JPS581516B2 - Insulating treatment method for power cable connections - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for insulating the connection portion of a power cable by winding an uncrosslinked rubber or plastic tape.

Conventionally, when insulating the connection part (or terminal part) of a high voltage Cv cable, a cable conductor connection part 1 is used as shown in FIG.
1, wind an uncrosslinked insulating tape 12 that serves as an insulator,
A presser tape 13 made of a heat-resistant material such as tetrafluoroethylene is wrapped thereon and heated and molded from the outside using an electric heating tube 14 or the like to form an insulator, or as shown in FIG. An uncrosslinked insulating tape 12 serving as an insulator is wound on top of the insulating tape 12, a presser tape 13 is wound on top of the tape, a tube body 15 made of heat-resistant rubber or the like is covered on the outside, and a heating wire 16 is wound around the outer circumference of the tube body 15. A method is used in which the uncrosslinked insulating tape 12 is heated under pressure by passing a heating fluid 17 inside the insulator to form an insulator by molding.

However, in the former method, the pressure tape 13 is simply wrapped around the outside of the uncrosslinked insulating tape 12 wound on the conductor connection part 11 and the internal pressure generated by the thermal expansion of the insulating tape 12 is utilized, so variations in pressure values tend to occur. , and presser tape 1
3, the pressure cannot be kept high, and there is a big drawback that voids remain because pressure does not act on the wound insulating tape 12 especially during cooling, and in the latter case, the wound insulating tape 12
Although uniform pressure is applied to the rubber tube 15, it is very difficult to seal the end of the rubber tube 15, resulting in leakage of pressurized fluid.

The present invention was conceived in view of the above points, and is a treatment method that uses heat-resistant foamed rubber as an intermediate pressurizing medium to reliably prevent the formation of voids inside the insulator treatment on the connection portion.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 3, reference numeral 1 denotes an uncrosslinked polyethylene tape containing a crosslinking agent or an ethylene propylene rubber tape-wrapped insulator applied on the cable conductor connection portion, as shown in the figure. After winding the separator tape 2 on the insulator 1, a halved heat-resistant foam rubber body 3 having an inner cavity having the outer shape of the insulator 1 is placed thereon, and the foam rubber body 3 is held under a predetermined pressure. The insulator 1 is compressed from the outside with a mold 4 until it is obtained, and then heated and molded.

If the foaming rate of the heat-resistant foamed rubber body 3 is set appropriately, the volume expands and contracts with slight pressure changes, so the volumetric expansion of the insulator 1 during heating and the contraction during cooling are the
A substantially constant pressure is always applied to the insulator 1 during heating and cooling during molding, and a uniform insulator 1 without defects such as voids is formed.

Figure 4 shows the relationship between the compression pressure and the compression ratio of the foamed rubber body when silicone foam rubber with a foaming rate of 400% is used as the foamed rubber body at 20°C (indicated by the symbol A in the figure) and at 150°C (indicated by the symbol A in the figure). FIG.

As is clear from this figure, when a halved foam 3 is made of silicone foam rubber with a foaming rate of 400% and the insulator 1 is heated and molded using the foam 3 as an intermediate pressurizing medium, the mold 2
If the set pressure at 0℃ is 4kg/cm2, it will be 150
If the thermal expansion of the insulator is 10% of that of the foam, the weight will be approximately 5.5 kg/cm2. 9 kg/cm2,
This level of pressure increase is within a range that does not cause any problem in forming the molded insulator.

According to the treatment method of the present invention, by using a heat-resistant foamed rubber body as an intermediate pressurizing medium, a constant pressure is applied to the insulator during molding and cooling of the insulator 1, so that voids exist inside the insulator. It is possible to easily form an insulator with excellent voltage resistance.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing the conventional insulation treatment method, Figure 3 is an explanatory diagram showing an example of the treatment method of the present invention, and Figure 4 is the compressibility and pressure characteristics of heat-resistant foam rubber bodies. shows the relationship curve. 1...Insulator, 2...Separator tape, 3...Heat-resistant foam rubber body, 4...
··Mold.

Claims (1)

[Claims] 1. An insulator wrapped with uncrosslinked insulating tape was applied on the cable conductor connection part, a 2-split heat-resistant foam rubber body was placed on top of the insulator, and the foam rubber body was compressed from the outside through a mold until a predetermined pressure was obtained. A method for insulating power cable connections, characterized by heat-molding a post-insulator.