JPS608509Y2 - Cable end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a cable termination, and particularly to a cable termination with improved corona discharge characteristics.

Recently, when forming the terminations of high voltage cables, especially rubber/plastic insulated high voltage cables, in order to make this intense work easy and speedy, so-called coneless types, which do not form stress cones on the cable insulation, are being used. Cable terminations are often used.

As shown in FIG. 1, such a coneless type cable termination section is made of a high-permittivity heat-shrinkable material extending from the cable outer semiconducting layer 1 or cable shielding layer 2 to the cable insulating layer 3 where electrical stress is concentrated. It is known that the tube 4 is closely covered.

However, in the cable termination section with such a configuration, as shown in FIG. 2, which is an enlarged view of the circled area in FIG. This gap easily occurs, and this gap deteriorates the corona discharge characteristics at the end of the cable.

For this reason, silicone grease is applied to the gap at the end of a coneless type cable that uses a heat shrink tube, but in such a case,
There are disadvantages such as the silicone grease spreading to areas other than where it is needed, and areas where it is insufficiently filled.

Furthermore, JP-A No. 52-21695 discloses that a semiconductive compound or a soft tape-like material is applied to the stepped portion between the cut end of the semiconductive layer of the cable and the cable insulator so as to communicate with the semiconductive layer of the cable. A cross-linked material that is smoothly arranged or wrapped to fill the above-mentioned step part using a heat-shrinkable material, and then a heat-shrinkable tube with a high dielectric constant is placed over it, or a heat-shrinkable tape is wrapped around it to shrink it by heating. A method of terminating a polyethylene vinyl sheathed cable is disclosed.

However, with this method, it is not possible to provide sufficient shrinkage force to the heat-shrinkable tube or heat-shrinkable tape.
Furthermore, when heat-shrinkable tubes are used, air bubbles are easily trapped, and when heat-shrinkable tape is used, there is a step at the interface due to the tape edge, which becomes an electrically discontinuous surface, making it difficult to demonstrate sufficient electrical properties. The problem was that it was not possible.

In order to address these difficulties, the present applicant first developed an α-olefin copolymer that contains 1 part by weight of an α-olefin copolymer that is crosslinked with an organic peroxide and contains a large amount of tertiary carbon atoms that are decomposed by the organic peroxide. Polymer 10-100! The base material mainly consists of i parts,
Titanium compound 100-65 parts, carbon black 1
A composition sheet containing 0 to 9 parts by weight and 1 to 1 part by weight of an organic peroxide such as dicumyl peroxide is heated to crosslink the α-olefin copolymer and to crosslink the third copolymer.
Developed electric field relaxation self-fusion by decomposing a polymer containing a large amount of carbon atoms, and applied for a patent (Japanese Patent Publication No. 57-5
187 dirt).

This electric field mitigation self-fusing tape can be simply wrapped from the outer semiconducting layer at the end of the cable to between the cable insulation layers.
Due to its self-bonding properties, it adheres closely to the cable insulation layer to form an integrated welding layer and exhibits an excellent electric field mitigation effect.

However, at the stripped end of the cable, there is a step between the cable external semiconducting layer and the cable insulation layer, so even when this self-bonding tape is used, gaps often occur at the step. In this case, there was a problem that the initial characteristics could not be developed.

The present invention was developed by focusing on these points, and involves wrapping unvulcanized rubber tape or adhesive tape around the outer circumference of the boundary between the cable outer semiconducting layer and the cable insulating layer, which is exposed by peeling off the end of the cable. A high-resistance, high-permittivity tape having a volume resistivity of 107 to 1α3Ω·o1 and a dielectric constant of 10 or more is wound on this wound layer, spanning between the cable external semiconducting layer and the cable insulation layer. 100 parts by weight of an α-olefin copolymer crosslinked with an organic peroxide, the high resistance, high dielectric constant tape having a protective layer provided on the outer periphery;
A base material mainly consisting of 10 to 10 parts of a polymer containing a large amount of tertiary carbon atoms that can be decomposed by organic peroxides,
Titanium compound lOO~65 parts, carbon black 1
A composition sheet containing 0 to 9 parts by weight and 1 to 1 part by weight of an organic peroxide such as dicumyl peroxide is heated to crosslink the α-olefin copolymer and to crosslink the third copolymer.
The object of the present invention is to provide a cable termination section characterized by being a self-bonding tape made by decomposing a polymer containing a large amount of carbon atoms.

The present invention will be explained below based on the drawings of one embodiment.

3 with the same numbers attached to the same parts as in Figures 1 and 2.
In the figure, an uncrosslinked rubber tape 5 is wrapped around the outer periphery of the boundary between the external semiconducting layer 1 and the insulating layer 3, which is exposed by peeling off the end of the cable.
1013Ω・o1 Preferably 1σ to 1012Ω・o1 A high resistance, high dielectric constant self-bonding tape 6 with a dielectric constant of 10 or more, preferably 15 or more is wound across the outer semiconducting layer 1 and the cable insulation layer 3. Further, on this wound layer, a protective layer 7 made of a heat shrinkable tube, a wound layer of self-adhesive tape, etc. is provided so as to cover the wound layer of self-adhesive tape.

