JPS6031124Y2 - Rubber/plastic insulated power cable - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rubber/plastic insulated cable cable, and particularly aims to provide a crosslinked polyethylene cable (CV cable) with excellent dimensional stability.

A shrink-back phenomenon occurs in C■ cables, in which the conductor slightly pops out when cut, and this is considered a real problem.

This phenomenon occurs because the strain in the cable insulation is released at the end by cutting, causing the insulation to contract in the longitudinal direction.

When the insulator shrinks, the surface pressure at the interface between the molded rubber/plastic part and the insulator decreases, for example at a cable connection, and in extreme cases, this can lead to delamination at the interface.

Such a phenomenon leads to a decrease in the dielectric breakdown strength of the connection portion, which in turn impairs the reliability of the line, and must be avoided as much as possible.

The present invention solves the above problems in CV cables, and
The purpose of the present invention is to provide a CV cable that gives satisfactory results in the cable dimensional stability test specified in EIC, No. 5-75, which has minute irregularities formed on the conductor surface.
The present invention relates to a rubber/plastic insulated capeple in which an insulating layer or a semiconducting layer is extruded and coated on the conductor.

FIG. 1 is a partially cutaway perspective view showing the structure of this cable, in which minute irregularities 2 are formed concentrically or spirally at intervals on the surface of a conductor 1, and a semiconducting layer 3 and An insulating layer 4 is provided.

CV cables have traditionally been manufactured by extruding and coating a wire conductor with an uncrosslinked polyethylene insulation composition, and then crosslinking it under pressure and heat in a continuous vulcanizer (temperature of about 160°C, pressure of about 6ko/c4). However, the dimensional stability of the cable obtained by this method, expressed in terms of the amount of shrinkage specified by the above-mentioned AEIC, was about 4 to 6 wn, and the shrink-back phenomenon could not be avoided.

In order to improve this problem, attempts have been made to wrap a polyester tape around the stranded conductor and then extrude it to cover it with low density polyethylene and continuously crosslink it, but the amount of shrinkage was 3 to 6rr.
The effect was only about that of rIn, and no effect as great as that on the left was observed.

The inventors of the present invention arrived at the present invention as a result of various studies on this point, and in this invention, with the intention of increasing the sliding friction at the interface between a conductor and an insulator or a semiconductor,
The surface of the conductor is provided with slight irregularities, and for this purpose, it is preferable to continuously inscribe the irregularities on the conductor using, for example, a roller.

Furthermore, making the pitch of the stranded conductors shorter than usual is effective in increasing the sliding friction at the interface.

The thus processed conductor is coated with an uncrosslinked polyethylene insulating composition or a semiconductive composition by extrusion, and then pressurized and crosslinked in a continuous vulcanizer in a conventional manner to produce a product.

In this case, by increasing the pressure in the continuous vulcanizer compared to the conventional one, the composition can be penetrated deeper between the stranded wires and shrinkage of the insulator can be prevented.

Next, examples of the present invention will be given, but the present invention is not limited to these.

Example 1 150ml! ±1rIr on the stranded conductor at a-la! f
After providing unevenness of t at an interval of 2 frames, an uncrosslinked polyethylene (MI; 2) insulator was extruded and coated with a thickness of 3 mm, and an electric wire was manufactured at 160 °C and a pressure of 6 kg/c4 in a continuous vulcanizer. .

When the dimensional stability of this material was measured by the AEIC method, the amount of shrinkage was 0.477 Illl, while that of the material without unevenness was 4.6.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of the rubber/plastic insulated capeple of the present invention. 1...Conductor, 2...Minute unevenness, 3...
... Semi-conducting layer, 4... Insulating layer.

Claims (1)

[Scope of utility model registration request] A rubber/plastic insulated capeple formed by forming minute irregularities on the surface of a conductor and extruding an insulating layer or a semiconducting layer onto the conductor.