JP2001169455A - Branch connection part for power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive branch connection part for power cable which has a light and simple structure, high conductor pulling resistance for high durability of a conductor connection part. SOLUTION: This branch connection part is provided with a branch connection spacer 12 formed by insulation-covering the outer periphery of a branch conductor 14 branched at a plurality of conductor connection pieces 14a with a mold insulator 16, the conductor connection part 18 formed by compressively connecting the conductor connection pieces 14a of the spacer 12 with the conductors 10a of a plurality of branch-connected power cable 10 lines, and a normal temperature shrinking rubber unit 20 fitted on the outer periphery of the conductor connection part 18, so as to extend over the mold insulator 16 side of the spacer 12 and the insulation layer 10b side of the power cable 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branch connection for a rubber or plastic insulated power cable (hereinafter simply referred to as a power cable).

[0002]

2. Description of the Related Art Conventionally, as a branch connection portion for a power cable used to take a branch at a predetermined location, for example, a 66 kV class CV cable, a prefabricated connection is excellent because of its excellent performance, quality and workability. Type branch connections are widely used.

[0003] The structure of the connection portion is, for example, that each of the conductor terminals is made of an epoxy resin molded insulator having an insulation sleeve for receiving a power cable by insulating a conductor connector having three conductor terminal mounting portions. The power cable conductor is fitted and mounted in the mounting portion, and a rubber stress cone fitted to the tip of the insulating layer of the power cable is passed through the insulating sleeve of the mold insulator, and is passed through the tapered hole of the mold insulator. The stress cone is inserted and pressed, and the stress cone is forcibly pressed by a plurality of springs uniformly arranged on the circumference. With this forced pressure, the necessary surfaces of the two interfaces of the prefabricated branch connection, ie, the epoxy resin mold insulator-rubber stress cone interface, the power cable insulation layer-rubber stress cone interface Pressure is ensured and stable electrical characteristics are obtained over a long period of time (Japanese Patent Laid-Open No.
0-136549).

[0004] In such a prefabricated branch connection, a large voltage is applied to the mold insulator or the rubber stress cone, which has a great effect on the electrical insulation performance. These parts are manufactured in advance in a factory where quality control is easy, and those that have passed various shipping tests are used. For this reason, the quality of these components is generally good and stable. Therefore, the advantages of the prefabricated branch connection are good electrical insulation performance and high reliability.

[0005]

However, the epoxy resin mold insulator has a conductor connector having a conductor terminal mounting portion, an electric cable, an insulating sleeve for accommodating a rubber stress cone and a tapered hole as described above. Therefore, when the mold insulator is moved to the site during the on-site assembling work, a special large-sized gantry is required in some cases.

[0006] Further, there is a problem that the number of parts is increased and the material cost is increased because a stress cone pressing tool or the like by a spring is required to press the rubber stress cone.

Furthermore, since the conductor connection portion is formed by inserting the conductor of the power cable into the conductor terminal mounting portion of the molded insulator, the insertion method is a multi-contact method or the like.
It cannot be formed by the conductor compression method. For this reason, there also existed a problem that the conductor pull-out strength of the conductor connection portion was weakened and the conductor was expensive. In particular, since the number of power cables connected at the left and right and the like often differs at the branch connection portion, the axial force acting on the conductor of the power cable tends to be unbalanced. If the degree is large, the conductor pull-out strength of the conductor connection portion is weak, and in the worst case, the conductor of the power cable may fall out of the branch connection portion and cause a dielectric breakdown accident.

The present invention has been made in view of the above points, and has a light weight, a simple structure, excellent assembling workability, a strong conductor pull-out strength of a conductor connecting portion, durability, and low power consumption. A cable branch connection is provided.

