failure.
It is necessary to prevent dielectric breakdown. For this reason, gas insulated equipment is usually subjected to a partial discharge test at the factory to avoid corrosion.
It has been devised so that internal defects can be detected in advance.

Generally, such factory tests are performed on a unit-by-unit basis, so
Defects in the unit can be reliably detected by partial discharge testing at the factory.

However, after passing the factory test, gas insulated equipment is shipped unit by unit to the site, where many units are reassembled. The unit may be defective. Therefore, in order to improve the reliability of gas insulation equipment, it is necessary to detect such defects on-site before operation begins, so partial discharge tests are usually conducted after on-site assembly. .

However, unlike inside a factory, there are various electrical and mechanical noises, making it difficult to perform highly sensitive partial discharge tests. A partial discharge measuring means has been proposed, and an example thereof will be explained based on FIG. That is, as shown in FIG. 3, a high voltage conductor 2 is disposed inside a metal container 1 which is at ground potential, and a medium 3 containing an insulator with excellent insulation performance such as SF6 gas is heated at a predetermined gas pressure. It is compressed and filled. Also,
The metal container 1 is held at ground potential via a ground wire 4.

Pass this ground @ 4 inside to create a high frequency current transformer (CT).
5 is installed. Furthermore, a measuring device 6 for detecting and displaying the output is connected to the cable 7 on the secondary side of the CT5.
connected via.

Therefore, in such a partial discharge measuring device,
When an equal current flows through the grounding wire 4 due to a partial discharge occurring inside the metal container 1, for example on the surface of the high voltage conductor 2, this pulsed current i is detected by the CT 5 and sent to the measuring circuit 6. It will be input via cable 7,
The occurrence of partial discharge can be detected.

However, in gas-insulated switchgear, the frequency of partial discharge, J Lus, during SF6 is extremely high, for example, its rise time is usually on the order of nS, and such /4 Luss current in the outer frequency range is due to the skin effect. Therefore, the light propagates along the inner surface of the metal container 1 in both directions. therefore,
As shown in Fig. 3, the partial discharge detection device that uses CT5 to detect the 1,000 ls current flowing through the grounding wire 4 has low detection sensitivity and is naturally limited in its detection, so it can measure partial discharges with sufficient accuracy for practical use. The current situation is that it is not possible to do so.

For this reason, a partial discharge detection device as shown in FIG. 4 has been proposed. That is, a metal container at ground potential, a high voltage conductor 2 housed in this metal container 1, and an SF6
In a gas insulated device made of an insulating gas medium 3 such as gas, a metal plate 8 is provided inside the metal container 1 along its inner surface.

As seen in the sectional view shown in FIG. 5, the metal plate 8 is installed with a slight gap between it and the metal container 1, and faces the high voltage conductor 2.

Further, the details of the metal plate 8 are shown in FIG. 6. A slot 9 is cut approximately in the center of the metal plate 8, and by using this slot 9 as an antenna, the antenna can be installed in the insulation equipment. It attempts to detect electromagnetic waves caused by partial discharges that occur.

(Problem to be Solved by the Invention) However, in the partial discharge detection device shown in FIGS. 4 to 6, the metal plate 8 is installed in the metal container 1 facing the high voltage conductor 2. Because of this necessity, insulation reliability was compromised and it was not necessarily put into practical use. A major problem with this type of partial discharge detection device for cameras is that the slot 9 shown in FIG. 6 is used as an antenna.
Naturally, it is necessary to extract the voltage induced in this slot 9 to the outside of the metal container I. This is a major problem in insulating equipment in which an insulating gas such as SF6 is compressed and optically filled inside the metal container 1, as it directly leads to a decrease in reliability such as gas leakage.

The present invention can detect the number t of parts generated within a metal container with high sensitivity, has a simple configuration, and is inexpensive.

The purpose of the present invention is to provide a highly reliable partial discharge detection device for gas insulated equipment that is free from the risk of gas leakage.

[Structure of the Invention (Means for Solving the Problems)] In order to achieve the above object, the present invention includes a high-voltage conductor disposed in a metal container at ground potential in which a gas is compressed and sealed. In the partial discharge detection device for gas insulated equipment, the metal container is provided with a slot having a length corresponding to half the wavelength of electromagnetic waves emitted due to partial discharge in the gas insulated equipment. .

