JPH0328135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to power cable connections, particularly rubber-plastic power cable connections.

Generally, when connecting this type of cable, the work of stripping the end coating layer of the cable is as follows:
Everything is done by hand by skilled workers using tools such as knives, glass pieces, and saws.

On the other hand, when looking at this type of connection from an electrical point of view, the strongest electric field is near the end of the cable's external semiconducting layer and near the shield layer provided on the circumference of the conductor connection. Therefore, if the cable insulation layer is scratched with a knife during the previous stage stripping process, or if unevenness is formed on the surface of the shield layer, the insulation performance of the cable connection part will be significantly reduced. It will be put away. For this reason, this type of work requires highly skilled workers.

However, due to the recent shortage of skilled workers, there has been a desire to develop cable connections that can be installed in a short time even by unskilled workers without deteriorating performance.

The present invention has been made in view of the above situation, and it is an object of the present invention to provide a cable connection part that can obtain a good electric field relaxation effect without requiring sophisticated working techniques.

[Summary of the Invention] That is, the gist of the present invention is to use a cable in which an inner semiconducting layer, an insulating layer, a high resistance layer, an outer semiconducting layer, a shielding layer, and a sheath are sequentially formed on a conductor. Both cable conductors are exposed by sequentially stripping off the sheath, shielding layer, external semiconducting layer, and insulating layer at the ends, leaving the high-resistance layer, and then removing the high-resistance layer in a tapered shape toward the tip. The cable conductor is constructed by sequentially forming a shield layer, a high resistance layer for the connection part, an insulating layer, and an external semiconducting layer on the periphery of the cable conductor connection part formed by connecting the cable conductors.

[Embodiment] Next, an embodiment of the power cable connection part of the present invention will be described with reference to the accompanying drawings, in which 1 represents a sheath (omitted) at its own end, a shielding layer 2, an outer semiconducting layer 3 and an insulating layer. 5 is sequentially stripped off leaving the high resistance layer 4, and then the high resistance layer 4 and the insulating layer 5 are tapered off from the outer semiconducting layer 3 side toward the cable tip side to form a rubber layer to be connected to each other. It is a plastic power cable. In addition, although the high resistance layer 4 and the insulating layer 5 are removed in a tapered shape here, this may be performed only for the high resistance layer 4.

High resistance layer 4 left in communication with external semiconducting layer 3
The length is 10 of the length of the insulating layer 5 (i.e. from the edge of the outer semiconducting layer 3 to its own tip).
% or more is good. In other words, the desired electric field relaxation effect can be expected at the end portion of the external semiconducting layer 3 if only this amount is required.

Reference numeral 7 denotes a conductor connecting tube that connects the ends of the conductors 6 of both cables 1 exposed as described above.

8 is the conductor connecting pipe 7 and both cable insulation layers 5
A shielding layer is provided at the end of the periphery, spanning the outer periphery.
A heat-shrinkable tube or the like is used.

Reference numeral 9 denotes a high-resistance layer for a connecting portion provided over the outer periphery of the end of the shield layer 8, both cable insulating layers 5, both cable high-resistance layers 4, both cable external semiconducting layers 3, and both cable shielding layers 2. . For example, a putty-like material, tape, heat-shrinkable tube, etc. can be used for this high-resistance layer 9, but heat-shrinkable tubes are used because they are easy to install and can effectively prevent entrapment of voids. Good to use.
Moreover, the electrical resistance of the high resistance layer 9 has a volume resistivity of 10 ⁸
It is best to set it to ~10 ¹³ Ω-cm. Volume resistivity 10 ⁷ Ω
If it is less than -cm, it will become semi-conductive and may generate heat, and if it is more than 10 ¹⁴ Ω-cm, it will become like an insulator and a sufficient electric field relaxation effect cannot be expected. After all, a good electric field relaxation effect can be expected when the volume resistivity is 10 ⁸ to 10 ¹³ Ω-cm.

Reference numeral 10 denotes a connection insulating layer of a predetermined thickness provided on the periphery of the high resistance layer 9. For example, a twisted layer of insulating tape or a laminated layer of heat-shrinkable tubes may be used for this purpose, but the latter is more suitable in terms of workability.

Reference numeral 11 is an external semiconductive layer for a connecting portion provided on the circumference of the insulating layer 10 so that both ends thereof are in contact with the cable shielding layer 2, and this includes, for example, a wrapped layer of semiconductive tape, A semi-conductive heat-shrinkable tube or a composite tube formed by integrally providing a semi-conductive heat-shrinkable tube around the outer periphery of an insulating heat-shrinkable tube is used.

[Effects of the Invention] According to the power cable connection section of this embodiment configured in this way, the cable high resistance layer provided in advance on the cable is used as the electric field relaxation layer at the end of the cable external semiconducting layer. Therefore, even if there is some electrical defect such as peeling or void entrapment in the vicinity of the external semiconducting layer, the electric field can be effectively relaxed and the practical problem can be solved. Furthermore, since the cable high-resistance layer is tapered off toward the tip side, complete adhesion is achieved in the area surrounded by the three layers: the cable high-resistance layer, the cable insulation layer, and the high-resistance layer for the connection part. As a result, a structure further free from electrical defects can be achieved. Incidentally, if the tip of the cable high-resistance layer has a surface perpendicular to the cable axis direction, a gap is created in the area surrounded by the three layers, and this area becomes electrically unstable. It is easy to become a defective point.

As described above, the present invention can provide a power cable connection portion having excellent electrical performance without requiring particularly sophisticated working techniques, and can be said to have extremely great practical value.

[Brief explanation of the drawing]

The figure is an upper half vertical cross-sectional view showing an embodiment of the power cable connection part of the present invention. 1: Cable, 2: Cable shielding layer, 3: Cable external semiconducting layer, 4: Cable high resistance layer, 5:
Cable insulation layer, 6: cable conductor, 7: conductor connection tube, 8: shield layer, 9: high resistance layer for connection part,
10: Insulating layer for connecting portion, 11: External semiconducting layer for connecting portion.

Claims (1)

[Scope of Claims] 1. A cable to be connected in which an inner semiconducting layer, an insulating layer, a high-resistance layer, an outer semiconducting layer, a shielding layer, and a sheath are sequentially formed on the outer periphery of a conductor; The sheath, the shielding layer, the outer semiconducting layer, and the insulating layer are sequentially stripped off leaving the high resistance layer, and the high resistance layer is further removed in a tapered shape from the outer semiconducting layer toward the cable tip to expose it. a conductor connecting tube that connects both cable conductors to each other; a shield layer formed across the outer periphery of the ends of the conductor connecting tube and the insulating layer of both cables; the shield layer, the high resistance layer of both cables, and the outside of both cables; A high-resistance layer for a connection portion formed across the outer periphery of the end portions of the semiconductive layer and both cable shielding layers, and an insulating layer for a connection portion and an external semiconductive layer formed in sequence around the outer periphery of the high-resistance layer for a connection portion. A power cable connection part characterized by comprising: 2. The power cable connecting portion according to claim 1, which is tapered and removed across the cable high-resistance layer and the cable insulation layer.