JPH0423486B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a connecting part of a power cable.
This relates to the connection of solid insulated cables such as plastic.

(Prior art and its problems) A structure as shown in FIG. 1 is adopted for the connection part of this type of power cable. In Fig. 1, 1 is a cable insulator such as rubber or plastic, 2 is a conductor, 3 is an internal semiconductive layer of the cable, 4 is a sleeve, 5 is an internal semiconductive layer of a connecting part, and 6 is a rubber or plastic cable. It is an insulator for connection parts such as.

That is, in the above case, the cable insulator 1 is pencil-sharpened (the insulator is sharpened with a slope), the semiconductive layer 3 is exposed inside the cable, and the conductor 2 is
The inner semiconducting layer 5 of the connecting portion is placed over the sleeve 4 to which the cable is connected, so as to contact and bridge the inner semiconducting layer 3 of the cable.

However, scraping out the interface between the pencil sharpener and the cable's internal semiconducting layer is a manual process, and this process is difficult. There was a possibility that this would significantly reduce the electrical performance of the connection. That is, since the processing work is manual work, the skill of the worker is an important factor, that is, a factor that determines the electrical performance of the connection part.

(Structure of the Invention) The present invention has been developed in view of the above, and provides a connection portion of this type that is easy to work with and has stable electrical performance.

That is, the connection portion of the power cable of the present invention is made of rubber,
In a solid insulated cable connection section made of plastic or the like, the internal semiconducting layer of the cable on the conductor overlaps the internal semiconducting layer of the connection section on the sleeve, and the overlapping cable has a cable between both semiconducting layers of the connection section. It is characterized by leaving an insulating layer.

The invention will now be explained in detail with reference to the illustrative drawings, in which: FIG. In FIG. 2 showing the present invention, 1 is a cable insulator, 2 is a conductor, 3 is an internal semiconducting layer of the cable, 4 is a sleeve, 5 is an internal semiconducting layer of a connection part,
As in FIG. 1, 6 is a connection insulator.

However, in the present invention, it is performed as follows.

When pencil-sharpening the insulator 1 of the cable, the internal semiconducting layer 3 of the cable is not exposed, and only a thickness t of 3 mm or less is left in the insulator portion without the slope. On the remaining insulator is a semiconducting layer 5 inside the connection part.
overlap. The overlapping length L is 0.5 mm or more.

By overlapping, local electric field concentration can be avoided. Furthermore, when sharpening the cable insulator, the internal semiconducting layer of the cable is not exposed, making the work easier.

In the above, the connecting portion may be formed by various methods such as an extrusion mold joint, a tape-wound joint, a prefabricated joint, etc.

Experimental results will be described below to aid understanding of the present invention.

Figure 3 shows the electrical breakdown test results of connection samples, where A is a sample with a conventional structure (Figure 1) in which the internal semiconducting layer has been removed too much and the conductor is in contact with the connection insulator, and B is a sample with the conventional structure (Figure 1). Figure 1) shows a sample in which the internal semiconducting layer is uniformly present, and C shows a sample with the structure of the present invention (Figure 2). The above test was conducted using a tape-wrapped connection of a 66KV1 x 150mm ² CV cable.

As shown in FIG. 3, sample C having the structure of the present invention has electrical breakdown characteristics equivalent to that of B having the conventional structure (when the internal semiconducting layer is uniformly present: when there are no mistakes).

This shows that the structure of the present invention has a structure that can prevent work errors like A.
This prevents the electrical insulation performance of the connection portion from significantly deteriorating.

(Effects of the Invention) Although the present invention has been described above, the present invention has the following advantages.

Since the cable insulation is usually left with a thickness of 3 mm or less, it is possible to prevent the conductor from coming into direct contact with the connection part insulation due to accidental damage. Therefore, even in a cable having a thin internal semiconducting layer, the internal semiconducting layer is not scratched too much, and the conductor does not come into contact with the connecting portion insulator, which causes a deterioration in the electrical insulation performance of the connecting portion.

Local electric field concentration is almost eliminated by overlapping the internal semiconducting layer of the connecting portion to a length L which is usually 0.5 mm or more. Therefore, there is almost no local electric field concentration at the edges where the cable insulation remains.

The thickness t of the remaining cable insulation was determined by electric field analysis, and it was found that 3 mm or less was sufficient. Therefore, the remaining thickness of the cable insulation is 3
Easy to work with a wide likelihood of less than mm.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view for explaining the connecting part of a conventional power cable, and Fig. 2 is a vertical cross-sectional view (Fig. a) for explaining the connecting part of the power cable of the present invention, and its circled x An enlarged view of the section (Fig. b) and Fig. 3 respectively illustrate diagrams for explaining the experimental results of the present invention. DESCRIPTION OF SYMBOLS 1...Cable insulator, 2...Conductor, 3...Inner semiconducting layer of cable, 4...Sleeve, 5...
Internal semiconducting layer of the connection part, 6...connection part insulator.

Claims (1)

[Scope of Claims] 1. A cable in which a cable internal semiconducting layer on a conductor and a connecting portion internal semiconducting layer on a sleeve overlap in a solid insulated cable connection portion made of rubber, plastic, etc.
A connecting portion of a power cable, characterized in that a cable insulation layer is left between both semiconductive layers of the connecting portion. 2. The connecting portion of a power cable according to claim 1, wherein the cable insulating layer left between both semiconductive layers of the cable and connecting portion has a thickness of 3 mm or less. 3. The connecting portion of a power cable according to claim 1, wherein the length of overlap between both semiconductive layers of the cable and connecting portion is 0.5 mm or more.