JPS61102109A - Gas insulated switchgear - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas insulated switchgear with an improved grounding configuration.

[Technical Background of the Invention] Conventionally, gas-insulated switchgears have housed high-voltage charging parts such as a cutoff part, a disconnection part 2, and a current-carrying part together with an insulating gas such as sulfur hexafluoride (SFs gas) in a metal case. It is made up of. In addition, the legs of the switchgear main body configured in this way are fixed on an embedded base placed in the foundation concrete at the bottom of the switchgear main body, and the embedded base roughly receives the load of the switchgear main body. Generally, it is connected to reinforcing bars (rebar arrangement) installed inside the foundation concrete. Furthermore, a grounding mesh (grounding network) made of copper or aluminum is installed within or below the foundation concrete, and this buried grounding mesh and the case of the gas-insulated switchgear main body are They are usually connected at multiple locations by wires. Here, the grounding mesh is connected to the several hundred kHz generated in the case and low-pressure control system when a switch such as a disconnector or step switch in the main body of a gas-insulated switchgear operates.
Several meters (2 to 4 meters) for the purpose of reducing high-frequency surges with frequencies ranging from z to several tens of MHz and stabilizing the ground system potential.
It is organized by interval.

[Problems in the Background Art] However, in gas insulated switchgear with such a grounding configuration, there are problems as shown below. Providing a grounding mesh is very costly. Also, since the basic structure becomes very complicated,
The workability is poor and this also causes high costs. Further, it is not preferable to embed a large amount of stranded wires made of copper or aluminum as a ground mesh in a concrete foundation due to the mW strength.

[Purpose of the Invention] The present invention was made to eliminate the above-mentioned problems, and the purpose is to provide a system that has a good suppressing effect on high frequency surges, has a simple basic structure, is inexpensive, and has no problems in terms of strength. Our objective is to provide gas insulated switchgear.

[Summary of the Invention] In order to achieve the above object, in the present invention, the grounding mesh, which was conventionally made of copper or aluminum, is made of reinforcing bars, and the case, bridge, etc. of the gas insulated switchgear body is connected to the reinforcing bars. At the same time, at locations where the sheath current is discontinuous, the buried grounding wire and the case are connected to allow high-frequency sheath current to flow into the grounding wire, and a mesh-like structure is formed between the connection points between the grounding wire and the case. It is characterized in that the configured reinforcing bars and the grounding case are connected.

[Embodiments of the Invention] First, the concept of the present invention will be described. Generally, iron has a high magnetic permeability, and also has high self-inductance and resistance, so iron is not used for the grounding mesh. However, as shown in Figures 4 and 5, for high-frequency waves of several hundred KHz to several tens of M2, H2, there is almost no difference in impedance between meshes made of iron and meshes made of copper. It was found through actual measurements that there was no

Therefore, the grounding mesh constructed of reinforcing bars that will be buried in the foundation concrete at intervals of several meters is sufficiently effective in suppressing the high-frequency surges induced in the case and low-pressure control system during switch operation of gas-insulated switchgear. However, as shown in Figures 4 and 5, in the low frequency wA range, that is, the commercial frequency range, the resistance of iron increases.

The inductance is significantly larger than that of copper. Therefore, if a large commercial frequency current, ie, sheath current, flows into the reinforcing bars, the reinforcing bars will heat up, which will lead to problems such as cracks in the foundation concrete. Therefore, care should be taken to prevent a large sheath current from flowing into the reinforcing bars forming the mesh.

An embodiment of the present invention based on the above concept will be described below with reference to the drawings. FIG. 1 shows a front view of an example of the groove formation of the gas insulated switchgear according to the invention. 1 is the case of the gas-insulated switchgear body, and the main circuit (
When current flows through the high voltage circuit), the current flows here (sheath current)
flows. 2 is a case flange insulation part, where the sheath current becomes discontinuous. According to actual measurements and analysis, it has been found that the current flowing into the grounding wire 3 connected to the case 1 is significantly larger at locations where the sheath current is discontinuous than at locations where the sheath current is discontinuous. (In other places, case 1 has lower impedance, so almost no sheath current flows into the grounding wire 3 etc. connected to case 1.) Also, in the actual image, the sheath current flows through the grounding mesh and reinforcement. It has been found that the induced current is concentrated at the outermost part of the constructed loop. Therefore, as shown in Figure 1, the case 1 and the grounding wire 3 made of a good conductor such as copper or aluminum with low impedance even for commercial frequencies are set up near the point where the sheath current becomes discontinuous. Ground wire 31
By connecting through the wire, most of the sheath current flows into the ground wire 31 and the ground wire 3, and
Almost no water flows into the grounding mesh made of reinforcing bars 4 arranged at predetermined intervals, for example, several meters apart, and into the connecting wire 41 connecting this mesh to the case 1. Therefore, there is no need to worry about the reinforcing bars 4 heating up, and since the grounding wire 31 through which most of the sheath current flows has an impedance that is more than one order of magnitude lower than that of the reinforcing bars, there is no need to worry about heating up. Also the first
By configuring as shown in the figure, it is equivalent to having a grounding mesh at several meters intervals at the bottom of the gas insulated switchgear body against high frequency surges. Since it is connected at multiple points to the main body of the gas-insulated switchgear, the power level 1 in case 1 is stable and the high-frequency surge induced in the low-voltage control system can be reduced. Since there is no need to construct a mesh with ground wires over the entire area, the foundation structure becomes simple, work efficiency is improved, and construction costs can be reduced.

