JPS6015386Y2 - Cable grounding part - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an improvement of the cable grounding section.

Generally, at the aerial termination of a cable line, as shown in Figure 1, there is a 60-
Grounding wire 2 made of 0V vinyl electric wire (hereinafter referred to as IV), etc.
is installed.

By the way, in cable lines of 275 kV or 500 kV class ultra-high voltage systems, when an air circuit breaker is turned on, a high-frequency sheath surge occurs between the cable sheath 3 and surrounding metal members such as the pedestal 4 or cleats. However, this sheath surge may create a hole in the oil supply AI pipe 5, causing an oil leakage accident.

This accident is thought to be due to the large inductance component of the impedance of the ground wire at the end of the cable.

However, in the past, the size and installation method of this grounding wire was only considered based on the magnitude of fault current on the line.

This invention was made with attention to these points, and IV
The above-mentioned drawbacks are attempted to be overcome by using a cylindrical grounding fitting having an annular flange at the upper end in place of the grounding wire.

Hereinafter, the present invention will be explained based on the drawings of one embodiment.

In FIG. 2, the aerial cable terminal end 6 is set perpendicularly to the ground via a pedestal 7.

On the outer periphery of the lower copper tube 8 constituting the cable termination part, there is a third
As shown in the figure, a cylindrical grounding fitting 10 having an annular flange 9 formed at its upper end is fitted, and the entire or part of the inner circumference of the flange is connected to the lower copper pipe 8, and the vicinity of the outer edge is connected to the pedestal 7. are electrically connected to each other.

The grounding fitting 10 is disposed to cover the manhole neck 11, and its lower outer peripheral edge is grounded.

As shown in FIG. 4, the grounding fitting 10 is made of a highly conductive plate or wire made of copper or aluminum, and has a mesh 12 of about 10 to 20 cr.
It is also possible to carve it out of a mesh-like object and make it into a basket shape.

When forming a cage-shaped grounding metal fitting, it is desirable to have a fine mesh, and all positions where wires or plates intersect are electrically connected.

Incidentally, since the total cross-sectional area of the grounding fitting 10 is determined by the magnitude of the fault current, from the viewpoint of suppressing sheath surge, the characteristics are better when the cable 13 is surrounded without gaps.

Therefore, it is preferable that the grounding fitting 10 be of a sealed type all around rather than having a cage shape.

However, when a cage-shaped grounding member is used as a grounding metal fitting, there is an advantage that maintenance and inspection of the cable is easy because even if the cable itself is surrounded by the cage-shaped member, the inside of the cable can be seen.

It is preferable that the grounding fitting 10 is divided into two parts, for example, so that it can be easily attached or removed.

As described above, in the present invention, a cylindrical grounding fitting with an annular flange is inserted into the outer periphery of the lower copper pipe, and the flange is connected to the lower steel pipe, and the outer periphery of the lower end is connected to the ground. It is possible to provide a cable grounding section whose impedance can be significantly reduced compared to conventional ones, thereby suppressing the occurrence of sheath surge.

In addition, in the present invention, since the manhole entry is shielded with a lower flange, only the portion above the lower copper pipe is exposed above the ground.

In other words, the cable portion below the lower copper tube is housed in a kind of shield room, further improving the electrical characteristics.

Furthermore, the grounding metal fitting of the present invention can reduce its impedance to about 110 or less when compared with a conventional grounding wire, so that the sheath surge voltage can be reduced to 1/10 or less of the conventional grounding wire.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional cable grounding part, Fig. 2 is an explanatory diagram of the cable grounding part of the present invention, Fig. 3 is a perspective view of a grounding fitting, and Fig. 4 shows another embodiment of the grounding fitting. It is a schematic perspective view. 8... Lower copper pipe, 9... Flange, 1
0...Grounding metal fitting, 11...Manhole neck, 13...Cable sheath.

Claims (1)

[Claims for Utility Model Registration] 1. A cylindrical grounding fitting with an annular flange formed at the upper end is fitted onto the outer periphery of the lower steel pipe constituting the cable termination, and the flange of this fitting is electrically connected to the lower copper pipe. A cable grounding section characterized by connecting and grounding the lower end. 2. The cable grounding part according to claim 1 of the utility model registration claim, in which the grounding metal fitting is formed of a mesh-like material.