JPH022951A - Partial discharge detecting apparatus for gas insulating equipment - Google Patents

Abstract

PURPOSE:To make it possible to detect partial discharge which is generated in a gas insulating equipment highly sensitively by providing a sensor which detects electromagnetic waves in the vicinity of the boundary of the connecting part of a metal container and a bushing. CONSTITUTION:When the pulse of the partial discharge which is propagated in a metal container 11 reaches the discontinuous part of the metal container 11, i.e. at the boundary part between the metal container 11 and a bushing 12, an electromagnetic wave caused by the initial partial discharge is emitted to the outside of the metal container because the metal container 11 is terminated at the boundary part. Therefore, a voltage is induced in a loop antenna 16. The voltage is transmitted to a measuring device 18 through a cable 17. The detected signal is displayed on the measuring device 18. In this way, the partial discharge can be detected highly sensitively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective 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 SF6 gas.

(Traditional Limb Technique) In recent years, in substations, etc., high voltage conductors are placed in metal containers at ground potential, and the high voltage conductors are compressed and filled with a gas with excellent insulation performance, such as SF6 gas, to insulate the high voltage conductors. A gas insulated switchgear is used. The SF6 gas used in this gas-insulated switchgear exhibits very excellent insulation properties under an even electric field, but has 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 operation, which may eventually lead to a serious situation of total 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 without inclusion in the factory test.
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 after the factory test 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 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. 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 SF6 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 CT5 and
This is input to the J11 constant circuit 6 via the cable 7, and the occurrence of partial discharge is detected.

(Problem to be solved by the invention) However, in gas-insulated switchgear, the frequency of the partial discharge pulse in SF6 gas is extremely high, for example, its rise time is usually nS, and the pulse current in such a frequency range is Due to this effect, it propagates along the inner surface of the metal container 1 in both directions. 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 has a limit to its detection. At present, it is not possible to carry out measurements.

The present invention provides a simple and inexpensive partial discharge system for gas insulated equipment that can detect partial discharge occurring in gas insulated equipment with high sensitivity. 1 li detection device! The purpose is to improve.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention arranges a high-voltage conductor in a metal container at ground potential filled with an insulating gas, and further includes a bushing for the high-voltage conductor. In the partial discharge detection device for gas insulated equipment, which is connected to an overhead line outside the metal container via a This configuration includes a sensor that detects electromagnetic waves radiated to the outside.

(Function) Therefore, in the partial discharge detection device for gas insulated equipment having such a configuration, a sensor detects electromagnetic waves near the boundary of the connection between the metal container and the bushing where the surge impedance of the gas insulated equipment changes. By providing this, it becomes possible to detect partial discharge generated inside the gas insulated equipment with high sensitivity.

(Example) An embodiment of the present invention will be described below 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, reference numeral 11 denotes a metal container that is placed horizontally on the ground and supported at appropriate intervals by supporting members (not shown). Inside this metal container 11 is a high voltage conductor (not shown). At the same time, for example, SF6 gas having excellent insulation performance is compressed and filled at a predetermined pressure. Further, a bushing 12 is fixed to the upper part of the metal container 11 via each flange 13.
A high voltage conductor (not shown) inside is connected to an overhead line 14 through this bushing 12.

In the gas insulated switchgear having such a configuration, in this embodiment, a loop antenna 16 is attached to the connection boundary between the metal container 11 and the bushing 12 via the support member 15. This loop antenna 16 is connected to the metal container 1
The device detects electromagnetic waves radiated to the outside when a partial discharge occurs within the device 1, and the induced voltage is transmitted via a cable 17 to a measuring device 18, where it is displayed and recorded.

In addition, 12a and 12b in the figure are air shield rings provided on the high pressure side and the ground side of the bushing 12.

In a partial discharge detection device for a gas insulated switchgear having such a configuration, when a partial discharge occurs in the metal container 11, a current pulse with an extremely high frequency with a rise time of several nanoseconds is generated. Due to the skin effect, this pulse begins to propagate in two directions in the axial direction on the inner surface of the metal container 11. At this stage, the electromagnetic waves leaking to the outside of the metal container 11 are minute and difficult to detect with the loop antenna 16. However, when the pulse that has subsequently propagated within the metal container 11 reaches a discontinuous portion of the metal container 11, that is, the boundary between the metal container 11 and the bushing 12,
Since the metal container 11 is at this point, the electromagnetic waves caused by the partial discharge are radiated to the outside of the metal container 11 for the first time at this point.

Therefore, a voltage is induced in the loop antenna 16, and this voltage is transmitted to the measuring device L\18 via the cable 17.

Therefore, by detecting electromagnetic waves generated due to partial discharge using the loop antenna 16 and displaying the detection signal on the measuring device 18, it is possible to easily detect partial discharge with high sensitivity on-site. can.

In this way, in this embodiment, the metal container 11 and the bushing 12 are
A loop antenna 16 is provided near the flange 13, that is, near the connection boundary, to detect electromagnetic waves radiated to the outside from the boundary of the metal container 11 caused by partial discharge. can be detected with high sensitivity, and extremely high-quality measurements can be easily carried out on-site under operating conditions, without having to consider attenuation due to grounding wires, etc., as in the past.

In the above embodiment, the case of a gas insulated switchgear in which a high voltage conductor is disposed inside the metal container 11 has been described, but even in the case of other equipment 2 such as a gas insulated transformer, the same method described above can be applied. Similar effects can be obtained.

[Effects 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 in gas insulated equipment with high sensitivity. be able to.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a partial discharge detection device for gas insulated equipment according to the present invention, and FIG. 2 is a configuration diagram for explaining a conventional partial discharge detection device. 11... Metal container, 12... Bushing, 13...
- Flange, 14... overhead wire, 15... support member,
16...Loop antenna, 17...Cable, 18
···measuring device. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] In a partial discharge detection device for gas-insulated equipment, the high-voltage conductor is arranged in a metal container at ground potential filled with an insulating gas, and the high-voltage conductor is connected to an overhead line outside the metal container via a bushing. , a partial discharge detection device for gas insulated equipment, characterized in that a sensor for detecting electromagnetic waves radiated to the outside of the metal container when a partial discharge occurs in the gas insulated equipment is provided near the boundary between the metal container and the bushing. .