FIG. 2 shows another embodiment of the present invention in front view. In this case, the locations where the sheath current is not 1IhE are the case flange insulating portion 2 on one side and the air bushing connection portion on the other. Furthermore, if the point where the sheath current is discontinuous and the point where the mesh is connected to the reinforcing bar 4 are too close, it is expected that the commercial frequency induced current will flow into the reinforcing bar 4. Therefore, in this embodiment, the lower part of the bushing case 11 By disposing an insulating plate 5 between the case frame 12 and the reinforcing bars 4, commercial frequency current (sheath current) is prevented from flowing into the reinforcing bars 4.

FIGS. 3(a) and 3(b) show a plan view and a front view of another embodiment of the gas insulated switchgear according to the present invention. In this embodiment, a grounding wire 3 made of a good conductor such as copper or aluminum is arranged around the reinforcing bar 4 so as to surround it. The induced current that flows into the foundation tends to concentrate at the outermost part of the loop as described above, so by forming a loop with the ground m3 at the outermost part of the reinforcing bar 4, a large current can flow through the reinforcing bar 4. flows and the reinforcing bars 4 are not heated.

[Effects of the Invention] As explained above, according to the present invention, the grounding mesh is constructed at intervals of several meters by reinforcing bars buried in the foundation concrete on which the main body of the gas insulated switchgear is placed, so that the foundation structure is It is possible to provide an extremely reliable gas insulated switchgear which is simple and low-mounted, has no problems in terms of strength, has a good suppressing effect on high frequency surges, and does not cause overheating of reinforcing bars due to inflow of commercial frequency current.

[Brief explanation of drawings]

FIG. 1 is a front view showing one embodiment of the present invention, FIG. 2 is a front view showing another embodiment of the present invention, and FIGS.
) is a plan view showing another embodiment of the present invention, and FIGS. 4 and 5 are diagrams for explaining the present invention in detail. DESCRIPTION OF SYMBOLS 1...Case, 2...Flange insulation part, 3...Grounding wire 31...Standing grounding wire, 4...Reinforcing bar, 41...
・Connection wire, 5...Insulating plate, 11...Bushing case, 12...Karireijin Agent Patent Attorney Takehiko Suzue Figure 1j 4 Figure 3 (a)

Claims (5)

[Claims] (1) Reinforcement reinforcing bars embedded in the foundation concrete on which the gas insulated switchgear body is placed are placed at appropriate intervals, and the intersections of the reinforcing bars are fixed within the specified intervals. A gas insulated switchgear characterized in that the reinforcing bars are electrically connected to a case or a frame of a main body of the gas insulated switchgear at appropriate locations. (2) Reinforcement reinforcing bars embedded in the foundation concrete on which the gas-insulated switchgear body is placed are placed at appropriate intervals, and the intersections of the reinforcing bars are fixed within the specified intervals. to form a grounding mesh, electrically connect the reinforcing bars and the case or frame of the gas-insulated switchgear main body at appropriate points, and install it around the reinforcing bars in the gas-insulated switchgear main body and foundation concrete. A grounding wire is arranged to surround the gas-insulated switchgear main body, and the case and frame of the gas-insulated switchgear main body are connected to the grounding wire at a position near the end of the gas-insulated switchgear main body and the case flange insulation part. A gas insulated switchgear characterized by: (3) Claim No. 2, characterized in that the case and reinforcing bars are electrically insulated at a position near a point where the current flowing through the case of the gas-insulated switchgear main body becomes discontinuous.
Gas insulated switchgear described in ). (4) The gas insulated switchgear according to claim (3), wherein the case and the reinforcing bars are insulated in the commercial frequency range using a capacitor or a nonlinear resistance element. (5) The gas insulated switchgear according to claim (2), wherein a ground mesh made of reinforcing bars and a buried ground wire are electrically connected.