JPH0256780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grounding device that reduces the grounding resistance of a grounded object such as a power transmission tower.

Lightning rods and the like installed on power transmission towers or buildings are grounded with low resistance to the earth through ground wires (buried ground wires, ground electrodes). However, even if the ground wire is directly buried in the soil, it may not be possible to obtain the desired resistance value depending on the soil quality. In such cases, a material that reduces the resistance value is buried in a trench or vertical hole dug in the ground along with the ground wire to ensure an appropriate resistance value.

Conventionally, grounding devices of this type have used copper sheet or a mixture of gypsum and an electrolyte, or a mixture of carbon produced from coal or petroleum and an alkaline cement as a grounding resistance reducer.

However, for example, in grounding equipment that uses a mixture of gypsum and electrolyte, it is necessary to mix water during mixing, which is inconvenient for construction in mountainous areas where water is difficult to obtain. The drawback was that it flowed to the lower part of the slope, making it difficult to work. In addition, in equipment that uses a mixture of carbon granules produced from coal, petroleum, etc. and an alkaline caking agent, it is not necessary to mix water.
Since the production of carbon grain powder itself requires a complicated process,
The disadvantage is that the price is high.

The present invention was made to solve the drawbacks of such conventional grounding devices, and uses inexpensive rock powder produced from a naturally abundant rock commonly called serpentinite, simply or This is a grounding device that is constructed by making a mixture with an alkaline solidifying material such as cement material and constructing it without adding water.

An example of the grounding device of the present invention will be explained based on FIG.

1 is a grounding device; 2 is a groove drilled in the ground 4 near the earthed object 3 when constructing the earthing device 1; and 5 is a grounding wire connected to the earthed object 3 installed in the groove 2. or the ground electrode 6 is buried in the slot 2 together with the ground wire 5.
It consists of one of the substances shown in Items 1 and 2 and covering soil 7 formed by covering the upper surface of this substance 6 to an appropriate thickness.

In the grounding device 1 configured as described above, the substance 6 spread within the slot 2 is in the form of powder.
It has good contact with the ground, and can be sprayed while adapting to the shape of the slot 2, increasing the utilization of the slot 2.

Next, an experimental example of the grounding device according to the present invention will be explained below.

The following samples were prepared for use in this grounding device.

Sample 1 Rock powder produced from serpentinite Sample 2 A mixture of rock powder produced from serpentine at a weight ratio of 1 to cement material 0.1 Sample 3 Rock powder produced from serpentine at a weight ratio of 1 Mixture sample 4 made by mixing 0.3 of cement material with serpentinite in a weight ratio of 1 to 0.5 of cement material.The specific resistance of Examples 1 to 4 above was adjusted to saturated moisture conditions. The measured results are shown in Table 1. As can be seen from the table, the specific resistance of sample 1 is 6.9KΩ-
cm, and the specific resistance of Samples 2, 3, and 4 is 0.21 to 1.3 KΩ-cm, and all samples are practically perfect in soils (specific resistance of about 20 KΩ-cm or more) in areas where it is difficult to secure the required ground resistance value. It can be seen that it is a good substance as a grounding resistance reducing agent because it can be regarded as a conductor.

Figures 2 and 3 show an experimental example of a grounding device using Samples 1 and 3, and Figure 3 shows an earth wire with the dimensions and shape shown in Figure 2, the same shape as in Figure 2, and a width of 0.5 m. In the case of the earthing device of the present example, which was arranged in a slot with a depth of 0.5 m and was constructed by spraying sample 1 at a rate of 16 kg per 1 m ² of the slot without adding water (Fig. 3A),
In the case of the grounding device of this example (Fig. 3B), in which sample 3 was sprayed in place of sample ¹ at a rate of 16 kg per square meter of slot without adding water, and in the case of the earthing wire with the shape shown in Fig. 2. When simply buried in the ground (Figure 3C)
The measurement results show that the grounding device of this embodiment can reduce the grounding resistance by 35% compared to a case where the ground wire is simply buried in the ground.

As mentioned above, the mechanism by which the grounding device of the present invention exhibits a remarkable effect is that the rock powder produced from serpentinite alone or in a mixture mainly composed of it dissolves alkaline magnesium or calcium, etc. This is thought to be because it neutralizes the slightly acidic water contained in the soil and concentrates and absorbs ions that lower the resistivity in the water.

It should be noted that the weight mixing ratio of the substance to be buried together with the ground wire or ground electrode described in claim 2 may be such that the specific resistance of the mixture is sufficiently smaller than the specific resistance of the soil in which it is to be buried. . Specifically, for the mixture described in Section 2, serpentine powder 1
It is about 1 to 0.1 to the alkaline solidifying material.

As described above, the grounding device according to the present invention uses inexpensive serpentine powder as a grounding resistance reducing agent, and therefore is very economical, with the cost being about half that of conventional devices. Moreover, since no water is required for construction, it has excellent workability even in mountainous areas, and because it does not include the temporary ground resistance reduction effect caused by water as in the past, the construction resistance value is the true or similar ground resistance. It can be understood as such and construction can be carried out efficiently. Furthermore, since serpentine powder alone or a mixture containing serpentinite powder as a main component is powdery and has no fluidity, it can be easily applied even on slopes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the grounding device according to the present invention, FIG. 2 is an explanatory diagram of an experiment in the present invention, and FIG.
The figure is a graph showing the measurement results in the experiment shown in FIG. 1... Earthing device, 2... Groove, 3... Earthed object, 4... Earth, 5... Earth wire, 6... Grounding resistance reducing agent, 7... Soil covering.

【table】

Claims (1)

[Claims] 1. Grounding of an earthed body connected to a ground wire or ground electrode by burying rock powder produced from serpentinite together with a ground wire or ground electrode in a trench or vertical hole excavated in the ground. A grounding device characterized by reducing resistance. 2. The grounding device according to claim 1, wherein the material buried together with the grounding wire or the grounding electrode is a mixture of rock powder produced from serpentinite and an alkaline consolidation material.