JP7457301B2 - Lightning protection methods for electrical facilities - Google Patents

Description

The present invention relates to technology for protecting electrical facilities from lightning.

For example, in addition to wireless relay stations, advanced information buildings, high-tech factories, and other electrical facilities such as power generation and substations, power transmission and distribution lines, and information and communication systems, semiconductor systems and other electrical equipment must be reliably protected from lightning surges. Lightning protection measures are necessary. Lightning protection measures here refer to energy processing measures to minimize the effects of lightning strikes on electrical equipment such as semiconductor systems that are susceptible to lightning surges.

In Patent Document 1, in a structure housing electrical equipment in which a lightning transformer is inserted in the input power line, a ring grounding wire is provided around the structure, and an insulated wire connecting the lightning strike point and the ring grounding wire is connected to the outer wall of the structure. A lightning protection method for electrical facilities is disclosed, in which the grounding of the electrical facilities is provided in a ring ground wire.

Patent No. 3143882

Here, Patent Document 1 states that if an insulating wall plate is buried entirely or partially in the inner circumference of the annular ground wire, it is possible to further suppress the intrusion of charges into the inside of the annular ground wire. (paragraph [0014]). However, in reality, it is difficult to place the boards underground, and furthermore, it is extremely difficult to bury the insulating wall boards at specific positions along the inside of the ring grounding wire. It is. Furthermore, there is no specific information on how to bury the electrical equipment. It is unknown.

In view of the above-mentioned problems, the present invention provides a lightning-proofing method for electrical facilities that is easy to implement.

In one aspect of the present invention, in the lightning protection method for an electrical facility, the electrical facility is provided with a lightning protection grounding electrode that is independent of the grounding electrode of the electrical facility around the electrical facility, and the grounding electrode of the electrical facility is An insulating material is laid between the ground electrode and the ground electrode for lightning protection, at a position spaced apart from the ground electrode for lightning protection, from the surface of the earth toward below the ground. The insulating material is a sheet-like insulating material, or a sheet with an insulating material sprayed onto it. The insulating material is laid down to a predetermined depth from the ground surface, and the predetermined depth is in a range of 50 cm to 2 m.

According to this embodiment, an insulating material is laid between the ground electrode of the electrical facility and the lightning protection ground electrode independent of the ground electrode of the electrical facility from the ground surface toward the lower part of the ground. This allows the laid insulating material to suppress the lightning current flowing into or out of the electrical facility during a lightning event. In addition, the insulating material is not required to be laid along the inside of the lightning protection ground electrode, but is required to be laid at a position spaced apart from the lightning protection ground electrode, so that the degree of freedom in the position where the insulating material is laid is increased, and construction is facilitated. Note that the "ground surface" here includes the surface of the ground or a part slightly buried below the surface of the ground. In addition, the insulating material is not required to be a wall panel, but may be a sheet-like insulating material or a sheet sprayed with insulating material, so construction is further facilitated. In addition, the insulating material is required to be laid to a depth of 50 cm to 2 m from the ground surface, so that construction is further facilitated.

According to the present invention, it is possible to easily install an insulating material for suppressing lightning current flowing into or flowing out of electrical facilities when lightning occurs.

Configuration example of electrical facility to which lightning protection method according to embodiment is applied A schematic vertical cross-sectional view of the configuration example in FIG. 1 Another configuration example of an electrical facility to which the lightning protection method according to the embodiment is applied Other configuration examples of electrical facilities to which the lightning protection method according to the embodiment is applied Another configuration example of an electrical facility to which the lightning protection method according to the embodiment is applied

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment)
FIG. 1 is a diagram showing an example of the configuration of an electrical facility to which a lightning protection method according to an embodiment is applied. Further, FIG. 2 is a schematic longitudinal sectional view of the configuration example of FIG. 1.

As shown in FIG. 1, a station building 2 in which various equipment 3 is arranged is installed under a steel tower 1. The station building 2 is an example of an electrical facility to be protected from lightning. The tower foot 4 of the steel tower 1 and the steel frame 5 of the station building 2 are electrically connected. A ground electrode 11 is provided in the ground surrounding the station building 2. The steel frame 5 of the station building 2 is electrically connected to this ground electrode 11, and the ground of the equipment 3 arranged in the station building 2 is also connected.