[0009]

In order to solve the above-mentioned problems, a power cable branch connector according to the present invention comprises a molded insulator on the outer periphery of a branch conductor that is branched into a plurality of conductor connectors in the middle. A branch connection spacer formed by insulating coating, a conductor connection portion formed by compression-connecting a plurality of power cable conductors branch-connected to the conductor connector of the spacer, and a branch at an outer periphery of the conductor connection portion. A room-temperature shrinkable rubber unit is provided so as to extend over the mold insulator side of the connection spacer and the insulating layer side of the power cable.

The branch connection spacer used in the branch connection portion of the present invention does not have a conductor terminal mounting portion, an insulating sleeve for accommodating a rubber stress cone and a tapered hole.
It is small and lightweight, and can significantly reduce the labor required for movement during on-site assembly.

[0011] Further, since the cold-shrinkable rubber unit for reinforcing and insulating the conductor connection portion is expanded and held by the expanded-diameter holding material, the conductor is connected to the cable sheath so as not to hinder the conductor compression work. Can be moved.
Then, after the conductor compression connection, return this rubber unit to the conductor connection part, pull out the string of the diameter expansion holding material,
Due to the self-shrinkage action of the rubber unit, the rubber unit can be pressed against the outer peripheral surface of the conductor connection part. For this reason, since there is no need for a conventional spring pressing tool or the like, the number of parts is small, the structure and size of the parts are simple and compact, and the total material cost can be lower than that of the conventional one. Also, this cold-shrinkable rubber unit has the same structure as the cold-shrinkable rubber unit used in the straight connection part of the power cable, and there is no need to specially manufacture another structure for branch connection. Accordingly, the cost of the branch connection can be reduced.

[0012] In addition, the construction cost can be reduced by only the conductor compression connection operation and the shrinkage of the cold-shrinkable rubber unit, so that the conductor connection can be reinforced and insulated. Can perform the connection process. Therefore, in the total cost of the material cost and the construction cost, the present invention is cheaper than the conventional one. Furthermore,
The branch connection of the present invention enables the formation of a conductor connection by mechanical compression, which has not been possible with a low-cost branch connection in the past.

The conductor compression method has an advantage that the conductor withdrawal strength is much higher than the conventional multi-contact method. For this reason, in the branch connection portion, the axial force acting on the conductor of the power cable becomes unbalanced on the left and right and the like, and even if the pulling force acts concentrated on one power cable, the conductor of the power cable is connected in a branch connection. Because it is difficult to get out of the part,
The decrease in electrical performance is reduced, and the durability and reliability are improved.

As described above, when the conductor pull-out strength of the power cable is increased, the number of options for underground transmission line design increases,
Track design becomes easy. For example, conventionally, the allowable range of axial force imbalance has been limited, so when forming a new branch connection, it is necessary to newly install a large manhole, expand an existing manhole, or install a new manhole. In some cases, the expansion was difficult due to the existence of the underground structure, and the branch connection could not be installed. By using the branch connection of the present invention, a new manhole of a normal size can be installed or the existing manhole can be used in time, so that civil engineering costs can be significantly reduced and the installation of the branch connection can be avoided. become.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Since the three power cables and the connection configuration thereof are the same, one of them is connected.
A description will be given of the connection, and the description of the configuration of the other two connection portions will be omitted. FIGS. 1 and 2 show an example in which the present invention is applied to a Y-type branch connection portion of a power cable which is a 66 kV class CV cable. In the present invention, the three power cables 10
Is used for branch connection. As shown in detail in FIGS. 3 and 4, the branch connection spacer 12 includes a branch conductor 14 having three conductor connectors 14a formed by being branched into a Y shape in the middle, and a conductor connection on the outer periphery thereof. It is made of a Y-shaped mold insulator 16 which is insulated and coated so that the tip of the child 14a is exposed. Each of the conductor connectors 14a has a circular cross section, and is made of a highly conductive metal material such as copper, aluminum, or an alloy thereof. The molded insulator 16 is a molded insulator 16a formed by molding an insulating material such as an epoxy resin, and an internal semiconductive layer integrally formed on the inner surface of the molded insulator 16a in contact with the conductor connector 14a. (Omitted) and an external semiconductive layer 16b integrally formed on the outer surface of the molded insulator 16a.
Consists of The outer semiconductive layer 16b is not formed at a portion covered by a cold-shrinkable rubber unit described later. The outer semiconductive layer 16b may be formed by applying a conductive paint such as silver paint.

