JPS58204406A - Insulating paper and oil immersed paper power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an insulating paper with excellent electrical insulation properties, and an insulating paper using the insulating paper that can be used in electrical cables. Insulating paper for power cables has been continuously improved in response to the trend toward ultra-high pressure, but the required characteristics include a reduction in C0-δ, a significant increase in impulse withstand voltage, and maintenance of low oil flow resistance. A new goal is given.

For this reason, a number of improvement proposals have been proposed, and although mixed insulating paper, which is made by mixing kraft pulp with glass fiber, has shown some success as a solution, it is still insufficient. The inventor examined the reason for this and found that in conventional mixed paper, the shape of the glass fibers mixed with kraft pulp was
Straight or crimp-shaped fibers with a circular cross section, a diameter of 15 to 25 μm, and a length of 2 to 5+w were used.

Mixed paper made by mixing such plastic fibers into kraft pulp has a small strong electric current in the wet paper state, and it is difficult to form a continuous paper web during the paper making process. It was extremely difficult to do so. Furthermore, when such laminated paper is thermally bonded singly or in multiple layers, although the mechanical strength increases, the airtightness increases more than necessary7, and the oil flow resistance increases significantly compared to kraft paper. This shortcoming was noticeable.

The present invention was made to improve these drawbacks, so flat N! By using a male material, the entanglement with the kraft fibers is strengthened, and by making the cut length short, the paper quality is improved, maintaining good mechanical strength and electrical strength, and reducing oil flow resistance. It can be kept low, and in terms of 4I characteristics, it is possible to achieve 41 points and 41 points.

To explain the present invention in more detail, as a plastic fiber, the thickness is 15 μm or less, the width is 150 μm or less, and the length is 4000 μm.
Since fine flat fibers with a diameter of 10 μm or less are used, paper quality is formed by good intertwining with kraft fibers having similar shapes and dimensions, and more preferably a thickness of 10 μm.
Hereinafter, by using a fiber having a length of -50 μm or less and a length L500 Im or less, it is possible to further promote the entanglement of both fibers and achieve better electrical uniformity.

On the other hand, plastic fibers with a circular cross section, which have been tried in the past, have poor dispersibility in kraft pulp, tend to become entangled with kraft fibers, and have a slightly worse heat transfer effect than flat fibers. Thermal bonding of plastic fibers and kraft pulp requires higher pressure and greater amount of heat, and tends to produce a large number of continuous film layers in multiple stages in the thickness direction of the paper web, resulting in high air density. However, the disadvantage is that the fluid resistance through the paper increases significantly.

The plastic fiber material used in the present invention is polypropylene, which is a polymeric material with a melting point of 150°C or higher, and has a small ε and -δ and a relatively high impulse rupture strength.
Polymethylpentene, polyester, polyester/ether copolymer, polycarbonate, ethylene/tetrafluoroethylene copolymer, tetrafluoroethylene/hexafluoropropylene copolymer, etc. are used.

In the present invention, by using the above-mentioned polymeric material with a melting point of 150°C or higher as the plastic fiber material of mixed paper, it is possible to reduce lead work and short-time overtime when connecting cables when made into oil-immersed electrical cables. Insulating paper that withstands temperature changes caused by electric current and is wound in multiple layers on a conductor and then mixed with flat cylindrical fibers in the kraft pulp of the present invention, and forged paper with ordinary circular cross-section plastic fibers mixed in kraft pulp. The results of a comparative test are shown in Table 1.

Next, by using the configuration shown in Examples 1 and 2 above, a 125μ
m, tsoμm and 200μm mixed paper insulating paper is manufactured,
An OF cable was manufactured using this.

As shown in the figure, the inside of the conductor 1 is an oil passage, and the inside of the conductor 1 is covered with carbon paper, kinpokagi, etc.
13, an oil-immersed insulation 1-4 made of the above-mentioned mixed insulating paper is provided on the outside, and an external shield 1115 made of gold-finished insulating paper or the like is provided.
and aluminum sheath 6, outer cover layer 7
This is an 11th order.

Next, using the insulating paper of the above example and comparative example, 275K
Table 2 shows the results of manufacturing an OF cable of V and λ500- and measuring the dielectric properties and bypass flow resistance of the cable according to the present invention.

Table 2 (Note) PP: Polypropylene TPX: Polymethylpentene As is clear from the results shown above, the characteristics of the insulating paper mixed with the flat plastic fibers of the present invention and the electrical cable using the same are the same as those of the comparative example. It will be understood that there is a remarkable improvement in properties compared to paper mixed with plastic fibers having a circular cross section and electric cables using the same.

The greatest effect of the present invention, F'i, is the good load characteristics and breakdown characteristics, as well as the bypass flow resistance compared to ordinary kraft paper insulation O.
Since it can be held as easily as the F cable, it is possible to increase the power transmission capacity by cooling the inside of the cable.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a cross-sectional view showing an example of an oil-impregnated paper type capsule according to the present invention. 1 Conductor 2 Oil passage 3 Half-double layer 4 Oil-immersed insulating paper 5 External shielding layer 6 Metal base 7 Gallery cover 1 Method) July 4, 1980 % eaves Kazuo Wakasugi book 1 display 1988 % ni 10m No. 18807 2 name of invention i 15 trout M) ni hirlh acid paper bill Kacouf A. 3 Car 11
Relationship with Nagisa Santo 1, which is located in Nagisa Santo 1, %to Applicant address: 5% No. 1, Kiba-chome, Koto-ku, Tokyo (5
18) 11 A' Kinsen Co., Ltd. Representative Kagaya -- 4th Manager 〒101 6. Subject of amendment #dI Title of the invention 7. Contents of the name of the letter J VL Subtitled.

Claims (1)

[Claims] (1) Insulating paper characterized by being made by mixing kraft pulp and flat plastic am (2) A patent claim in which the flat plastic fibers are made of an island molecular material having one point of 150°C or higher (3) An oil-impregnated paper electrical cable characterized by being wrapped around a full conductor made of paper made from a mixture of kraft pulp and flat plastic fibers.