JPH0342579A - Measurement of partial discharge of gas insulation device - Google Patents

Abstract

PURPOSE:To detect with high sensitivity a partial discharge generated in a gas insulation device by connecting a measuring device directly to the end part of an insulated metal container. CONSTITUTION:If a metal powder 10 is included in the metal container 1, this powder is affected by an electric force to start the motion and a current pulse with extremely high frequency is generated at the same time. This current pulse is made to travel inside of the container 1 while repeating complicated reflections on the inside wall of container 1 or the surface of a high voltage conductor 2, etc., to reach the end part 3. At this time, a pulsative voltage caused by the partial discharge is generated at the end part 3 since an insulating plate 4 is interposed between the end part 3 and the container 1. This voltage is detected by a sensor 6 and introduced to a measuring instrument 9 through a measuring cable 8. Then, a specified display and recording are carried out here, thereby the partial discharge generated in the container 1 can be measured. Thus, the partial discharge generated in the gas insulation device is measured by making use of the end part 3 which is insulated from other metal containers; therefore, the pulse with high frequency generated according to a reflection phenomenon at the end part 3 of partial discharge pulse can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a partial discharge detection method 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, in substations, etc., high voltage conductors are placed in metal containers at ground potential, and the high voltage conductors are insulated by compressing and filling gases with excellent insulation performance, such as SF gas. A gas insulated switchgear is used. 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 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.
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, gas insulated equipment is disassembled in a factory test machine and 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 commencing operation.
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. 2. That is, as shown in FIG. 2, a high voltage conductor 2 is placed in a metal container 1 that is at ground potential, and an insulating medium 3 with excellent insulation performance, such as SFG gas, is compressed and filled at a predetermined gas pressure. has been done. Further, the metal container 1 is held at a ground potential via a grounding wire 4, and this grounding wire 4 is passed through the interior to form a high frequency current transformer (CT).
) 5 is installed. Furthermore, a measuring device 6 for detecting and displaying the output of the CT 5 is connected to the secondary side of the CT 5 via a cable 7.

Therefore, in such a partial discharge measuring device,
When a pulsed current flows through the grounding wire 4 due to a partial discharge generated inside the metal container 1, for example on the surface of the high voltage conductor 2, this pulsed current is detected by the CT 5 and connected to the measurement circuit 6 by the cable 7. As a result, the occurrence of one partial discharge is detected.

(Problem to be solved by the invention) However, in gas-free switchgear, SF.

The frequency of the partial discharge pulse in the gas is extremely high, for example, its rise time is usually nS, and the pulse current in such a frequency range propagates in both directions along the inner surface of the metal container 1 due to the skin effect. Therefore, as shown in Fig. 2, a partial discharge detection device that uses CT to detect the pulse current flowing through the grounding wire 4 has low detection sensitivity and there is a limit to its detection. At present, it is not possible to measure discharge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and inexpensive method for detecting partial discharges in gas-insulated equipment, which can detect partial discharges occurring in gas-insulated equipment with high sensitivity.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides partial discharge measurement of gas-insulated equipment in which a high-voltage conductor is disposed in a metal container at ground potential in which an insulating gas is compressed and sealed. In the method, the terminal part of the metal container is connected insulated from other containers, and the partial discharge in the gas insulated equipment is measured by measuring the signal generated in the terminal part container. There is.

(Function) Therefore, in the partial discharge measurement method for gas-insulated equipment with such a configuration, the terminal end of the metal container is insulated and the measuring device is directly connected to this part, so the part of the gas-insulated equipment is It becomes possible to detect the signal generated at the end of the metal container due to the electric discharge with high sensitivity, and high-sensitivity measurement can be realized especially in on-site measurement.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure shows an example of the configuration of a partial discharge measuring method for insulated equipment according to the present invention.

In FIG. 1, reference numeral 1 denotes a metal container placed approximately horizontally on the ground. A high voltage conductor 2 is disposed inside the metal container 1, and a gas having excellent insulation performance, such as SFs gas, is compressed and filled at a predetermined pressure.

At the end of the metal container 1, a bowl-shaped metal container 3 is connected to the metal container 1 via a ring-shaped insulating plate 4. Further, at the end of the metal container, the high voltage conductor has a roughly spherical shape as shown in the figure.

The metal container 1 is connected to a ground mesh (not shown) via a ground wire 5. On the other hand, the terminal container 3
is connected via a sensor 6 to a ground mesh, also not shown, by a lead wire 7.

Note that the output of the detection impedance is led to a measuring device 9 through a measuring cable 8.

In FIG. 1, if metal particles IO are mixed into the metal container 1, the particles start moving under the influence of an electric force, and a current pulse with an extremely high frequency with a rise time of several nanoseconds is generated. This current pulse travels inside the metal container 1 while repeating complex reflections on the inner wall of the metal container 1 or the surface of the high voltage conductor 2, and finally reaches the terminal end 3 of the metal container 1. At this time, since the insulating plate 4 is interposed between the terminal end portion 3 and the metal container 1, a pulse-like voltage is generated in the terminal end container 3 due to partial discharge. This voltage is detected by the sensor 6 and further guided to a measuring device via a measuring cable 8. Here, predetermined display and recording are performed, and the partial discharge generated within the metal container 1 can be measured.

As described above, in this example, since the partial discharge generated in the gas-insulated equipment is measured using the terminal end container 3 which is insulated from other metal containers, the reflection phenomenon at the end of the partial discharge pulse can be measured. high pulses can be obtained. In addition, even if the equipment is already installed, it requires extensive disassembly because it is a terminal part.

This embodiment can be applied without assembly.

In the above embodiment, the case of a gas insulated switchgear in which a high voltage conductor is disposed inside the metal container 1 has been described, but the same method as described above can be applied to other equipment, such as a gas insulated transformer. Similar effects can be obtained.

〔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 drawings]

゛Figure 1 is a configuration diagram showing a cross-section of essential parts of an embodiment of the partial discharge detection device for gas-insulated equipment according to the present invention, and Figure 2 is a configuration diagram for explaining a conventional partial discharge detection device. . l...Metal container, 2...High voltage conductor, 3...
・Terminal part, 4... Insulating plate, 5... Grounding wire,
6...Sensor, 7...Lead wire,
8...Measuring cable, 9...Measuring device, 10
...Metal particles.

Claims (1)

[Claims] In partial discharge measurement of gas insulated equipment in which a high voltage conductor is placed inside a metal container at ground potential filled with insulating gas, the terminal end of the metal container is insulated and connected from other metal containers, and the terminal end metal A method for measuring partial discharge in gas insulated equipment, characterized in that a container is used to detect partial discharge in gas insulated equipment.