JPS5819887A - Method of forming reinforced insulating layer in connector of rubber, plastic insulated wire cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a supplementary insulating layer at a connecting portion of a rubber, rubber, or plastic insulated electric wire cable.

Rubber or plastic insulated wire cables, especially cross-linked polyethylene insulated wire cables, are increasingly being used as high voltage cables in recent years.

Accordingly, connection parts formed by a molding method, which is considered to be highly reliable, have come to be widely used in the connection parts of electric wires and cables.

The molding method is used to form a reinforcing insulating layer at the connection part of an electric wire/cable by wrapping rubber or plastic in the form of a tape or casting it using a mold. This is a method in which this reinforcing insulating layer is integrated with the insulating layer of the electric wire cable by applying a layer and then applying pressure and heating. In this method, in order to raise the temperature until the insulating layer of the electric wire cable and the reinforcing insulating layer are integrated, the heating part must be sufficiently longer than the connection length of the electric wire cable, and the insulating layer of the electric wire cable must also be heated. Must be. The reason for this is that heat is dissipated through the conductor of the electric wire cable, and the effect becomes even greater especially when connecting electric wire cables with large conductors.

Particularly when gas pressure or hydraulic pressure is used as a pressurizing means during heating, the heating device becomes large.

Also, if you try to shorten the heating time, it becomes necessary to heat the insulation layer of the longer electric wire cable.
The heating device becomes larger.

If such a large heating device were to be used, there was a problem in that the connection work would be extremely difficult in the manhole where the connection was actually made.

This invention was made in order to solve the above-mentioned problems in connecting electric wires and cables using the above-mentioned molding method, and the gist of the invention is to provide reinforcement made of rubber or plastic to the outside of the conductor connection part. The insulating layer is heated under pressure by a main heating section that sufficiently covers the reinforcing insulating layer, and the rubber and plastic insulated wire cables on both sides of the main heating section are heated to a required length, PTC (positive temperature coefficient, Po5itiv).
e Temperature Coefficien
A rubber or plastic insulated wire or cable, characterized in that the reinforcing insulating layer and the insulating layer of the electric wire cable are integrated together with the reinforcing insulating layer by heating with an auxiliary heater having the characteristic (abbreviation of t). A method for forming a reinforcing insulating layer at a connection portion.

An embodiment of the invention will be described with reference to the drawings.

Figure 1 is a longitudinal cross-section of the present invention when a main heating section and an auxiliary heater are provided at the electric wire cable connection section, showing the conductor # of the rubber or plastic insulated electric wire cable (1) (1)' and the connection section (2). A reinforcing insulating layer (3) is applied to the outside by wrapping rubber or plastic in the form of a tape or by casting using a mold, and then an anti-corrosion layer (4) is applied to the edges.
The reinforcing insulating layer (3) is covered with the main heating part (6) so as to straddle the electric wire cable (1) (1)' from which the insulating layer (5) (5)' is exposed by removing the insulating layer (5) (5)'. The reinforcing insulating layer (3) is preferably pressurized by winding a vulcanized rubber tape while applying tension, or by applying pressure with a fluid, since the surface of the reinforcing insulating layer becomes smooth. When pressurizing using a fluid such as gas or oil, the main heating section (6) also serves as a pressurizing container by providing seal sections (7) at both ends of the main heating section (6).

Electric wires and cables (1) on both sides of the main heating section (6) (1γ
On the anti-corrosion layer (4) (4)', a heater is provided as an auxiliary heater (8) (8)' to control the temperature at a constant level using PTC characteristics (positive temperature coefficient of resistance).

Auxiliary heater (8) (8)' is a long heater equipped with a conductive material whose volume resistivity increases rapidly at the temperature between two parallel conductors. The required length on the wire or cable, for example 50 to 100 cI1
1) Wrap it in a spiral shape.