A lightning rod 6 is provided on top of the steel tower 1. In the configuration example of FIG. 1, an insulated electric wire 7 arranged along the outer wall of the steel tower 1 and the station building 2 is used as the down conductor of the lightning rod 6. A ring-shaped ground wire 12 for lightning protection is provided in the ground around the station building 2, further outside the ground electrode 11. In FIG. 2, the depth of the ring-shaped ground wire 12 is deeper than the depth of the ground electrode 11. The ring-shaped ground wire 12 is an example of a ground electrode for lightning protection. The ring-shaped ground wire 12 is independent of the ground electrode 11. The insulated electric wire 7 is electrically connected to the ring-shaped ground wire 12.

When lightning strikes, if the lightning current is downward, the current from the thundercloud flows from the lightning rod 6 toward the ground, and spreads widely underground. This current is more likely to flow toward the annular ground wire 12, because of the high resistance in the soil between the ground electrode 11 and the annular ground wire 12. On the other hand, if the lightning current is upward, the current flows from the ground toward the lightning rod 6, but because the resistance in the soil between the ground electrode 11 and the annular ground wire 12 is high, it is less likely to flow toward the ground electrode 11, and instead flows from the annular ground wire 12 toward the lightning rod 6. This makes it possible to suppress the lightning current flowing to the ground electrode 11, and the equipment 3 in the station 2 is protected from lightning surges.

In the lightning protection method according to the present embodiment, an insulating material 13 is laid between the grounding electrode 11 and the annular grounding wire 12 at a position spaced from the annular grounding wire 12 from the ground surface downward underground. . This insulating material 13 further increases the electrical resistance between the ground electrode 11 and the annular ground wire 12, so that lightning current flowing through the ground electrode 11 can be further suppressed. Note that, from the viewpoint of appearance, the upper end of the insulating material 13 may be slightly buried below the soil, or may be visible separately from the soil. That is, the "ground surface" here includes the surface of the ground or a portion slightly buried below the surface of the ground.

The insulating material 13 is, for example, a sheet-like insulating material. Alternatively, the insulating material 13 is a sheet onto which the insulating material has been sprayed. For example, the insulating material 13 is laid by attaching a sheet such as a mesh to the ground surface and spraying the insulating material onto the sheet. The insulating material 13 is laid to a predetermined depth from the ground surface. This predetermined depth is, for example, about 50 cm. Alternatively, this predetermined depth is about 1 m. It is preferable that the depth at which the insulating material 13 is laid is, for example, in the range of 50 cm to 2 m.

Here, the findings obtained by the inventors of the present application will be explained. These findings are unique and were obtained through numerical simulations and experimental verification conducted by the inventors.

First, regarding the position where the insulating material is placed, it was found that there is no difference in effectiveness depending on the placement position as long as it is between the ground electrode and the lightning protection ground electrode. Specifically, when an insulating material is provided at a depth of several tens of centimeters from the ground surface, whether the insulating material is near the grounding electrode, near the lightning protection grounding electrode, or between the grounding electrode and the lightning protection grounding electrode, There was no difference in the effect even at a position midway between the ground electrode and the ground electrode. That is, it has been found that the insulating material does not need to be placed along the inside of the lightning protection ground electrode, and may be placed freely between the ground electrode and the lightning protection ground electrode.

As for the thickness of the insulating material, it was found that if a material with an insulating strength of about 15 kV/mm is used, a thickness of about 1 mm can adequately withstand the overvoltage generated when a direct lightning strike occurs with a current of about 200 kA. In this case, materials that can be used as insulating material include, for example, polyvinyl chloride and rubber. In other words, it was found that it is not necessary to provide a wall panel as insulating material, and that, for example, sheet-like insulating material can be used.

Furthermore, regarding the size of the insulating material in the depth direction, it was found that lightning protection effects can be obtained as long as the size is about several tens of centimeters from the ground surface. Further, if the size in the depth direction is set to about 1 m, a greater lightning protection effect can be obtained, and if the size in the depth direction is further increased, the lightning protection effect is improved. On the other hand, as the depth increases, the electric field strength applied to the insulating material during a lightning strike increases, so the insulating material must be made thicker. Considering the lightning protection effect, the thickness of the insulating material, and the ease of construction, it has been found that the depth at which the insulating material is laid is preferably in the range of, for example, 50 cm to 2 m.

Therefore, according to this embodiment, the insulating material 13 is laid between the grounding electrode 11 of the station building 2 and the annular grounding wire 12 that is independent of the grounding electrode 11 from the surface of the ground toward the lower part of the ground. Thereby, when lightning occurs, the lightning current flowing through the ground electrode 11 can be suppressed by the installed insulating material 13. Furthermore, since the insulating material 13 need only be laid at a position away from the annular grounding wire 12 rather than at a position along the inside of the annular grounding wire 12, the degree of freedom in the location where the insulating material 13 is laid is increased, and construction is easier. becomes easier.