(Function) Therefore, in the partial discharge detection device having such a configuration, it is possible to efficiently and reliably detect electromagnetic waves caused by partial discharge generated within the metal container using the slot provided directly in the metal container. In addition, external noise can be completely shielded.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of a partial discharge detection device for gas insulated equipment according to the present invention. In FIG. 1, a metal container 1 in which a high voltage conductor (not shown) is arranged is placed substantially horizontally on the ground. The inside of the metal container 1 is compressed and filled with an insulating gas medium 3 such as gas 1 having excellent insulating performance, such as SF6 gas at a predetermined pressure.

Further, a bushing 1 is fixed to the upper 7 flange portion 10 of the metal container 1, and a high voltage conductor (not shown) of the metal container 1 is connected to an overhead line 12 via this bushing 1. It will be counterfeited.

Further, a high pressure shield ring 13 is provided on the head of the bushing 11, and a ground shield ring 14 is provided on the ground side.
is fixed.

Further, a slot 15 is cut in the metal container IK, and as will be described later, this slot 15 is connected to a measuring device 17 via a cable 16 in order to measure the induced voltage.

Next, a detailed view of the main parts of the slot slot 5 is shown in FIG.

The length of the slot 15 provided in the metal container 1 is λ/2
(λ: partial discharge detection frequency), the width W is the length λ/
Compared to 2, it is so narrow that it can be ignored. Further, the cable 16 is connected to two opposing points, P and Q, approximately at the center of the slot 15 in the longitudinal direction. Further, the interior part 8 of the slot 15 is sealed with an insulating material, such as epoxy resin, to seal the SF6 gas compressed and filled in the metal container 1.

In the partial discharge detection device for gas insulated equipment configured in this way, if a partial discharge now occurs in the metal container 1,
Electromagnetic waves are emitted. This electromagnetic wave propagates inside the metal container 1 and reaches the point where the slot J5 is cut.

Here, the slot 15 acts as a so-called aperture antenna. That is, since the length of the slot 15 is λ/2, an electromagnetic wave component having a wavelength of λ is efficiently detected by the slot 15.

The induced voltage thus generated at the two opposing points P and Q of the slot 15 in FIG. 2 is guided to the measuring device 17 via the cable 16 connected to these two points.
Recording and display are performed here. Therefore, partial discharge in gas-insulated equipment can be detected with high sensitivity.

In this way, in this embodiment, the slot 15 is provided in the metal container 1 and used as an aperture antenna.
The electromagnetic waves emitted due to partial discharge of the insulated equipment can be detected with high sensitivity.

In the above embodiment, the metal container 1 has one slot 1.
Although the structure has been described in which slots 5 are provided, the same effect can be obtained even if the number of slots is two or more.

Moreover, although the case of a gas-insulated device in which the high-voltage conductor 2 is disposed within the metal container 1 has been described, similar functions and effects can be obtained with other devices, such as a gas-insulated transformer.

[Effects of the Invention] As described above, according to the present invention, in a partial discharge detection device for insulated equipment in which a high voltage conductor is disposed in a metal container at ground potential in which an insulating gas medium is compressed and sealed, A slot with a length corresponding to a half wavelength of the partial discharge detection frequency is provided in the metal container, and this slot is used as an antenna to detect electromagnetic waves caused by partial discharge, so that the partial discharge generated within the metal container can be detected. It can be detected with high sensitivity, has a partial structure, is inexpensive, and has no risk of gas leakage.
A highly reliable partial discharge detection device for gas-insulated equipment can be obtained.

[Brief explanation of drawings]

Fig. 1 is a front view showing one embodiment of the present invention, Fig. 2 is an enlarged view of the main parts, Figs. 3 to 5 are sectional views showing the conventional partial discharge detection device, and Fig. 6 is the same main part. FIG. l...Metal container, 2...High voltage conductor, 3...Insulating gas medium, 4...Grounding wire, 15...Slot, 16
... Cable, 17... Measuring instrument.

Claims (1)

[Claims] In a partial discharge detection device for gas insulated equipment in which a high voltage conductor is disposed within a metal container at ground potential in which an insulating gas medium is compressed and sealed, the metal container has a length corresponding to a half wavelength of the partial discharge detection frequency. 1. A partial discharge detection device for gas-insulated equipment, characterized in that a slot is provided, and the slot is used as an antenna for detecting electromagnetic waves caused by partial discharge.