The main heating section (6) and the auxiliary heater (8) provided as above.
) (Reinforced insulation layer (3) and electric wire cable (1) by 8γ
) (When 1γ is heated, the reinforcing insulating layer (3) is crosslinked and integrated, and this reinforcing insulating layer (3) and the insulating layer (5) of the electric wire cable (5Y) are integrated.

In this invention, the PTC characteristic refers to a characteristic in which the volume resistivity increases rapidly at certain temperatures, as shown in FIG. 2, and examples of conductive materials having such characteristics include polyethylene, Materials that are made by adding conductive substances such as carbon black to ethylene-vinyl acetate copolymer, ethylene-acrylic copolymer, etc. to give conductivity are used, and the electrical resistance increases dramatically in the range of 40℃ to 100℃. It is something to do.

When this conductive material is placed between the electrodes and energized, the temperature rises to a point where the volume resistivity suddenly changes, and at that temperature the material itself becomes a relay-controlled heater.

The auxiliary heater used in this invention utilizes this characteristic.

This invention uses an auxiliary heater to heat the electric wire cables on both sides of the main heating section, so the heat radiation from the conductor during heating molding of the reinforcing insulating layer can be suppressed without damaging the anti-corrosion layer of the electric wire cable. .

Therefore, the heating time can be shortened, and when fluid is pressurized, the pressurizing and heating device can be made smaller. Furthermore, the auxiliary heater only needs to be wrapped around the anti-corrosion layer of the electric wire cable, and does not require much space, so it is excellent in workability on site.

The reason why a heater having PTC characteristics is used as the auxiliary heater is that the temperature can be controlled uniformly over the length of the heating section, and there is no risk of damaging the anti-corrosion layer made of PVC1 polyethylene or the like. When a normal electric heater is used, a separate temperature controller is required, and depending on the method of temperature detection, the temperature may locally rise and damage the corrosion protection layer.

As explained above, the connection of rubber and plastic cables according to the present invention can shorten the heating time and has excellent workability.

In order to see the effect of this invention, a conductor cross section of 1000B"
A crosslinked polyethylene insulated, vinyl sheathed cable with an insulation thickness of 20 m was used, and a reinforcing insulating layer of polyethylene containing a crosslinking agent was cast to a thickness of 25B, heated by various methods shown in the table, and used in Examples 1 to 8. The auxiliary heater is made of P, in which a conductive material made of 100 parts of polyethylene and 40 parts of carbon black is provided between two parallel conductors.
This is a long heater with TC characteristics. The auxiliary heater used in Comparative Example 8 was a 0.1 iuc thick aluminum plate wrapped around it, a sheet of heat and heat wrapped around it, and a thermocouple attached to the center of the length to control the temperature.

The required heating time for each heating method and the presence or absence of damage to the anticorrosion layer of the electric wire and cable are also listed in the table.

As is clear from this table, according to the present invention (Examples 1 to 3), the corrosion protection layer is not damaged, and the heating unit as a whole is small, so the workability of connection is excellent and the heating time is short. Can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the present invention when a main heating part and an auxiliary heater are provided at the electric wire cable connection part, and Fig.
FIG. 3 is a diagram showing an example of volume resistivity-temperature characteristics of a heater having C characteristics.

Claims (2)

[Claims] (1) The reinforcing insulating layer made of rubber or plastic applied to the outside of the conductor connection part is heated under pressure by the main heating part that sufficiently covers the reinforcing insulating layer, and the rubber or plastic on both sides of the main heating part is heated. A rubber characterized in that the reinforcing insulating layer and the insulating layer of the electric wire cable are integrated together with the reinforcing insulating layer by heating a required length of the insulated electric wire cable with an auxiliary heater having PTC characteristics. A method for forming a reinforcing insulating layer at a connection part of a plastic insulated electric wire cable. (2) A method for forming a reinforcing insulating layer at a connecting part of a rubber or plastic insulated electric wire cable according to claim (1), wherein the reinforcing insulating layer is heated under pressure by injecting fluid into the main heating part. .