JPH06335133A - Connection of cv cable - Google Patents

Abstract

PURPOSE:To provide a connection method with a cable connection part, in which good electric characteristics are obtained and almost no partial discharge is generated. CONSTITUTION:At first, inner conductors of CV cables 1a and 1b are connected electrically and an inner semiconductive layer is formed around the inner conductor connection part. An insulating layer 2 made of uncrosslinked- or semicrosslinked-state polyethylene is formed. Then, a crosslinked tube 5 is put around the insulating layer 2, and the inside of the crossliked tube 5 is charged with a high-pressure electrically negative gas 8 (SF6) so that the insulating layer 2 is put under higher pressure. Then, the insulating layer 2 is heated with a heater 6 that is turned on, and the insulating layer 2 is crosslinked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a molded CV cable in which the connection portion is molded with the same material as the insulator of the CV cable to reinforce the insulation of the connection portion.

[0002]

2. Description of the Related Art In the case of reinforcing an insulating layer of a connecting portion of a CV cable, a mold type connecting portion which heat-molds a material of the same kind as the insulator of the CV cable to reinforce the insulating portion has electrical characteristics and mechanical properties. Excellent in terms of characteristics.

As a method of forming the mold type connecting portion, T
MJ (Taping Molded Joint) method and EMJ (Extrusio
n Molded Joint) method. In the TMJ method, a tape of polyethylene containing a cross-linking agent and irradiated polyethylene (semi-cross-linked polyethylene), which is the same type as the cable insulator, is wrapped around the inner conductor connection to form an insulation layer, and then this insulation layer is pressed. It is a method of heating and molding.
In the EMJ method, an extruder is used to inject a material of the same type as the cable insulator into a mold surrounding the inner conductor connecting portion, and then the material is heated under pressure to form an insulating layer. Is the way.

FIG. 2 is a sectional view showing a conventional method for connecting a CV cable by the EMJ method.

First, two CV cables 11 to be connected
The sheaths at the tips of a and 11b and the insulating layers 12a and 12b are stripped off to expose the internal conductors 13a and 13b. Further, the tips of the insulating layers 12a and 12b are formed into a conical shape.

Next, the inner conductors 13a and 13b of the CV cables 11a and 11b are inserted into the conductor connecting pipe 14 from both sides, and the conductor connecting pipe 14 is compressed to form the inner conductors 13a and 13b.
b are electrically connected to each other. After that, the inner semiconductive layer 15 is formed around the conductor connecting portion.

Next, a mold (not shown) is attached to the periphery of the conductor connecting portion, an uncrosslinked polyethylene containing a crosslinking agent is injected and filled into the mold by an extruder, and the insulating layer 16 is cooled.
To form. In the TMJ method, the insulating layer 16 is formed by winding a tape made of uncrosslinked or semi-crosslinked polyethylene.

Next, the outer shield layer 1 is formed around the insulating layer 16.
7 is formed, and a bridging pipe (not shown) is attached so as to surround the insulating layer 16. Then, an inert gas such as high-pressure nitrogen gas is sealed in the cross-linking tube, and the insulating layer 16 is heated by the heater provided in the cross-linking tube.
The polyethylene of the insulating layer 16 is crosslinked. Then CV
A protective copper tube 18 is attached to the stripped portion of the cables 11a and 11b, and an end portion of the protective copper tube 18 is reinforced with a metal water blocking layer 19, a water blocking tape layer 20, an anticorrosion tape 21, and the like. This completes the connection of the CV cable.

[0009]

However, the above-mentioned conventional CV cable connection method has the following problems. That is, in the TMJ method, since the tape is wound at the work site, voids are likely to occur between the tapes. At the work site, although the environment is managed to remove dust and the like, it is difficult to completely remove foreign matter, so foreign matter may be mixed between the tapes,
A protrusion may be formed. Further, also in the EMJ method, voids may be generated in the mold layer or foreign matter may be mixed in. If there are voids, foreign matter, protrusions, or the like in the insulating layer, partial discharge is likely to occur at that portion, and the reliability of the cable connection portion is reduced.

The present invention has been made in view of the above problems. Even if a void or foreign matter is mixed in the mold layer, the occurrence of partial discharge can be suppressed and the reliability of the cable connecting portion can be improved. It is an object to provide a CV cable connection that can be improved.

[0011]

A method of connecting a CV cable according to the present invention comprises a step of electrically connecting the internal conductors of a plurality of CV cables to each other to form an internal conductor connection part, and the internal conductor. A step of forming an insulating layer composed of an insulating material in an uncrosslinked or semi-crosslinked state around the connection part, and a step of heating the insulating layer with a heat source while pressurizing the insulating layer with an electrically negative gas to crosslink the insulating material. And the electrically negative gas is SF ₆ .