Each of the three power cables 10 branch-connected to the branch connection spacer 12 is stripped at its end so as to be shielded from an end of the cable sheath 10e, an outer semiconductive layer 10c, and an insulating layer. 10b and the conductor 10a are sequentially exposed. Such a power cable 10
Each conductor 10a and each conductor connector 14a of the branch connection spacer 12 are compression-connected by a compression sleeve 18a to form a conductor connection portion 18.

In order to reinforce and insulate the conductor connection portion 18, a cold-shrinkable rubber unit 20 is provided on the outer periphery of the conductor connection portion 18 so as to straddle the mold insulator 16 of the branch connection spacer 12 and the insulating layer 10 b of the power cable 10. Attached to.
The cold-shrinkable rubber unit 20 is generally formed of a cold-shrinkable insulating material having a high insulating property and excellent processability, such as ethylene propylene rubber or silicone rubber as a base rubber, and is formed into a cylindrical shape. 20a, the reinforcing insulating layer 20b, and the external conductive layer 20c are integrally molded. The rubber unit 20 has a smaller inner diameter than the outer diameter of the cable branch connection processing portion in order to maintain good adhesion with the branch connection processing portion of the power cable and maintain interface insulation performance. As shown in FIG. 5, a plastic string 22a is wound in a spiral cylindrical shape until it is mounted on the outer periphery of the conductor connection portion for branch connection processing. The diameter is held by the diameter holding member 22 so that the diameter is not reduced.

The cold-shrinkable rubber unit 20 is passed through the power cable 10 from the end of the power cable 10 before the conductor connection portion 18 is formed.
It is moved above the cable sheath 10e so as not to hinder the conductor compression operation. After the conductor connection is formed by compressing the conductor, the rubber unit 20 is returned to a position directly above the conductor connection 18. Thereafter, as shown in FIG. 5, the plastic cord 22 of the large-diameter holding member 22 is pulled out, and the string is pulled through the cold-shrinkable rubber unit 20 to the outside at the other end to thereby obtain the large-diameter holding member 22. Are sequentially dismantled and removed from one end. As a result, the room-temperature shrinkable rubber unit 20 is gradually reduced in diameter from one end side and is closely fixed to the outer periphery of the conductor connection portion 18, and the branch connection spacer 12 on the side of the mold insulator 16 and the insulating layer of the power cable 10. On the 10b side, in this example, it is mounted so as to straddle the insulating layer 10b and the external semiconductive layer 10c.

At the end of the cold-shrinkable rubber unit 20 on the side of the branch connection spacer 12, the outer conductive layer 20c of the rubber unit 20 and the outer semiconductive layer 16b of the mold insulator 16 in the branch connection spacer 12 are straddled. Then, a conductive tape is wound to provide a conductive treatment layer 24. Also,
At the end of the cold-shrinkable rubber unit 20 on the power cable 10 side, a conductive tape is wound over the outer conductive layer 20c of the rubber unit 20 and the outer semiconductive layer 10c of the power cable 10 to form a conductive treatment layer 25. Is provided. In addition,
Although not shown, the outer conductive layer 20c and the power cable 10
The shielding layer 10d is also electrically connected to each other by winding a conductive wire or the like around the outer periphery so as to straddle both.

A split-type metal case 26 made of a conductive material such as a copper tube is attached to the outer periphery of the branch connection spacer and the cold shrinkable rubber unit provided in this manner so as to cover them. The space in the metal case 26 is provided with a waterproof coating layer 28 by filling with a waterproof mixture or by casting and curing a resin material such as an epoxy resin. Reference numeral 30 denotes a waterproof treatment layer formed by winding a waterproof tape between the power cable lead-out portion of the metal case 26 and the cable sheath 10e.