The unvulcanized rubber tape 5 is made of a material that is thermally and electrically stable for a long period of time, such as butyl rubber, silicone rubber, ethylene/propylene rubber, Hypalon rubber, chlorinated polyethylene, urethane rubber, or chloroprene rubber.

The unvulcanized comb tape 5 may be made of a semiconductive material, but preferably an insulating material with a volume resistivity larger than that of a self-bonding tape with a high resistance and a high dielectric constant, for example, about 1010Ω·0. It is desirable to use

The reason for this is that when stripping the end of a cable, the insulating layer of the cable may be accidentally damaged, but in this case, the damaged part can be repaired using the insulating unvulcanized rubber tape. .

The thickness of the unvulcanized rubber tape is 2rIr! N or less, preferably 0.5 to 0.2 rrrrn, is easy to use.

Further, when wrapping the unvulcanized rubber tape, the wrap width L1 with the external semiconductive layer 1 is 2 orrrIn or less, preferably 2 to
Although it is not necessary to specify the wrap width L2 between the insulating layer 3 and the insulating layer 3, both wrap widths are made so that they do not exceed the winding range of the high-resistance, high-permittivity self-fusing tape 6.

Instead of unvulcanized rubber tape, use an adhesive tape with an adhesive layer made of butyl rubber, ethylene-propylene rubber, vinyl acetate copolymer, etc. formed on at least one side of a thin holding body such as polyethylene or soft vinyl chloride resin. You may.

The self-bonding tape with high resistance and high dielectric constant is made of 100 parts by weight of α-olefin copolymer that is cross-linked with organic peroxide, and tertiary grade material that decomposes with organic peroxide, such as butyl rubber and high molecular weight polyisobutylene. Polymer 1 containing a large amount of carbon atoms
A base material mainly containing 0 to 10 parts by volume, 100 to 65 parts by volume of a titanium compound, 10 to 9 parts by volume of carbon black, and 1 to 10 parts by volume of organic peroxide such as dicumyl peroxide.
A composition sheet containing 1 part of saliva was heated, and the α-
It is produced by crosslinking an olefin copolymer and decomposing a polymer containing a large amount of tertiary carbon atoms.

Examples of α-olefin copolymers crosslinked with the above organic peroxide include ethylene/propylene rubber, ethylene/vinyl acetate copolymer, ethylene/ethyl acrylate copolymer, etc. Titanium compounds include titanium dioxide, titanium dioxide, Examples include barium titanate.

In the cable termination portion of the present invention formed in this manner, the unvulcanized rubber tape is deformed by the winding force from the high resistance, high dielectric constant self-fusing tape and/or the protective layer, and fills the gap G described above. This, combined with the electric field relaxation effect of the tape, further improves the corona discharge characteristics at the cable termination.

In particular, since the gear 716 is the part where the electrical stress is highest and corona discharge is likely to occur, this effect is extremely large.

Incidentally, when the present invention is applied to the terminal end of a 6.6 kV class cross-linked polyethylene cable, the corona level is 1 to 10 at an applied voltage of 15 to 30 (kV), as shown in Figure 4.
(pC).

In addition, what is shown as a comparative example in the figure is the characteristic of the cable terminal part having the same structure as the example except that the winding of the unvulcanized rubber tape was omitted.

In the figure, 8 indicates a conductor, and 9 indicates a cable sheath.

In summary, in the cable termination of the present invention, the gap that occurs at the boundary between the external semiconducting layer and the insulating layer is filled with unvulcanized rubber tape or adhesive tape, so there is no void at the cable termination and the electric field is relaxed. The original characteristics of the self-fusing tape can be exhibited and the corona discharge characteristics can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a conventional cable termination section, Fig. 2 is an enlarged view of the circular portion in Fig. 1, Fig. 3 is a longitudinal cross-sectional view showing an embodiment of the present invention, and Fig. 4 is a vertical cross-sectional view showing an embodiment of the present invention. It is a graph which shows the characteristic of a cable termination part. 1... External semiconducting layer, 3... Insulating layer,
5...Unvulcanized rubber tape, 6...High resistance, high dielectric constant self-bonding tape, 7...Protective layer.

Claims (1)

[Scope of utility model registration request] An unvulcanized rubber tape or adhesive tape is wound around the boundary between the cable external semiconducting layer and the cable insulating layer, which is exposed by peeling off the end of the cable.・A high resistance, high dielectric constant tape with a dielectric constant of 10 or more is wound across the cable external semiconducting layer and the cable insulation layer, and a protective layer is provided on the outer periphery of the cable. The tape is mainly composed of 100 parts by weight of an α-olefin copolymer crosslinked with an organic peroxide and 10 to 1 part by weight of a polymer containing a large amount of tertiary carbon atoms that decomposes with an organic peroxide. A composition sheet containing 100 to 650 parts by weight of a titanium compound, 10 to 9 parts by weight of carbon black, and 1 to 1 part by weight of an organic peroxide such as dicumyl peroxide is heated to form a base material. A cable termination section characterized in that it is a self-bonding tape made by crosslinking an α-olefin copolymer and decomposing a polymer containing a large amount of tertiary carbon atoms.