[0012]

In the present invention, an electrically negative gas (SF ₆ ) is used as a pressurized gas when the insulating layer made of an uncrosslinked or semi-crosslinked insulator is pressurized and heated to be crosslinked. . The SF ₆ penetrates inside the voids or around the foreign matters or protrusions in the insulating layer during pressurization and heating, and is enclosed inside the voids or around the foreign matters or protrusions by the cross-linking of the insulating layer. SF ₆ has an excellent insulating property and is unlikely to generate sparks, and therefore has a high partial discharge inception voltage. Therefore, even if there are voids or foreign matter inside the insulating layer after cross-linking, partial discharge is less likely to occur, and the reliability of the cable connection portion can be improved.

[0013]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a method of connecting a CV cable according to an embodiment of the present invention. This embodiment is different from the conventional one in that an electrically negative gas (SF
₆ ) is to pressurize the insulating layer, and other configurations are basically the same as the conventional one.

In the present embodiment, first, as in the conventional case, the inner conductors 1a and 1b of the two CV cables are electrically connected to each other by using a conductor connecting pipe, and the inner conductors are connected around the inner conductor connecting portion. After the semiconductive layer is formed, the insulating layer 2 made of uncrosslinked or semicrosslinked polyethylene is formed around the inner conductor connecting portion. The insulating layer 2 may be formed by extruding uncrosslinked or semi-crosslinked polyethylene into a mold by the EMJ method, or TMJ.
It may be formed by winding an uncrosslinked or semi-crosslinked polyethylene tape around the inner conductor connecting portion by a method. After that, the outer shielding layer 3 and the edging portion 4 are formed around the insulating layer 2.

Next, C is formed so as to surround the insulating layer 2.
The bridge pipe 5 is attached to the V cables 1a and 1b. A heater 6 is provided on the inner peripheral surface of the bridge tube 5, and seal members 7 are provided at both ends. After attaching the bridge pipe 5 to the CV cables 1a and 1b, the bridge pipe 5
A high pressure electrically negative gas (SF ₆ ) 8 is filled therein. Since the seal members 7 are provided at both ends of the bridge tube 5,
The inside of the cross-linking pipe 5 is maintained at a high pressure. After that, the heater 6 is energized to heat the insulating layer 2 and crosslink the polyethylene. In this pressurizing and heating step, the electrically negative gas 8 penetrates into the voids existing in the insulating layer 2 or around the foreign matters or protrusions, and when the cross-linking of polyethylene is completed, the voids or the surroundings of the foreign matters or protrusions. It will be in the state of being enclosed in.

Thereafter, as in the conventional case, a protective copper pipe is attached to the stripped portion of the sheath, and the end portion of the protective copper pipe is reinforced with a metal water-blocking layer, a water-blocking tape layer, an anticorrosion tape, or the like. This completes the connection of the CV cable.

In this embodiment, since the electrically negative gas is filled in the voids existing in the insulating layer or around the foreign matter or the protrusion, partial discharge is unlikely to occur and the electrical characteristics of the CV cable are remarkably high. improves.

In the above embodiment, the case where only the SF ₆ is filled in the bridge pipe has been described.
₆ and a fluorocarbon liquid (C ₈ F ₁₆ O) may be used in combination.

[0020]

As described above, according to the present invention, the insulating layer is present in the insulating layer because the insulating layer is pressed by the electrically negative gas when the insulating layer is pressed and heated for crosslinking. The electrically negative gas is filled in the void or around the foreign substance or the protrusion, and the starting voltage of the partial discharge is increased, resulting in CV
It is possible to obtain the effect that the reliability of the connection portion of the cable is significantly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method for connecting a CV cable according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional method for connecting a CV cable.

[Explanation of symbols]

 1a, 1b, 11a, 11b; CV cables 2, 12a, 12b, 16; insulating layer 3, 17; external shielding layer 5; bridge tube 6; heater 7; sealing member 8; electrically negative gas 13a, 13b; internal Conductor 14; Conductor connection tube 18; Protective copper tube

Claims (1)

[Claims] 1. A step of electrically connecting the inner conductors of a plurality of CV cables to each other to form an inner conductor connecting portion,
A step of forming an insulating layer made of an insulating material in an uncrosslinked or semi-crosslinked state around the inner conductor connecting part, and heating the insulating layer with a heat source while pressurizing the insulating layer with an electrically negative gas to form the insulating material. It includes a step of crosslinking, the, CV method for connecting a cable, wherein the electrically negative gas is SF _6.