JPH047530Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an oil-filled power cable in which the cable insulation layer is formed of composite insulating paper.

[Prior art] For example, like the composite insulating paper 10a in FIG.
It is known that a cable insulation layer is formed by winding (gap winding) a plastic film 20 (polypropylene or the like) with paper 30 (cellulose paper or the like) pasted on both sides.

Due to the presence of the plastic film 20, this type of composite insulating paper 10a is superior in terms of dielectric loss, impulse breakdown strength, mechanical strength, etc., compared to a single paper such as cellulose paper.

[Problem that the idea aims to solve] However, there are problems with the following points.

(1) Since the plastic film 20 itself does not allow oil to pass through, the cable insulation layer made of this composite insulating paper has very high oil flow resistance in the radial direction.

Recently, as shown in FIG. 5, cooled oil is flowed radially inside the cable insulation layer 40 from the internal oil passage 44 inside the cable conductor 42, and the heat generated by the dielectric loss generated inside the cable insulation layer 40 is removed. Cooling methods that reduce the apparent thermal resistance and reduce the apparent thermal resistance are being considered.

This is particularly effective in the case of ultra-high voltage cables in which dielectric loss is extremely large, but cannot be applied to cables using the composite insulating paper 10a to which the plastic film 20 is laminated.

(2) The plastic film 20 swells with the oil.

(3) During cable production, drying and impregnation take a long time.

[Purpose of the invention] To provide an oil-filled power cable free from the above-mentioned problems while forming a cable insulating layer using composite insulating paper and taking advantage of the advantages of composite insulating paper.

[Means for Solving the Problems] (1) As shown in Figures 1a and 1b, (1) Paper 30 is pasted on both sides of a plastic film 20 as the composite insulating paper 10, and the width of the plastic film 20 is (2) The composite insulating paper 10 is gap-wound to form the cable insulating layer 40.

[Example] An example of the composite insulating paper 10 used is shown in FIG. 1a.

This is the same as the conventional case in that paper 30 is pasted on both sides of the plastic film 20, but the slits 22 are provided in the plastic film 20 as described above.

The slit 22 is provided in the width direction of the plastic film 20, that is, in the direction perpendicular to the length direction of the plastic film 20. The slit 22 is formed from one end (side edge) of the plastic film 20.
It is threaded through to the other end.

Further, the slit 22 may be formed halfway in the width direction of the plastic film 20, as shown in FIG. 1b.

The plastic film 20 is made of polypropylene, fluorinated ethylene propylene, crosslinked polyethylene, polymethylpentene, or the like.

Materials for the paper 30 include cellulose paper, cellulose paper, polydiphenylphenylene oxide, synthetic fiber paper (including nonwoven fabric) of polyester + polycarbonate, plastic fibers such as polypropylene, polyethylene, polyphenylene oxide, and cellulose. It consists of mixed paper with fibers, and mixed paper with plastic flakes such as polypropylene or polyethylene and cellulose fiber.

In addition, the term "paper" is used in the scope of the utility model registration claims to combine the above ~ into one.

It comes from the JIS term ``paper,'' meaning ``a material made by intertwining and adhering plant fibers and other fibers.In a broad sense, it also includes synthetic paper that uses synthetic polymeric substances as a material.''I'm using it.

Common properties among them include fiber aggregation, porosity, and air permeability.

As shown in FIG. 2, the composite insulating paper 10 described above is gap-wound on a cable conductor 42 to form a cable insulating layer 40. 46 is a cable sheath.

[Function] (1) A part of the cable insulating layer 40 in FIG. 2 is enlarged and schematically shown in FIGS. 3a and 3b.

FIG. 3a shows a case where the composite insulating paper 10 of FIG. 1a is used, and FIG. 3b shows a case where the composite insulating paper 10 of FIG. 1b is used.

In both cases, the slit 22 necessarily opens into the oil gap 48 at both ends (FIG. 3a) or at one end (FIG. 3b).

Thus, oil entering the innermost oil gap 48 through the cable conductor 42 enters the slit 22, then through the paper 30 into the oil gap 48 of the outer layer, and so on.

Note that some of the oil is absorbed by the paper 30 and the slit 22.
Flows outward while passing sequentially.

Therefore, it is possible to flow in the cable insulation layer 40 in the radial direction.

(2) As shown in FIGS. 3a and 3b, a slit 22 is added to the conventional oil gap 48 in the cable insulation layer 40.

However, the depth A of the slit 22 is smaller than the depth B of the oil gap 48. Therefore, there is almost no problem with the dielectric strength decreasing due to the presence of the slits 22, and this has been confirmed through experiments. Note that the slits 22 provided in the plastic film 20 do not necessarily have to be perpendicular to the longitudinal direction of the film 20, but may be slit diagonally.

[Effect of the invention] Paper 30 is pasted on both sides of the plastic film 20, and the composite insulating paper 10, which has a slit 22 in the width direction of the plastic film 20 with at least one end reaching the end of the film, is wound in a gap to insulate the cable. (1) As described above, a cooling method of flowing oil in the radial direction of the cable insulation layer 40 can be adopted.

(2) The slit 22 absorbs the swelling of the plastic film 20 due to oil.

(3) Cable drying and impregnating time is significantly reduced.

[Brief explanation of the drawing]

Figures 1a to 3b show examples of the present invention; Figures 1a and 1b are explanatory diagrams of different examples of composite insulating paper used; Figure 2 is a partial cross-sectional diagram; Figures 3a and 3b are schematic diagrams showing enlarged portions of Figure 2, Figure 4 is an explanatory diagram of conventional composite insulating paper, and Figure 5 is a cooling method in which oil is flowed in the radial direction of the cable insulation layer. An explanatory diagram. 10...Composite insulating paper, 20...Plastic film, 22...Slit, 30...Paper, 40...
... Cable insulation layer, 42 ... Cable conductor, 44
... Internal oil passage, 46 ... Cable sheath, 48
...Oil gap.

Claims (1)

[Scope of utility model registration request] A composite insulating paper 10 in which paper 30 is pasted on both sides of the plastic film 20 and a slit 22 is provided in the width direction of the plastic film 20 with at least one end reaching the end of the film is gap-wound to form a cable insulating layer 40. An oil-filled power cable featuring: