JPH03135312A - Partial discharge detector for gas-insulating equipment - Google Patents

Abstract

PURPOSE:To detect partial discharge to be generated in a gas-insulating equipment, well in sensitivity by bridging an insulating flange section with metallic plates having slits. CONSTITUTION:When partial discharge is generated in a metallic vessel 1, then the high-frequency current of an extremely high rise time is generated. At the same time as such high-frequency current flows through a high tension conductor 3, it flows also through the internal surface of the metallic vessel 1. When the resonance frequency of slits 7 coincides with the frequency of the high-frequency current due to the partial discharge and when the high-frequency current flowing through the internal surface of the metallic vessel 1 flows around the slits 7 of metallic plates 10, then signal due to the partial discharge can be detected well in the ratio of S/N. As a result, the partial discharge detector of the gas-insulating equipment of simple composition and a low cost which can detected the partial discharge to be generated in a gas- insulating equipment, in high sensitivity, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a partial discharge detection device for gas insulated equipment in which a high voltage conductor is insulated by an insulating medium such as SF or gas.

(Prior art) In recent years, high-voltage conductors have been installed in metal containers at ground potential in strange places, and gases with excellent insulation performance,
For example, a gas insulated switchgear configured to insulate a high voltage conductor by compressing and filling gas, such as SF, is employed. SF and gas used in this gas insulated switchgear exhibit very excellent insulation properties under an equal electric field, but have a property that the insulation performance is extremely degraded under an unequal electric field.

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 possible causes include poor contact in the high voltage section due to assembly errors, and defects in the insulating spacer such as voids.

If an unequal electric field is formed in gas-insulated equipment due to such a defect, partial discharge may occur during operating conditions, which may eventually lead to a serious situation of total circuit failure.6 Therefore, total circuit failure may occur. Reliably detects previous partial discharges,
It is necessary to prevent dielectric breakdown. For this reason, gas insulated equipment is usually subjected to a partial discharge test at the factory.
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 transported unit by unit to the site, where a large number of units are assembled. The unit may be defective.

Therefore, in order to improve the reliability of gas-insulated equipment, it is necessary to detect such defects on-site before starting operation, and therefore partial discharge tests are usually conducted after on-site assembly. However, unlike in a factory, there are various electrical and mechanical noises on site, making it difficult to perform highly sensitive partial discharge tests.

In order to deal with such problems, various partial discharge measuring means have been proposed in the past, and examples thereof will be explained with reference to FIG. That is, as shown in FIG. 5, a high-voltage conductor 3 is disposed in the metal containers 1 and 2 which are at ground potential, and an insulating medium 4 having excellent insulation performance such as SF or gas is placed at a predetermined gas pressure. It is compressed and filled with. An insulating spacer 5 is installed between the metal containers 1 and 2 to provide electrical insulation, and a cable 6 is connected to monitor the voltage between the metal containers.

In such a partial discharge measuring device, when a pulse voltage is generated between the metal containers 1 and 2 due to a partial discharge generated inside the metal container 1 or 2, for example, on the surface of the high voltage conductor 3, this pulse voltage will be transmitted through the cable 6 and monitored by the monitoring device.

(Problem to be solved by the invention) However, in substations, noise voltages of various frequencies propagate through power transmission lines, etc., and from these superimposed monitor waveforms, only the signal voltage due to partial discharge can be detected. I need to take it out. A partial discharge detection device that monitors the voltage between two insulated metal containers as shown in Figure 5 does not have such a frequency selection function, so it monitors only the signal caused by partial discharge with a good S/N ratio. I can't.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and inexpensive partial discharge detection device for gas insulated equipment that can detect partial discharge occurring in gas insulated equipment with high sensitivity.

[Structure of the invention]

(Means for Solving the Problems) The partial discharge detection device for gas insulated equipment of the present invention has a high voltage conductor disposed in a metal container compressed and sealed with an insulating gas, and the metal container and the metal container are electrically connected to each other. In a gas insulated device having an insulating flange portion insulated from the outside, the insulating flange portion is bridged with a metal plate having a slit, and a signal generated in the slit of the metal plate due to partial discharge within the gas insulated device is detected. It is characterized by being configured to do so.

