JPH0133914B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for forming a termination part of a power cable;
In particular, it relates to a method of forming power cable terminations using capacitor cones.

[Prior Art and Problems to be Solved by the Invention] A conventional method for forming the terminal end of this type of electric field mitigation cable is to alternately wrap layers of insulating tape and metallic electrode layers on the circumference of the cable terminal. A common method is to form the tape by laminating it, but it takes time and effort to wind the tape around the cable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that eliminates the drawbacks of the prior art described above, has good workability, and can form an electric field relaxation cable termination using a capacitor cone in a short time.

[Means for Solving the Problems] The gist of the present invention is to sequentially strip off a shielding layer, an external conductor layer, and an insulator layer at a cable terminal end,
Then, a heat-shrinkable material made of a high-resistance material with conductive material pre-applied or adhered to a plurality of inner or outer surfaces so as to continuously cover the end of the shielding layer, the outer conductor layer, and the insulator layer at the end of the cable. The tubes are fitted one by one and heated to shrink, thereby forming an electrode layer made of the conductive material on the ends of the shielding layer, the outer conductor layer, and the insulator layer to form a high-resistance electrode layer. The point is that a desired capacitor cone can be formed by forming a stepped shape through a heat-shrinkable tube made of the material.

[Function] According to the above method, the electric field relaxing cable end can be formed simply by fitting a heat shrink tube around the circumference of the cable end and heat shrinking it, so the working time can be significantly reduced. I can figure it out.

[Example] An example of the present invention will be described below based on the drawings.

First, the insulator layer 2, the outer conductor layer 3, and the shield layer 4 of a power cable consisting of the conductor 1, the insulator layer 2, the outer conductor layer 3, and the shield layer 4 are stripped in order. Then, a pre-prepared 4
Heat-shrinkable tube 10,1 made of high-resistance material
1, 12, and 13 are coated one by one and heated to shrink. Here, heat shrink tubes 11, 12,
13 is provided with electrode layers 20, 21, 22 made of a coated layer of a conductive material on its inner surface, and as shown in the figure, each electrode layer 20, 21, 22 is located at the end of the shielding layer 4, exposed. The capacitors are arranged stepwise through heat shrink tubes 10, 11, 12, and 13 so as to cover the entire outer conductor layer 3 and a part of the insulator 2, thereby forming a desired capacitor cone as a whole. do.

Note that the capacitance of this capacitor cone is selected to be greater than the capacitance of the cable. By doing so, the voltage sharing at the end of the shielding layer can be reduced to 1/2 or less of that without a capacitor.
Therefore, the electric field strength at this portion becomes low, and the breakdown voltage can be increased. The number of high-resistance layers (heat-shrinkable tubes) and the number of electrode layers are arbitrary and can be appropriately selected depending on the cable used and its usage conditions.

Incidentally, a power cable with a conductor with a cross-sectional area of 185 mm ² and an insulating coating of 4.5 mm thick is connected to a length of 300 mm from the end.
A laminate of three high-resistance layers (heat-shrinkable tube) is provided on this as shown in Figure 1, and then a high-resistance layer (heat-shrinkable tube) is formed.
When an electrode layer (2 layers) is provided in between, the width is 1
When we measured the breakdown voltage when applying an impulse voltage of ×40μs and an AC voltage, we found that in the case of the former
It was found that 210KV, and in the latter case 90KV, was sufficient for practical use.

[Effects of the Invention] As described above, according to the method of forming an electric field relaxation cable termination part of the present invention, a heat shrinkable tube is fitted around the circumference of the cable termination part and heat-shrinked. A desired capacitor cone-based field mitigation cable termination can be formed.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating an embodiment of the method for forming the termination portion of an electric field relaxation cable according to the present invention. 1: conductor, 2: insulator layer, 3: outer conductor layer,
4: Shielding layer, 10, 11, 12, 13: High resistance layer (heat shrink tube), 20, 21, 22: Electrode layer.

Claims (1)

[Claims] 1. The shielding layer,
The outer conductor layer and the insulator layer are sequentially stripped off, and a conductive material is applied to a plurality of inner or outer surfaces so as to continuously cover the ends of the shielding layer and the exposed outer conductor layer and insulator layer, respectively. Heat-shrinkable tubes made of a high-resistance material coated or attached in advance are fitted one by one and heated to shrink, thereby forming the conductive material on the ends of the shielding layer, the outer conductive layer, and the circumference of the insulating layer. 1. A method for forming an electric field relaxation cable terminal portion, which comprises forming an electrode layer made of a material in a stepped manner through a heat-shrinkable tube made of a high-resistance material.