JP2003125528A - Premolded rubber insulation tube and plastic insulation power cable connection part therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a rubber insulation tube, formed out of an internal semiconductor layer, an insulation layer, and external semiconductor layer used for a conventional CV cable, needing a mold for each layer in manufacturing it, because of its structure, causing manufacturing time and cost. SOLUTION: This insulation tube is a tubular rubber block formed out of a rubber series material used as its base, and its internal layer is formed into a high dielectric layer, its middle layer is formed into an insulation layer, and its external layer is formed into a semiconductor layer, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premolded rubber insulating tube used for connecting a plastic insulated power cable,
In particular, the present invention relates to a pre-molded rubber insulating tube that can simplify the structure and reduce the cost, and a connecting portion of a plastic insulated power cable equipped with the rubber insulating tube.

[0002]

2. Description of the Related Art Plastic-insulated power cables represented by cross-linked polyethylene insulation are rapidly becoming versatile due to their excellent insulation and easy handling. Along with this, the total number of cable connecting works is increasing, and demands for simplification and shortening of these works are increasing.

In recent years, as a joint which has a short connection time and can be easily connected, a prefabricated type connecting portion using a rubber block formed of an inner semiconductive layer, an insulating layer and an outer semiconductive layer, and further, FIG. The connection part equipped with the one-piece pre-molded rubber insulating tube shown in the figure has been put into practical use.

The connecting portion shown in FIG. 4 covers the connecting portion of the conductor 2 and the cable insulator 5, and the premolded rubber insulating tube 20 attached to the outer periphery of the cable so as to straddle the outer semiconductive layer 6 of the cable. Although not shown, the insulating cylinder 20
It is provided with a two-part type protective cover for covering and a waterproof processing part formed at both ends thereof. The pre-molded rubber insulating tube 20 shown in FIG. 4 generally uses an ethylene propylene rubber having high insulation performance and excellent moldability as a base rubber, and has an inner semiconductive layer 21, a reinforcing insulation layer 22 and an outer semiconductive layer. 23 and 23 are integrally molded, and are configured by one component (one piece) as a whole, and simplification is being promoted in terms of connection construction.

[0005]

However, in order to manufacture the above-mentioned pre-molded rubber insulating cylinder, a mold is required for each layer, which causes a problem that manufacturing time and cost are increased.

The present invention has been made in view of the above problems. An object of the present invention is to shorten the manufacturing time by simplifying the structure of the pre-molded rubber insulating cylinder and to reduce the rubber insulating cylinder. Is made compact, the assembling work of the connecting portion is simplified, and the cost required for forming the connecting portion is reduced.

[0007]

In order to achieve the above object, in the present invention, an internal semiconductive layer which is an internal electrode of a rubber insulating cylinder, which is conventionally required for electric field shielding and electric field control, is omitted. However, instead, a high dielectric rubber layer is provided on the entire inner surface of the rubber insulating cylinder to control the electric field.

The pre-molded rubber insulating cylinder of the present invention is a pre-molded rubber insulating cylinder for connecting a plastic power cable, which comprises a plurality of layers formed of a rubber material as a base, and the inner layer of the pre-molded rubber insulating cylinder. A high dielectric rubber layer having a relative dielectric constant of at least 10 is formed on the entire surface.

Further, the present invention is characterized in that an internal electrode integrally formed with a semiconductive layer having a sheet-shaped cross section is provided at the center of the inner surface of the premolded rubber insulating cylinder.

Furthermore, a high dielectric oil layer is provided at the boundary between the tip of the internal electrode and the high dielectric rubber layer.

In the plastic insulated power cable connecting portion of the present invention, the premolded rubber insulating tube is connected to the conductor connecting portion exposed by stripping off the end portion of the cable, the cable insulators on both sides of the connecting portion, and the external semiconducting conductor. It is characterized in that it is attached so as to cover the layers.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of a premolded rubber insulating cylinder 10 according to the present invention. This pre-molded rubber insulation cylinder 10 uses ethylene propylene rubber as a base rubber, which has high insulation performance and excellent moldability, and has a high dielectric rubber layer 11, an insulation layer 12 and an external semiconductive layer 13 which are integrated with each other. Moulded, 1 overall
It consists of one part (1 piece). The rubber insulating cylinder 10 is molded by winding a high dielectric rubber tape around the mold core and then setting the mold (outer mold), or extruding the high dielectric rubber tube in advance. This is set in a mold core, the mold is set, the insulating rubber layer and the external semiconductive layer are extruded into the mold, and then heat-molded.

FIG. 2 is a sectional view showing the construction of another embodiment of the premolded rubber insulating cylinder 10 according to the present invention. The pre-molded rubber insulating tube 10 shown in FIG. 2 is formed by integrally molding a semiconductive layer, which is an internal electrode 14 having a sheet-shaped cross section, at the center of the inner surface of the rubber insulating tube having the configuration shown in FIG. Molding in this case is performed by winding a semi-conductive rubber tape and a high-dielectric rubber tape around the mold core, or by setting each tube molded in advance in the mold core and molding in the same manner as the above molding method. it can. Further, as shown in the enlarged view, voids are formed by filling the boundary surface (gap) between the tip of the internal electrode 14 and the high dielectric rubber layer 11 with the high dielectric oil 15.