(Function) In the present invention, the resonant frequency of the slit antenna formed in the portion surrounded by the slit conductor of the insulating flange portion can be changed by adjusting the width of the slit. By adjusting the resonant frequency to the frequency of the signal caused by the partial discharge, it is possible to monitor the signal caused by the partial discharge with a good S/N ratio from among the signals on which noise is superimposed.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
1 and 2 show an example of the configuration of a partial discharge detection device for gas insulated equipment according to the present invention. Figures 1 and 2
In the figure, reference numerals 1 and 2 are metal containers placed on the ground and supported by supporting members (not shown) at an appropriate interval, and a high voltage conductor 3 is disposed inside the metal containers 1 and 2. and has excellent insulation performance, such as SF,
Gas 4 is compressed and filled at a predetermined pressure.

In the present invention, an insulating spacer 5 is disposed between the metal container 1 and the metal container 2, and a slit with a variable opening length d in the circumferential direction is provided on the insulating spacer 5. A metal plate 10 having 7 is provided. Furthermore, a coaxial cable 6 for transmitting voltage between opposite sides of the slit opening is arranged at the opening of the slit 7, and its core wire and sheath are connected to the opposite sides of the slit 7.

Therefore, the metal plate 10 having the slit 7 and the cable 6 constitute a slit antenna.

In a partial discharge detection device for a gas insulated switchgear having such a configuration, when a partial discharge occurs in the metal container (2), an extremely high high frequency current with a rise time of several ns is generated. Such high frequency current flows through the high voltage conductor 3 and at the same time flows through the inner surface of the metal container 1.

If the resonant frequency of the slit 7 matches the frequency of the high-frequency current caused by partial discharge, when the high-frequency current flowing on the inner surface of the metal container 1 flows around the slit 7 of this metal plate 10, the S/N ratio is good and the partial discharge occurs. The frequency of the high-frequency current caused by the zero partial discharge that can be detected may vary depending on the configuration of the substation, but since the length of the slit is variable, the slit antenna can be adjusted depending on each substation. Resonant frequency can be adjusted.

In this way, in this embodiment, a metal container 1 sandwiching an insulating material is used.
A slit antenna is constructed by attaching a metal plate having a slit with a variable opening length to the flange of the metal container 2. By adjusting the resonance frequency, only signals caused by partial discharge can be detected. can be selectively monitored with good S/N. Furthermore, the present invention can be easily applied to an existing gas-insulated switchgear, as long as it has an insulating flange portion, by simply attaching a conductor slit and a cable.

In the above embodiment, the slit was attached to the outside of the flange, but the same effect can be obtained even if the slit is placed on the inner surface of the metal container of the insulator of the flange as shown in FIGS. 3 and 4. Can be done.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a simple and inexpensive partial discharge detection device for gas insulated equipment that can detect partial discharge occurring within gas insulated equipment with high sensitivity.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of a partial discharge detection device for gas-insulated equipment according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention. A configuration diagram showing an example,
FIG. 4 is a sectional view taken along line A-A in FIG. 3, and FIG. 5 is a configuration diagram for explaining a conventional partial discharge detection device. 1.2...Metal container 3...High voltage conductor 4...Insulating medium 5...Insulating spacer 6...Cable 7...Slit lO...Metal plate 1st group

Claims (1)

[Claims] In a gas insulated device in which a high voltage conductor is disposed within a metal container at ground potential that is compressed and sealed with an insulating gas, and the connecting portion of the metal container has an electrically insulating structure, the insulator of the connecting portion of the metal container is slit. 1. A partial discharge detection device for gas insulated equipment, characterized in that the device is configured to detect a signal generated in a slit of the metal plate due to partial discharge in the gas insulated equipment.