In addition, the insulating material 13 may be a sheet-like insulating material or a sheet with an insulating material sprayed onto it, instead of a wall plate, which further facilitates construction. Furthermore, since the insulating material only needs to be laid to a depth of 50 cm to 2 m from the ground surface, construction becomes easier.

Although the grounding electrode 11 and the annular grounding wire 12 are illustrated so as to surround the entire circumference of the station building 2, they are not limited to this. may be provided. Further, although the insulating material 13 is illustrated so as to surround the entire circumference of the station building 2, the insulating material 13 is not limited to this. It suffices if it is installed in the specified position.

(Other configuration examples)
FIG. 3-5 is a diagram showing another example of the configuration of an electrical facility to which the lightning protection method according to the embodiment is applied.

In the configuration example shown in FIG. 3, a structure is used as the down conductor of the lightning rod 6. Specifically, the tower pedestal 4 of the steel tower 1 and the steel frame 5 of the station building 2 are used as the down conductor of the lightning rod 6. That is, the tower legs 4 of the steel tower 1 and the steel frame 5 of the station building 2 are electrically connected, and the steel frame 5 is connected to the annular grounding wire 12 by the insulated wire 8. An insulating material 13 is laid between the ground electrode 11 and the annular ground wire 12 from the ground surface downward into the ground.

In the configuration example shown in FIG. 4, the steel tower 1 and the station building 2 are installed apart from each other. The ground electrode 11 is provided underground around the station building 2. An annular grounding wire 12 for lightning protection is provided so as to surround the steel tower 1 and the station building 2. A tower pedestal 4 of the steel tower 1 is used as a down conductor for the lightning rod 6, and the tower pedestal 4 is connected to an annular grounding wire 12 by an insulated wire 9. An insulating material 13 is laid between the ground electrode 11 and the annular ground wire 12 from the ground surface downward into the ground. The insulating material 13 is provided so as to surround the station building 2, but not the periphery of the steel tower 1.

In the configuration example shown in FIG. 5, a station building 2 that is to be protected from lightning is adjacent to a steel tower 1 that has a high risk of receiving a direct lightning strike. A lightning rod 6 on the steel tower 1 is connected to a ground electrode 21 provided underground around the steel tower 1 via a tower pedestal 4. In the station building 2, the grounding electrode 11 is provided underground around the station building 2, and the annular grounding wire 12 for lightning protection is provided so as to surround the station building 2 and the grounding electrode 11. An insulating material 13 is laid between the ground electrode 11 and the annular ground wire 12 from the ground surface downward into the ground.

The configuration example shown in FIGS. 3-5 also provides the same effects as the embodiment described above. That is, by laying the insulating material 13 from the ground surface downward underground between the grounding electrode 11 of the station building 2 and the ring-shaped grounding wire 12 independent of the grounding electrode 11, the station Lightning current flowing through the ground electrode 11 of the building can be suppressed. Furthermore, since the insulating material 13 need only be laid at a position away from the annular grounding wire 12 rather than at a position along the inside of the annular grounding wire 12, the degree of freedom in the location where the insulating material 13 is laid is increased, and construction is easier. becomes easier.

Note that the lightning protection method according to the present embodiment may include a step of providing a grounding electrode for lightning protection in addition to the step of laying an insulating material. Further, in the lightning protection method according to the present embodiment, for example, when constructing an electrical facility, a grounding electrode for the electrical facility is provided, a lightning protection grounding electrode is provided, and an insulating material is further laid.

The present invention is useful for lightning protection of electrical facilities because it is possible to easily install an insulating material for suppressing lightning current flowing into or flowing out of electrical facilities when lightning occurs.

2 Station building (electrical facilities)
11 Grounding electrode 12 Annular grounding wire (grounding electrode for lightning protection)
13 Insulating material

Claims (1)

A lightning protection method for electrical facilities, the method comprising:
The electrical facility is provided with a lightning protection grounding electrode that is independent from the grounding electrode of the electrical facility around the electrical facility,
Between the grounding electrode of the electrical facility and the lightning protection grounding electrode, an insulating material is laid at a position away from the lightning protection grounding electrode from the ground surface downward underground;
The insulating material is a sheet-like insulating material, or a sheet with an insulating material sprayed on it ,
The insulating material is laid from the ground surface to a predetermined depth,
The predetermined depth is in a range of 50 cm to 2 m.
A lightning protection method for electrical facilities characterized by the following.

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