FIG. 3 shows a plastic insulated power cable connecting portion N using the premolded rubber insulating tube 10 according to the present invention.
It is a sectional view showing the main composition of. This connection portion N is a conductor connection formed by inserting the ends of two conductors 2 exposed by stripping the ends of the plastic insulated power cable from both sides of the conductor connection pipe 3 and compressing the same. Part 4
And a pre-molded rubber insulating tube 10 attached to the outer periphery of the cable insulating material 5 on both sides thereof and so as to straddle the cable outer semiconductive layer 6. In addition, 7
Is a cover of the metal or conductive rubber conductor connecting pipe 3 which is provided so as to cover the conductor connecting portion 4 and electrically connects the conductor 2 and the internal electrode 14 of the premolded rubber insulating cylinder 10, and 8 is It is a semiconductive rubber tape winding portion that electrically connects the outer semiconductive layer 13 of the premolded rubber insulating cylinder 10 and the cable outer semiconductive layer 6. Although not shown in the figure, a protective cover is provided on the outside so as to cover the whole, and a waterproofing part for liquid-tightly sealing the ends of the protective cover and the cable sheath is provided.

The pre-molded rubber insulating cylinder 10 shown in FIG. 3 is replaced by the pre-molded rubber insulating cylinder shown in FIG.
It is also possible to wind a semi-conductive tape around the outer periphery of the conductor connecting portion 4 to form an internal electrode. In this case, a high dielectric oil is applied to the tip of the semiconductive tape winding layer and the premolded rubber insulating cylinder is attached.

The relative permittivity of the high dielectric rubber layer 11 of the premolded rubber insulating cylinder 10 is set to at least 10 because the outer semiconductive layer end portion of the cable or the inner semiconductive layer end portion on the conductor connection portion. This is because it is the lower limit for reducing the electric field gradient and obtaining the necessary electric insulation performance.

[0017]

According to the present invention, since the structure of the rubber insulating cylinder is simplified, the mold for each layer is not required, and the manufacturing time and the manufacturing cost can be greatly reduced. In the plastic insulated power cable connection part using this, since the inner layer of the rubber insulating cylinder is formed of the high dielectric rubber layer,
The electric field at the interface between the cable insulator and the rubber insulating cylinder can be relaxed. As a result, the insulating thickness of the rubber insulating cylinder can be reduced, the size of the rubber insulating cylinder can be made compact, and its handling becomes easy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a half portion of a premolded rubber insulating cylinder according to the present invention.

FIG. 2 is a half longitudinal sectional view of another embodiment of the pre-molded rubber insulating cylinder according to the present invention.

FIG. 3 is a half sectional view showing a main configuration of a connecting portion of a CV cable using a premolded rubber insulating tube according to the present invention.

FIG. 4 is a half sectional view of a CV cable connecting portion using a conventional premolded rubber insulating tube.

[Explanation of symbols]

N intermediate connection 1 CV cable 2 conductors 3 conductor connection tube 5 cable insulation 6 Cable outer semi-conductive layer 10 Pre-molded rubber insulation tube 11 High dielectric rubber layer 12 Insulation layer 13 External semiconductive layer 14 internal electrodes 15 High dielectric oil

Continued front page    F term (reference) 5E085 BB06 BB12 DD05 DD12 DD13                       DD16 EE11 EE12 FF01 GG11                       GG16 JJ17 JJ36 JJ38 JJ50                 5G355 AA03 BA01 BA15                 5G375 AA02 BA26 BB43 CA02 CA14                       CB03 CB07 CB18 CB39 CB53                       DB32

Claims (4)

[Claims] 1. A premolded rubber insulating tube for connecting a plastic power cable, which is formed of a plurality of layers based on a rubber material and has a relative permittivity of at least 10 on the entire inner layer of the premolded rubber insulating tube. A premolded rubber insulating tube, characterized in that a high dielectric rubber layer is formed. 2. A premolded rubber insulating tube having an inner electrode integrally formed with a semiconductive layer having a sheet-shaped cross section at the center of the inner surface of the premolded rubber insulating tube according to claim 1. 3. The pre-molded rubber insulating tube according to claim 2, wherein a high dielectric oil layer is provided on a boundary surface between the tip of the internal electrode and the high dielectric rubber layer. 4. The pre-molded rubber insulating cylinder according to claim 1, wherein the conductor connecting portion exposed by stripping off the end portion of the cable, the cable connecting body on both sides of the conductor connecting portion, and the outer half. A plastic insulated power cable connection part, which is mounted so as to cover the conductive layer.