JPS59176681A - Detecting method of partial discharge of gas insulation opening and closing device - Google Patents

Abstract

PURPOSE:To determine externally an occurrence position of partial discharge of a device under operation by measuring a partial discharging current from a conductor provided outside of an opening and closing device while a measurement point is moved. CONSTITUTION:The gas insulation opening and closing device 1 is connected directly to a transformer 2 by an insulating bushing 3 and the low-impedance conductor 5 is laid outside of their containers 1a and 2a in parallel. The conductor 5 is connected to a grounding terminal T0 at one terminal and to a probe 6 movable on the container 1a at the other terminal, and a search coil 7 is inserted between the conductor 5 and probe 6 and connects with a detector 8. If partial discharge occurs to a point P of the main conduction part of the conductor 4 while the devices 1 and 2 are in operation, the discharging current of the capacity C0 of its corona is shunt to the conductor 5 and measured continuously through a coil 7 and the detector 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a partial discharge detection method for gas insulated switchgear (hereinafter referred to as GIS).

Currently, there is no established method for measuring whether or not partial discharge is occurring during operation of a GIS, and it is said to be extremely difficult to know where partial discharge is occurring. This is because the charging part of the GIS is housed in a grounded container and sealed.

Some GIS have a bus line PT and a bus line FDP, and in this case, it is theoretically possible to measure partial discharge using the connections between the bus line and FT, and the bus line and FD. However, with this method, the GIS that is in the charging state while driving
The disadvantage is that the components must be touched.

The present invention provides a method that makes it possible to detect partial discharges and determine the location of occurrence by routing conductors only on the ground side, regardless of the presence or absence of busbars FT and busbar PD, and even when GIS is in operation. This is what we provide.

The present invention will be explained below with reference to the drawings. The figure is a schematic diagram showing an example of connecting a transformer to GIs.
S, 2 is a transformer directly connected to this, 6 is an insulating bushing,
4 is the leading conductor. GISl, transformer 2 containers 1a, 2
A is grounded at points 1E and 2E, respectively.

The containers 1a and 2a are filled with an insulating medium to insulate the live parts.

5 is a low impedance conductor that is laid parallel to the containers 1a and 2aK of the transformer 2, and one end is connected to the grounding point (ground terminal) To on the container 2a, and the other end is connected to the grounding point (ground terminal) To on the container 2a.
It is connected to a probe 6 which is fully movable above a. The resistive impedance conductor 5 is made of a compressible material as required. A search coil 7 is inserted between the low impedance conductor 5 and the probe 6.
A detector 8 such as a meter is connected.

The low impedance conductor 5 is made of a conductor such as a copper plate so that its impedance is sufficiently lower than the impedance of the container between the ten points and the connection point 10 of the probe 6.

Furthermore, CT is the stray capacitance in transformer 2, and CO is the GIS
The capacity of the partial discharge part (corona discharge part) of l, C1 exists in series with the said capacitance CO, and C2 is the stray capacitance t'af of GjSi which exists in parallel with the said volume C01C1. f.

Right now, oIsl and transformer 2 are in operation, main conductor 4
Let us consider the case where a partial discharge occurs at point P in the main current section.

At this time, considering the discharge current path of the corona volume iCo, there are the following six circuits.

(1) Point P - Main conductor 4 - Main conductor of transformer 2 Point T - Stray volume fi OT - Point 'I'o - Vessel 2a - Vessel 1a
-P.

Point - Stray Capacity C1 - Corona Capacity ico -P Point (2) P
Point-main conductor 4-T point-stray capacitance Cr-T.

Point - Low impedance conductor 5 - Probe 6 - 20 points - Stray capacitance C1 - Capacity of corona Co - Point P (3) Point P - Stray capacitance C2 - Container 1a - Stray capacitance C1 - Capacity of corona C0 -
Point P Comparing the paths (1) and (2) above, in the former, points 10 and 20 are connected by the impedance of the containers 2a and 1a, but in the latter, the conductor 5 has an impedance sufficiently lower than this impedance. Since the conductor 5 is connected to the conductor 5, most of the discharge current of the corona is diverted to the conductor 5.

Furthermore, when comparing routes (2) and (3), the stray capacitance CT of the transformer (in the case of oil-immersed transformer) is usually larger than the stray capacitance C2 of the GIS, so the former has more corona. The discharge current of the capacitor CO is divided.

Therefore, the discharge flow of the corona 'lQ amount Co that is shunted to the low impedance conductor 5 is measured via the search coil 7 and the detector 8, and the occurrence of partial discharge is detected.

Alternatively, by moving 20 points to each part of the container 1a and determining the magnitude of the detection signal based on the measured current, the location P of partial discharge can be determined.
can be determined from outside the container 1a.

For this reason, it is preferable that the low impedance conductor 5 be constructed of a tetherable material, but it may be constructed of a rigid body and a tethered lead wire may be used between it and the probe 6.

Note that since the stray capacitance of transformer 2 is larger than that of GISI, partial discharge can be detected with higher sensitivity by using the former.

The above describes the case where the GIS is directly connected to the transformer +a2 and one end of the low impedance conductor 5 is fixedly connected to the transformer 2 side, but other parts of the GIS, such as the current transformer C
Alternatively, one end of the low impedance conductor 5 may be fixedly connected to a container such as PI'r or PI to measure all partial discharges of GIS.

As described above, the present invention is configured such that a low impedance conductor is installed in parallel with the GIS, and the shunt current is measured, and the measurement point can be moved. Therefore, the occurrence of partial discharge during the operation of the GIS can be prevented from occurring in the charging section. This has the effect of not only being able to easily and easily know the occurrence without touching it, but also being able to determine the location of occurrence from outside the GIS.

[Brief explanation of the drawing]

The figure is the first one to explain the present invention, and is it a transformer in GIS?
1...GIS 2 transformers 1a, 2a which is a schematic diagram when connected.
...Container 4 Main conductor 5/Low impedance conductor Patent applicant Nissin Electric Co., Ltd.

Claims (1)

[Claims] A method for detecting partial discharge in a gas insulated switchgear, characterized by measuring a partial discharge current flowing through a single low impedance conductor arranged in parallel outside the container of the gas insulated switchgear while moving measurement points.