JPS6140025Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic tape-wrapped, gas or oil-filled power cable, and particularly to the structure of the insulating layer and the outermost layer of the cable insulation layer in contact therewith.

Prior Art In "Figure 1", 10 is a cable conductor, 1
2 is a conductive layer.

Reference numeral 14 denotes a cable insulation layer, which is made of a wound layer of tape made of plastic, such as polypropylene (hereinafter referred to as PP).

Reference numeral 16 denotes an insulating layer made of a wound layer of metallized plastic tape, semiconductive plastic tape, or the like.

18 is a reinforcing layer, 20 is a sheath, and 22 is an insulating gas or oil.

Conventionally, the insulating and stiff layer 16 was constructed by wrapping tape as described above, which resulted in the following problems: 1. The electric field may be concentrated on the edges of the tape, worsening the partial discharge characteristics; 2. Due to bending or heat cycling. There were problems such as there being a risk that the cable insulation layer 14 would be separated or disturbed, causing irregularities in the electric field.

The above points have been improved.

Prior Art Therefore, it was proposed that the insulating and thin layer 16 be formed by extruding semiconductive plastic to form a solid state (Utility Application No. 1983-
No. 007205 (Utility Model No. 57-121022)).

Note that solid means that there are no gaps between layers or tape edges like in tape wrapping, and the whole is in a solid, integrated state.

By making the insulating thin layer 16 solid in this manner, the concentration of the electric field at the thin thin layer tape edge, which is the problem 1) mentioned above, has been solved.

Furthermore, if the insulating layer 16 is constructed by extrusion as described above, the plastic tape of the outermost layer of the cable insulating layer 14 will melt and fuse with the insulating layer 16 due to the heat during molding. However, the above-mentioned problem 2), in which the insulating layer 16 and the cable insulating layer 14 are separated from each other, causing electric field irregularities, can be solved to some extent.

However, since the insulating layer 16 and the cable insulating layer 14 are not actively fused and integrated, they may become separated during repeated bending and heat cycles. , it was not possible to completely prevent it.

The present invention further improves this point and completely prevents separation between the insulation layer 16 and the cable insulation layer 14.

Structure of the present invention As shown in "Figure 2", 1. Insulating layer 16 and cable insulating layer 14
The outer thin layer portion 140 is integrally formed into a solid layer, and 2. The solid portion is provided with a radial through hole 24.

Note that "to make the insulating hard layer 16 and the part 140 into a solid body" means that the two parts are brought into close contact with each other so that they become completely one piece. .

Materials for the insulating layer 16 include, for example, semiconductive polyethylene (hereinafter referred to as PE) and PP.
The material for the part 40 is insulating PP or PE.

To solidify portions of the insulating and refrigerant layer 16 and 140 together, for example, 12 layers may be coextruded and crosslinked. Note that the crosslinking is performed by a known method such as silane crosslinking or electron beam irradiation crosslinking.

2. This can be done by known means such as wrapping an uncrosslinked PE tape and a semiconductive tape, heat molding, and crosslinking at the same time.

In order to provide the radial through hole 24 in the solid portion, for example, the following procedure is performed.

1 Create continuous holes using known chemical foaming. Carboxylic acid amide etc. are used as a foaming agent.

2.Made mechanically. That is, methods such as passing the material through a hole-forming roll immediately after extrusion or providing vertical slits here and there are used.

Note that the parts other than the above are the same as in the conventional case.

Effects of the invention (1) Since the formation of a gap between the insulation layer 16 and the cable insulation layer 14 is completely prevented, the withstand voltage characteristics are improved.

Although it is conceivable that the solid portion 140 and the tape-wrapped portion 142 may be separated from each other and a gap may be created, the flexible electrodes will not be disturbed and no unequal electric field will be generated. Further, since the gap is between the same insulators and is filled with gas or oil 22, the withstand voltage characteristics will not be deteriorated.

(2) Because of the through holes 24, there is no problem with the flow of gas or oil 22, facilitating vacuum processing and gas impregnation, and also enables forced cooling by flowing gas or oil in the radial direction.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the prior art, and FIG. 2 is an explanatory diagram of the embodiment of the present invention. 10: cable conductor, 14: cable insulation layer,
16: Insulating layer, 22: Gas or oil.

Claims (1)

[Claims for Utility Model Registration] Cable insulation layer 14 on the outside of cable conductor 10
is provided, an insulating layer 16 is provided thereon, and the inside is filled with insulating gas or oil 22. Among the insulating layer 16 and the cable insulating layer 14, The outer thin layer portion 140 of the cable insulation layer 14 is in a state of being integrally solidified, and the portion 1 of the cable insulation layer 14 other than the outer thin layer portion 140 that has been made solid
42 is a plastic tape-wrapped cable comprising a wound layer of plastic tape, and the solid portion is provided with a radial through hole 24.