JPH10233127A - D.c. oil-immersed paper solid cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the number of manufacturing days, and improve an electric insulation characteristic, by specifying the airtightness, density, and paper thickness of an insulating paper, constituting a cable insulating layer; impregnating the insulating paper with a high-viscosity oil, and reducing the artightness and the density, and increasing the paper thickness toward a metallic sheath side from a conductor side. SOLUTION: A carbon paper 12 is wound as an inside shield on the periphery of a conductor 11, and thereon an insulating paper; having a Gurley air tightness 5000s/100cc or less, a density of 0.95-1.2g/cm<3> , and a paper thickness of 50-250μm; is wound to form an insulating paper layer 13. A carbon paper 14 is wound as an outside shield on the insulating paper layer 13, and a metallic sheath 15 and a corrosionproof layer 16 are applied to form a cable. Moreover the insulating paper layer 13 is impregnated with a high-viscosity insulating oil, consequently the high-viscosity oil can be sufficiently penetrated into the fibers of the insulating paper, to improve a counter-voltage characteristic, also the handling at the time of manufacture, thereby shortening the number of manufacturing days.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct current oil-impregnated solid cable, and more particularly to an improved impregnation property of high-viscosity oil.
This is intended to shorten the number of manufacturing days and improve the electrical insulation properties.

[0002]

2. Description of the Related Art Oil immersion paper solid cables have a simple structure, are suitable for long distances, and require no oil supply equipment.
It has many achievements as a DC submarine cable.

[0003] As a general structure of a DC oil-impregnated solid cable, the insulating layer generally has a structure in which a high-density insulating paper is impregnated with a high-viscosity oil having a kinematic viscosity of 2000 cst or more at 40 ° C.

The above-described oil-immersed paper cable insulator is a composite dielectric of insulating paper and insulating oil, and is a laminated insulator of oil-immersed paper.
The properties of oil-immersed paper insulators are greatly affected by the properties of insulating paper and insulating oil.

[0005] Taking oil-immersion paper for an OF cable as an example, the insulating paper of a DC OF cable has a high density paper density (g / c).
m ³ ) 0.95 to 1.0 or more, air tightness 5000 to 100
A 00 Gurley tightness (S / 100 cc) is used.

The insulating paper of an AC OF cable has a density (g / g).
cm ³ ) 0.7 to 0.85, air tightness 1000 to 7000
Gurley tightness (S / 100 cc) is used.

[0007] The airtightness of the insulating paper is expressed in terms of the fineness or fineness of the fiber of the paper, and the unit used is Emanueli airtightness (EU) or Gurley airtightness (S / 100 cc). The relationship between paper properties and density and airtightness is complicated, and there are various opinions on the relationship between airtightness and breakdown voltage. However, it is generally considered that the breakdown voltage increases as the airtightness increases.

Although the relationship between the breakdown voltage and the density is more unclear than the relationship between the air density, the density does not substantially affect the lightning impulse breakdown voltage and the AC breakdown voltage.
It is considered that there is a tendency to slightly decrease at a large area of 9 g / cm ³ or more. This is probably because the higher the density, the higher the dielectric constant and the higher the stress in the oil gap.

The dielectric constant ε and dielectric tangent tan δ of the oil-immersed paper are
Since the density of the insulating paper is closely related to the fact that reduction of the density has a great effect on reduction of the dielectric loss, the density of the AC OF cable is reduced.

On the other hand, a DC OF cable uses a high-density, high-air-tightness insulating paper having a high electric breakdown strength because there is no problem of dielectric loss.

The thinner the insulating paper, the higher the breakdown voltage tends to be. This is presumably because the use of thin paper causes the oil gap to be subdivided, and as the thickness decreases, the fiber arrangement in the papermaking direction and the width direction increases, and the partition wall effect increases.

However, thin paper of less than 70 μm is hardly used because of the great negative influence due to the deterioration of mechanical properties.

[0013]

When the high-density paper of the above-mentioned DC OF cable is used for the purpose of improving the electrical characteristics in the DC oil-immersed paper solid cable, there is a problem that the high-viscosity oil is not impregnated between the fibers of the insulating paper. Occurs.

