JPS5849377B2 - Rubber plastic cable set up - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a rubber-plastic cable connection.

Conventionally, as a method for forming the insulating layer of this type of cable connection part, there is a method of forming it by winding up a self-bonding insulating tape.

In this method, the tape is wound under tension and pressure is applied to the lower layer of wound tape in order to eliminate voids in the wraps of the tape, but it is unavoidable that some voids remain.

In order to eliminate such voids, a reinforcing layer is sometimes formed as a tape retainer to apply pressure over the external shielding layer provided on the tape-wrapped insulating layer, but even then, voids cannot be completely eliminated. There wasn't.

In addition, an insulating layer wrapped with a tape that has a low thermal deformation rate does not lose its shape during heat cycles during cable use, and in that sense does not cause a decrease in electrical properties, which is preferable. This is inconvenient because the voids that occur at the tape windings are not crushed and remain and there is a high risk of corona generation.

Another method for forming an insulating layer at a cable connection part is the so-called molding method, in which the insulator provided on the connection part is heated and pressurized to promote its softening and melt and integrate into a void-free state. However, this method requires high temperature and high pressure, and has the disadvantage that the operation for pressurizing at high pressure is particularly complicated, and is accompanied by technical difficulties.

In view of this point, the present invention forms the insulating layer of the cable connection part by winding a self-fusible or self-adhesive tape as in the former conventional method, but the tape is deformed by heating. The purpose is to eliminate voids in the insulating layer even if a tape with a low adhesiveness is used and to improve the dielectric strength by improving the adhesiveness.Examples will be described in detail below. do.

As shown in the figure, a cable conductor 1 is connected by a conductor connecting tube 2, an internal conductive layer 3 is formed by winding a conductive tape or the like over the conductor connecting tube 2 and the exposed portion of the conductor 1, and the upper part and both connecting cables A connecting portion insulating layer 5 is formed by winding a self-adhesive or self-adhesive insulating tape over the insulators 4, 4.

The process up to now is the same as before.

After adjusting the shape of the connection part in this way, its outer periphery is covered with a heating tube 8 containing a heating wire, and the inside of the connection part insulating layer 5 is heated to a high temperature in the range of about 60°C below the maximum operating temperature of the cable. Heating is continued until voids in the insulating layer 5 disappear.

Deterioration of insulation due to heating depends on the heating temperature and heating time, but taking these into consideration, heating up to the short-time overload temperature that is normally allowed for cables is permitted, and therefore it is possible to heat the insulation at temperatures below the cable's maximum operating temperature. If so, the electrical properties of the tape itself and the cable insulator will not deteriorate, and if the temperature is as high as about 60° C., voids can be completely eliminated.

Note that the heating means is not limited to electric heating tubes, and means such as hot air heating and gas heating may of course be used.

An example of comparing the state of the connection insulating layer between the method of the present invention and the conventional method is as follows. , heating deformation rate is 90℃
6% at 110'C, 6.5% at 110'C, and the tensile strength is 0.
When using a self-adhesive tape based on ethylene-propylene rubber with an elongation of 5 kg/mm, an elongation of 650%, a 200% modulus of 0.18 k9/m4, and an adhesive force of 1.8 kg, the results are as shown in Table 1. Ta.

Next, we will discuss the connection section using the method of the present invention and the connection section using the conventional method.
Table 2 shows the comparative experimental results of the AC breakdown characteristics of individual connections for connections of 60 KV class cross-linked polyethylene cables.

That is, when the method of the present invention is used, the AC breakdown voltage is significantly improved.

This is due to the elimination of voids and improved adhesion between each turn of the tape and between the tape and the cable insulation.

In this way, even if a tape with the lowest level of fusion adhesion is used, a connection with excellent electrical properties can be obtained.

As described above, the present invention provides a process in which a connection insulating layer formed by winding a self-fusing or self-adhesive tape is heat-treated at a high temperature in the range of about 60° C. below the maximum operating temperature of the cable. This is an extremely simple process that does not involve any technical difficulties, and even when using tape with a low thermal deformation rate, it improves the adhesion not only between each tape winding but also between the tape and the cable insulation, and eliminates voids. This can improve the voltage resistance of the connection.

Moreover, it is possible to always obtain a good connection without variations in characteristics due to differences in operators, and when providing the presser reinforcing layer 7, it is only necessary to provide reinforcement to prevent the shape of the connection part insulating layer from deforming. It can be made into a thin layer.

[Brief explanation of drawings]

The figure is an explanatory diagram of an implementation state of the present invention showing a half part in cross section. 5... Connection insulating layer, 8... Heating tube.

Claims (1)

[Claims] 1. A method characterized by heating all the layers of the connection insulating layer formed by winding self-fusing or self-adhesive insulating tape at a high temperature in the range of about 60°C below the maximum operating temperature of the connected cable. How to make rubber/plastic cable connections.