The branch connection of the present invention is configured as described above. Since both the branch connection spacer 12 and the cold-shrinkable rubber unit 20 are manufactured in advance at the factory, the quality is good, the structure is simple and the weight can be reduced. It is also possible to form a conductor connection by compression connection. It is possible to provide a connecting portion having high strength, excellent assembling workability, and low cost. In the above-described embodiment, the Y-shaped branch connection portion has been described. However, as shown in FIG. 6A, a T-shaped branch conductor 34 is formed by insulating the outer periphery of a T-shaped branch conductor 34 with a mold insulator 36. As shown in FIG. 6B, a branch connection spacer 32 and a y-type branch connection spacer 38 formed by insulatingly coating a mold insulator 42 on the outer periphery of a y-type branch conductor 40 are used. A branch connection of a type or y-type may be formed. Although not shown, the present invention can be applied to an h-type or H-type branch connection portion using an h-type or H-type branch connection spacer.

[0022]

According to the present invention, as described above, a branch connection spacer formed by insulatingly coating a mold insulator on the outer periphery of a branch conductor branched into a plurality of conductor connectors in the middle, A conductor connection portion that compression-connects the conductor connector of the spacer and the conductor of the plurality of power cables to be branched and connected,
Since the outer periphery of the conductor connection portion is provided with the mold insulator of the branch connection spacer and the cold-shrinkable rubber unit mounted so as to straddle the insulating layer of the power cable, the number of components is small, and the structure of the components is small. In addition, the size is simple and compact, the workability of assembling the branch connection part is improved, and the cost can be reduced. In the branch connection,
Since conductor connection by compression connection can be easily performed, the conductor pullout strength of the conductor connection portion increases, and even if the axial force acting on the conductor of the power cable becomes unbalanced, the conductor is hard to come off from the branch connection portion, and electrical Performance degradation is reduced, and durability and reliability are improved. Further, since the conductor pull-out strength of the power cable is increased, the number of options for designing the underground transmission line is increased, and the line design is facilitated.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view showing an embodiment of a branch connection portion for a power cable according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a half sectional front view showing a branch connection spacer.

FIG. 4 is a right side view of FIG. 3;

FIG. 5 is a schematic diagram showing a state in which a cold-shrinkable rubber unit is mounted on the outer periphery of a conductor connection portion.

FIGS. 6A and 6B are schematic diagrams showing modified examples of the branch connection spacer, wherein FIG. 6A is an example of a T-type and FIG. 6B is an example of a y-type.

[Explanation of symbols]

 Reference Signs List 10 power cable 10a conductor 10b insulating layer 10c external semiconductive layer 10d shielding layer 10e cable sheath 12, 32, 38 branch connection spacer 14, 34, 40 branch conductor 14a conductor connector 16, 36, 42 molded insulator 16a molded insulation 16a Body 16b External semiconductive layer 18 Conductor connecting part 18a Compression sleeve 20 Cold-shrinkable rubber unit 20a Internal conductive layer 20b Reinforced insulating layer 20c External conductive layer 22 Large diameter holding material 22a Plastic string 24, 25 Conductive treatment layer 26 Metal case 28 Waterproof Coating layer 30 Waterproofing layer

Claims (1)

[Claims] 1. A branch connection spacer formed by coating a mold insulator on the outer periphery of a branch conductor branched into a plurality of conductor connectors in the middle, and a plurality of branch connections that are branch connected to the conductor connector of the spacer. And a cold-shrinkable rubber mounted on the outer periphery of this conductor connection part so as to straddle the mold insulator side of the branch connection spacer and the insulation layer side of the power cable. A branch connection part for a power cable, comprising: a unit.