In view of such circumstances, the present invention provides a novel DC oil-impregnated solid cable capable of reducing the number of days required for manufacturing and observing the characteristics of the oil-impregnated paper and improving the electrical insulation properties. The purpose is to:

[0015]

Accordingly, in order to achieve the above object, the present invention provides a DC oil-immersed paper solid cable, wherein the cable insulating layer has an air density of 5000 Gurley air density (S / 100 cc) or less, and 0.95--density
1.2 g / cm ³ insulating paper whose paper thickness is 50 to 250
It is formed by winding a μm insulating paper and impregnated with high-viscosity oil.

Further, the airtightness of the cable insulating layer decreases from the conductor side to the metal sheath side.

Further, the cable insulating layer has a density decreasing from the conductor side to the metal sheath side.

The cable insulation layer is characterized in that the thickness of the insulation paper increases stepwise from the conductor side to the metal sheath side.

Since the direct current oil immersion paper solid cable having the above configuration has an air density of 5000 Gurley air density S / 100 cc or less, high viscosity oil (5000 cstat at 40 ° C. or higher) can be sufficiently impregnated between the fibers of the insulating paper. Since the high-density paper is used, the breakdown voltage of the DC oil-immersion paper solid cable can be improved.

Further, since the air density, density, and paper thickness of the insulating paper are changed stepwise from the conductor side to the metal sheath side, the dry impregnation characteristics can be more effectively improved, and the number of production days can be reduced. As a result, the electrical insulation characteristics can be effectively improved.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a DC oil-immersion paper solid cable according to the present invention. A carbon paper roll 12 is provided around the conductor 11 as an internal shield, and the air density is Gurley air density 5000 s / 100 cc or less and the density is 0.9.
5 to 1.2 g / cm ³ insulating paper with a paper thickness of 50 to 2
An insulating paper layer 13 is formed by winding an insulating paper of 50 μm, a carbon paper winding 14 is applied thereon as an external shield, and a metal sheath 15 and an anticorrosion layer 16 are applied. The insulating paper layer 13 is impregnated with high-viscosity insulating oil.

Next, FIG. 2 shows another embodiment of the present invention. In the figure, the insulating paper layer 13 is configured as shown in the following table.

[0024]

[Table 1] Other configurations are the same as those in FIG.

Here, the results of an electrical characteristic test of the DC oil-immersion paper solid cable of the embodiment shown in FIG. 2 will be described.

This cable has a conductor size of 2000.
This is a DC ± 500 KV cable having an mm ² and an insulating layer of 21 mm.

(I) Withstand voltage test (Ii) Under heat cycle, Tc = max 60 ° C. Withstand voltage test DC ± 800 KV OK (iii) DC + Imp superimposed Tc = 60 ° C. Withstand voltage test As described above, excellent electrical characteristics have been demonstrated.

[0028]

As described above, in the DC oil-immersed solid cable of the present invention, since the insulating paper has a Gurley air density of 5000 s / 100 cc or less, the high-viscosity oil (5000 cstat 40 ° C. or more) is used for the insulating paper. Since the fibers can be sufficiently impregnated and high-density paper is used, the withstand voltage characteristics are improved.

Further, the airtightness and density of the insulating paper are reduced from the conductor side to the metal sheath side, and the paper thickness is increased stepwise from the conductor side to the metal sheath side. Better handling, more effective improvement in dry impregnation properties, and shorter production days.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a DC oil-immersion paper solid cable of the present invention.

FIG. 2 is a sectional view showing another embodiment of the DC oil-immersion paper solid cable of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Conductor 12,14 Carbon paper 13 Insulating paper layer 15 Metal sheath 16 Corrosion prevention layer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ikuo Shigeto 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Takenori Nakajima 1-5-1, Kiba, Koto-ku, Tokyo In Fujikura

Claims (4)

[Claims] The cable insulating layer is an insulating paper having an air density of 5000 Gurley air density (S / 100 cc) or less and a density of 0.95 to 1.2 g / cm ³ , and a paper thickness of 5 g / cm ^3.
A DC oil-impregnated solid cable, which is formed by winding insulating paper of 0 to 250 μm and impregnated with high-viscosity oil. 2. The direct current oil immersion paper solid cable according to claim 1, wherein the cable insulating layer has a low insulating paper density from the conductor side to the metal sheath side. 3. The DC oil-impregnated solid cable according to claim 1, wherein the density of the insulating paper in the cable insulating layer decreases from the conductor side to the metal sheath side. 4. The DC oil-impregnated solid cable according to claim 1, wherein the thickness of the cable insulating layer increases stepwise from the conductor side to the metal sheath side.